TY - CONF A1 - Kempf, A. T1 - Correlation between quasistatic und fatigue properties of additively manufactured AlSi10Mg using Laser Powder Bed Fusion N2 - In order to find a resource efficient approach for the fatigue lifetime prediction of laser powder bed fusion (L-PBF) processed AlSi10Mg material, results of tensile and fatigue tests were compared. The specimens were manufactured with three different L-PBF machines and studied in different heat treatment conditions (as-built, annealed, T6 heat treated). The investigations showed that the high attainable tensile strength properties after the manufacturing process are not beneficial in the high cycle fatigue (HCF) regime. In contrast, the applied heat treatments, which lead typically to a decrease of ultimate tensile strength, improved dramatically the fatigue behavior. Additionally, a clear correlation between the elongation at fracture and HCF resistance has been found for individual heat treatment conditions. This empiric relationship provides an estimation of the fatigue resistance in the presence of material defects and can be implemented in part and process approvals. T2 - Fatigue Design 2021 CY - Online meeting DA - 17.11.2021 KW - Additive Manufacturing KW - Laser powder bed fusion KW - AlSi10Mg KW - Tensile properties KW - Fatigue properties PY - 2021 AN - OPUS4-53792 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ponader, Marco A1 - Röder, Bettina A1 - Paul, Martin A1 - Weller, Michael G. T1 - Sintered glass monoliths as supports for affinity columns N2 - A novel stationary phase for affinity separations is presented. This material is based on sintered borosilicate glass readily available as semi-finished filter plates with defined porosity and surface area. The material shows fast binding kinetics and excellent long-term stability under real application conditions due to lacking macropores and high mechanical rigidity. The glass surface can be easily modified with standard organosilane chemistry to immobilize selective binders or other molecules used for biointeraction. In this paper, the manufacturing of the columns and their respective column holders by 3D printing is shown in detail. The model system protein A/IgG was chosen as an example to examine the properties of such monolithic columns under realistic application conditions. Several specifications, such as (dynamic) IgG capacity, pressure stability, long-term performance, productivity, non-specific binding, and peak shape, are presented. It could be shown that due to the very high separation speed, 250 mg antibody per hour and column can be collected, which surpasses the productivity of most standard columns of the same size. The total IgG capacity of the shown columns is around 4 mg (5.5 mg/mL), which is sufficient for most tasks in research laboratories. The cycle time of an IgG separation can be less than 1 min. Due to the glass material’s excellent pressure resistance, these columns are compatible with standard HPLC systems. This is usually not the case with standard affinity columns, limited to manual use or application in low-pressure systems. The use of a standard HPLC system also improves the ability for automation, which enables the purification of hundreds of cell supernatants in one day. The sharp peak shape of the elution leads to an enrichment effect, which might increase the concentration of IgG by a factor of 3. The final concentration of IgG can be around 7.5 mg/mL without the need for an additional nano-filtration step. The purity of the IgG was > 95% in one step and nearly 99% with a second polishing run. KW - Affinity Chromatography KW - Affinity Extraction KW - Affinity Separation KW - Protein Purification KW - Down Stream Processing KW - Antibody Purification KW - Diagnostic Antibodies KW - Therapeutic Antibodies KW - Automated Purification KW - HPLC KW - FPLC KW - IgG determination KW - Concentration step KW - Monoclonal Antibodies KW - Polyclonal Antibodies KW - Human Plasma KW - Glass Support KW - Borosilicate Glass KW - Monolith KW - Sintered Material KW - Additive Manufacturing KW - Column holder KW - Construction KW - Open Science KW - Citizen Science KW - Protein A KW - Regeneration KW - High-Speed Separations KW - Robustness PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-527581 DO - https://doi.org/10.3390/separations8050056 SN - 2297-8739 N1 - Geburtsname von Ponader, Marco: Wilke, M. - Birth name of Ponader, Marco: Wilke, M. VL - 8 IS - 5 SP - 1 EP - 16 PB - MDPI CY - Basel AN - OPUS4-52758 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Agea Blanco, Boris A1 - Walzel, S. A1 - Chi, J. A1 - Lüchtenborg, J. T1 - Making Binder Jetting Really Work for Technical Ceramics - Additive Manufacturing of Technical Ceramics N2 - As an alternative shaping method to the traditionally used processes, additive manufacturing (AM) can produce economical ceramic components in small lot sizes and/or with complex geometries. Powder-based additive manufacturing processes like binder jetting are popular in the field of metal AM. One reason is the increased productivity compared to other AM technologies. For ceramic materials, powder-based AM technologies result in porous ceramic parts, provided they are not infiltrated. CerAMing GmbH unites the advantages of powder-based processes with the production of dense ceramic by means of the Layerwise Slurry Deposition. By using a suspension, a high packing density of the powder bed is achieved which leads to high green body densities. Due to this advantage the approach overcomes the problems of other powder-based AM technologies. Furthermore, a very economical debinding time allows the production of parts with high wall thicknesses. KW - Additive Manufacturing KW - Binder Jetting KW - Layerwise Slurry Deposition KW - Lithography-based technologies KW - Technical Ceramics PY - 2021 SP - 49 EP - 52 PB - Göller Verlag CY - Baden-Baden AN - OPUS4-52948 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Werner, Tiago T1 - Comparison of the fatigue behavior of wrought and additively manufactured AISI 316L N2 - Additively Manufactured (AM) parts are still far from being used in safety-relevant applications, mainly due to a lack of understanding of the feedstock-process-propertiesperformance relationship. This work aims at providing a characterization of the fatigue behavior of the additively manufactured AISI 316L austenitic stainless steel and a direct comparison with the fatigue performance of the wrought steel. A set of specimens has been produced by laser powder bed fusion (L-PBF) and a second set of specimens has been machined out of hot-rolled plates. The L-PBF material shows a higher fatigue limit and better finite life performance compared to the wrought material, accompanied by an extensive amount of cyclic softening. T2 - Fatigue Design 2021 CY - Online meeting DA - 17.11.2021 KW - Additive Manufacturing KW - AM KW - 316L KW - Fatigue KW - High Cycle Fatigue KW - Low Cycle Fatigue PY - 2021 AN - OPUS4-53780 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kempf, Andreas A1 - Kruse, Julius A1 - Madia, Mauro A1 - Hilgenberg, Kai T1 - Correlation between quasistatic und fatigue properties of additively manufactured AlSi10Mg using Laser Powder Bed Fusion N2 - In order to find a resource efficient approach for the fatigue lifetime prediction of laser powder bed fusion (L-PBF) processed AlSi10Mg material, results of tensile and fatigue tests were compared. The specimens were manufactured with three different L-PBF machines and studied in different heat treatment conditions (as-built, annealed, T6 heat treated). The investigations showed that the high attainable tensile strength properties after the manufacturing process are not beneficial in the high cycle fatigue (HCF) regime. In contrast, the applied heat treatments, which lead typically to a decrease of ultimate tensile strength, improved dramatically the fatigue behavior. Additionally, a clear correlation between the elongation at fracture and HCF resistance has been found for individual heat treatment conditions. This empiric relationship provides an estimation of the fatigue resistance in the presence of material defects and can be implemented in part and process approvals. T2 - FATIGUE DESIGN 2021 CY - Online meeting DA - 17.11.2021 KW - Additive Manufacturing KW - Laser powder bed fusion KW - AlSi10Mg KW - Tensile properties KW - Fatigue properties PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-544921 DO - https://doi.org/10.1016/j.prostr.2022.03.009 SN - 2452-3216 VL - 38 SP - 77 EP - 83 PB - Elsevier B.V. AN - OPUS4-54492 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bettge, Dirk T1 - MGA Round Robin Test on Al-AM Fatigue Testing - Fractographic Results N2 - Presentation of results of an investigation of fracture mechanisms and crack start sites of an additive manufactured aluminium alloy after fatigue testing. Collaboration within the MGA initiative (Mobility Goes Additive). T2 - MGA Mid Term Meeting 2022 CY - Berlin, Germany DA - 05.07.2022 KW - Aluminium Alloy KW - Fractography KW - Additive Manufacturing PY - 2022 AN - OPUS4-55192 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Scheuschner, Nils T1 - In-situ Prozessüberwachung in der additiven Fertigung von Metallen (PBF-LB /M) mittels TT und ET N2 - Durch die additive Fertigung ergeben sich durch die nun mögliche wirtschaftliche Fertigung hochgradig individueller und komplexer metallischer Bauteile in kleinen Stückzahlen bis hinunter zum Einzelstück für viele Industriebereiche ganz neue Möglichkeiten. Gleichzeitig entstehen jedoch neue Herausforderungen im Bereich der Qualitätssicherung, da sich auf statistischen Methoden beruhende Ansätze nicht anwenden lassen, ohne wiederum die Vorteile der Fertigung massiv einzuschränken. Eine mögliche Lösung für dieses Problem liegt in der Anwendung verschiedener In-situ-Überwachungstechniken während des Bauprozesses. Jedoch sind nur wenige dieser Techniken kommerziell verfügbar und noch nicht so weit erforscht, dass die Einhaltung strenger Qualitäts- und Sicherheitsstandards gewährleistet werden kann. In diesem Beitrag stellen wir die Ergebnisse einer Studie über mittels L-PBF gefertigte Probekörper aus der Nickelbasis-Superlegierung Haynes 282 vor, bei denen die Bildung von Defekten durch lokale Variationen der Prozessparameter wie der Laserleistung provoziert wurde. Die Proben wurden in-situ mittels Thermographie, optischer Tomographie, Schmelzbadüberwachung und Wirbelstromprüfung sowie ex-situ mittels Computertomographie (CT) überwacht, mit dem Ziel, die Machbarkeit und die Aussichten der einzelnen Methoden für die zuverlässige Erkennung der Bildung relevanter Defekte zu bewerten. T2 - DGZfP Jahrestagung 2022 CY - Kassel, Germany DA - 23.05.2022 KW - Additive Manufacturing KW - Thermografie KW - Additive Fertigung KW - Thermography PY - 2022 AN - OPUS4-55851 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Scheuschner, Nils T1 - In-situ Monitoring of PBF-LB/M by thermography, optical tomography, melt-pool-monitoring and eddy current N2 - The formation of defects such as keyhole pores is a major challenge for the production of metal parts by Laser Powder Bed Fusion (LPBF). The LPBF process is characterized by a large number of influencing factors which can be hard to quantify. Machine Learning (ML) is a prominent tool to predict the outcome of complex processes on the basis of different sensor data. In this study, a ML model for defect prediction is created using thermographic image features as input data. As a reference, the porosity information calculated from an x-ray Micro Computed Tomography (µCT) scan of the produced specimen is used. Physical knowledge about the keyhole pore formation is incorporated into the model to increase the prediction accuracy. From the prediction result, the quality of the input data is evaluated and future demands on in-situ monitoring of LPBF processes are formulated. T2 - AM Bench 2022 CY - Bethesda, Washingthon DC, USA DA - 15.08.2022 KW - Additive Manufacturing KW - Thermography KW - Additive Fertigung KW - Thermografie PY - 2022 AN - OPUS4-55854 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Scheuschner, Nils T1 - In-situ monitoring of the laser powder bed fusion process by thermography, optical tomography and melt pool monitoring for defect detection N2 - For the wide acceptance of the use of additive manufacturing (AM), it is required to provide reliable testing methods to ensure the safety of the additively manufactured parts. A possible solution could be the deployment of in-situ monitoring during the build process. However, for laser powder bed fusion using metal powders (PBF-LB/M ) only a few in-situ monitoring techniques are commercially available (optical tomography, melt pool monitoring) but not researched to an extent that allows to guarantee the adherence to strict quality and safety standards. In this contribution, we present results of a study of PBF-LB/M printed parts made of the nickel-based superalloy Haynes 282. The formation of defects was provoked by local variations of the process parameters and monitored by thermography, optical tomography and melt pool monitoring. Afterwards, the defects were characterized by computed tomography (CT) to identify the detection limits of the used in-situ techniques. T2 - LiM Conference 2023 - Lasers in Manufacturing CY - Munich, Germany DA - 26.06.2023 KW - Thermography KW - High temperature alloys KW - Additive Manufacturing KW - PBF-LB/M PY - 2023 AN - OPUS4-57947 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Schumacher, David A1 - Waske, Anja T1 - XCT data of metallic feedstock powder with pore size analysis N2 - X-Ray computed tomography (XCT) scan of 11 individual metallic powder particles, made of (Mn,Fe)2(P,Si) alloy. The data set consists of 4 single XCT scans which have been stitched together [3] after reconstruction. The powder material is an (Mn,Fe)2(P,Si) alloy with an average density of 6.4 g/cm³. The particle size range is about 100 - 150 µm with equivalent pore diameters up to 75 µm. The powder and the metallic alloy are described in detail in [1, 2]. KW - Additive Manufacturing KW - Feedstock powder KW - Powder Characterization KW - X-Ray Computed Tomography PY - 2022 DO - https://doi.org/10.5281/zenodo.5796487 PB - Zenodo CY - Geneva AN - OPUS4-55556 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Drendel, Jan A1 - Logvinov, Ruslan A1 - Heinrichsdorff, Frank A1 - Hilgenberg, Kai T1 - Simulation-based controlling of local surface temperature in laser powder bed fusion using the process laser N2 - State-of-the-art laser powder bed fusion (PBF-LB/M) machines allow pre-heating of the substrate plate to reduce stress and improve part quality. However, two major issues have been shown in the past: First, with increasing build height the apparent pre-heat temperature at the surface can deviate drastically from the nominal pre-heat temperature in the substrate plate. Second, even within a single layer the local surface pre-heat temperature can show large gradients due to thermal bottlenecks in the part geometry underneath the top surface. Both lead to unwanted changes in microstructure or defects in the final parts. In this study, a first attempt is taken to show the feasibility of pre-heating the top surface with the onboard laser beam to overcome the mentioned issues. A single layer of a group of three parts built from IN718 to a height of 33.5 mm is pre-heated in a commercially available PBF-LB/M machine to an average steady state surface temperature of 200 °C using the onboard laser beam. The parts are continuously heated, omitting powder deposition and melting step. Temperatures are measured by thermocouples underneath the surface. The experiments are supported by a thermal finite element (FE) model that predicts the temperature field in the parts. When heating the parts uniformly with the laser beam, differences in surface temperatures as large as 170 K are observed. To overcome this inhomogeneity, the heat flux supplied by the laser beam is modulated. An optimized, spatial heat flow distribution is provided by the thermal FE model and translated into a scan pattern that reproduces the optimized heat distribution on the PBF-LB/M machine by locally modulating hatch distance and scan velocity. This successfully reduces the differences in surface temperature to 20 K. Thermographic imaging shows that a homogeneous surface temperature can be achieved despite the localized heat input by the beam. The potential for industrial application of the optimized laser-heating technique is discussed. KW - Additive Manufacturing KW - Simulation KW - Surface temperature KW - Laser powder bed fusion PY - 2023 DO - https://doi.org/10.1016/j.addma.2023.103854 SN - 2214-8604 VL - 78 SP - 1 EP - 16 PB - Elsevier B.V. AN - OPUS4-58825 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Epperlein, Martin A1 - Hilgenberg, Kai A1 - Hellfritz, Benjamin A1 - Löffler, Frank T1 - Digitisation of the quality infrastructure - using the example of additive manufacturing N2 - Rapidly advancing technologies and progressive digitisation are posing challenges to the established quality infrastructure (QI). In response, the key stakeholders of the German QI established the initiative QI-Digital aimed at developing new solutions for modern quality assurance. One of the central use cases herein is quality assurance for additive manufacturing, in which a fully interlinked additive manufacturing process chain is established. The intention is to collect and process data from each production step, allowing for a comprehensive digital view of the physical material flow. Within this process chain, prototypes of digital QI tools like machine readable standards and digital quality certificates are being demonstrated, tested, and evolved. This is complemented by research on the process level, comprising the evaluation and refinement of methods for in-situ and ex-situ quality assurance, as well as algorithms for registration, reduction, and analysis of process data. This paper presents the status, goals, and vision for the QI-Digital use case additive manufacturing. T2 - Metal Additive Manufacturing Conference 2023 CY - Wien, Austria DA - 17.10.2023 KW - Additive Manufacturing KW - Digitalisation KW - Quality Assurance PY - 2023 SP - 96 EP - 104 CY - Wien AN - OPUS4-58628 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Epperlein, Martin T1 - Digitisation of the quality infrastructure - Using the example of additive manufacturing N2 - Rapidly advancing technologies and progressive digitisation are posing challenges to the established quality infrastructure (QI). In response, the key stakeholders of the German QI established the initiative QI-Digital aimed at developing new solutions for modern quality assurance. One of the central use cases herein is quality assurance for additive manufacturing, in which a fully interlinked additive manufacturing process chain is established. The intention is to collect and process data from each production step, allowing for a comprehensive digital view of the physical material flow. Within this process chain, prototypes of digital QI tools like machine readable standards and digital quality certificates are being demonstrated, tested, and evolved. This is complemented by research on the process level, comprising the evaluation and refinement of methods for in-situ and ex-situ quality assurance, as well as algorithms for registration, reduction, and analysis of process data. This paper presents the status, goals, and vision for the QI-Digital use case additive manufacturing. T2 - Metal Additive Manufacturing Conference 2023 CY - Vienna, Austria DA - 17.10.2023 KW - Additive Manufacturing KW - Digitalisation KW - Quality Assurance PY - 2023 AN - OPUS4-58629 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Epperlein, Martin T1 - Eine digitale QI für die moderne Produktion: Datenbasierte Qualitätssicherung in der Additiven Fertigung N2 - Als Beispiel für moderne Produktion ist die additive Fertigung (ugs. „3D-Druck“) bei der Herstellung von hochkomplexen metallischen Bauteilen, bionisch inspiriertem Leichtbau oder Prototypen nicht mehr wegzudenken. Die Qualitätssicherung (QS) von Bauteilen für sicherheitskritische Anwendungen stellt jedoch noch eine Herausforderung dar. Die Additive Fertigung (AM) ist ein vergleichsweise junges und datenintensives Fertigungsverfahren. Daher ist es ideal geeignet, die neuen Werkzeuge einer digitalen Qualitätsinfrastruktur (QI) für die moderne Produktion zu erproben und weiterzuentwickeln. T2 - 2. QI-Digital Forum CY - Berlin, Germany DA - 10.10.2023 KW - Additive Manufacturing KW - Digitalisation KW - Quality Assurance PY - 2023 AN - OPUS4-58630 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Scheuschner, Nils A1 - Heinrichsdorff, F. A1 - Oster, Simon A1 - Uhlmann, E. A1 - Polte, J. A1 - Gordei, A. A1 - Hilgenberg, Kai T1 - In-situ monitoring of the laser powder bed fusion process by thermography, optical tomography and melt pool monitoring for defect detection N2 - For the wide acceptance of the use of additive manufacturing (AM), it is required to provide reliable testing methods to ensure the safety of the additively manufactured parts. A possible solution could be the deployment of in-situ monitoring during the build process. However, for laser powder bed fusion using metal powders (PBF-LB/M) only a few in-situ monitoring techniques are commercially available (optical tomography, melt pool monitoring), which have not been researched to an extent that allows to guarantee the adherence to strict quality and safety standards. In this contribution, we present results of a study of PBF-LB/M printed parts made of the nickel-based superalloy Haynes 282. The formation of defects was provoked by local variations of the process parameters and monitored by thermography, optical tomography and melt pool monitoring. Afterwards, the defects were characterized by computed tomography (CT) to identify the detection limits of the used in-situ techniques. T2 - Lasers in Manufacturing Conference 2023 CY - Munich, Germany DA - 26.06.2023 KW - Thermography KW - Optical tomography KW - Melt-pool-monitoring KW - Laser powder bed fusion KW - Haynes 282 KW - Additive Manufacturing PY - 2023 UR - https://www.wlt.de/lim2023-proceedings/system-engineering-and-process-control SP - 1 EP - 10 AN - OPUS4-58466 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Tabin, Jakub T1 - Deformation-Induced Martensitic Transformation In Fused Filament Fabricated Austenitic Stainless Steels During Tension At Wide Range Of Temperatures. Part 1: Experimental Results N2 - Structural components of superconducting magnets (e.g., collars, bladders, or keys) with complex shapes, operating at cryogenic temperatures (4K, 77K), as well as additional elements of tanks for storing liquid hydrogen (20K), such as hoses and valves, are made of austenitic steel. It is well known that achieving a complex shape for these elements using traditional machining methods is challenging. A viable solution lies in using additive manufacturing methods (AM), notably the cost-effective Fused Filament Fabrication (FFF) method. The scientific objective of the project is the experimental identification and numerical simulation of the evolution of the deformation-induced martensitic transformation in Fused Filament Fabricated Austenitic Stainless Steel (FFF ASS) 316L at a wide range of temperatures. We will investigate how deformation-induced phase transformation develops in printed austenitic steels, how the initial state of the sample (e.g., pore distribution) affects it, and whether deformation-induced martensitic transformation influences the rate of damage development, especially at very low temperatures. Does the manufacturing technology of the sample affect the rate of phase transformation or damage development? Finally, but no less