TY - CONF A1 - Charmi, Amir T1 - Mechanical anisotropy of additively manufactured stainless steel 316l: an experimental and numerical study N2 - This work aims for a yield function description of additively manufactured (AM) parts of stainless steel 316L at the continuum-mechanical macro-scale by means of so-called virtual experiments using a crystal plasticity model at meso-scale. T2 - 1st Workshop on In-situ Monitoring and Microstructure Development in Additive Manufacturing CY - BAM, Berlin DA - 10.12.2020 KW - Anisotropy KW - Crystal plasticity KW - Additive manufacturing PY - 2020 AN - OPUS4-51941 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hilgenberg, Kai T1 - Additive Manufacturing: Opportunities and challenges for NDT N2 - Additive manufacturing processes are increasingly being used in industrial applications. Especially powder bed fusion processes are of high interest due to their capability to economically produce individual, highly complex and functionally integrated components in small batches. However, the quality assurance of these components remains a challenge. Internal defects and undesirable microstructures and surface conditions can deteriorate the mechanical properties. Especially for use in safety-relevant applications, new design and inspection concepts are needed that take these factors into account. This talk presents typical defects and microstructure phenomena resulting from the laser powder bed fusion process and identifies challenges and opportunities for non-destructive testing from a manufacturing engineering perspective. In particular, the possibility of a process-integrated quality control is shown based on current research results. T2 - The 13th International Symposium on NDT in Aerospace 2021 CY - Online meeting DA - 05.10.2021 KW - Additive manufacturing KW - Laser powder bed fusion KW - In-situ monitoring PY - 2021 AN - OPUS4-53484 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ehlers, Henrik T1 - Online ET with MR Sensor Arrays for LPBF Parts N2 - In this presentation we discuss the online monitoring of LPFB parts using eddy current testing with magenoresistive sensor arrays. The underlying principle, the developed hardware and the results of the firt online monitoring are described in the presentation. T2 - 2. Online-Workshop "In-situ Monitoring and Microstructure Development in Additive Manufactured Alloys " CY - Online meeting DA - 19.04.2021 KW - Eddy current testing KW - LPBF KW - GMR KW - SLM KW - Haynes282 KW - Additive manufacturing PY - 2021 AN - OPUS4-52700 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Charmi, Amir T1 - Mechanical anisotropy of LPBF 316L: a modeling approach N2 - The underlying cause of mechanical anisotropy in additively manufactured (AM) parts is not yet fully understood and has been attributed to several different factors like microstructural defects, residual stresses, melt pool boundaries, crystallographic and morphological textures. To better understand the main contributing factor to the mechanical anisotropy of AM stainless steel 316L, bulk specimens were fabricated via laser powder bed fusion (LPBF). Tensile specimens were machined from these AM bulk materials for three different inclinations relative to the build plate. Dynamic Young's modulus measurements and tensile tests were used to determine the mechanical anisotropy. Some tensile specimens were also subjected to residual stress measurement via neutron diffraction, porosity determination with X-ray micro-computed tomography, and texture analysis with electron backscatter diffraction (EBSD). A crystal plasticity model was used to analyze the elastic anisotropy and the anisotropic yield behavior of the AM specimens, and it was able to capture and predict the experimental behavior accurately. Overall, it was shown that the mechanical anisotropy of the tested specimens was mainly influenced by the crystallographic texture. T2 - 2. Online-Workshop "In-situ Monitoring and Microstructure Development in Additive Manufactured Alloys " CY - Online meeting DA - 20.04.2021 KW - Anisotropy KW - Crystal plasticity KW - Additive manufacturing PY - 2021 AN - OPUS4-52603 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mishurova, Tatiana T1 - 3D imaging and residual stress analysis of AM materials at BAM N2 - The overview of the activity of group 8.5 Micro-NDT (BAM, Belin, Germany) in the field of additively manufacturing material characterization will be presented. The research of our group is focused on the 3D imaging of AM materials by means of X-ray Computed