important, is whether, as in the case of traditional austenitic steels, the adverse effect of the microdamage field is inhibited by deformation-induced martensitic transformation. Which of these effects dominates in printed austenitic steels and under what conditions? The experimental setup developed in the Institute of Fundamental Technological Research (IPPT PAN) allows for monitoring the evolution of the 3D strain field during the kinematically-controlled tensile tests of macroscopic specimens at 77K. Moreover, the correlation between plastic strain field evolution, martensitic transformation, thermal distributions and acoustic emission will be defined for FFF 316L at 77K and room temperatures. EBSD and EDS investigation of samples pre-strained in uniaxial tensile tests at a wide range of temperatures are also performed. T2 - 43rd Solid Mechanics Conference CY - Wroclaw, Poland DA - 16.09.2024 KW - Deformation-induced martensitic transformation KW - Austenitic Stainless Steel KW - Additive Manufacturing KW - DIC KW - Cryogenic temperatures PY - 2024 AN - OPUS4-61187 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Werner, Tiago T1 - Short fatigue crack propagation in L-PBF 316L stainless steel N2 - Fracture mechanics is a key to fatigue assessment in AM metal components. Short fatigue cracks are initiated at defects and pronounced surface roughness intrinsic to AM. The subsequent crack-propagation is strongly influenced by microstructural interactions and the build-up of crack-closure. The aim of the present study is to give an insight into short-crack propagation in AM-metals. Fatigue crack propagation resistance curves were determined experimentally for AISI 316L manufactured by Laser Powder Bed Fusion (L-PBF) which was heat treated at three different temperatures. Differences in the build-up of the fatigue-crack propagation threshold in between the L-PBF specimens and compared to wrought material are due to the residual stress states, a pronounced roughness of the crack-faces in the L-PBF specimens and phase transformation in the vicinity of the crack-tip, resulting in increased crack-closure. This, together with crack-branching found along the crack path, enhances the resistance to the propagation of fatigue cracks. T2 - ASTM International Conference on Additive Manufacturing 2020 CY - Online meeting DA - 16.11.2020 KW - Additive Manufacturing KW - Cyclic R-Curve KW - Component assessment KW - L-PBF KW - 316L KW - Residual Stress KW - Fatigue Crack Growth PY - 2020 AN - OPUS4-51585 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Werner, Tiago T1 - Damage tolerant design of metallic AM parts N2 - Additive Manufacturing (AM) opens new possibilities in the design of metallic components, including very complex geometries (e.g. structures optimized for certain loads), optimization of materials (e.g. gradient materials) and cost-effective manufacturing of spare parts. In the recent years, it has been used for the first safety-relevant parts, but the consideration of cyclic mechanical behavior in AM is still at the very beginning. The reason for this is the complexity of mechanical material properties, i.e. inhomogeneity, anisotropy and a large number of defects frequently textured and characterized by large scattering in size. Additionally, high surface roughness and residual stresses with complex distributions are typical of AM. Due to these reasons, the transferability of experimentally determined properties from specimens to components is a challenge. This presentation provides an overview of the questions concerning the application of AM to safety-relevant components. Possible strategies for the fatigue design of such components are presented. Besides the Kitagawa-Takahashi-diagram method and the cyclic R-curve analysis as approaches for damage-tolerant design, the identification of critical locations, the problem of representative material properties and the handling of residual stresses are addressed. T2 - 4th international symposium on Fatigue Design and Material Defects CY - Online meeting DA - 26.05.2020 KW - Additive Manufacturing KW - Cyclic R-Curve KW - Component assessment PY - 2020 AN - OPUS4-50938 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dávila, Josué A1 - Mohr, Gunther A1 - Hilgenberg, Kai T1 - Parameter development for Laser Powder Bed Fusion of nickel-based Haynes 282 using diverse density determination methods N2 - To manufacture functional components using laser powder bed fusion (PBF-LB/M), the execution of a parameter development with the specific material and machine is an indispensable step. Typically, in the search for the optimal parameter set, the volumetric energy density (VED) used to melt the material serves as an adjustment variable, while the resulting part density as the target parameter. Although this approach effectively reduces the process parameters search-space, additional criteria concerning part quality should be considered in the development. This paper introduces a systematic parameter selection approach, refining the characterization process for processing the nickel-based superalloy Haynes® 282®. The presented strategy not only incorporates the density as target condition but also considers the surface quality and dimensional accuracy of the manufactured samples, crucial for near-net-shape manufacturing. Additionally, three porosity measurement methods (Archimedes method, microscopy, gaspycnometry) for AM metal parts are compared, and their validity for this purpose is discussed. T2 - 13th CIRP Conference on Photonic Technologies [LANE 2024] CY - Fürth, Germany DA - 15.09.2024 KW - Additive Manufacturing KW - Laser powder bed fusion (PBF-LB/M) KW - Archimedes principle KW - Parameter development KW - Gaspycnometry KW - Density determination method KW - Density optimization PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-624417 VL - 124 SP - 93 EP - 97 PB - Elsevier CY - Amsterdam [u.a.] AN - OPUS4-62441 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pittner, Andreas A1 - Winterkorn, René T1 - Wire arc additive manufacturing of high strength al-mg-si alloys N2 - Direct energy deposition additive manufacturing technologies utilizing an electric arc offer a great potential in generating large volume metal components. However, the selection of process parameters that yield the desired near net shape design as well as the requested mechanical component behavior is not a trivial task due to the complex relationship. Exemplarily for additive manufacturing of high-strength precipitation hardening AlMgSi-aluminum alloy this paper shows the application of a newly developed matching solid welding wire doped with TiB as grain refiner. The correlation between process parameters and component quality is examined analyzing the size and distribution of pores as well as the grain morphology. Furthermore, the influences of different post-weld heat treatments are evaluated to meet the reference mechanical properties of the corresponding wrought material. Finally, the digital integration of the entire additive manufacturing chain enables an overall traceability of the relevant process steps which is the basis for a reliable subsequent quality assessment. T2 - THERMEC'2023 International Conference on PROCESSING & MANUFACTURING OF ADVANCED MATERIALS: Processing, Fabrication, Properties, Applications CY - Vienna, Austria DA - 02.07.2023 KW - Additive Manufacturing KW - DED-Arc KW - Grain refinement KW - High strength AlMgSi aluminium alloys KW - Mechanical properties PY - 2023 AN - OPUS4-59500 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - El-Sari, B. A1 - Biegler, M. A1 - Graf, B. A1 - Rethmeier, Michael T1 - Distortion-based validation of the heat treatment simulation of Directed Energy Deposition additive manufactured parts N2 - Directed energy deposition additive manufactured parts have steep stress gradients and an anisotropic microstructure caused by the rapid thermo-cycles and the layer-upon-layer manufacturing, hence heat treatment can be used to reduce the residual stresses and to restore the microstructure. The numerical simulation is a suitable tool to determine the parameters of the heat treatment process and to reduce the necessary application efforts. The heat treatment simulation calculates the distortion and residual stresses during the process. Validation experiments are necessary to verify the simulation results. This paper presents a 3D coupled thermo-mechanical model of the heat treatment of additive components. A distortion-based validation is conducted to verify the simulation results, using a C-ring shaped specimen geometry. Therefore, the C-ring samples were 3D scanned using a structured light 3D scanner to compare the distortion of the samples with different post-processing histories. KW - Directed Energy Deposition KW - Additive Manufacturing KW - Heat Treatment KW - Numerical Simulation KW - Finite Element Method PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-513153 DO - https://doi.org/10.1016/j.procir.2020.09.146 VL - 94 SP - 362 EP - 366 PB - Elsevier B.V. AN - OPUS4-51315 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Blasón Gonzalez, Sergio A1 - Chaudry, Mohsin Ali A1 - Elorriaga, A. A1 - Madia, Mauro A1 - Llavori, I. A1 - Hilgenberg, Kai T1 - Diseño de componentes fabricados aditivamente basado en propiedades locales del material T1 - Design of additively manufactured components based on locally representative material fatigue properties N2 - La tecnología de fabricación aditiva (AM) continúan progresando y permitiendo alcanzar diseños cada vez más complejos y optimizados. La industria química es uno de los sectores donde componentes AM han adquirido un gran interés. La falta hasta la fecha de una directiva europea que regule la inspección, certificación y aceptación de equipos sometidos a presión hace necesario progresar en esta línea. El objetivo que se persigue en este trabajo es el de desarrollar una metodología de diseño sobre componentes fabricados aditivamente basada en la estimación de vida a fatiga de las zonas más susceptibles de sufrir dicho tipo de fallo. El estudio comprende diversas facetas de análisis, simulaciones numéricas, análisis de la microestructura del material y una extensa campaña experimental. La evaluación de la integridad estructural se realiza aplicando mecánica de fractura. La historia térmica a lo largo del proceso de fabricación determina la microestructura del componente en cada región y, por ende, influye en las propiedades mecánicas en cada una. Se presentan los resultados preliminares de un proyecto de investigación en curso dirigido a la caracterización de propiedades mecánicas en recipientes de presión producidos por fusión láser en lecho de polvo (L-PBF, por sus siglas en inglés) de acero inoxidable 316L. Se detallan los resultados preliminares en términos de velocidad de crecimiento de grietas por fatiga (FCGR), y se comparan los resultados de probetas extraídas de diferentes regiones de los depósitos. N2 - Additive manufacturing (AM) technology continues to make progress and allows for reaching increasingly complex and optimised designs. The chemical industry is one of the sectors where AM components have acquired relevance. There is a lack of any European directive in order to regulate the inspection, certification as well as acceptance of additively manufactured (AM) equipment subjected to pressure loads, so progression in this line becomes necessary. This work aimed to develop a design methodology for AM components based on the estimation of fatigue lifetime on those regions with a higher risk of failure. Diverse facets are involved in this study, including numerical simulations, microstructure analysis and an extensive experimental campaign. The fatigue assessment is performed based on fracture mechanics. The microstructure characteristics are dependent on the thermal history along the manufacturing process for each region and, accordingly, the mechanical properties are likewise influenced. Preliminary results of an ongoing research project for characterizing the mechanical properties in demonstrator pressure vessels produced by laser powder bed fusion (L-PBF) on stainless steel 316L are presented. The preliminary findings obtained in terms of fatigue crack growth rate (FCGR) and are detailed. Results from specimens extracted from different regions of the vessel are compared. T2 - 5th Iberian Conference on Structural Integrity IbCSI 2022 CY - Coimbra, Portugal DA - 30.03.2022 KW - Fabricación Aditiva KW - Additive Manufacturing KW - Acero 316L KW - Mecánica de Fractura KW - Predicción vida a fatiga KW - Fit4AM KW - Steel 316L KW - Fracture Mechanics KW - Fatigue lifetime prediction PY - 2022 AN - OPUS4-55241 LA - spa AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - D'Accardi, E. A1 - Krankenhagen, Rainer A1 - Ulbricht, Alexander A1 - Pelkner, Matthias A1 - Pohl, Rainer A1 - Palumbo, D. A1 - Galietti, U. T1 - Capability to detect and localize typical defects of laser powder bed fusion (L‑PBF) process: an experimental investigation with different non‑destructive techniques N2 - Additive manufacturing (AM) technologies, generally called 3D printing, are widely used because their use provides a high added value in manufacturing complex-shaped components and objects. Defects may occur within the components at different time of manufacturing, and in this regard, non-destructive techniques (NDT) represent a key tool for the quality control of AM components in many industrial fields, such as aerospace, oil and gas, and power industries. In this work, the capability of active thermography and eddy current techniques to detect real imposed defects that are representative of the laser powder bed fusion process has been investigated. A 3D complex shape of defects was revealed by a μCT investigation used as reference results for the other NDT methods. The study was focused on two different types of defects: porosities generated in keyhole mode as well as in lack of fusion mode. Different thermographic and eddy current measurements were carried out on AM samples, providing the capability to detect volumetric irregularly shaped defects using non-destructive methods. KW - Additive Manufacturing KW - Defect detection KW - Thermography KW - Eddy-current testing KW - Micro-computed tomography PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-546680 DO - https://doi.org/10.1007/s40964-022-00297-4 SN - 2363-9512 VL - 7 IS - 6 SP - 1239 EP - 1256 PB - Springer AN - OPUS4-54668 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ulbricht, Alexander T1 - Do Microbes like Additively Manufactured Aluminium? First Details of a Corrosion Test using Sulphate-Reducing Bacteria N2 - Additively manufactured metals become relevant for industrial application. Although many studies on wet corrosion of these metals have been conducted, to the authors knowledge no study seems to contain microbiological corrosion (MIC). In the presented study an experiment was conducted on PBF-LB/AlSi10Mg to test this material's susceptibility for MIC. The tested specimen were analysed using Computed Tomography before and after the MIC experiment to enable a detailed characterisation the damage on the specimens' global and local level. A global reduction of material was observed. In addition, localised damage along process inherent features of the materials microstructure was observed. T2 - Beiratssitzung TF Umwelt CY - Berlin, Germany DA - 17.03.2025 KW - Computed Tomography KW - Additive Manufacturing KW - Biocorrosion KW - Sulphate-reducing Bacteria KW - Microbially influenced corrosion PY - 2025 AN - OPUS4-62772 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Oster, Simon A1 - Scheuschner, Nils A1 - Chand, Keerthana A1 - Altenburg, Simon T1 - Local porosity prediction in metal powder bed fusion using in-situ thermography: A comparative study of machine learning techniques N2 - The formation of flaws such as internal porosity in parts produced by Metal-based Powder Bed Fusion with Laser Beam (PBF-LB/M) significantly hinders its broader industrial application, as porosity can potentially lead to part failure. Addressing this issue, this study explores the efficacy of in-situ thermography, particularly short-wave infrared thermography, for detecting and predicting porosity during manufacturing. This technique is capable of monitoring the part’s thermal history which is closely connected to the flaw formation process. Recent advancements in Machine Learning (ML) have been increasingly leveraged for porosity prediction in PBF-LB/M. However, previous research primarily focused on global rather than localized porosity prediction which simplified the complex prediction task. Thereby, the opportunity to correlate the predicted flaw position with expected part strain to judge the severity of the flaw for part performance is neglected. This study aims to bridge this gap by studying the potential of SWIR thermography for predicting local porosity levels using regression models. The models are trained on data from two identical HAYNES®282® specimens. We compare the effectiveness of feature-based and raw data-based models in predicting different porosity types and examine the importance of input data in porosity prediction. We show that models trained on SWIR thermogram data can identify systematic trends in local flaw formation. This is demonstrated for forced flaw formation using process parameter shifts and, moreover, for randomly formed flaws in the specimen bulk. Furthermore, we identify features of high importance for the prediction of lack-of-fusion and keyhole porosity from SWIR monitoring data. KW - PBF-LB/M KW - In situ monitoring KW - Thermography KW - Additive Manufacturing KW - Process monitoring KW - Porosity prediction KW - Machine Learning KW - Feature extraction PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-621798 DO - https://doi.org/10.1016/j.addma.2024.104502 SN - 2214-7810 VL - 95 SP - 1 EP - 17 PB - Elsevier B.V. AN - OPUS4-62179 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mohr, Gunther T1 - Effects of inter layer time and build height on resulting properties of 316L stainless steel processed by laser powder bed fusion N2 - Das pulverbettbasierte selektive Laserstrahlschmelzen (engl. laser powder bed fusion, L-PBF) ist die am weitesten verbreitete additive Fertigungstechnologie für die Herstellung metallischer Komponenten. Unter der Vielzahl an Einflussfaktoren auf die Qualität und die mechanischen Eigenschaften von L-PBF-Bauteilen hat die Zwischenlagenzeit (engl. inter layer time, ILT) bisher kaum Beachtung in der wissenschaftlichen Literatur gefunden, obwohl sie je nach Bauraumausnutzungsgrad stark variieren kann. In diesem Vortrag werden Ergebnisse einer Studie präsentiert, die den Einfluss der ILT in Kombination mit der Bauteilhöhe und unter Berücksichtigung verschiedener Volumenenergiedichten am Beispiel der austenitischen Stahllegierung AISI 316L untersucht. Die Fertigungsprozesse wurden in-situ mittels Thermographiekamera überwacht. Auf diese Weise konnten intrinsische Vorerwärmungstemperaturen während der Bauteilfertigung lagenweise extrahiert werden. Es wurden signifikante Effekte der ILT und der Bauteilhöhe auf Wärmeakkumulation, Mikrostruktur, Schmelzbadgeometrie und Härte festgestellt. Ferner konnte ein Anstieg von Defektdichten bei einem gegenseitigen Wechselspiel aus Bauteilhöhe und ILT aufgezeigt werden. Die Zwischenlagenzeit wurde somit als kritischer Faktor für die L-PBF-Fertigung von Realbauteilen identifiziert. T2 - 74th IIW Annual Assembly and International Conference CY - Online meeting DA - 07.07.2021 KW - Additive Manufacturing KW - Laser powder bed fusion KW - In-situ process monitoring KW - Thermography KW - Preheating temperature KW - Inter layer time PY - 2021 AN - OPUS4-52954 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Waske, Anja T1 - A unique authenticator for additively manufactured parts derived from 3D microstructural information N2 - Additive manufacturing (AM) is rapidly emerging from rapid prototyping to industrial production [1]. Thus, providing AM parts with a tagging feature that allows identification, like a fingerprint, can be crucial for logistics, certification, and anti-counterfeiting purposes since nearly any geometry can be produced by AM with stolen data or reverse engineering of an original product. However, the mechanical and functional properties of the replicated part may not be identical to the original ones and pose a safety risk [2]. Several methods are already available, which range from encasing a detector to leveraging the stochastic defects of AM parts for the identification, authentication, and traceability of AM components. The most prevailing solution consists of local process manipulation, such as printing a quick response (QR) code [3] or a set of blind holes on the surface of the internal cavity of hollow components. Local manipulation of components may alter the properties. The external tagging features can be altered or even removed by post-processing treatments. Integrating electronic systems [4] in AM parts can be used to identify and authenticate components with complex or customized geometries. However, metal-based AM, especially in powder bed fusion (PBF-LB/M) techniques, has a strong shielding effect that interferes with the communication between the reader and the transponder. Our work suggests a methodology for the identification, authentication, and traceability of AM components using microstructural features in AM components. We will show a workflow that includes analysing 3D micro computed tomography data and selecting a set number of voids that fulfil the identification criteria. We will show the results this workflow produces for a series of 20 Al-based cuboid samples with identical processing parameters and discuss their prospects and limitations. The workflow can help to establish a non-tamperable connection between an additively manufactured part and its digital data and hence link the physical and the digital world. T2 - MSE Konferenz CY - Darmstadt, Germany DA - 24.09.2024 KW - Additive Manufacturing KW - Fingerprint KW - Computed tomography PY - 2024 AN - OPUS4-62288 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Altenburg, Simon A1 - Straße, Anne A1 - Gumenyuk, Andrey A1 - Maierhofer, Christiane T1 - In-situ monitoring of a laser metal deposition (LMD) process: comparison of MWIR, SWIR and high-speed NIR thermography N2 - Additive manufacturing offers a range of novel applications. However, the manufacturing process is complex and the production of almost defect-free parts with high reliability and durability is still a challenge. Thermography is a valuable tool for process surveillance, especially in metal additive manufacturing processes. The high process temperatures allow one to use cameras usually operating in the visible spectral range. Here, we compare the results of measurements during the manufacturing process of a commercial laser metal deposition setup using a mid wavelength infrared camera with those from a short wavelength infrared camera and those from a visual spectrum high-speed camera with band pass filter in the near infrared range. KW - Additive Manufacturing KW - Process monitoring KW - Thermography KW - LMD KW - Metal KW - MWIR KW - SWIR KW - NIR PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-516318 DO - https://doi.org/10.1080/17686733.2020.1829889 VL - 19 IS - 2 SP - 97 EP - 114 PB - Taylor & Francis Group CY - London, UK AN - OPUS4-51631 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Altenburg, Simon A1 - Scheuschner, Nils A1 - Straße, Anne A1 - Gumenyuk, Andrey A1 - Maierhofer, Christiane T1 - Towards the determination of real process temperatures in the LMD process by multispectral thermography N2 - Due to the rapid thermal cycles involved in additive manufacturing of metals, high internal stresses and peculiar microstructures