Tomography at the lab and at synchrotron, and the residual stress characterization by diffraction (nondestructive technique). T2 - Seminar at Chalmers University and Centre for Additive Manufacture (CAM2) CY - Gothenburg, Sweden DA - 19.05.2022 KW - Additive manufacturing KW - Laser powder bed fusion KW - Residual stress KW - Computed tomography KW - Synchrotron X-ray diffraction KW - X-ray refraction PY - 2022 AN - OPUS4-55019 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mishurova, Tatiana T1 - 3D Imaging and residual stress analysis of additively manufactured materials N2 - The focus of the presentation focus will be on 3D imaging by means of X-ray Computed Tomography (XCT) at the lab and at synchrotron, and the non-destructive residual stress (RS) characterization by diffraction of additively manufactured (AM) materials in BAM (Berlin, Germany). The manufacturing defects and high RS are inherent of AM techniques and affect structural integrity of the components. Using XCT the defects size and shape distribution as well as geometrical deviations can be characterized, allowing the further optimization of the manufacturing process. Diffraction-based RS analysis methods using neutron and synchrotron X-rays at large scale facilities offer the possibility to non-destructively spatially resolve both surface and bulk RS in complex components and track their changes following applied thermal or mechanical loads. T2 - The International Symposium on Nondestructive Characterization of Materials 2023 CY - Zurich, Switzerland DA - 15.08.2023 KW - Additive manufacturing KW - Residual stress KW - X-ray computed tomography PY - 2023 AN - OPUS4-58113 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mishurova, Tatiana T1 - Applications of x-ray computed tomography in material science N2 - The overview of the activity of Federal Institute for Material Research and Testing (BAM, Belin, Germany) in the field material characterization by X-ray imaging is presented. The principle of X-ray Computed Tomography (XCT) is explained. The multiple examples of application of quantitative analysis by XCT are reported, such as additive manufacturing, Li-ion battery, concrete research. T2 - Lecture for PhD students at Politecnico di Torino CY - Turin, Italy DA - 14.03.2024 KW - X-ray computed tomography KW - Additive manufacturing PY - 2024 AN - OPUS4-59689 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mishurova, Tatiana T1 - In-situ hot isostatic pressing combined with x-ray imaging and diffraction of laser powder bed fusion ti-6al-4v N2 - Hot Isostatic Pressing (HIP) is often introduced to tackle the porosity issue in additively manufactured (AM) materials. For instance, HIP post-processing is recommended to improve fatigue resistance of Laser powder bed fusion (PBF-LB) manufactured parts [1, 2]. Even though HIP cannot completely remove porosity, it significantly decreases the defect population and its average size below the critical threshold value leading to early crack initiation. In the present study, in-situ investigation of HIP procedure of PBF-LB Ti-6Al-4V parts was carried out to gain further insights into the densification mechanism occurring during HIP. The in-situ observations at high pressure and high temperature are uniquely possible at the PSICHE beamline of the Soleil synchrotron (France), thanks to the Ultrafast Tomography on a Paris-Edinburgh Cell (UToPEC) and the combination of the fast phase-contrast tomography and energy-dispersive diffraction [3, 4]. A detailed methodology was developed to ensure that the correct pressure and temperature were maintained during the experiments. The results allowed an estimation of the global dentification rate during HIP of PBF-LB Ti-Al-4V material, as well as a detailed quantitative characterization of the influence of pore size and shape on the densification process, thereby understanding the effectiveness of HIP process on different pore categories. After 20 mins, 75% of porosity can be considered as closed or has size below the resolution of the XCT reconstruction. We also observed that the smallest defects showed higher densification rate, while the defect shape did not have significant effect on such rate. The current development of in-situ HIP experiment allows experimental quantification and validation of the simulation work. Ultimately it paves the road to tailoring the HIP procedure for different materials depending on the porosity and microstructure. T2 - AAMS 2023 CY - Madrid, Spain DA - 26.09.23 KW - Additive manufacturing KW - HIP KW - X-ray computed