occur, which influence the parts mechanical properties. To systematically examine their formation, in-process measurements of the temperature are needed. Since the part emissivity is strongly inhomogeneous and rapidly changing in the process, the applicability of thermography for the determination of thermodynamic temperatures is limited. Measuring the thermal radiation in different wavelengths simultaneously, temperature and emissivity can be separated. Here, we present results of a preliminary study using multispectral thermography to obtain real temperatures and emissivities in directed energy deposition (DED) processes. T2 - Thermosense: Thermal Infrared Applications XLIII CY - Online meeting DA - 12.04.2021 KW - Additive Manufacturing KW - Process monitoring KW - Multispectral thermography KW - Laser metal deposition KW - TES KW - LMD KW - Temperature emissivity separation PY - 2021 DO - https://doi.org/10.1117/12.2587881 VL - 2021 SP - 77 EP - 83 PB - SPIE AN - OPUS4-52516 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Altenburg, Simon T1 - Introduction to ProMoAM N2 - A brief introduction to the project ProMoAM is given. T2 - 2nd Workshop on In-situ Monitoring and Microstructure Development in Additive Manufactured Alloys CY - Online meeting DA - 19.04.2021 KW - Additive Manufacturing KW - Process monitoring KW - ProMoAM PY - 2021 AN - OPUS4-52513 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Altenburg, Simon T1 - Unraveling thermal radiation by multispectral thermography: Real temperatures in LMD N2 - Additive manufacturing of metals offers the opportunity to build parts with a high degree of complexity without additional costs, opening a new space for design optimization. However, the processes are highly complex and due to the rapid thermal cycles involved, high internal stresses and peculiar microstructures occur, which influence the parts mechanical properties. To systematically examine the formation of internal stresses and the microstructure, in-process spatially resolved measurements of the part temperature are needed. If the emissivity of the inspected part is known, its thermodynamic temperature can be reconstructed by a suited radiometric model. However, in additive manufacturing of metals, the emissivity of the part surface is strongly inhomogeneous and rapidly changing due to variations of, e.g., the degree of oxidation, the material state and temperature. Thus, here, the applicability of thermography in the determination of thermodynamic temperatures is limited. However, measuring the process thermal radiation at different wavelengths simultaneously enables one to separate temperature and emissivity spatially resolved to obtain further insight into the process. Here, we present results of an initial study using multispectral thermography to obtain real temperatures and emissivities in the powderfree LMD process. T2 - 2nd Workshop on In-situ Monitoring and Microstructure Development in Additive Manufactured Alloys CY - Online meeting DA - 19.04.2021 KW - Additive Manufacturing KW - Process monitoring KW - Multispectral thermography KW - Laser metal deposition KW - TES KW - LMD KW - Temperature emissivity separation PY - 2021 AN - OPUS4-52514 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Altenburg, Simon T1 - Towards the determination of real process temperatures in the LMD process my multispectral thermography N2 - Due to the rapid thermal cycles involved in additive manufacturing of metals, high internal stresses and peculiar microstructures occur, which influence the parts mechanical properties. To systematically examine their formation, in-process measurements of the temperature are needed. Since the part emissivity is strongly inhomogeneous and rapidly changing in the process, the applicability of thermography for the determination of thermodynamic temperatures is limited. Measuring the thermal radiation in different wavelengths simultaneously, temperature and emissivity can be separated. Here, we present results of a preliminary study using multispectral thermography to obtain real temperatures and emissivities in directed energy deposition (DED) processes. T2 - Thermosense: Thermal Infrared Applications XLIII CY - Online meeting DA - 12.04.2021 KW - Additive Manufacturing KW - Process monitoring KW - Multispectral thermography KW - Laser metal deposition KW - TES KW - LMD KW - Temperature emissivity separation PY - 2021 DO - https://doi.org/10.1117/12.2587881 AN - OPUS4-52515 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Scheuschner, Nils T1 - In-situ Monitoring der Additiven Fertigung von Metallen im LPA Prozess mittels Optischer Emissionsspektrometrie (OES) und Thermografie (TT) N2 - Einer der aussichtsreichsten Ansätze, die Qualität und Sicherheit der gefertigten Teile in der metallbasierten additiven Fertigung (AM) zu erhöhen und die Notwendigkeit aufwändiger und zeitintensiver, zerstörender oder zerstörungsfreier Prüfungen (ZfP) nach der Fertigung zu verringern, liegt in dem Einsatz von in-situ Prozessüberwachungstechniken. Viele wichtige Prozessgrößen bei der additiven Fertigung sind thermischer Natur, wie z.B. die Temperatur des Schmelzbades. Aufgrund der Zugänglichkeit zum Werkstück während des Bauprozesses bieten sich optische Verfahren zur Temperaturbestimmung an. Für die Thermografie und Optische Emissionsspektrometrie im IR-Bereich, welche für die in-situ Anwendung prinzipiell als geeignet angesehen werden können, gibt es allerdings noch wenig konkrete praktische Umsetzungen, da die Möglichkeiten und individuellen Grenzen dieser Methoden, angewendet auf AM, noch nicht ausreichend erforscht sind. Aus diesem Grund verfolgt die BAM mit dem Projekt „Process Monitoring of AM“ (ProMoAM) im Themenfeld Material das Ziel, Verfahren des Prozessmonitorings zur in-situ Bewertung der Qualität additiv gefertigter Metallbauteile weiterzuentwickeln. Im Beitrag wird der Fokus auf eine Versuchsserie gelegt, bei der Aufbau von Probekörpern aus dem austenitischen Edelstahl 316L mittels Laser-Pulver-Auftragschweißen (LPA) durch od. mit Hilfe von IR-Spektrometrie und Thermografie in-situ überwacht wurde. Hierbei stellen u.a. die hohe Bandbreite der zu messenden Temperaturen, die Bestimmung der Emissivität und ihre Änderung bei Phasenübergängen des Metalls große experimentelle Herausforderungen dar, wobei jede Methode individuelle Vor- und Nachteile aufweist, welche verglichen werden. T2 - DGZfP-Jahrestagung 2021 CY - Online meeting DA - 10.05.2021 KW - Additive Manufacturing KW - Thermography KW - Direct Energy Deposition KW - Additive Fertigung KW - Thermografie KW - Laserauftragschweißen PY - 2021 AN - OPUS4-52744 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Altenburg, Simon T1 - Improving additive manufacturing technologies by in-situ monitoring: Thermography N2 - Additive manufacturing of metals gains increasing relevance in the industrial field for part production. However, especially for safety relevant applications, a suitable quality assurance is needed. A time and cost efficient route to achieve this goal is in-situ monitoring of the build process. Here, the BAM project ProMoAM (Process monitoring in additive manufacturing) is briefly introduced and recent advances of BAM in the field of in-situ monitoring of the L-PBF and the LMD process using thermography are presented. T2 - Anwenderkonferenz Infratec GmbH CY - Online meeting DA - 04.11.2021 KW - Additive Manufacturing KW - Process monitoring KW - Thermography PY - 2021 AN - OPUS4-54026 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Breese, Philipp Peter A1 - Becker, Tina A1 - Oster, Simon A1 - Altenburg, Simon A1 - Metz, C. A1 - Maierhofer, Christiane T1 - Aktive Laserthermografie im L-PBF-Prozess zur in-situ Detektion von Defekten N2 - Die zerstörungsfreie Prüfung von metallischen Bauteilen hergestellt mit additiver Fertigung (Additive Manufacturing - AM) gewinnt zunehmend an industrieller Bedeutung. Grund dafür ist die Feststellung von Qualität, Reproduzierbarkeit und damit auch Sicherheit für Bauteile, die mittels AM gefertigt wurden. Jedoch wird noch immer ex-situ geprüft, wobei Defekte (z.B. Poren, Risse etc.) erst nach Prozessabschluss entdeckt werden. Übersteigen Anzahl und/oder Abmessung die vorgegebenen Grenzwerte für diese Defekte, so kommt es zu Ausschuss, was angesichts sehr langer Bauprozessdauern äußerst unrentabel ist. Eine Schwierigkeit ist dabei, dass manche Defekte sich erst zeitverzögert zum eigentlichen Materialauftrag bilden, z.B. durch thermische Spannungen oder Schmelzbadaktivitäten. Dementsprechend sind reine Monitoringansätze zur Detektion ggf. nicht ausreichend. Daher wird in dieser Arbeit ein Verfahren zur aktiven Thermografie an dem AM-Prozess Laser Powder Bed Fusion (L-PBF) untersucht. Das Bauteil wird mit Hilfe des defokussierten Prozesslasers bei geringer Laserleistung zwischen den einzelnen gefertigten Lagen unabhängig vom eigentlichen Bauprozess erwärmt. Die entstehende Wärmesignatur wird ort- und zeitaufgelöst durch eine Infrarotkamera erfasst. Durch diese der Lagenfertigung nachgelagerte Prüfung werden auch zum Bauprozess zeitversetzte Defektbildungen nachweisbar. In dieser Arbeit finden die Untersuchungen als Proof-of-Concept, losgelöst vom AM-Prozess, an einem typischen metallischen Testkörper statt. Dieser besitzt eine Nut als oberflächlichen Defekt. Die durchgeführten Messungen finden an einer eigens entwickelten L-PBF-Forschungsanlage innerhalb der Prozesskammer statt. Damit wird ein neuartiger Ansatz zur aktiven Thermografie für L-PBF erforscht, der eine größere Bandbreite an Defektarten auffindbar macht. Der Ansatz wird validiert und Genauigkeit sowie Auflösungsvermögen geprüft. Eine Anwendung am AM-Prozess wird damit direkt forciert und die dafür benötigten Zusammenhänge werden präsentiert. T2 - DGZfP-Jahrestagung 2022 CY - Kassel, Germany DA - 23.05.2022 KW - Additive Manufacturing KW - Laser Powder Bed Fusion KW - Thermografie KW - Zerstörungsfreie Prüfung KW - Aktive Laserthermografie PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-550353 SN - 978-3-947971-25-1 VL - 177 SP - 1 EP - 9 PB - Deutsche Gesellschaft für Zerstörungsfreie Prüfung e.V. AN - OPUS4-55035 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Altenburg, Simon T1 - Process monitoring in metal AM @ BAM - The project ProMoAM N2 - Results of the project ProMoAM (Process monitoring in additive manufacturing) presented. Results from in-situ eddy current testing, optical emission spectroscopy, thermography, optical tomography as well as particle and gas emission spectroscopy are summarized and correlated to results from computed tomography for future in-situ defect detection. T2 - 3rd Meeting of WG6 (NDT in AM) of the EFNDT CY - Online meeting DA - 15.03.2022 KW - Additive Manufacturing KW - Process monitoring KW - ProMoAM PY - 2022 AN - OPUS4-54484 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Breese, Philipp Peter T1 - Aktive Laserthermografie im L-PBF-Prozess zur in-situ Detektion von Defekten N2 - Die zerstörungsfreie Prüfung von metallischen Bauteilen hergestellt mit additiver Fertigung (Additive Manufacturing - AM) gewinnt zunehmend an industrieller Bedeutung. Grund dafür ist die Feststellung von Qualität, Reproduzierbarkeit und damit auch Sicherheit für Bauteile, die mittels AM gefertigt wurden. Jedoch wird noch immer ex-situ geprüft, wobei Defekte (z.B. Poren, Risse etc.) erst nach Prozessabschluss entdeckt werden. Übersteigen Anzahl und/oder Abmessung die vorgegebenen Grenzwerte für diese Defekte, so kommt es zu Ausschuss, was angesichts sehr langer Bauprozessdauern äußerst unrentabel ist. Eine Schwierigkeit ist dabei, dass manche Defekte sich erst zeitverzögert zum eigentlichen Materialauftrag bilden, z.B. durch thermische Spannungen oder Schmelzbadaktivitäten. Dementsprechend sind reine Monitoringansätze zur Detektion ggf. nicht ausreichend. Daher wird in dieser Arbeit ein Verfahren zur aktiven Thermografie an dem AM-Prozess Laser Powder Bed Fusion (L-PBF) untersucht. Das Bauteil wird mit Hilfe des defokussierten Prozesslasers bei geringer Laserleistung zwischen den einzelnen gefertigten Lagen unabhängig vom eigentlichen Bauprozess erwärmt. Die entstehende Wärmesignatur wird ort- und zeitaufgelöst durch eine Infrarotkamera erfasst. Durch diese der Lagenfertigung nachgelagerte Prüfung werden auch zum Bauprozess zeitversetzte Defektbildungen nachweisbar. In dieser Arbeit finden die Untersuchungen als Proof-of-Concept, losgelöst vom AM-Prozess, an einem typischen metallischen Testkörper statt. Dieser besitzt eine Nut als oberflächlichen Defekt. Die durchgeführten Messungen finden an einer eigens entwickelten L-PBF-Forschungsanlage innerhalb der Prozesskammer statt. Damit wird ein neuartiger Ansatz zur aktiven Thermografie für L-PBF erforscht, der eine größere Bandbreite an Defektarten auffindbar macht. Der Ansatz wird validiert und Genauigkeit sowie Auflösungsvermögen geprüft. Eine Anwendung am AM-Prozess wird damit direkt forciert und die dafür benötigten Zusammenhänge werden präsentiert. T2 - DGZfP-Jahrestagung 2022 CY - Kassel, Germany DA - 23.05.2022 KW - Additive Manufacturing KW - Laser Powder Bed Fusion KW - Thermografie KW - Zerstörungsfreie Prüfung KW - Aktive Laserthermografie PY - 2022 AN - OPUS4-55040 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wandtke, Karsten T1 - Influence of the WAAM process on residual stresses in high-strength steels (IIW-Doc. II-A-408-2022) N2 - High-strength fine-grain structeural steels have great potential for weight optimization of many modern engineering structures. Efficient manufacturing can be achieved here above all by Wire Arc Additive Manufacturing (WAAM). First commercial high-strength welding consumables for WAAM are already available. However, due to a lack of knowledge and guidelines for the industry regarding welding residual stresses and component safety in manufacturing and operation, their application is still severely limited. Residual stresses play a crucial role here, as the sensitive microstructure of high-strength steels carries a high risk of cold cracking. For this reason, process- and material-related influences, as well as the design aspects on residual stress formation and the risk of cold cracking, are being investigated in a recent project (FOSTA-P1380/IGF21162BG). This high strength of the WAAM welding consumables is adjusted via a martensitic phase transformation. The volume expansion associated with martensite formation has a significant influence on residual stress evolution. However, this has not yet been investigated in relation to the processing of high-strength steels by WAAM. The aim of this work is to establish a WAAM cold crack test and easy-to-apply processing recommendations that will allow economical, expedient, and crack-resistant fabrication of high-strength steels, especially for SME. This paper focuses on the analysis of the effects of welding heat control and design of WAAM components on cooling conditions, microstructure, mechanical-technological properties and residual stresses. For this purpose, geometrically defined specimens (hollow cuboids) are welded fully automatically with a special, high-strength WAAM solid wire (yield strength >790 MPa). The heat control and specimen dimensions are varied within a statistical experimental design. The weld heat control is adjusted in such a way that the t8/5 cooling times are ensured within the recommended processing range (approx. 5–20 s). For this purpose, additional thermo-physical forming simulations using a dilatometer allowed the complex heat cycles to be reproduced and the resulting ultimate tensile strength of the weld metal to be determined. The WAAM welding of complex geometries with varying welding heat control and geometric factors or wall thicknesses not only has an effect on the cooling conditions, cooling times and microstructure, but also has a significant influence on the structural restraint conditions during welding. Hence, the welding experiments show significant effects of specimen scaling and heat input on the welding residual stresses, which may be detrimental regarding component properties and crack-critical tensile residual stresses. These complex interactions are analyzed within this investigation. T2 - Intermediate Meeting of IIW Comissions II and IX CY - Online meeting DA - 17.03.2022 KW - MAG-Welding KW - Additive Manufacturing KW - Residual stresses KW - high-strength steel KW - cold cracking safety PY - 2022 AN - OPUS4-56712 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Madia, Mauro T1 - Prediction of the fatigue limit of additively manufactured metallic materials N2 - Structural alloys are largely employed in key industrial sectors and their demand is predicted to rise rapidly for the next decades. Most of these materials require a large amount of energy for extraction and manufacturing, which causes the emission of greenhouse gases and other pollutants. Therefore, strategies for improving the sustainability of structural metallic alloys are urgently needed. Additive Manufacturing (AM), in particular Laser Powder Bed Fusion (PBF-LB/M), aims to be a sustainable manufacturing process, as it allows the build-up of complex geometry in near net-shape from 3D models, while minimizing material waste and the energy required for the process and post-process treatments. Nevertheless, the application of additively manufactured parts in structural safety-relevant applications is still hindered by the poor fatigue performance. The cause of this has been mainly attributed to the presence of manufacturing defects and surface roughness. Therefore, a huge effort has been made to optimize the process parameters and to introduce post-process treatments to minimize the defect content. However, material flaws cannot be fully eliminated, but these can be considered in a damage tolerance framework for the prediction of the fatigue performance of additively manufactured metallic materials, which is essential for part design and qualification. This work aims at presenting different modelling strategies for the prediction of the fatigue limit of AM metals. Simple empirical models and more complex models based on fatigue short crack propagation are proposed. The investigated material is an AlSi10Mg alloy fabricated by PBF-LB/M and subjected to two different low-temperature heat-treatments (265°C for 1 h and 300°C for 2h). The results show that the models can provide good approximation of the fatigue limits and help in the interpretation of the scatter of fatigue data. T2 - ASTM International Conference on Advanced Manufacturing CY - Washington DC, USA DA - 30.10.2023 KW - Additive Manufacturing KW - AlSi10Mg KW - Fatigue KW - Residual stress KW - Microstructure PY - 2023 AN - OPUS4-58866 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Madia, Mauro T1 - Damage Tolerant Approach in Additively Manufactured Metallic Materials N2 - Damage tolerance counts as one of the most widespread approach to fatigue assessment and surely as one of the most promising in understanding the process-structure-property-performance relationships in additively manufactured metallic materials. Manufacturing defects, surface roughness, microstructural features, short and long crack fatigue propagation, residual stresses and applied loads can be taken into consideration in a fracture mechanics-based fatigue assessment. Many aspects are crucial to the reliable component life prediction. Among those a prominent role is played by an accurate measurement and modelling of the short crack fatigue behavior, and reliable statistical characterization of defects and residual stresses. This work aims at addressing the issues related to both experimental testing, fatigue and fatigue crack propagation, and fracture mechanics-based modelling of fatigue lives. Examples will be provided on an additively manufactured AISI 316 L. T2 - TMS2021 VIRTUAL CY - Online meeting DA - 15.03.2021 KW - AISI 316L KW - Additive Manufacturing KW - Damage Tolerance KW - Microstructure KW - Defects KW - Residual Stress PY - 2021 AN - OPUS4-52293 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, V. A1 - Marko, A. A1 - Kruse, T. A1 - Biegler, M. A1 - Rethmeier, Michael T1 - Analysis and recycling of bronze grinding waste to produce maritime components using directed energy deposition N2 - Additive manufacturing promises a high potential for the maritime sector. Directed Energy Deposition (DED) in particular offers the opportunity to produce large-volume maritime components like propeller hubs or blades without the need of a costly casting process. The post processing of such components usually generates a large amount of aluminum bronze grinding waste. The aim of the presented project is to develop a sustainable circular AM process chain for maritime components by recycling aluminum bronze grinding waste to be used as raw material to manufacture ship Propellers with a laser-powder DED process. In the present paper, grinding waste is investigated using a dynamic image Analysis system and compared to commercial DED powder. To be able to compare the material quality and to verify DED process parameters, semi-academic sample geometries are manufactured. T2 - LiM 2021 CY - Munich, Germany DA - 21.06.2021 KW - Additive Manufacturing KW - Maritime Components KW - Powder Analysis KW - Recycling KW - Directed Energy Deposition PY - 2021 SP - 1 EP - 9 AN - OPUS4-54067 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Marquardt, R. A1 - Biegler, M. A1 - Rethmeier, Michael T1 - Laser-Pulver-Auftragschweißen von funktional gradierten Materialien auf Cobalt-Chrom Basis N2 - Um Bauteile vor Verschleiß und Korrosion zu schützen werden Beschichtungen aus resistenteren Materialien aufgetragen. Hierzu zählen unter anderen die Legierungen auf Cobalt-Chrom Basis. Der diskrete Materialsprung ist jedoch unter thermischen und mechanischen Belastungen häufig Ursache für das Versagen der Beschichtung. In dieser Arbeit werden daher Materialgradierungen von verschiedenen Stahllegierungen zu einer Cobalt-Chrom Basislegierung untersucht. Die Ergebnissen werden dafür auch mit Resultaten zu vorangegangenen Untersuchungen verglichen. Kern der Arbeit bilden geätzte Schliffbilder der Materialpaarungen und Auswertungen mittels Farbeindringprüfung sowie die metallografische Bestimmung der Porosität. Ziel der Arbeit ist ein defektfreier Aufbau der funktional gradierten Materialpaarungen. T2 - 43. Assistentenseminar Fügetechnik CY - Päwesin, Germany DA - 20.09.2023 KW - Directed Enery Deposition KW - Funktionally Graded Material KW - Additive Manufacturing KW - DED KW - FGM KW - AM PY - 2023 SN - 978-3-96144-212-6 SP - 1 EP - 6 PB - DVS Media GmbH AN - OPUS4-59116 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mohr, Gunther A1 - Scheuschner, Nils A1 - Hilgenberg, Kai T1 - In situ heat accumulation by geometrical features obstructing heat flux and by reduced inter layer times in laser powder bed fusion of AISI 316L stainless steel N2 - Material qualification for laser powder bed fusion (L-PBF) processes are often based on results derived from additively manufactured (AM) bulk material or small density cubes, although it is well known that the part geometry has a tremendous influence on the heat flux and, therefore, on the thermal history of an AM component. This study shows experimentally the effect of simple geometrical obstructions to the heat flux on cooling behavior and solidification conditions of 316L stainless steel processed by L-PBF. Additionally, it respects two distinct inter layer times (ILT) as well as the build height of the parts. The cooling behavior of the parts is in-situ traced by infrared (IR) thermography during the built-up. The IR signals reveal significant differences in cooling conditions, which are correlated to differences in melt pool geometries. The acquired data and results can be used for validation of computational models and improvements of quality assurance. KW - Selective laser beam melting KW - Thermography KW - Melt pool depth KW - Inter layer time KW - Ppreheating temperature KW - Additive Manufacturing PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-512549 DO - https://doi.org/10.1016/j.procir.2020.09.030 VL - 94 SP - 155 EP - 160 PB - Elsevier B.V. AN - OPUS4-51254 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Werner, Tiago T1 - Experimentelle Ermittlung zyklischer R-Kurven in additiv gefertigtem AISI 316L Stahl N2 - Diese Untersuchung beschäftigt sich mit der Charakterisierung von Kurzrisswachstum in mittels Laser-Pulverbett-Verschmelzen (LPBF - Laser Powder Bed Fusion) hergestelltem rostfreien austenitischen Stahl. Spezifischer wird die Ermittlung zyklischer R-Kurven untersucht. Diese beschreiben den Aufbau des Widerstands gegen Ermüdungsrisswachstum - d.h. des Schwellenwertes - aufgrund von Rissschließeffekten bei physikalisch kurzen Rissen. Mit Hilfe der zyklischen R-Kurven kann die Fähigkeit eines Bauteils, physikalisch kurze Risse zu arretieren, charakterisiert werden. Wir verfügen damit über eine Schnittstelle zwischen klassischer Ermüdung und Bruchmechanik. Das ist gerade auch für additiv gefertigte (AM – Additive Manufacturing) Materialien von Interesse. Diese weisen prozessintrinsische Defekte auf, die als Initiierungsstellen kurzer Ermüdungsrisse agieren. Im Rahmen der experimentellen Untersuchungen wurden zyklische R-Kurven für konventionellen und LPBF AISI-316L-Stahl ermittelt. Insbesondere wurde der Einfluss verschiedener Wärmebehandlungen (WB1: 450°C, WB2: 800°C und WB3: 900°C) auf das Wachstumsverhalten physikalisch kurzer Risse im LPBF-Material untersucht. Aufgrund hoher Eigenspannungen war die Ermittlung des Kurzrisswachstumsverhaltens bei WB1 nicht möglich. Für WB2 und WB3 ergaben sich sehr unterschiedliche zyklische R-Kurven. Untersuchungen der Eigenspannungen, der Bruchfläche (insbesondere der Rauheit) und der Mikrostruktur sollen die Ursachen für das unterschiedliche Verhalten erklären. Die Ergebnisse werden mit den Verhältnissen in konventionellem Material verglichen. T2 - Tagung des Arbeitskreises Bruchmechanik und Bauteilsicherheit CY - Online meeting DA - 18.02.2021 KW - Additive Manufacturing KW - Zyklische R-Kurve KW - Ermüdungsriss KW - L-PBF KW - 316L PY - 2021 AN - OPUS4-52250 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - D'Accardi, E. T1 - Capability of active thermography to detect and localize pores in Metal Additive Manufacturing materials N2 - A powerful tool to understand, demonstrate and explain the limits of the pulsed technique in terms of detectability and localizability of AM keyhole pores has been assessed by comparing the active thermographic approach (both experimental and FEM simulations) to Computed Tomography results; ✓ µCT results demonstrate that the intended defect geometry is not achieved; indeed a network of voids (microdefects consisting of small sharp-edged hollows with a complicated, almost fractal, inner surface) was found; ✓ both Exp-PT and FEM results explains clearly why no indication of defect related to the thermal contrasts could be found during the investigation of an uncoated surface. However, the application of further data evaluations focusing on the thermal behavior and emissivity evaluation (PPT post data processing) enable the detection of some defects; ✓ coating facilitates a closer inspection of inner defects, but inhomogeneities of the coating could impair the spatial resolution and lead to the emergence of hotspots (the FEM simulation reached its limit with this extreme geometry where a 25 µm thin disc is considered at a 1 cm thick specimen in millisecond time resolution); ✓ both Exp-PT and FEM results allow the conclusion that very short pulses of 200 ms or shorter should be sufficient to detect these defects below, but near the surface; besides a short duration of the thermal phenomenon it should be emphasized, about 0.04 s (high frame rate camera); T2 - Convegno AIAS 2020 CY - Online meeting DA - 02.09.2020 KW - Additive Manufacturing KW - Laser powderbed fusion KW - Pores KW - Thermography PY - 2020 AN - OPUS4-51922 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Breese, Philipp Peter T1 - Comparison of NIR and SWIR thermography for defect detection in laser powder bed fusion N2 - Since laser powder bed fusion (PBF-LB/M) is prone to the formation of defects during the building process, a fundamental requirement for widespread application is to find ways to assure safety and reliability of the additively manufactured parts. A possible solution for this problem lies in the usage of in-situ thermographic monitoring for defect detection. In this contribution we investigate possibilities and limitations of the VIS/NIR wavelength range for defect detection. A VIS/NIR camera can be based on conventional silicon-based sensors which typically have much higher spatial and temporal resolution in the same price range but are more limited in the detectable temperature range than infrared sensors designed for longer wavelengths. To investigate the influence, we compared the thermographic signatures during the creation of artificially provoked defects by local parameter variations in test specimens made of a nickel alloy (UNS N07208) for two different wavelength ranges (~980 nm and ~1600 nm). T2 - 13th CIRP Conference on Photonic Technologies - LANE 2024 CY - Fürth, Germany DA - 15.09.2024 KW - Additive Manufacturing KW - Laser Powder Bed Fusion KW - Nondestructive Testing KW - Defect Detection KW - Thermography PY - 2024 AN - OPUS4-61285 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wandtke, Karsten T1 - Residual stress formation in DED-arc manufactured high strength steel components N2 - Additive manufacturing (AM) processes enable the efficient production of advanced constructions. New developments in topology optimization are leading to weight-optimized designs of increasing complexity. Direct energy deposition processes (DED) such as wire and arc-based additive manufacturing are an important method of additive manufacturing. The wire filler metals enable a wide range of materials, while the arc process provides a high deposition rate compared to laser and powder-based processes. Combined with the use of high-strength steels, the thickness of walls or components can be significantly reduced in the context of lightweight construction, which results in significant savings in energy, costs, time and resources. Suitable high-strength steel filler metals are commercially available for DED-arc AM processes. However, guidelines and quantitative knowledge about welding stresses and cold cracking issues during component production and service are lacking. This limits the industrial application considerably. In a joint project of BAM and Chemnitz University of Technology, the main influences and complex interactions of material, production process, design and processing steps on the residual stress level are investigated. The aim is to develop processing recommendations and a cold cracking test for economical processing and stress-related design of high-strength steels with DED-arc. This study focuses on residual stress analysis by neutron diffraction (ND) and X-ray diffraction (XRD) on defined test specimens. The ND analysis were performed at the Paul Scherrer Institute- Villigen, Switzerland (PSI) and the XRD analysis at BAM. The study shows a quantitative and qualitative comparison of the residual stress magnitudes and distribution between the component bulk (ND) and surface (XRD) analyses. The ND analysis reveals that in DED-arc AM walls the residual stresses dominate in the direction of welding and are negligibly small in each case transverse to the direction of welding. The topology of the analyzed residual stresses shows almost identical residual stress maps compared to XRD. In addition, the residual stresses are significantly influenced by the solid phase transformation of the material due to low cooling times and less post heat treatment cycles of following AM layers in the area of the top layer. T2 - IIW Intermediate Meeting C-XIII CY - Online meeting DA - 20.04.2023 KW - Additive Manufacturing KW - High strength steel KW - Residual Stress PY - 2023 AN - OPUS4-59308 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schröpfer, Dirk A1 - Scharf-Wildenhain, R. A1 - Hälsig, A. A1 - Wandtke, Karsten A1 - Kromm, Arne A1 - Kannengießer, Thomas T1 - Process-related influences and correlations in wire arc additive manufacturing of high-strength steels N2 - High-strength fine-grained structural steels have great potential for weight-optimized, efficient structures in many modern steel applications. Further advances in efficiency can be achieved through additive manufacturing and bionic design. Commercial high-strength filler materials for wire arc additive manufacturing (WAAM) are already provided by the consumable producers. Today, application would be strictly limited due to absence of quantitative findings or any guidelines for the industry regarding welding-related stresses and component safety during manufacturing and service. Hence, process- and material-related influences and design-related restraint conditions associated with formation of residual stresses and cold cracking risk are investigated. The aim is the accessibility of special WAAM self-restraining cold cracking tests and easy applicable processing recommendations, enabling an economical, fit-for-purpose and crack-safe WAAM of high-strength steels. This first study focuses on determination of interactions between WAAM process parameters, resulting layer geometry, microstructure and residual stresses, analyzed via X-ray diffraction. Defined reference specimens are automated welded using a special WAAM solid wire (yield strength >820 MPa). Geometric properties can be specifically adjusted by wire feed and welding speed, but cannot be varied arbitrarily, since a high heat input causes local overheating, inadmissible changes of microstructure and mechanical properties, defects and comparable high tensile residual stresses. T2 - 22. Werkstofftechnischen Kolloquium der TU Chemnitz CY - Online meeting DA - 24.03.2021 KW - Residual stresses KW - Additive Manufacturing KW - High-strength steel PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-533300 DO - https://doi.org/10.1088/1757-899X/1147/1/012002 VL - 1147 SP - 012002 PB - IOP Publishing Ltd AN - OPUS4-53330 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Becker, Tina A1 - Altenburg, Simon A1 - Scheuschner, Nils A1 - Breese, Philipp Peter A1 - Metz, C. A1 - Hilgenberg, Kai A1 - Maierhofer, Christiane T1 - In-situ monitoring of the Laser Powder Bed Fusion build process via bi- chromatic optical tomography N2 - As metal additive manufacturing (AM) is entering industrial serial production of safety relevant components, the need for reliable process qualification is growing continuously. Especially in strictly regulated industries, such as aviation, the use of AM is strongly dependent on ensuring consistent quality of components. Because of its numerous influencing factors, up to now, the metal AM process is not fully controllable. Today, expensive part qualification processes for each single component are common in industry. This contribution focusses on bi-chromatic optical tomography as a new approach for AM in-situ quality control. In contrast to classical optical tomography, the emitted process radiation is monitored simultaneously with two temperature calibrated cameras at two separate wavelength bands. This approach allows one to estimate the local maximum temperatures during the manufacturing process, thus increases the comparability of monitoring data of different processes. A new process information level at low investment cost is reachable, compared to, e.g., infrared thermography. T2 - LANE 2022 CY - Fürth, Germany DA - 04.08.2022 KW - Optical tomography KW - Additive Manufacturing KW - L-PBF KW - In-process monitoring PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-560270 DO - https://doi.org/10.1016/j.procir.2022.08.035 SN - 2212-8271 VL - 111 SP - 340 EP - 344 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-56027 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Breese, Philipp Peter T1 - In-situ Prüfung additiv gefertigter L-PBF-Bauteile mit aktiver Laserthermografie N2 - Die additive Fertigung von metallischen Bauteilen (Additive Manufacturing - AM; auch 3D-Druck genannt) bietet eine Vielzahl an Vorteilen gegenüber konventionellen Fertigungsmethoden. Durch den schichtweisen Auftrag und das selektive Aufschmelzen von Metallpulver im Laser Powder Bed Fusion Prozess (L-PBF) sind u.a. optimierte und flexibel anpassbare Designs und die Nutzung von neuartigen Materialien möglich. Aufgrund der Komplexität des AM-Prozesses und der Menge an Einflussfaktoren ist eine Qualitätssicherung der gefertigten Bauteile unabdingbar. Verschiedene in-situ Monitoringansätze werden bereits angewendet, jedoch findet eine dedizierte Prüfung erst im Nachgang der Fertigung ex-situ statt. Der Grund dafür ist, dass die Entstehung von geometrischen Abweichungen und Defekten auch zeitversetzt zum eigentlichen Materialauftrag und damit auch zum Monitoring stattfinden kann. Die Notwendigkeit geeigneter in-situ Prüfmethoden für L-PBF, um die Erforderlichkeit einer Nacharbeitung frühzeitig festzustellen und Ausschuss zu vermeiden ist angesichts kostenintensiver Ausgangsstoffe und einer oftmals mehrstündigen bis mehrtägigen Prozessdauer besonders hoch. Daraus motiviert wird im Rahmen des Projektes ATLAMP die Möglichkeit der aktiven Laserthermografie mit Hilfe des defokussierten Fertigungslasers untersucht. Damit ist, bei vergleichsweise geringer Laserleistung, eine zerstörungsfreie Prüfung mittels Flying Spot Thermografie möglich. Diese findet jeweils anschließend an die Fertigung einer Schicht statt, womit der reale Status des Bauteils im Verlauf des AM-Prozesses geprüft wird. Als Grundlage dafür werden im Rahmen dieser Arbeit mit AM gefertigte, defektbehaftete Probekörper zunächst losgelöst vom Fertigungsprozess untersucht. Damit werden die Grundlagen für den neuartigen Ansatz der aktiven in-situ Laserthermografie im L-PBF-Prozess mittels des Fertigungslasers geschaffen. Auf diese Weise lassen sich auch zeitversetzt auftretende Defekte zerstörungsfrei im Prozessverlauf feststellen und eine aussagekräftige Qualitätssicherung des Ist-Zustands des Bauteils erreichen. T2 - Thermographie-Kolloquium 2022 CY - Saarbrücken, Germany DA - 28.09.2022 KW - Additive Manufacturing KW - Laser Powder Bed Fusion KW - Defekte KW - Zerstörungsfreie Prüfung KW - Aktive Laserthermografie PY - 2022 UR - https://www.dgzfp.de/Portals/thermo2022/BB178/Inhalt/18.pdf SN - 978-3-947971-27-5 AN - OPUS4-56810 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Becker, Tina T1 - Two approaches for multi measurand in-situ monitoring of the L-PBF process – bicolor- and RGB-optical tomography N2 - Since metal additive manufacturing (AM) becomes more and more established in industry, also the cost pressure for AM components increases. One big cost factor is the quality control of the manufactured components. Reliable in-process monitoring systems are a promising route to lower scrap rates and enhance trust in the component and process quality. The focus of this contribution is the presentation and comparison of two optical tomography based multi measurand in-situ monitoring approaches for the L-PBF process: the bicolor- and the RGB-optical tomography. The classical optical tomography (OT) is one of the most common commercial in-situ monitoring techniques in industrial L-PBF machines. In the OT spatial resolved layer-images of the L-PBF process are taken from an off-axis position in one near infrared wavelength window. In addition to the explanatory powers classical OT, both here presented approaches enable the determination of the maximum surface temperature. In contrast to thermography that may also yield maximum temperature information, the needed equipment is significantly cheaper and offers a higher spatial resolution. Both approaches are implemented at a new in-house developed L-PBF system (Sensor-based additive manufacturing machine - SAMMIE). SAMMIE is specifically designed for the development and characterization of in-situ monitoring systems and is introduced as well. T2 - ICAM2022 CY - Orlando, FL, USA DA - 31.10.2022 KW - Additive Manufacturing KW - L-PBF KW - In-process monitoring KW - Optical tomography PY - 2022 AN - OPUS4-56594 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Breese, Philipp Peter T1 - In-situ defect detection for laser powder bed fusion with active laser thermography N2 - Defects are still common in metal components built with Additive Manufacturing (AM). Process monitoring methods for laser powder bed fusion (PBF-LB/M) are used in industry, but relationships between monitoring data and defect formation are not fully understood yet. Additionally, defects and deformations may develop with a time delay to the laser energy input. Thus, currently, the component quality is only determinable after the finished process. Here, active laser thermography, a non-destructive testing method, is adapted to PBF-LB/M, using the defocused process laser as heat source. The testing can be performed layer by layer throughout the manufacturing process. The results of the defect detection using infrared cameras are presented for a custom research PBF-LB/M machine. Our work enables a shift from post-process testing of components towards in-situ testing during the AM process. The actual component quality is evaluated in the process chamber and defects can be detected between layers. T2 - 2023 Annual International Solid Freeform Fabrication Symposium CY - Austin, TX, USA DA - 14.08.2023 KW - Additive Manufacturing KW - Additive Fertigung KW - Laser Powder Bed Fusion KW - Nondestructive Testing KW - Flying Spot Laser Thermography PY - 2023 AN - OPUS4-58137 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Breese, Philipp Peter T1 - In-situ defect detection via active laser thermographic testing for PBF-LB/M N2 - Great complexity characterizes Additive Manufacturing (AM) of metallic components via laser powder bed fusion (PBF-LB/M). Due to this, defects in the printed components (like cracks and pores) are still common. Monitoring methods are commercially used, but the relationship between process data and defect formation is not well understood yet. Furthermore, defects and deformations might develop with a temporal delay to the laser energy input. The component’s actual quality is consequently only determinable after the finished process. To overcome this drawback, thermographic in-situ testing is introduced. The defocused process laser is utilized for nondestructive testing performed layer by layer throughout the build process. The results of the defect detection via infrared cameras are shown for a research PBF-LB/M machine. This creates the basis for a shift from in-situ monitoring towards in-situ testing during the AM process. Defects are detected immediately inside the process chamber, and the actual component quality is determined. T2 - Lasers in Manufacturing (LiM) CY - Munich, Germany DA - 26.06.2023 KW - Additive Manufacturing KW - Laser Powder Bed Fusion KW - Nondestructive Testing KW - Defect Detection KW - Flying Spot Laser Thermography PY - 2023 AN - OPUS4-57922 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Breese, Philipp Peter T1 - Hyperspektrale Thermografie im metallischen Laser-Pulverbettschweißen (PBF-LB/M): Grundlagen für eine in-situ Realtemperatur-Bestimmung N2 - Die additive Fertigung (Additive Manufacturing AM, auch als 3D Druck bekannt) von Metallen nimmt einen stetig wachsenden Stellenwert in industriellen Anwendungen ein. Gründe dafür sind u.a. die Möglichkeit der Umsetzung komplexer Bauteildesigns und die Nutzung neuartiger Werkstoffe. Damit hebt sich AM von konventionellen Fertigungsmethoden wie der subtraktiven Fertigung (Drehen, Fräsen, etc.) ab. Das für Metalle am weitesten verbreitete AM-Verfahren ist das Laser-Pulverbettschweißen (Laser Powder Bed Fusion PBF-LB/M, auch als Selective Laser Melting SLM bekannt). Es besitzt aktuell den höchsten Industrialisierungsgrad und die größte Anzahl an eingesetzten Maschinen. Bei PBF-LB/M liegt der metallische Ausgangswerkstoff unter Inertgasatmosphäre innerhalb einer Prozesskammer in einem Bett als Pulver vor und ein Laser schmilzt dieses lokal auf. Durch wiederholtes Auftragen einer neuen Pulverschicht und anschließendes selektives Schmelzen mit Hilfe des Lasers findet der lagenweise Aufbau eines Bauteils statt. Die dabei auftretenden lokalen Temperaturverteilungen bestimmen sowohl die Eigenschaften des gefertigten Bauteils als auch das mögliche Auftreten von Defekten wie Poren oder Risse. Durch diese Relevanz der thermischen Historie wäre die Aufzeichnung der auftretenden Realtemperaturen in zeitlicher und räumlicher Abhängigkeit optimal. Mit quantitativen Werten wären Vergleichbarkeit und Wiederholbarkeit des AM-Prozesses gegeben, was sich auch positiv auf Qualität und Sicherheit des gefertigten Bauteils auswirkt. Außerdem wäre ein Beitrag zur Validierung von Simulationen sowie zur Gewinnung eines tieferen Verständnisses des Fertigungsprozesses gegeben. Jedoch findet aktuell lediglich ein qualitatives Monitoring statt (bspw. mittels Überwachung des Schweißbades durch eine Photodiode) und sicherheitsrelevante Bauteile müssen zeit- und kostenaufwändig im Nachgang ex-situ geprüft werden. Grund dafür sind auch die herausfordernden Bedingungen des PBF-LB/M-Prozesses mit hohen Scangeschwindigkeiten bei geringem Durchmesser des Laserspots. Des Weiteren erschweren die auftretenden Emissionsgradänderungen mit hoher Dynamik (zeitlich, räumlich) und den gegebenen Abhängigkeiten (temperatur-/wellenlängenabhängig) eine berührungslose Temperaturbestimmung basierend auf emittierter Infrarotstrahlung deutlich. Klassische Thermografie bietet zwar sehr gute qualitative Einblicke, ist dabei jedoch ohne eine aufwändige Temperaturkalibrierung inklusive Bildsegmentierung und Zuweisung von vorher ermittelten Emissionsgraden für eine verlässliche Bestimmung der Realtemperatur nicht ausreichend. Aus diesem Grund wird in dieser Veröffentlichung der Ansatz der hyperspektralen Thermografie für den PBF-LB/M Prozess vorgestellt: Die emittierte Infrarotstrahlung wird gleichzeitig bei einer Vielzahl von benachbarten Wellenlängenbereichen gemessen. Dies wird in dieser Untersuchung mittels einer selbst zusammengestellten hyperspektralen Linienkamera, die im kurzwelligen Infrarotbereich arbeitet, realisiert. Hierbei wird die thermische Strahlung einer Linie auf dem Messobjekt spektral aufgespalten und detektiert, sodass die spektrale spezifische Ausstrahlung entlang dieser Linie vermessen werden kann. Bewegt sich das Schmelzbad des PBF-LB/M Prozesses bei ausreichender Bildfrequenz durch diese Linie, ist eine räumliche Rekonstruktion eines effektiven Schmelzbades möglich. Ein Ansatz, um aus diesen hyperspektralen Daten die gesuchten Emissionsgrade sowie die Realtemperatur zu ermitteln, sind Methoden der Temperatur-Emissionsgrad-Separation (TES). Ein Hauptproblem besteht darin, dass n spektrale Messungen verfügbar sind, jedoch n+1 Kenngrößen für jeden Bildpixel gesucht werden (n Emissionsgrade + eine Temperatur). TES-Methoden liefern die Möglichkeit, dieses mathematisch unterbestimmte Problem verlässlich und nachvollziehbar zu approximieren, indem der spektrale Emissionsgrad mit wenigen Freiheitsgraden analytisch parametriert wird. Mit Hilfe dieses Ansatzes werden Setup und Methoden an SAMMIE (Sensor-based Additive Manufacturing Machine), einer Forschungsmaschine für PBF-LB/M, angewendet. Erste Ergebnisse unter AM-Prozessbedingungen werden gezeigt, welche die Grundlage für die Bestimmung von Realtemperaturen im PBF-LB/M-Prozess bilden. Dies leistet einen wichtigen Beitrag zur verbesserten