tomography PY - 2023 AN - OPUS4-58482 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mishurova, Tatiana T1 - 3D imaging and residual stress analysis for AM Materials N2 - The overview of the activity of Federal Institute for Material Research and Testing (BAM, Belin, Germany) in the field of additively manufacturing material characterization will be presented. The research of our group is focused on the 3D imaging of AM materials by means of X-ray Computed Tomography at the lab and at synchrotron, and the residual stress characterization by diffraction (nondestructive technique). T2 - Seminar at Integrated Additive Manufacturing center, Politecnico Torino CY - Turin, Italy DA - 14.02.2023 KW - Additive manufacturing KW - Laser powder bed fusion KW - Residual stress KW - Computed tomography KW - Synchrotron X-ray diffraction PY - 2023 AN - OPUS4-57047 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Farahbod, L. T1 - Assessment of additively manufactured lattice structures for gas turbine applications N2 - Additive Manufacturing (AM) allows for the unique combination of building highly complex parts with integrated functional design. One particular design feature is known as lattice structures, which provide opportunities for innovative applications in the high-temperature regime of gas turbines. These structures require the development of reliable manufacturing methods to produce dependable structural integrity and geometrical accuracy. Consequently, the subsequent validation of these thin structures must also be examined in depth and differently than with current approaches. In this study, a holistic assessment of Ni based high temperature lattice structures is pursued, utilizing a systematic design-follows-complexity approach. Single struts of different geometries and orientations are investigated first, then combined to a variety of unit cell types and finally multiplied to complex lattice structures. Initial test trials with these thin structures proved a dependency of geometrical accuracy, microstructure and structural properties to the AM process setup. The trials underlined the need for design guidelines and a distinction between bulk and thin structures, as they showed differences in microstructural and mechanical behaviour. By application of high resolution, non destructive characterization methods such as computer tomography (CT and µCT), evaluation of defects and the thin structures’ metrology has been performed. First results revealed a number of defects compromising the structural integrity and therefore limiting the lifing behaviour. This was confirmed in destructive testing (e.g. tensile and compression). Furthermore, it was proven that the distribution, the number, the size and the type of defects are also dependent on the AM process setup. While there are large potentials for use of lattice structures in gas turbine applications, the experiments indicate the strong need for an increased understanding of manufacturing and design for these complex structures and that this gap needs to be bridged. T2 - EUROMAT 2017 CY - Thessaloniki, Greece DA - 17.09.2017 KW - Additive manufacturing KW - Computer tomography KW - Lattice structures KW - IN625 PY - 2017 AN - OPUS4-42948 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Graf, B. T1 - 3D laser metal deposition in an additive manufacturing process chain N2 - Laser metal deposition is described with its applications for additive manufacturing. The necessary process chain is discussed, with regard to weld bead dimensions and 3D build-up strategy. Metallurgical cross sections, x-ray and tensile tests are conducted. As demonstrative components, a gas turbine burner and a turbine blade are shown T2 - 1st International Congress on Welding, Additive Manufacturing and Associated Non-Destructive Testing CY - Metz, France DA - 17.05.2017 KW - Additive manufacturing KW - Ti-6Al-4V KW - Process chain KW - Turbine industry KW - Laser metal deposition PY - 2017 AN - OPUS4-44477 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hilgenberg, Kai T1 - Build-up strategies for additive manufacturing of three-dimensional Ti-6Al-4V-parts produced by Laser Metal Deposition N2 - Laser metal deposition (LMD) has been applied as coating technology for many years. Today, the technologies capacity to produce 3D depositions leads to a new field of application as additive manufacturing method. In this paper, 3D laser metal deposition of titanium alloy Ti-6Al-4V is studied with special regard to the demands of additive manufacturing. Therefore, only the