Vergleichbarkeit und Wiederholbarkeit der Fertigung, zur Validierung von Simulationen sowie zum Verständnis des Prozesses selbst. Das unterstützt langfristig dabei das Vertrauen in die Sicherheit von AM-Produkten zu stärken. T2 - TEMPERATUR 2024 CY - Berlin, Germany DA - 05.06.2024 KW - Additive Manufacturing KW - Laser Powder Bed Fusion KW - Schmelzbadtemperatur KW - Hyperspectral Imaging KW - Emissionsgrad KW - Quantitative Temperatur PY - 2024 AN - OPUS4-60753 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Altenburg, Simon T1 - SAMMIE – PBF-LB/M Research System for the Development of in-situ Monitoring methods N2 - The additive manufacturing of metals has now reached a level of maturity that enables its use in many branches of industry or brings it within reach. The main advantages are the ability to produce complex components that cannot be produced conventionally or only at great expense, as well as in the production of highly individualized components in small quantities. However, the additive manufacturing process is highly complex and prone to errors. In order to guarantee the quality control required particularly for safety-relevant components, complex downstream nondestructive testing NDT of the individual components is currently necessary. In-situ process monitoring and testing could offer alternatives, but these have not yet reached a sufficient level of functionality. Industrial production facilities offer little or no flexibility and accessibility to enable extensive investigations in this area. For this reason, we developed a system for the powder bed fusion process of metals (PBF-LB/M) called SAMMIE. It offers a completely open system architecture with full control over the process and flexible access to the build chamber, e.g., optically both on-axis and off-axis to the production laser. In this contribution, we present the system and show first experimental results of in-situ monitoring and testing, e.g., high-resolution thermographic melt pool monitoring, multispectral optical tomography, and high-speed videos of the process. SAMMIE enables us to conduct fundamental investigations that will help to further develop in-situ process monitoring and testing, gain new insights into the process, and improve its safety and reliability. T2 - 48th MPA-Seminar CY - Stuttgart, Germany DA - 08.10.2024 KW - PBF-LB/M KW - In situ monitoring KW - Custom machine KW - Additive Manufacturing KW - Process monitoring PY - 2024 AN - OPUS4-61350 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Becker, Tina T1 - PBF-LB/M: Prozess Monitoring mittels Multispektraler OT N2 - Die metallische additive Fertigung hat in den letzten Jahren in der industriellen Fertigung zunehmend an Bedeutung gewonnen. Hierbei dominiert das Laser-Pulverbettschweißen von Metallen (PBF/LB-M) die Fertigung von kleinformatigen Bauteilen mit hoher Oberflächengüte. Die anspruchsvolle und kostspielige Qualitätssicherung stellt aber weiterhin ein Hindernis für eine breitere und kostengünstigere Anwendung der additiven Fertigung dar. Dies resultiert teilweise aus fehlenden zuverlässigen In-situ-Monitoringsystemen. Belastbarere Prozessüberwachungsdaten würden eine oft erforderliche teure nachgelagerte Prüfung mittels Computertomografie entbehrlich machen. Die Aufzeichnung der thermischen Signaturen des Aufbauprozess mittels Thermografie-Kameras zeigen hier vielversprechende Ergebnisse. Eine Korrelation zu auftretender Porosität, Delaminationen und Deformationen scheinen möglich. Die geringe räumliche Auflösung und die hohen Anschaffungskosten für thermografische Kamerasysteme stehen jedoch einer größeren industriellen Nutzung im Wege. Ein bereits industriell angewendeter Ansatz zur in-Situ Überwachung des PBF-LB/M Prozesses ist die Optische Tomografie (OT). Hierbei wird die emittierte Prozessstrahlung jeder Bauteilschicht mittels einer hochauflösenden günstigen Kamera für den sichtbaren Wellenlängenbereich in einer Langzeitbelichtung dokumentiert. Die zeitliche Information der emittierten Strahlung geht hierbei verloren. Der gesamte Bauprozess kann jedoch in einem vergleichsweise kleinen Datensatz dokumentiert werden (ein Bild pro Schicht). Eine direkte Korrelation zu auftretenden Defekten gestaltet sich aufgrund der reduzierten thermischen Informationsdichte jedoch schwierig. In diesem Beitrag soll deshalb das Prinzip der Multispektralen Optischen Tomografie (MOT) vorgestellt und erste Messergebnisse an der Forschungsanlage SAMMIE diskutiert werden. Bei der MOT handelt es sich um eine Übertragung des Prinzips der Quotientenpyrometrie auf das etablierte Verfahren der Optischen Tomografie. Die auftretende Prozessstrahlung wird in mehreren Wellenlängenbereichen ortsaufgelöst über die gesamte Bauplattform erfasst und zeitlich in einer Langzeitbelichtung integriert. Hierbei kommen günstige Kamerasysteme für den sichtbaren Wellenlängenbereich zum Einsatz. Das erfasste Signal I jedes Bildpixels für jeden separat erfassten Wellenlängenbereich kann als Maß für das zeitliche Integral der spezifischen Ausstrahlung M des Schmelzbades in diesem Wellenlängenbereich gesehen werden. Nach dem Stefan-Boltzmann-Gesetz hängt die abgestrahlte thermische Leistung P eines idealen Schwarzen Körpers in der vierten Potenz von dessen absoluten Temperatur T ab. Wird nur, wie z.B. bei der klassischen OT angewendet, der nahinfrarote Wellenlängenbereich betrachtet, lässt sich mit dem Planck’schen Strahlungsgesetz sogar eine Proportionalität zur siebten Potenz der Temperatur zeigen. Deshalb liegt ein starker Einfluss der maximal auftretenden Oberflächentemperatur Tmax auf das erfasste Messsignal vor. Das erfasste Signal I wird aber auch durch die spektrale Transmission τ der verwendeten optischen Komponenten des Kamera-Setups, z.B. Filter und Objektive, durch die spektrale Sensitivität S der verwendeten Kamera-Sensoren und den nur sehr schwer zu bestimmenden Emissionsgrad ε der emittierenden (flüssigen) Oberfläche beeinflusst. In einer ersten Näherung wird das Schmelzbad hier als Graukörper, also ein Körper mit wellenlängenunabhängigem Emissionsgrad ε, betrachtet. Basierend auf dieser Annahme und vermessenen optischen Eigenschaften des verwendeten Systems ist es möglich, eine erste Schätzung der maximalen Oberflächentemperatur Tmax vorzunehmen, selbst ohne genaue Kenntnis des tatsächlichen Emissionsgrades ε. Dies wird durch die Anwendung des Planck‘schen Strahlungsgesetzes und die Quotienten Bildung aus den einzelnen erfassten Signalen I ermöglicht. Auch bei diesem Verfahren geht die zeitliche Information einer Schicht, also das Aufwärm- und Abkühlverhalten des Schmelzbades, verloren. Zudem sind die Messergebnisse in Hinblick auf tatsächlich gemessene „maximal auftretende Oberflächentemperatur“ mit gebotener Zurückhaltung zu interpretieren. Trotzdem konnten erste Ergebnisse bereits zeigen, dass die MOT-Daten auch in Bereichen mit Doppelbelichtungen (das teilweise notwendige mehrfache Scannen eines Bereiches mittels des Fertigungslasers) im Gegensatz zur klassischen OT erwartbare Maximaltemperaturen liefern. Abbildung 1 zeigt das erfasste Messergebnis für drei aufeinanderfolgende Schichten eines Bauteils einmal mit MOT (links) und einmal mit einfacher OT (rechts). Deutlich zu erkennen ist das durch die doppelte Belichtung hohe Signal bei der OT. Die Daten der MOT zeigen hier keine erhöhten Werte. Um die ermittelten Temperaturwerte mittels MOT besser einordnen zu können, sind u.a. vergleichende Messungen an Referenzmaterialien geplant. Um die Auswertung der gemessenen Daten zu verbessern, wird zudem der Zeitverlauf des Abkühlens und Aufheizens des Schmelzbades sowie die Einflüsse von Prozessbeiprodukten wie Schmauch und Spritzer näher untersucht. Auch werden Messungen zum Emissionsgrad ε an additiv gefertigten Proben und Metallschmelzen vorgenommen. T2 - Temperatur 2024 CY - Berlin, Germany DA - 05.06.2024 KW - PBF-LB/M KW - In situ monitoring KW - Optische Tomografie KW - Additive Fertigung KW - Prozessüberwachung KW - Additive Manufacturing PY - 2024 AN - OPUS4-60235 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Altenburg, Simon T1 - SAMMIE: Eigenbau-Anlage für Metall-AM zur Sensorentwicklung und Qualifizierung N2 - Im additiven Fertigungsprozess Laser-Pulverbettschweißen wird Metallpulver lagenweise mittels eines Lasers aufgeschmolzen, um Bauteile zu generieren. Hierbei werden die Eigenschaften der Bauteile zu einem großen Teil durch die im Verlauf des Prozesses vorliegenden Temperaturen bestimmt. Dies beinhaltet unter anderem Materialeigenschaften wie Mikrostruktur, Härte, thermische und elektrische Leitfähigkeiten sowie die Ausbildung von Defekten wie z.B. Anbindungsfehler, Keyhole-Porosität (Gaseinschlüsse) oder auch die Ausbildung von Rissen. Zur Überwachung bzw. Vorhersage dieser Eigenschaften sowie zum Abgleich von Simulationen ist eine orts- und zeitaufgelöste Messung der Temperaturverteilung im Prozess daher von herausragender Bedeutung. In der Industrie kommen optische Verfahren, die auf der Messung der thermischen Strahlung basieren, regelmäßig zum Einsatz. Allerdings dienen diese bislang nur der statistischen Auswertung und der Identifikation von Abweichungen vom Normalprozess. Der quantitativen Auswertung zur Temperaturbestimmung stehen aktuell noch eine Vielzahl von Herausforderungen entgegen. Einerseits stellt der Prozess an sich hohe Anforderungen an die Datenerfassung und -auswertung: der Emissionsgrad verändert sich dynamisch im Prozess und lokale Schmauchbildung sorgt für potenzielle Absorption oder Streuung der thermischen Strahlung oder auch des Fertigungslasers. Weiterhin stellt der hochdynamische Prozess hohe Anforderungen an Orts- und Zeitauflösung der eingesetzten Sensorik (z.B. Kameratechnik). Andererseits erschweren an üblichen kommerziell erhältlichen Fertigungsanlagen praktische Hindernisse wie eine eingeschränkte optische Zugänglichkeit und der fehlende Zugriff auf die Anlagensteuerung sowie fehlende Möglichkeiten der Synchronisation der Messtechnik mit dem Prozess eine eingehende Untersuchung dieser Effekte. Um letztere Hindernisse zu umgehen, wurde an der BAM die Forschungsanlage SAMMIE (sensor-based additive manufacturing machine) entwickelt. Einerseits bietet das System alle Möglichkeiten, die auch übliche kommerzielle Systeme bieten. Dies beinhaltet die Fertigung ganzer Bauteile (maximale Größe ca. 65mm x 45 mm x 30 mm) und den Einsatz einer Inertgasatmosphäre inkl. gefiltertem Schutzgasstrom. Andererseits bietet es aber auch einen besonders kompakten Bauraum, um die Sensorik möglichst nah an den Prozess führen zu können, sechs optische Fenster zur Prozessbeobachtung aus unterschiedlichen Winkeln und die Möglichkeit der Prozessbeobachtung koaxial zum Fertigungslaser. Des Weiteren besteht eine einfache Austauschbarkeit aller Fenster, Spiegel und Strahlteiler, um den gesamten optischen Pfad der aktuellen Messaufgabe flexibel anzupassen. Die komplette Anlagensteuerung ist eine Eigenentwicklung und bietet daher auch völlige Anpassbarkeit. Eine synchrone und frei konfigurierbare Triggerung diverser Sensoriken und synchrone Datenerfassung bieten maximale Kontrolle über die Sensorsteuerung. Dieser Beitrag gibt einen Überblick über die Fertigungsanlage SAMMIE. Wissenschaftliche Ergebnisse sowie laufende Arbeiten an der Anlage werden in weiteren Beiträgen vorgestellt. T2 - Temperatur 2024 CY - Berlin, Germany DA - 05.06.2024 KW - PBF-LB/M KW - In situ monitoring KW - Anlage KW - Additive Fertigung KW - Prozessüberwachung KW - Additive Manufacturing PY - 2024 AN - OPUS4-60234 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Becker, Tina T1 - Emissivity – Gamechanger for quantitative in-situ monitoring N2 - For a deep process understanding of the laser powder bed fusion process (PBF-LB/M), recording of the occurring surface temperatures is of utmost interest and would help to pave the way for reliable process monitoring and quality assurance. A notable number of approaches for in-process monitoring of the PBF-LB/M process focus on the monitoring of thermal process signatures. However, due to the elaborate calibration effort and the lack of knowledge about the occurring spectral directional emissivity, only a few approaches attempt to measure real temperatures. In this study, to gain initial insights into occurring in the PBF-LB/M process, measurements on PBF-LB/M specimens and metal powder specimens were performed for higher temperatures up to T = 1290 °C by means of the emissivity measurement apparatus (EMMA) of the Center for Applied Energy Research (CAE, Wuerzburg, Germany). Also, measurements at ambient temperatures were performed with a suitable measurement setup. Two different materials—stainless steel 316L and aluminum AlSi10Mg—were examined. The investigated wavelength λ ranges from the visible range (λ-VIS = 0.40–0.75 µm) up to the infrared, λ = 20 µm. The influence of the following factors were investigated: azimuth angle φ, specimen temperature TS, surface texture as for PBF-LB/M surfaces with different scan angles α, and powder surfaces with different layer thicknesses t. T2 - Rapid.Tech 3D 2024 CY - Erfurt, Germany DA - 14.05.2024 KW - PBF-LB/M KW - In situ monitoring KW - Emissivity KW - Additive Manufacturing PY - 2024 AN - OPUS4-60148 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Breese, Philipp Peter A1 - Altenburg, Simon T1 - Absolute temperature determination in laser powder bed fusion (PBF-LB/M) via hyperspectral thermography N2 - Temperature is a key characteristic in laser powder bed fusion of metals (PBF-LB/M). As a quantitative physical property, the temperature can determine the actual process quality independently from the nominal process parameters. Thus, establishing a process evaluation on temperatures rather than the comparison of process conditions is expected to be more effective. However, quantitative in situ temperature measurements with classical thermographic methods are virtually impossible. The reason is that the required emissivity value changes drastically throughout the process. Additionally, large temperature ranges along with the highly dynamic nature of the PBF-LB/M process make temperature measurements difficult. Based on this challenge, this work presents a method for hyperspectral temperature determination. The spectral exitance (in W/m2⋅nm) was measured in situ at many adjacent wavelengths in the short-wave infrared (SWIR). This enabled a local temperature determination via Planck’s law in combination with a spectral emissivity function. The temperature field of the melt pool crossing the 1D measurement line was reconstructed from the information, gathered at nearly 20 kHz sampling rate. The reconstructed melt pool had a spatial resolution of 17 µm by 40 µm, and temperatures between 2700 and 1300 K were observable. Comparison of the 316L stainless steel solidification temperature and the observed solidification plateau in the gathered thermal data revealed a relative error of less than 6% in the absolute temperature measurement. These initial results of hyperspectral temperature determination in PBF-LB/M show the potential in the method. It allows for physically founded process evaluation, and the prospects for tuning and validation of numerical simulations are highly promising. KW - Additive Manufacturing KW - Infrared Thermography KW - In-situ Monitoring KW - Quantitative Temperature Measurement KW - Emissivity PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-631977 DO - https://doi.org/10.1007/s40964-025-01148-8 SN - 2363-9512 SP - 1 EP - 10 PB - Springer Science and Business Media LLC AN - OPUS4-63197 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Breese, Philipp Peter A1 - Becker, Tina A1 - Oster, Simon A1 - Metz, C. A1 - Altenburg, Simon T1 - In-situ defect detection for laser powder bed fusion with active laser thermography N2 - Defects are still common in metal components built with Additive Manufacturing (AM). Process monitoring methods for laser powder bed fusion (PBF-LB/M) are used in industry, but relationships between monitoring data and defect formation are not fully understood yet. Additionally, defects and deformations may develop with a time delay to the laser energy input. Thus, currently, the component quality is only determinable after the finished process. Here, active laser thermography, a nondestructive testing method, is adapted to PBF-LB/M, using the defocused process laser as heat source. The testing can be performed layer by layer throughout the manufacturing process. We study our proposed testing method along experiments carried out on a custom research PBF-LB/M machine using infrared (IR) cameras. Our work enables a shift from post-process testing of components towards in-situ testing during the AM process. The actual component quality is evaluated in the process chamber and defects can be detected between layers. T2 - 2023 International Solid Freeform Fabrication Symposium CY - Austin, TX, USA DA - 14.08.2023 KW - Additive Manufacturing KW - Laser Powder Bed Fusion KW - Nondestructive Testing KW - Thermography KW - Defect Detection PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-606288 DO - https://doi.org/10.26153/tsw/51096 SP - 1978 EP - 1989 PB - University of Texas at Austin CY - Austin, TX, USA AN - OPUS4-60628 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Oster, Simon T1 - A comparison of machine learning approaches for porosity prediction in PBF-LB/M based on thermography N2 - Metal-based additive manufacturing processes are increasingly used in industry to produce complex-shaped components. In this regard, the laser-based Powder Bed Fusion process (PBF-LB/M) is one of the key technologies due to its capability to produce components in high spatial accuracy. The formation of porosity during manufacturing poses a serious risk to the safety of the printed parts. For quality assessment, in-situ monitoring technologies such as thermography can be used to capture the thermal history during production. It was shown that discontinuities within the thermal history can be correlated with the probability of porosity or defect formation. In this context, Machine Learning (ML) algorithms have achieved promising results for the task of porosity prediction based on thermographic in-situ monitoring data. One important technique is the use of thermogram features for porosity prediction that are extracted from the raw data (e.g., features related to the melt pool geometry or spatter generation). However, the reduction from large thermogram data to discrete features holds the risk of losing potentially important thermal information and, thereby, introducing bias in the model. Therefore, we present a raw data-based deep learning approach that uses thermographic image sequences for the prediction of local porosity. The model takes advantage of the self-attention mechanism that considers not only the thermogram information but also its positional context within the sequence. The model is used to predict porosity in the form of a many-to-one regression. It is trained and tested on a dataset retrieved from the manufacturing of HAYNES282 cuboid specimens. The model results are compared against state-of-the-art thermogram feature-based ML models and artificial neural networks. The raw data model outperforms its feature-based counterparts in terms of prediction scores and, therefore, seems to make better use of the information available in the thermogram data. T2 - 4th Symposium on Materials and Additive Manufacturing CY - Berlin, Germany DA - 12.06.2024 KW - PBF-LB/M KW - In situ monitoring KW - Thermography KW - Additive Manufacturing KW - Machine learning KW - Porosity prediction PY - 2024 AN - OPUS4-62472 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Scheuschner, Nils T1 - SAMMIE - Research PBF-LB/M system for the development of in-situ monitoring methods N2 - By allowing economic on-demand manufacturing of highly customized and complex workpieces, metal based additive manufacturing (AM) has the prospect to revolutionize many industrial areas. Since AM is prone to the formation of defects during the building process, a fundamental requirement for AM is to find ways to assure the safety and reliability of the additively manufactured parts to become applicable in most fields. A possible solution for this problem lies in the deployment of various in-situ monitoring techniques. However, only a few of these techniques are commercially available and are not researched to an extent that allows to guarantee the adherence to strict quality and safety standards. Since commercial AM machines are not designed for research applications, they provide only limited access to the build chamber during the process and little control over the exact timing and parameters of the process. Therefore, for our research at BAM, we built a laser powder bed fusion system (PBF-LB/M), called “Sensor-based Additive Manufacturing MachInE” (SAMMIE). It provides a fully open system architecture with flexible accesses to the build camber and full control of the complete process. In this contribution, we show first results using thermographic cameras and optical tomography. The flexibility of SAMMIE allows us to use the multiple cameras either fixed relatively to the build plate or coaxially to the process laser. T2 - 20th World Conference on Non-Destructive Testing (WCNDT) CY - Incheon, South Korea DA - 27.05.2024 KW - PBF-LB/M KW - In situ monitoring KW - Custom machine KW - Additive Manufacturing KW - Thermography PY - 2024 AN - OPUS4-62471 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Altenburg, Simon T1 - SAMMIE – Forschungssystem für die additive Fertigung von Metallen (PBF-LB/M) zur Entwicklung von In-situ-Überwachungs- und -prüfmethoden N2 - Die additive Fertigung von Metallen hat inzwischen einen Reifegrad erreicht, der einen Einsatz in vielen Industriezweigen ermöglicht oder in greifbare Nähe rückt. Die Vorteile liegen vor allem in der Möglichkeit der Fertigung komplexer Bauteile, die sich konventionell nicht oder nur sehr aufwändig produzieren lassen, sowie in der Fertigung von hochindividualisierten Bauteilen in kleinen Stückzahlen. Allerdings ist der additive Fertigungsprozess hoch komplex und fehleranfällig. Um eine insbesondere für sicherheitsrelevante Bauteile notwendige Qualitätskontrolle zu gewährleisten, ist aktuell aufwändige nachgelagerte ZfP der einzelnen Bauteile notwendig. Alternativen könnten die In-situ-Prozessüberwachung und -prüfung bieten, die aktuell aber noch keinen ausreichenden Entwicklungsstand erreicht haben. Industrielle Fertigungsanlagen bieten keine oder nur geringe Flexibilität und Zugänglichkeit, um umfangreiche Untersuchungen auf diesem Gebiet zu ermöglichen. Daher haben wir an der BAM ein System für den Prozess des selektiven Laserschmelzens (PBF-LB/M) entwickelt, genannt SAMMIE. Es bietet eine komplett offene Systemarchitektur mit voller Kontrolle über den Prozess und flexiblem Zugang zur Baukammer, z.B. optisch sowohl direkt als auch koaxial zum Fertigungslaser. In diesem Beitrag stellen wir das System vor und zeigen erste experimentelle Ergebnisse der In-situ-Überwachung und -prüfung: Thermografische Schmelzbadüberwachung, optische Tomografie und In-situ-Laserthermografie. SAMMIE ermöglicht uns grundlegende Untersuchungen, die helfen werden, die In-situ-Prozessüberwachung und -prüfung weiterzuentwickeln, neue Erkenntnisse über die additive Fertigung zu gewinnen und die Sicherheit und Zuverlässigkeit des Prozesses zu verbessern. T2 - DGZfP-Jahrestagung 2024 CY - Osnabrück, Germany DA - 06.05.2024 KW - PBF-LB/M KW - In situ monitoring KW - Anlage KW - Additive Fertigung KW - Prozessüberwachung KW - Additive Manufacturing PY - 2024 AN - OPUS4-60149 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Altenburg, Simon A1 - Scheuschner, Nils A1 - Maierhofer, Christiane A1 - Mohr, Gunther A1 - Hilgenberg, Kai T1 - Thermography in laser powder bed fusion of metals: time over threshold as feasible feature in thermographic data N2 - Thermography is one on the most promising techniques for in-situ monitoring of metal additive manufacturing processes. Especially in laser powder bed fusion processes, the high process dynamics and the strong focus of the laser beam cause a very complex thermal history within the produced specimens, such as multiple heating cycles within single layer expositions. This complicates data interpretation, e.g., in terms of cooling rates. A quantity that is easily calculated is the time a specific area of the specimen is at a temperature above a chosen threshold value (TOT). Here, we discuss variations occurring in time-over-threshold-maps during manufacturing of an almost defect free cuboid specimen. T2 - 15th Quantitative InfraRed Thermography conference CY - Online meeting DA - 21.09.2020 KW - Additive Manufacturing KW - Process monitoring KW - Thermography KW - L-PBF KW - Time over threshold PY - 2020 DO - https://doi.org/10.21611/qirt.2020.005 SP - 1 EP - 5 PB - QIRT Council CY - Quebec, Canada AN - OPUS4-52014 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Scheuschner, Nils T1 - Infrared Thermography of the DED-LB/M and PBF LB/M processes N2 - Infrared thermography is a technique that allows to measure the temperatures of objects by analyzing the intensity of the thermal emission without the need of direct contact with very high spatial and temporal resolution. As the temperature is a fundamental factor for the additive manufacturing processes of metals, infrared thermography can provide experimental data that can be used for the validation of simulations and improving the understanding of the processes as well as for in-situ process monitoring for nondestructive evaluation (NDE) for quality control. In this talk we will provide an overview over the possibilities of state of the art thermographic in-situ monitoring systems for the DED-LB/M and PBF-LB/M processes and the challenges such as phase transitions and unknown emissivity values in respect to the determination of real temperatures. We define the requirements for different camera systems in various configurations and give examples on the selection of appropriate measurement parameters and data acquisition techniques as well as on techniques for data analysis and interpretation. Finally, we compare in-situ monitoring methods against post NDE methods by analyzing the advantages and disadvantages of both. This research was funded by BAM within the Focus Area Materials. T2 - Coupled2021 - IX International Conference on Coupled Problems in Science and Engineering CY - Online meeting DA - 13.06.2021 KW - Additive Manufacturing KW - Thermography KW - Direct Energy Deposition PY - 2021 AN - OPUS4-54399 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Altenburg, Simon T1 - Measurement of real temperatures in metal powder bed fusion: Hyperspectral thermography N2 - Detailed knowledge about the physics of the PBF-LB/M process is still lacking, and the simulation of the fast and small-scale process is challenging. Especially the experimental validation of complex simulations lacks a suitable measurement technique for temperature distributions at high speeds and spatial resolution. The complicated process physics, specifically the rapidly changing emissivity in and around the meltpool, pose a severe challenge for usual thermographic approaches. Here, we present first results of a hyperspectral measurement approach to reconstruct temperature and emissivity maps during the PBF-LB/M process in a custom manufacturing machine. The camera setup measures the thermal radiation of the process along a line at a rate of 20 kHz, spectrally resolved between 1 µm and 1.6 µm. When the meltpool travels perpendicularly across this line, a typical meltpool can be reconstructed by pointwise fitting for temperature emissivity separation, based on typical spectral emissivities from reference measurements. T2 - Lasers in Manufacturing Conference - LiM CY - Munich, Germany DA - 23.06.2025 KW - PBF-LB/M KW - In situ monitoring KW - Thermography KW - Additive Manufacturing KW - Process monitoring KW - Hyperspectral PY - 2025 AN - OPUS4-63564 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Breese, Philipp Peter T1 - Fundamentals of quantitative temperature determination during laser powder bed fusion of metals (PBF-LB/M) via hyperspectral thermography N2 - Additive manufacturing (AM, also known as 3D printing) of metals is becoming increasingly important in industrial applications. Reasons for this include the ability to realize complex component designs and the use of novel materials. This distinguishes AM from conventional manufacturing methods such as subtractive manufacturing (turning, milling, etc.). The most widely used AM process for metals is laser powder bed fusion (PBF-LB/M, also known as selective laser melting SLM). Currently, it has the highest degree of industrialization and the largest number of machines in use. In PBF-LB/M, the feedstock is present as metal powder in an inert gas atmosphere inside a process chamber where a laser melts it locally. By repeatedly lowering the build platform, applying a new layer of powder, and then selectively melting it with the laser, a component is built up layer by layer. The local temperature distributions that occur during this process determine not only the properties of the finished component, but also the possible formation of defects such as pores and cracks. Due to the high relevance of the thermal history for precise geometries and defect formation, a temporally and spatially resolved measurement of quantitative (or real/actual) temperatures would be optimal. Quantitative values would ensure comparability and repeatability of the AM process which would also positively affect the quality and safety of the manufactured component. Furthermore, it would also contribute to the validation of simulations and to a deeper understanding of the manufacturing process itself. At present, however, only qualitative monitoring of the thermal radiation is performed (e.g., by monitoring the melt pool using a photodiode), and safety-relevant components must be inspected ex situ afterwards which is time-consuming and costly. A reason for the lack of quantitative temperature data from the process are the challenging conditions of the PBF-LB/M process with high scanning speeds and a small laser spot diameter. Furthermore, the emissivity of the surface changes at high dynamics (temporally/spatially) as well as with temperature and wavelength. This specifically makes contactless temperature determination based on emitted infrared radiation challenging for PBF-LB/M. Although classical thermography offers very good qualitative insights, it is not sufficient for a reliable quantitative temperature determination without a complex temperature calibration including image segmentation and assignment of previously determined emissivities. For this reason, this publication presents the hyperspectral thermography approach for the PBF-LB/M process: The emitted infrared radiation is measured simultaneously at many adjacent wavelengths. In this study, this is realized via a fast hyperspectral line camera that operates in the short-wave infrared range. The thermal radiation of a line on the target is spectrally dispersed and detected to measure the radiant exitance along that line. If the melt pool of the PBF-LB/M process moves through this line at a sufficient frame rate, a spatial reconstruction of an effective melt pool is possible. One approach to determine the desired emissivities and the quantitative temperature from this hyperspectral data are temperature-emissivity separation (TES) methods. A major problem is that n spectral measurements are available, but n+1 parameters are required for each image pixel (n emissivity values + one temperature value). TES methods offer the possibility to approximate this mathematically underconstrained problem in a reliable and traceable way by analytically parameterizing the spectral emissivity with a few degrees of freedom. Using this approach, setup and method are applied to a research machine for PBF-LB/M, called SAMMIE (Sensor-based Additive Manufacturing Machine). First results under AM process conditions are shown which form the basis for the determination of quantitative temperatures in the PBFLB/M process. This marks an important contribution to improving the comparability and repeatability of production, validating simulations, and understanding the process itself. When fully developed and validated, the presented method can also provide reference measurements to evaluate and optimize other, more practical monitoring methods, such as melt pool monitoring or optical tomography. In the long run, this will help to increase confidence in the safety of AM products. T2 - QIRT 2024 CY - Zagreb, Croatia DA - 01.07.2024 KW - Additive Manufacturing KW - Additive Fertigung KW - Real Temperature KW - Melt Pool KW - Emissivity PY - 2024 AN - OPUS4-60762 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Altenburg, Simon T1 - Thermography in laser powder bed fusion of metals: time over threshold as feasible feature in thermographic data N2 - Thermography is one on the most promising techniques for in-situ monitoring for metal additive manufacturing processes. The high process dynamics and the strong focus of the laser beam cause a very complex thermal history within the produced specimens, such as multiple heating cycles within single layer expositions. This complicates data interpretation, e.g., in terms of cooling rates. A quantity that is easily calculated is the time a specific area of the specimen is at a temperature above a chosen threshold value (TOT). Here, we discuss variations occurring in time-over-threshold-maps during manufacturing of a defect free cuboid specimen. T2 - 15th Quantitative InfraRed Thermography conference CY - Online meeting DA - 21.09.2020 KW - Additive Manufacturing KW - Process monitoring KW - Thermography KW - L-PBF KW - Time over threshold PY - 2020 AN - OPUS4-51630 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mohr, Gunther T1 - In situ heat accumulation by geometrical features obstructing heat flux and by reduced inter layer times in laser powder bed fusion of AISI 316L stainless steel N2 - Material qualification for laser powder bed fusion (L-PBF) processes are often based on results derived from additively manufactured (AM) bulk material or small density cubes, although it is well known that the part geometry has a tremendous influence on the heat flux and, therefore, on the thermal history of an AM component. This study shows experimentally the effect of simple geometrical obstructions to the heat flux on cooling behavior and solidification conditions of 316L stainless steel processed by L-PBF. Additionally, it respects two distinct inter layer times (ILT) as well as the build height of the parts. The cooling behavior of the parts is in-situ traced by infrared (IR) thermography during the built-up. The IR signals reveal significant differences in cooling conditions, which are correlated to differences in melt pool geometries. The acquired data and results can be used for validation of computational models and improvements of quality assurance. T2 - 11th CIRP Conference on Photonic Technologies (LANE 2020) CY - Online meeting DA - 07.09.2020 KW - Additive Manufacturing PY - 2020 AN - OPUS4-51255 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mohr, Gunther T1 - Prozessinduzierte Vorerwärmung beim pulverbasierten Laserstrahlschmelzen und deren Auswirkung auf die Bauteileigenschaften austenitischer Stahlbauteile N2 - Heterogene Fehlstellendichten und Mikrostrukturausbildungen sind große Heraus-forderungen für den Einsatz des pulverbettbasierten Laserstrahlschmelzens (L PBF) besonders für sicherheitskritische Bauteile. Unter der Vielzahl an Einflussfaktoren auf die Qualität und die mechanischen Eigenschaften von L PBF-Bauteilen hat die Zwischenlagenzeit (ILT) bisher wenig Beachtung gefunden. Sie nimmt ebenso wie die Bauteilgeometrie Einfluss auf die thermische Historie während der Fertigung. Ihr Einfluss auf die intrinsische Vorerwärmung ist in Kombination mit der Bauteilhöhe mittels thermografischer Temperaturmessung untersucht worden. Signifikante Unterschiede in der thermischen Historie konnten dabei mit variierenden Schmelzbaddimensionen, Korngrößen und Fehlstellendichten am Beispiel der austenitischen Stahllegierung AISI 316L in Zusammenhang gebracht werden. T2 - DVM Tagung Additiv gefertigte Bauteile und Strukturen CY - Berlin, Germany DA - 03.11.2021 KW - Additive Manufacturing KW - Laser powder bed fusion KW - In-situ process monitoring PY - 2021 AN - OPUS4-53729 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Merz, Benjamin T1 - Position Detection for Hybrid Repair of gas turbine blades using PBF-LB/M N2 - This poster presents a workflow for camera-based position detection of components within PBF-LB/M machines. This enables a hybrid repair process of highly stressed components such as gas turbine blades using PBF-LB/M. T2 - Kuratoriumsführung CY - Berlin, Germany DA - 21.06.2022 KW - Additive Manufacturing KW - PBF-LB/M KW - Position detection KW - Camera KW - Image processing PY - 2022 AN - OPUS4-56587 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gupta, Kanhaiya T1 - Microstructural fingerprinting of additively manufactured components prepared by PBF LB/M N2 - Additive manufacturing (AM) is rapidly emerging from rapid prototyping to industrial production [1]. Thus, providing AM parts with a tagging feature that allows identification, like a fingerprint, can be crucial for logistics, certification, and anti-counterfeiting purposes since nearly any geometry can be produced by AM with stolen data or reverse engineering of an original product. However, the mechanical and functional properties of the replicated part may not be identical to the original ones and pose a safety risk [2]. Several methods are already available, which range from encasing a detector to leveraging the stochastic defects of AM parts for the identification, authentication, and traceability of AM components. The most prevailing solution consists of local process manipulation, such as printing a quick response (QR) code [3] or a set of blind holes on the surface of the internal cavity of hollow components. Local manipulation of components may alter the properties. The external tagging features can be altered or even removed by post-processing treatments. Integrating electronic systems [4] in AM parts can be used to identify and authenticate components with complex or customized geometries. However, metal-based AM, especially in powder bed fusion (PBF-LB/M) techniques, has a strong shielding effect that interferes with the communication between the reader and the transponder. Figure 1: Selection of the few most prominent pores sorted according to decreasing volume that are suitable for tagging and authentication. Our work aims to provide a new methodology for the identification, authentication, and traceability of AM components using microstructural feathers in AM components without altering their properties. Further, we set various benchmark points that can be used in generating the fingerprints for both identification and authentication. This can help digitalize traceability information and tagging features via the link between the physical and cyber worlds through a deeper understanding of the printed object-tag-virtual twin integration. T2 - MSE Konferennz CY - Darmstadt, Germany DA - 24.09.2024 KW - Fingerprint KW - Additive Manufacturing KW - Computed tomography PY - 2024 AN - OPUS4-62286 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Meinel, Dietmar T1 - Classic Materials Testing in the Light of CT N2 - Currently, mandatory requirements and recommendations for the detection of irregularities in laser beam welded joints are based on classic micrographs as set out in the standard ISO 13919-1:2019. Compared to classic micrographs, computed tomography enables a non-destructive, three-dimensional and material-independent mode of operation, which delivers much more profound results. Even in building material testing, methods with limited informative value can be checked and supplemented by CT examinations. T2 - 13th International Conference on Industrial Computed Tomography (iCT2024) CY - Wels, Austria DA - 06.02.2024 KW - Computed Tomography KW - Additive Manufacturing KW - Machine-Learning Segmentation KW - Air Void System PY - 2024 AN - OPUS4-59568 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schröpfer, Dirk T1 - Process-related influences and correlations in wire arc additive manufacturing of high-strength steels N2 - High-strength fine-grained structural steels have great potential for weight-optimized, efficient structures in many modern steel applications. Further advances in efficiency can be achieved through additive manufacturing and bionic design. Commercial high-strength filler materials for wire arc additive manufacturing (WAAM) are already provided by the consumable producers. Today, application would be strictly limited due to absence of quantitative findings or any guidelines for the industry regarding welding-related stresses and component safety during manufacturing and service. Hence, process- and material-related influences and design-related restraint conditions associated with formation of residual stresses and cold cracking risk are investigated. The aim is the accessibility of special WAAM self-restraining cold cracking tests and easy applicable processing recommendations, enabling an economical, fit-for-purpose and crack-safe WAAM of high-strength steels. This first study focuses on determination of interactions between WAAM process parameters, resulting layer geometry, microstructure and residual stresses, analyzed via X-ray diffraction. Defined reference specimens are automated welded using a special WAAM solid wire (yield strength >820 MPa). Geometric properties can be specifically adjusted by wire feed and welding speed, but cannot be varied arbitrarily, since a high heat input causes local overheating, inadmissible changes of microstructure and mechanical properties, defects and comparable high tensile residual stresses. T2 - 22. Werkstofftechnischen Kolloquium der TU Chemnitz CY - Online meeting DA - 24.03.2021 KW - Additive Manufacturing KW - High-strength steel KW - Residual stresses PY - 2021 AN - OPUS4-53328 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Marquardt, R. A1 - Biegler, M. A1 - Rethmeier, Michael T1 - Funktional gradierte Materialien auf Basis von Stellite und Stahl im Laserpulver-Auftragschweißen N2 - Das Hinzufügen von Stellite auf Stahl ist eine typische Vorgehensweise um Bauteile gegen Verschleiß und Korrosion zu schützen. Der Sprung in den Materialeigenschaften kann jedoch zu Rissen und somit zum Versagen der Beschichtung führen. Um die Lebensdauer von Beschichtungen zu erhöhen wird daher ein gradierter Übergang mit verschiedenen Materialpaarungen untersucht. T2 - 13. Fachtagung Verschleiss- und Korrosionsschutz von Bauteilen durch Auftragschweißen CY - Haale (Saale), Germany DA - 22.06.2022 KW - FGM KW - DED KW - AM KW - Functionally Graded Materials KW - Additive Manufacturing KW - Directed Energy Deposition PY - 2022 SP - 66 EP - 73 AN - OPUS4-55504 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Marquardt, R. A1 - Bähring, S. A1 - Biegler, M. A1 - Rethmeier, Michael T1 - Künstliche Neuronale Netze zur Qualitätsprognose von Funktional Gradierten Materialien im laserbasierten Directed Energy Deposition N2 - Durch pulverbasiertes Directed-Energy Deposition lassen sich Gradierungen fertigen, um diskrete Materialübergänge zu vermeiden und die Lebensdauer von Hartschichten zu erhöhen. Die Kombination aus Stahl als Basiswerkstoff und einer verschleiß- und korrosionsbeständigen Co-Cr Legierung verspricht durch Vermeiden von Spannungskonzentrationen das Verhindern von Abplatzungen und Rissen in der Schutzschicht. Um die Qualität des gefertigten Bauteils zu beurteilen, liegen für solche Funktional Gradierten Materialien (FGM) wenig Erkenntnisse vor. Daher wird im Rahmen dieser Studie eine Methodik erarbeitet, um die relative Dichte eines Funktional Gradierten Materials auf Stahl und Co-Cr Basis mittels Maschinendaten zu bestimmen. Anschließend wird unter Einsatz eines künstlichen neuronalen Netzes anhand von Sensordaten die relative Dichte vorhergesagt. Das trainierte Netz erreicht eine Vorhersagegenauigkeiten von 99,83%. Abschließend wird eine Anwendung anhand von einem Demonstrator gezeigt. T2 - 3. Fachtagung Additive Manufacturing CY - Halle, Germany DA - 05.10.2023 KW - Directed Enery Deposition KW - Künstliche Neuronale Netze KW - Additive Manufacturing KW - DED KW - KI KW - AM PY - 2023 SP - 1 EP - 8 PB - SLV Halle AN - OPUS4-58692 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Marquardt, R. A1 - Osayi, J. A1 - Kmieciak, S. A1 - Biegler, M. A1 - Rethmeier, Michael T1 - Verschleißschutz einer Schneckengeometrie durch funktional gradierte Materialien N2 - Hochbelastete Stahlbauteile lassen sich durch Auftragen von Kobalt-Chrom Legierungen vor Verschleiß schüt-zen. Die plötzliche Änderung der Materialeigenschaften führt jedoch zu Spannungen und Rissen im Anbindungs-bereich. Daraus resultierende Abplatzungen stellen eine Gefahr für die Funktionsfähigkeit der Maschine und damit für Mensch und Umwelt dar. Um die Belastbarkeit der Schutzschicht zu verbessern, kann die Anbindung durch einen gradierten Materialübergang optimiert werden. Diese funktional gradierten Materialien können mit-tels pulverbasiertem Directed Energy Deposition aufgetragen werden. Die Methodik zum Aufbau und zur Quali-tätssicherung solcher Materialien wurde in vorangegangenen Arbeiten für dickwandige Geometrien gezeigt. Für dünnwandige Geometrien ist die Anwendbarkeit bisher unzureichend untersucht worden. Diese Arbeit zeigt am Beispiel einer dünnwandigen gradierten Schneckengeometrie die Einsatzfähigkeit der Methodik. Dafür wird die Gefügestruktur der Gradierung auf Fehler untersucht und der Härteverlauf gemessen. Außerdem wird die relative Dichte anhand eines bereits trainierten neuronalen Netzes vorhergesagt und mit einer Porositätsuntersuchung verglichen. T2 - 14. Tagung Verschleiß- und Korrosionsschutz von Bauteilen durch Auftragschweißen CY - Halle (Saale), Germany DA - 12.06.2024 KW - Directed Enery Deposition KW - Funktionally Graded Material KW - Additive Manufacturing KW - DED KW - FGM KW - AM PY - 2024 AN - OPUS4-62688 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Winkler, Michael T1 - Automated Repair of Gas Turbine Blades Using DED-Arc N2 - Gas turbine blades are critical components in aerospace and power generation, often subject to wear, erosion, and fatigue-induced damage. Traditional repair methods are labor-intensive, costly, prone to inconsistencies, and not rapidly adaptable. This work presents an automated approach for repairing gas turbine blade tips using Wire and Arc Directed Energy Deposition (DED-Arc) in combination with a high-precision point to point registration technique of laser line triangulation (LLT) 3D scans. The proposed workflow begins with affixation of the milled down turbine blade to a work piece manipulator using a 3D printed clamping mechanism and a rough alignment of the turbine tip. Subsequently, the turbine blade’s geometry is acquired using a fully integrated 3D laser triangulation sensor, transforming, and aggregating the captured 2D line data into a 3D scan in the working user coordinate system using live feedback data from a finely calibrated industry robot. This point cloud representation of the real-world turbine blade is then used as the target during an advanced point-to-point shape registration technique transforming the digital representation of the repair process containing all relevant tool path and geometry data into the coordinate system of the real-world turbine blade. Afterwards, the turbine tip is then iteratively repaired whereby the turbine tip geometry is divided into differentiated sections, each with its own optimized process parameter set. A key innovation in this approach is the adaptability of the repair process through a closed-loop monitoring system. After each DED-Arc deposition, a 3D scan is performed to document the deposited geometry, to detect the interaction of the different process parameter sets, to activate an intervention if necessary, and calculate subsequent tool paths based on current geometry data. The results indicate that the combination of precise 3D scan registration with DED-Arc is a viable solution for the industrial-scale repair of gas turbine blades leading to significant reduction in labor, tooling, process, and time related cost. T2 - IIW Assembly CY - Genoa, Italy DA - 22.06.2025 KW - DED-Arc KW - Additive Manufacturing KW - Repair KW - Turbine Blade KW - Automation PY - 2025 AN - OPUS4-63624 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Altenburg, Simon T1 - Machine Learning and Thermography as Tools for Local Porosity Prediction in AM of Metals N2 - Quality assurance of metal additive manufacturing (PBF-LB/M) is still a challenge. Offering deep process insights, thermography is a well-suited monitoring technique. Here, we show how machine learning based on thermographic data enables a local part porosity prediction. T2 - Laser Applications Conference (LAC) CY - Prague, Czech Republic DA - 19.10.2025 KW - PBF-LB/M KW - In situ monitoring KW - Thermography KW - Additive Manufacturing KW - Process monitoring KW - Porosity prediction KW - Machine Learning KW - Feature extraction PY - 2025 AN - OPUS4-64669 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Chaurasia, Prashant Kumar A1 - Fabry, Çağtay A1 - Pittner, Andreas A1 - De, Amitava A1 - Rethmeier, Michael T1 - Automated in situ monitoring and analysis of process signatures and build profiles during wire arc directed energy deposition N2 - Wire arc directed energy deposition (DED-Arc) is an emerging metal additive manufacturing process to build near-net shaped metallic parts in a layer-by-layer with minimal material wastage. Automated in situ monitoring and fast-responsive analyses of process signatures and deposit profiles during DED-Arc are in ever demand to print dimensionally consistent parts and reduce post-deposition machining. A comprehensive experimental investigation is presented here involving real-time synchronous measurement of arc current, voltage, and the deposit profile using a novel multi-sensor monitoring framework integrated with the DED-Arc set-up. The recorded current–voltage transients are used to estimate the time-averaged arc power, and energy input in real time for an insight of the influence of wire feed rate and printing travel speed on the deposit characteristics. A unique attempt is made to represent the geometric profiles of the single-track deposits in a generalized mathematical form corresponding to a segmented ellipse, which has exhibited the minimum root-mean-square error of 0.03 mm. The dimensional inconsistency of multi-track deposits is evaluated quantitatively in terms of waviness using build profile monitoring and automated estimation, which is found to increase with an increase in step-over ratio and energy input. For the multi-track mild steel deposits, the suitable range of step-over ratio for the minimum surface waviness is observed to lie between 0.6 and 0.65. Collectively, the proposed framework of synchronized process monitoring and real-time analysis provides a pathway to achieve dimensionally consistent and defect-free parts, and highlights the potential for closed-loop control systems for a wider industrial application of DED-Arc. KW - Additive Manufacturing KW - Arc welding KW - DED-arc KW - Real-time monitoring and control KW - Dimensional inconsistency PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-642029 DO - https://doi.org/10.1007/s40964-025-01333-9 SN - 2363-9512 SP - 1 EP - 20 PB - Springer Science and Business Media LLC CY - Cham AN - OPUS4-64202 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Chaurasia, Prashant Kumar T1 - Automated In-situ Monitoring and Analysis of Process Signatures and Build Profile During Arc-based Directed Energy Deposition N2 - Automated in-situ synchronous monitoring and analysis of key process signatures during arc-based directed energy deposition (DED) process are the key challenges for layer-by-layer printing of large-scale parts. An attempt is presented here for real-time monitoring of process transients, deposit profile, and quantitative assessment of arc power, energy input and its influence on deposit dimensions. The workflow including setup, job generation and data analysis is fully automated in Python to allow large scale experiments with fast analysis results. T2 - 2nd Online Young Welding Professional International Conference CY - Online meeting DA - 06.02.2025 KW - Additive Manufacturing KW - Arc welding KW - DED-arc KW - Monitoring KW - Deposition profile PY - 2025 AN - OPUS4-62663 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fabry, Çağtay T1 - Towards arc welding reference data: Open Science laboratories at BAM N2 - As industries move for ever faster development and adoption cycles of emerging new technologies in the field of welding, the meticulous and longer-winded approach of the scientific research process can feel harder to integrate. To help bridge this gap and increase the speed, quality, and adoption rate of publicly funded research, the Bundesanstalt für Materialforschung und -prüfung (BAM) continues to work towards enabling scientists with direct access to necessary software tools and - in the future – highest quality welding research reference data to further foster collaborations. On the experimental side, the arc welding group at BAM division 9.3 “welding technologies” is continuing to expand and upgrade its capacities of robotic welding systems with integrated state of the art sensor technologies and software solutions. This allows all experiments to be recorded and measured in micro-millimeter accuracy and at sub-millisecond precision, including welding process data, complete spatial geometry and temperature measurements, process video recordings and more. The custom software-based solutions and interfaces allow scaling of the welding systems from large thick plate offshore applications to small additive repair weldments in wind turbine blades to multi-hour continuous weldments in additive manufacturing applications. In addition to the data gathered during the welding process itself, the relevant testing results and materials properties produced at BAM or externally can be integrated seamlessly. This allows detailed traceability of all results back to the actual welding process. Regardless of the scope and application, complete datasets can be made accessible for research or industry partners in the highest resolution based on the open source WelDX (welding data exchange) file format. Figure 1. Welding experiment representation including dynamic process data, cross-section imaging and hardness measurements from a single weldx file. The talk will give an overview of the experimental facilities and workflows as well as current software developments with a focus on research data quality assurance, traceability, and accessibility. Based on the integration into latest research trends and activities of the “welding technologies” division, the path to publishing reference datasets for arc welding process for various applications and materials is outlined and discussed. T2 - 4th Symposium on Materials and Additive Manufacturing - Additive 2024 CY - Berlin, Germany DA - 12.06.2024 KW - Additive Manufacturing KW - Arc welding KW - DED-arc KW - Research data KW - Reference data PY - 2024 AN - OPUS4-60249 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Marquardt, R. A1 - Osayi, J. A1 - Kmieciak, S. A1 - Biegler, M. A1 - Rethmeier, Michael T1 - Verschleißschutz einer Schneckengeometrie durch funktional gradierte Materialien N2 - Hochbelastete Stahlbauteile lassen sich durch Auftragen von Kobalt-Chrom Legierungen vor Verschleiß schützen. Die plötzliche Änderung der Materialeigenschaften führt jedoch zu Spannungen und Rissen im Anbindungsbereich. Daraus resultierende Abplatzungen stellen eine Gefahr für die Funktionsfähigkeit der Maschine und damit für Mensch und Umwelt dar. Um die Belastbarkeit der Schutzschicht zu verbessern, kann die Anbindung durch einen gradierten Materialübergang optimiert werden. Diese funktional gradierten Materialien können mittels pulverbasiertem Directed Energy Deposition aufgetragen werden. Die Methodik zum Aufbau und zur Qualitätssicherung solcher Materialien wurde in vorangegangenen Arbeiten für dickwandige Geometrien gezeigt. Für dünnwandige Geometrien ist die Anwendbarkeit bisher unzureichend untersucht worden. Diese Arbeit zeigt am Beispiel einer dünnwandigen gradierten Schneckengeometrie die Einsatzfähigkeit der Methodik. Dafür wird die Gefügestruktur der Gradierung auf Fehler untersucht und der Härteverlauf gemessen. Außerdem wird die relative Dichte anhand eines bereits trainierten neuronalen Netzes vorhergesagt und mit einer Porositätsuntersuchung verglichen. T2 - 14. Tagung Verschleiß- und Korrosionsschutz von Bauteilen durch Auftragschweißen CY - Halle a. d. Saale, Germany DA - 12.06.2024 KW - Directed Enery Deposition KW - Funktionally Graded Material KW - Additive Manufacturing KW - DED KW - FGM KW - AM PY - 2024 SP - 1 EP - 7 PB - SLV Halle AN - OPUS4-60721 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mohr, Gunther T1 - Comparability issues of test specimens in laser powder bed fusion - how to consider differences in thermal history of complex components and primitive test specimens N2 - The capability to produce complexly and individually shaped metallic parts is one of the main advantages of the laser powder bed fusion (PBF-LB/M) process. However, the thermal history during additive manufacturing of complex components can differ significantly from the thermal history of geometrically primitive test specimens. This can result in divergent microstructures and resulting mechanical properties. It drastically limits the comparability of different built parts and requires expensive full component testing. Moreover, the thermal history as the spatiotemporal temperature distribution has been identified as a major cause for flaw formation. Therefore, it can be hypothesized that a similar thermal history between components and test specimens enhances their comparability. In this talk, the concept of representative test specimens is introduced, which enables the transfer of thermal histories from complex geometries to simple geometries, which can lead to better comparability of material properties. T2 - 4th Asia-Pacific International Conference on Additive Manufacturing (APICAM) CY - Melbourne, Australia DA - 30.06.2025 KW - Additive Manufacturing PY - 2025 AN - OPUS4-64527 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hébrard, Louis T1 - Comparison of Room and High Temperature Fatigue Behavior of a New LPBF VDM 780 Alloy N2 - The actual environmental challenges require a huge effort from all industrial sectors to reduce their emissions of greenhouse gasses and pollutants. In this context, aeronautics is deeply concerned as one of the most emissive industrial sectors (cf. EU Green Deal). The answer to this pressing challenge is complex and involves new fuels and engine concepts, new aerostructures with higher weight-savings, as well as new, energy-efficient, and sustainable manufacturing technologies and materials. Two technologies may contribute particularly to achieving the goals: (i) new and more energy-efficient processes such as additive manufacturing (AM) can be used for part production; (ii) the engine efficiency of airplanes can be significantly improved to save fuel and reduce gas emissions. The latter can be achieved by increasing the engine thermal efficiency, i.e., increasing the turbine inlet temperature. Currently, only single-crystalline cast materials are available to be used for the thermally highest-loaded parts in the gas turbine engine, i.e., the turbine blades in the high-pressure turbine just behind the combustion chamber. These materials rely on a special casting technology, although they lose these original material performances when additive manufactured. In addition, current materials suitable for metal additive manufacturing have a limited range of temperature application. Therefore, the focus is on the development of new materials targeting higher in-service operation temperatures and durability. Recently, a new Ni-based superalloy (VDM 780) has been developed to ensure microstructural stability up to 800 °C. The goal of this work is to provide a deeper understanding of the high temperature fatigue properties of this alloy. This will enable the identification of the maximum operating temperature of this alloy and assess its performance in order to establish its potential in view of a new generation of more efficient aero-engines. T2 - 11th Edition of Fatigue Design International Conference CY - Senlis, France DA - 19.11.2025 KW - Fatigue KW - Additive Manufacturing KW - Ni-based superalloy KW - High Temperature PY - 2025 AN - OPUS4-64992 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Witte, Julien T1 - The Impact of Ultrasonic-Assisted Milling and Alloying Elements on the Surface Integrity of Additively Manufactured Iron Aluminides N2 - The increasing focus on energy and resource efficiency has driven the implementation of additive manufacturing (AM) of high-performance materials, particularly in lightweight constructions with optimization of material efficiency. Iron aluminides (FeAl) hold great potential due to their low density, excellent corrosion and wear resistance, high-temperature stability, and vast availability. However, the inherent heterogeneity and anisotropy of FeAl-AM structures pose significant challenges, especially regarding hardness and brittleness. These material characteristics complicate the mostly necessary post-processing via mechanical finish machining, often resulting in elevated cutting forces, accelerated tool wear, and suboptimal surface integrity. Ultrasonic-assisted milling (USAM), a hybrid machining process, offers significant advantages over conventional milling (CM), including the reduction of cutting forces and tool wear. Notably, USAM has been demonstrated to decrease surface defect density and mitigate tensile residual stresses, while potentially inducing beneficial compressive residual stresses within the depth profile of the component’s surface. These effects can significantly enhance crack propagation resistance, improve corrosion behavior, and extend the fatigue life of components in safety-relevant applications. The present study investigates the effects of additional alloying elements such as molybdenum, nickel, titanium and Vanadium in FeAl as well as milling parameters, including cutting speed vc and feed rate fz, on the surface integrity with special regard to residual stress formations. T2 - 4th International Conference on Advanced Joining Processes CY - Coimbra, Portugal DA - 16.10.2025 KW - Additive Manufacturing KW - Wear Protection KW - Ultrasonic-assisted Milling KW - Iron-aluminides KW - MPEA KW - Surface Integrity KW - Residual Stresses PY - 2025 AN - OPUS4-65235 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ávila Calderón, Luis T1 - Creep behavior and microstructural evolution of LPBF 316L N2 - This presentation shows some experimental results of the characterization of the creep behavior of LPBF 316L, which has been poorly studied and understood to date. The presentation includes results regarding the mechanical properties, the initial microstructural state and its evolution under loading, and the damage mechanism. This work was done within the BAM focus area materials project AGIL. As a benchmark to assess the material properties of the LPBF 316L, a conventionally manufactured variant was also tested. T2 - 2nd Workshop on In-situ Monitoring and Microstructure Development in Additive Manufactured alloys at BAM CY - Online Meeting DA - 19.04.2021 KW - 316L KW - Additive Manufacturing KW - Creep behavior PY - 2021 AN - OPUS4-52682 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Madia, Mauro T1 - Towards the Use of Representative Specimens for the Qualification of Additively Manufactured Parts N2 - The understanding of the process-structure-property-performance relationship is the key challenge for the qualification of safety-relevant parts made of additively manufactured metallic materials. The complexity of the manufacturing process and the number of influencing parameters affect the properties of test coupons and parts even fabricated in the same batch. This poses the problem of using reliable witness specimens for part qualification. This work presents a new approach which aims at the fabrication of test coupons tailored to the specific microstructure and fatigue properties of a component. The first step consisted in the evaluation of the temperature field by means of process monitoring during the production of parts. The results were used to tailor finite element models which were then used to design witness specimens representative of the thermal history in the component. Finally, the fatigue properties of designed specimens were compared to coupons machined out of the component. T2 - TMS2024 – 153rd Annual Meeting & Exhibition CY - Orlando, FL, USA DA - 03.03.2024 KW - Additive Manufacturing KW - Process simulation KW - Thermal history KW - Structural integrity KW - Damage tolerance PY - 2024 AN - OPUS4-65072 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ferrari, Bruno T1 - Microstructural evolution of PBF-LB/M Inconel 718 during solution-aging heat treatments - an in-situ x-ray diffraction study N2 - Inconel 718 (IN718) is a traditional age-hardenable nickel-based alloy that has been increasingly processed by additive manufacturing (AM) in recent years. In the as-solidified condition, IN718 exhibits chemical segregation and the undesired Laves phase, requiring a solution annealing (SA) prior to aging. The material produced by AM does not respond to the established thermal routines in the same way as conventionally produced IN718, and there is still no consensus on which routine yields optimal results. This work aims to provide a fundamental understanding of the heat treatment (HT) response by continuously monitoring the microstructural evolution during SA via time-resolved synchrotron x-ray diffraction, complemented by ex-situ scanning electron microscopy (SEM). The samples were produced by laser powder bed fusion to a geometry of 10x20x90 mm³, from which Ø1x5 mm³ cylindric specimens were extracted. Two different scanning strategies – incremental 67° rotations, Rot, and alternating 0°/67° tracks, Alt – were used, leading to two different as-built conditions. 1-hour SAs were carried out in the beamline ID22 of the ESRF at 50 KeV. Two SA temperatures, SA1 = 1020 °C, and SA2 = 1080 °C were tested for each scanning strategy. Data were processed using the software PDIndexer. In the as-built state, all samples showed typical subgrain columnar cell structures with predominant Nb/Mo segregation and Laves phase at the cell walls, as seen by SEM. The Alt scan induced higher intensity on the Laves peaks than the Rot scan, suggesting a greater content of Laves. Chemical homogenization in the SA was largely achieved during the heating ramp (Fig. 1). SA2 eliminated the Laves peaks just before reaching 1080 °C, and mitigated differences between Rot and Alt samples. On the other hand, SA1 induced the precipitation of the generally detrimental δ phase, also observed by SEM. Furthermore, the Rot scan showed higher δ peak intensities than the Alt scan, indicating a higher content of δ in the latter. No signs of recrystallization were observed in any of the investigated SAs. T2 - FEMS EUROMAT 2023 CY - Frankfurt a. M., Germany DA - 03.09.2023 KW - Additive Manufacturing KW - X-Ray Diffraction KW - Inconel 718 KW - Heat Treatments KW - Microstructure PY - 2023 AN - OPUS4-58392 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Chaurasia, Prashant Kumar A1 - Cagtay, Fabry A1 - Andreas, Pittner A1 - Rethmeier, Michael T1 - Automated in situ monitoring and analysis of process signatures and build profiles during wire arc directed energy deposition N2 - Wire arc directed energy deposition (DED-Arc) is an emerging metal additive manufacturing process to build near-net shaped metallic parts in a layer-by-layer with minimal material wastage. Automated in situ monitoring and fast-responsive analyses of process signatures and deposit profiles during DED-Arc are in ever demand to print dimensionally consistent parts and reduce post-deposition machining. A comprehensive experimental investigation is presented here involving real-time synchronous measurement of arc current, voltage, and the deposit profile using a novel multi-sensor monitoring framework integrated with the DED-Arc set-up. The recorded current–voltage transients are used to estimate the time-averaged arc power, and energy input in real time for an insight of the influence of wire feed rate and printing travel speed on the deposit characteristics. A unique attempt is made to represent the geometric profiles of the single-track deposits in a generalized mathematical form corresponding to a segmented ellipse, which has exhibited the minimum root-mean-square error of 0.03 mm. The dimensional inconsistency of multi-track deposits is evaluated quantitatively in terms of waviness using build profile monitoring and automated estimation, which is found to increase with an increase in step-over ratio and energy input. For the multi-track mild steel deposits, the suitable range of step-over ratio for the minimum surface waviness is observed to lie between 0.6 and 0.65. Collectively, the proposed framework of synchronized process monitoring and real-time analysis provides a pathway to achieve dimensionally consistent and defect-free parts, and highlights the potential for closed-loop control systems for a wider industrial application of DED-Arc. T2 - IIW Annual Assembly 2025 CY - Genova, Italy DA - 23.06.2025 KW - Additive Manufacturing KW - Arc welding KW - Real-time monitoring and control KW - Dimensional inconsistency KW - DED-arc PY - 2025 AN - OPUS4-65231 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Waske, Anja T1 - A unique authenticator for additively manufactured parts derived from their microstructure N2 - Components produced using additive manufacturing can be marked for unique identification and secure authentication [1,2]. Serial numbers and machine-readable codes can be used to identify the component, and link digital product-related data (i.e., a digital product passport) to the actual components. The most prevailing solution consists of local process manipulation, such as printing a quick response (QR) code [3] or a set of blind holes on the surface of the internal cavity of hollow components. However, local manipulation of components may alter the properties, and external tagging features can be altered or even removed by post-processing treatments. This work therefore aims to provide a new methodology for identification, authentication, and traceability of additively manufactured (AM) components using microstructural features that are unique to each part. X-ray computed tomography (XCT) was employed to image the microstructural features of AlSi10Mg parts. Based on size and geometry, the most prominent features were selected to create a unique digital authenticator. We implemented a framework in Python using open-access modules that can successfully create a digital object authenticator using the segmented microstructure information from XCT. The authenticator is stored as a QR code, along with the 3D information of the selected features. T2 - MRS Spring Meeting Seattle CY - Seattle, WA, USA DA - 07.04.2025 KW - Additive Manufacturing KW - Fingerprint KW - Non-destructive testing PY - 2025 AN - OPUS4-65199 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Witte, Julien T1 - The Impact of Ultrasonic-Assisted Milling and Alloying Elements on the Surface Integrity of Additively Manufactured Iron Aluminides N2 - The increasing focus on energy and resource efficiency has driven the implementation of additive manufacturing (AM) of high-performance materials, particularly in lightweight constructions with optimization of material efficiency. Iron aluminides (FeAl) hold great potential due to their low density, excellent corrosion and wear resistance, high-temperature stability, and vast availability. However, the inherent heterogeneity and anisotropy of FeAl-AM structures pose significant challenges, especially regarding hardness and brittleness. These material characteristics complicate the mostly necessary post-processing via mechanical finish machining, often resulting in elevated cutting forces, accelerated tool wear, and suboptimal surface integrity. Ultrasonic-assisted milling (USAM), a hybrid machining process, offers significant advantages over conventional milling (CM), including the reduction of cutting forces and tool wear. Notably, USAM has been demonstrated to decrease surface defect density and mitigate tensile residual stresses, while potentially inducing beneficial compressive residual stresses within the depth profile of the component’s surface. These effects can significantly enhance crack propagation resistance, improve corrosion behavior, and extend the fatigue life of components in safety-relevant applications. The present study investigates the effects of additional alloying elements such as molybdenum, nickel, titanium and Vanadium in FeAl as well as milling parameters, including cutting speed vc and feed rate fz, on the surface integrity with special regard to residual stress formations. T2 - BMDK der OvGU Magdeburg CY - Magdeburg, Germany DA - 10.12.2025 KW - Additive Manufacturing KW - Wear Protection KW - Ultrasonic-assisted Milling KW - Iron-aluminides KW - MPEA KW - Surface Integrity KW - Residual Stresses PY - 2025 AN - OPUS4-65234 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Quosdorf, Heike T1 - Digital object identifier for additively manufactured parts as software package N2 - A method to uniquely identify samples without printed or handwritten labels is an advantage not just for additively manufactured parts. To kickstart industry use cases, it is also important to provide a ready-made implementation kit. Following an open-science and open-source software approach Germanys Federal Institute for Materials Research and Testing (BAM) seeks to promote digital solutions of ongoing research projects. With this software package a novel method based on microstructural features as identifiers – DOI4AM (digital object identifier for additively manufactured parts) – will be explained alongside its implementation as open-source Python software package. The digital object identifier (DOI) links product data clearly and forgery-proof with real components. Its implementation helps to identify and securely authenticate additively manufactured components during its product life cycle by using characteristic microstructure features - just like a fingerprint. To calculate the DOI fingerprint, a few preprocessing steps need to be performed to detect the uniquely distributed microstructure features that occur during the 3D printing process. A go-through guide shows the preprocessing steps that include CT image capturing, feature segmentation, and data distribution with CSV files. While all steps can be followed along in a Jupyter notebook, the software package includes an application for creating and checking of previously created fingerprints, as well, as a containerized API (application programming interface) service for implementation in existing software platforms or workflows. While data visualization is crucial to understanding the methodology and an essential tool to check for data correctness, an implementation in an industry use case needs to be slim and resource efficient. Therefor the software’s API can be used as an independent service. The project's industry partner proofs its first successful implementation in their digital product passport web solution PASS-X. T2 - AI MSE 2025 CY - Bochum, Germany DA - 18.11.2025 KW - Authentication KW - Unique identification KW - Digital object identifier KW - Additive Manufacturing KW - Non-destructive testing KW - Open Source Software KW - Digital fingerprint KW - X-ray Computed Tomography KW - Open Science PY - 2025 AN - OPUS4-65293 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - THES A1 - Ávila Calderón, Luis T1 - Mechanisches Verhalten von additiv gefertigtem nichtrostendem Stahl X2CrNiMo17-12-2 (AISI 316L) und Vergleich zur konventionell gefertigten Variante T1 - Mechanical behavior of additively manufactured stainless steel X2CrNiMo17-12-2 (AISI 316L) and comparison with a conventionally manufactured variant N2 - Die additive Fertigung (AM) metallischer Werkstoffe ist eine Technologie, die zunehmend Gegenstand von Forschungsaktivitäten und industrieller Anwendung ist. Dennoch steht sie noch vor Herausforderungen, um eine breite Nutzung in sicherheitsrelevanten Anwendungen zu erreichen. Die Hauptgründe für die Verzögerung des technologischen Durchbruchs zugunsten von AM-Metallen gegenüber konventionell hergestellten Varianten sind das Fehlen eines tieferen Verständnisses der Prozess-Struktur-Eigenschafts-Beziehungen und die begrenzte Verfügbarkeit von Daten zu den Materialeigenschaften. In diesem Kontext stellt diese Arbeit einen Beitrag sowohl zum Verständnis der Prozess-Struktur-Eigenschafts-Beziehungen als auch zur Verbesserung der Datenlage von 316L dar, einem häufig als Konstruktionswerkstoff in verschiedenen Hochtemperaturbauteilen verwendeten Werkstoff. Die Arbeit legt den Fokus auf die mittels Laser-Pulverbettschmelzen hergestellte Werkstoffvariante, PBF-LB/M/316L. Eine konventionell hergestellte Variante, HR/316L, wurde auch untersucht. Bei PBF-LB/M/316L wurde zusätzlich der Effekt ausgewählter Wärmebehandlungen ausgewertet. Die Untersuchung umfasste die Charakterisierung der mechanischen Eigenschaften und der Verformungs- und Schädigungsmechanismen bei erhöhten Prüftemperaturen bei LCF und Kriechen, wo die Daten und Wissenslage am spärlichsten ist. Außerdem hat die untersuchte PBF-LB/M/316L-Wersktoffvariante einen geringen Porositätsgrad. Somit hat diese Arbeit die Mikrostruktur stärker in den Fokus genommen als die meisten bisher in der Literatur verfügbaren Studien. Die mechanische Prüfkampagne umfasste Zugversuche zwischen Raumtemperatur und 650 °C, LCF-Versuche zwischen Raumtemperatur und 600 °C sowie Kriechversuche bei 600 °C und 650 °C. In Ermangelung konkreter Richtlinien und Normen wurde die Charakterisierung zumeist anhand der bestehenden internationalen Prüfnormen und Probengeometrien durchgeführt. Aus jedem dieser Prüfverfahren wurden die entsprechenden Festigkeits- und Verformungskennwerte ermittelt. Darüber hinaus wurde mit Hilfe gezielter mikrostruktureller Untersuchungen ein Beitrag zum Verständnis des Zusammenhangs zwischen der Mikrostruktur und den mechanischen Eigenschaften in Bezug auf die Verformungs- und Schädigungsmechanismen geleistet. Die Dehngrenze von PBF-LB/M/316L ist etwa doppelt so hoch wie die von HR/316L und dieser Trend setzt sich mit ansteigender Prüftemperatur fort. Die Bruchdehnung ist bei allen Prüftemperaturen geringer. PBF-LB/M/316L weist über den größten Teil der Ermüdungslebensdauer vor allem bei Raumtemperatur höhere zyklische Spannungen als HR/316L auf. Ausschließlich bei den kleinsten Dehnungs-schwingbreiten sind die Ermüdungslebensdauer ausgeprägt kürzer. Das Wechselverformungsverhalten von PBF-LB/M/316L ist durch eine Anfangsverfestigung gefolgt von einer kontinuierlichen Entfestigung charakterisiert, welche bis zum Auftreten der zum Versagen führenden Entfestigung stattfindet. Die Kriechbruchzeiten und die Dauer jeder Kriechphase sind bei allen Kombinationen von Prüfparametern bei PBF-LB/M/316 kürzer als bei HR/316L. Die Spannungsabhängigkeit von PBF-LB/M/316L ist im Vergleich zu HR/316L geringer und die Duktilität beim Kriechen kleiner. Die minimale Kriechrate wird bei allen geprüften Parameterkombinationen bei deutlich geringeren Kriechdehnungen erreicht. Eine Wärmebehandlung bei 450 °C / 4 h bewirkt keine wesentliche Änderungen der Mikrostruktur und Zugversuchseigenschaften. Eine zusätzliche Wärmebehandlung bei 900 °C / 1 h verursacht eine Abnahme der Dehngrenze des PBF-LB/M/316L. Diese blieb aber immer noch um den Faktor 1,5x höher als bei HR/316L. Die Verformungsmerkmale wurden kaum davon beeinflusst. Bezüglich des Kriechverhaltens hat die Wärmebehandlung bei 900 °C / 1 h längere sekundäre und tertiäre Kriechstadien bewirkt und die Kriechdehnung hat sich signifikant erhöht. Die Bruchbilder unterscheiden sich generell nicht nur aber vor allem mit ansteigender Prüftemperatur, bei der bei PBF-LB/M/316L oft interkristalline Rissbildung beobachtet wurde. Die Zellstruktur trägt als der Hauptfaktor zu den unterschiedlichen mechanischen Eigenschaften im Vergleich zur HR/316L-Variante bei. Darüber hinaus spielen mutmaßlich die Kornmorphologie, die Stapelfehlerenergie und der Stickstoffgehalt eine Rolle. N2 - Metal additive manufacturing (AM) is a technology that is increasingly the subject of research activities and industrial applications. However, it still faces challenges to achieve widespread use in safety-relevant applications. The main reasons for the delay of this technological breakthrough in favor of AM metals over conventionally manufactured variants are the lack of a deeper understanding of process-structure-property relationships and the limited availability of data on material properties. In this context, this work contributes to both achieving a better understanding of process-structure-property relationships and the improvement of data for 316L, an alloy frequently used as a structural material in various high-temperature components. The work focuses on a material variant produced by laser pow-der bed fusion, PBF-LB/M/316L. A conventionally produced variant, HR/316L, was also investigated. For PBF-LB/M/316L, the effect of selected heat treatments was also evaluated. The investigation included the characterization of the mechanical properties and the related deformation and damage mechanisms at elevated test temperatures in LCF and creep, where data and knowledge are scarce. The PBF-LB/M/316L variant studied has a low degree of porosity. Thus, this work is more focused on the microstructure than most studies available in the literature. The mechanical test campaign included tensile tests between room temperature and 650 °C, LCF tests between room temperature and 600 °C, and creep tests at 600 °C and 650 °C. In the absence of concrete guidelines and standards for testing of AM metals, the characterization mostly took place using existing international test standards and specimen geometries. From each of the test methods, corresponding strength, and deformation characteristic values were determined. In addition, targeted microstructural investigations contributed to understanding the relationship between the microstructure and the mechanical properties in terms of deformation and damage mechanisms. The proof stress of PBF-LB/M/316L is about twice that of HR/316L. This trend remains with increasing test temperature. The elongation after fracture is lower at all test temperatures. Regarding LCF, PBF-LB/M/316L exhibits higher cyclic stresses than HR/316L for most of the fatigue life, especially at room temperature. Exclusively at the smallest strain amplitudes, the fatigue lives of PBF-LB/M/316L are markedly shorter than in HR/316L. The cyclic stress-strain deformation behavior of PBF-LB/M/316L features an initial strain hardening followed by a continuous softening, which occurs until the softening leading to failure takes place. The creep rupture times and the duration of each creep stage are shorter for PBF-LB/M/316 than for HR/316L for all combinations of test parameters. The stress dependence of PBF-LB/M/316L is lower, and the creep ductility is smaller compared to HR/316L. The minimum creep rate is reached at significantly lower creep extensions for all parameter combinations tested. A heat treatment at 450 °C / 4 h did not cause significant changes in the microstructure and tensile behavior. An additional heat treatment at 900 °C / 1 h caused a decrease in the proof stress of PBF-LB/M/316L. However, it still remained higher than the one of HR/316L by a factor of 1.5x. The deformation characteristics were hardly affected. Regarding the creep behavior, this latter heat treatment at 900 °C / 1 h caused longer secondary and tertiary creep stages, and the creep strain increased significantly. The fracture characteristics generally differed, which happened not only but especially with increasing test temperature, where intergranular cracking often took place in PBF-LB/M/316L. The cellular structure is considered the main factor contributing to the different mechanical properties compared to the HR/316L variant. In addition, grain morphology, stacking fault energy, and nitrogen content might play a role. KW - AGIL KW - Additive Fertigung KW - Laser-Pulverbettschmelzen KW - Mikrostrukturentwicklung KW - 316L KW - LCF KW - Kriechen KW - Additive Manufacturing KW - Microstructure KW - Mechanical Properties KW - Mechanische Eigenschaften PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-597143 DO - https://doi.org/10.14279/depositonce-19828 SP - 1 EP - 190 CY - Berlin AN - OPUS4-59714 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ávila Calderón, Luis T1 - Low cycle fatigue behavior of DED-L Ti-6AL-4V N2 - Laser powder-based directed energy deposition (DED-L) is a technology that offers the possibility for 3D material deposition over hundreds of layers and has thus the potential for application in additive manufacturing (AM). However, to achieve broad industrial application as AM technology, more data and knowledge about the fabricated materials regarding the achieved properties and their relationship to the manufacturing process and the resulting microstructure is still needed. In this work, we present data regarding the low-cycle fatigue (LCF) behavior of Ti-6Al-4V. The material was fabricated using an optimized DED-L process. It features a low defect population and excellent tensile properties. To assess its LCF behavior two conventionally manufactured variants of the same alloy featuring different microstructures were additionally tested. The strain-controlled LCF tests were carried out in fully reversed mode with 0.3 % to 1.0 % axial strain amplitude from room temperature up to 400°C. The LCF behavior and failure mechanisms are described. For characterization, optical microscopy (OM), scanning electron microscopy (SEM), and micro-computed tomography (µCT) were used. The low defect population allows for a better understanding of the intrinsic material’s properties and enables a fairer comparison against the conventional variants. The fatigue lifetimes of the DED-L material are nearly independent of the test temperature. At elevated test temperatures, they are similar or higher than the lifetimes of the conventional counterparts. At room temperature, they are only surpassed by the lifetimes of one of them. The principal failure mechanism involves multiple crack initiation sites. T2 - Ninth International Conference on Low Cycle Fatigue (LCF9) CY - Berlin, Germany DA - 21.06.2022 KW - AGIL KW - Additive Manufacturing KW - Ti-6Al-4V KW - Low-Cycle-Fatigue KW - Microstructure PY - 2022 AN - OPUS4-55123 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ulbricht, Alexander A1 - Ávila Calderón, Luis A1 - Sommer, Konstantin A1 - Mohr, Gunther A1 - Evans, Alexander A1 - Skrotzki, Birgit A1 - Bruno, Giovanni T1 - Evolution of Creep Damage of 316L Produced by Laser Powder Bed Fusion N2 - The damage mechanisms of metallic components produced by process laser powder bed fusion differ significantly from those typically observed in conventionally manufactured variants of the same alloy. This is due to the unique microstructures of additively manufactured materials. Herein, the focus is on the study of the evolution of creep damage in stainless steel 316L specimens produced by laser powder bed fusion. X-ray computed tomography is used to unravel the influence of the process-specific microstructure from the influence of the initial void distribution on creep damage mechanisms. The void distribution of two specimens tested at 600 °C and 650 °C is analyzed before a creep test, after an interruption, and after fracture. The results indicate that the formation of damage is not connected to the initial void distribution. Instead, damage accumulation at grain boundaries resulting from intergranular cracking is observed. KW - Creep KW - Computed Tomography KW - PBF-LB/M/316L KW - Laser Powder Bed Fusion KW - Microstructure KW - AISI 316L KW - Additive Manufacturing PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-574127 DO - https://doi.org/10.1002/adem.202201581 SP - 1 EP - 9 PB - Wiley-VCH GmbH CY - Weinheim AN - OPUS4-57412 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ávila Calderón, Luis A1 - Rehmer, Birgit A1 - Schriever, Sina A1 - Ulbricht, Alexander A1 - Agudo Jácome, Leonardo A1 - Sommer, Konstantin A1 - Mohr, Gunther A1 - Skrotzki, Birgit A1 - Evans, Alexander T1 - Creep and creep damage behavior of stainless steel 316L manufactured by laser powder bed fusion N2 - This study presents a thorough characterization of the creep properties of austenitic stainless steel 316L produced by laser powder bed fusion (LPBF 316L) contributing to the sparse available data to date. Experimental results (mechanical tests, microscopy, X-ray computed tomography) concerning the creep deformation and damage mechanisms are presented and discussed. The tested LPBF material exhibits a low defect population, which allows for the isolation and improved understanding of the effect of other typical aspects of an LPBF microstructure on the creep behavior. As a benchmark to assess the material properties of the LPBF 316L, a conventionally manufactured variant of 316L was also tested. To characterize the creep properties, hot tensile tests and constant force creep tests at 600 °C and 650 °C are performed. The creep stress exponents of the LPBF material are smaller than that of the conventional variant. The primary and secondary creep stages and the times to rupture of the LPBF material are shorter than the hot rolled 316L. Overall the creep damage is more extensive in the LPBF material. The creep damage of the LPBF material is overall mainly intergranular. It is presumably caused and accelerated by both the appearance of precipitates at the grain boundaries and the unfavorable orientation of the grain boundaries. Neither the melt pool boundaries nor entrapped gas pores show a significant influence on the creep damage mechanism. KW - 316L KW - Laser Powder Bed Fusion (LPBF) KW - Creep behavior KW - Additive Manufacturing KW - AGIL PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-539373 DO - https://doi.org/10.1016/j.msea.2021.142223 SN - 0921-5093 VL - 830 SP - 142223 PB - Elsevier B.V. AN - OPUS4-53937 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schröder, Jakob A1 - Fritsch, Tobias A1 - Luzin, Vladimir A1 - Ferrari, Bruno A1 - Simón-Muzás, Juan A1 - Evans, Alexander A1 - Bruno, Giovanni T1 - Impact of scan strategy on principal stresses in laser powder bed fusion N2 - Additive manufacturing techniques, such as laser powder bed fusion (PBF-LB), are well known for their exceptional freedom in part design. However, these techniques are also characterized by the development of large thermal gradients during production and thus residual stress (RS) formation in produced parts. In this context, neutron diffraction enables the non-destructive characterization of the bulk RS distribution. By control of the thermal gradients in the powder-bed plane by scan strategy variation we study the impact of in-process scan strategy variations on the microstructure and the three-dimensional distribution of RS. Microstructural analysis by means of electron backscatter diffraction reveals sharp microstructure transitions at the interfaces ranging from 100-200 µm. The components of the RS tensor are determined by means of neutron diffraction and the principal stress directions and magnitudes are determined by eigenvalue decomposition. We find that the distribution of RS in the powder-bed plane corresponds to the underlying scan strategy. When the alternating scan vectors align with the x- and y sample coordinate axes, the principal stress directions co-align. In the present geometry, nearly transverse isotropic stress states develop when the scan vectors are either aligned 45° between x and y or continuously rotated by 67° between each layer. KW - Additive Manufacturing KW - Laser Powder Bed Fusion KW - Electron Backscatter Diffraction KW - Neutron Diffraction KW - Residual Stress KW - Principal Stress PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-607910 DO - https://doi.org/10.1016/j.matdes.2024.113171 SN - 0264-1275 VL - 244 SP - 1 EP - 10 PB - Elsevier Ltd. AN - OPUS4-60791 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni A1 - Mishurova, Tatiana A1 - Serrano-Munoz, Itziar A1 - Ulbricht, Alexander A1 - Fritsch, Tobias A1 - Sprengel, Maximilian A1 - Evans, Alexander A1 - Kromm, Arne A1 - Madia, Mauro ED - Bruno, Giovanni T1 - A Critical Discussion on the Diffraction-Based Experimental Determination of Residual Stress in AM Parts N2 - As opposed to reviewing results on experimental determination of residual stress by diffraction, this paper discusses the open issues when dealing with residual stress determination in additive manufactured parts, in particular those manufactured with laser powder bed fusion techniques. Three points are addressed in detail: (a) the proper determination of the strain-free reference d0, (b) the problem of the determination of the principal axes, and (c) the use of the correct diffraction elastic constants. It is shown that all methods to determine the strain-free reference d0 suffer from caveats, and care must be taken in evaluating the most suitable for the problem being tackled. In addition, it is shown that, in some systems, the principal axes do correspond to the geometrical axes of the specimen, but this needs to be systematically checked, especially in the case of uni- or bidirectional hatching strategies. Finally, the need to experimentally determine the proper diffraction elastic constants is underlined, especially in the case of strongly textured specimens, which again depends on the deposition strategy. T2 - ASTM ICAM 2020 – ASTM International Conference on Additive Manufacturing CY - Online meeting DA - 16.11.2020 KW - Additive Manufacturing KW - Diffraction KW - Residual Stress PY - 2020 DO - https://doi.org/10.1520/STP163120190148 VL - STP1631 SP - 122 EP - 138 PB - ASTM International CY - USA AN - OPUS4-51347 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sprengel, Maximilian T1 - Using Neutron Diffraction to Monitor Stress Relaxation in Additively Manufactured 316L N2 - The relaxation of residual stress in laser powder bed fused stainless steel 316L parts was monitored using monochromatic and time-of-flight neutron diffraction. T2 - ISIS student meeting CY - Online meeting DA - 26.10.2020 KW - Stainless Steel KW - Residual Stress KW - Additive Manufacturing PY - 2020 AN - OPUS4-51469 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -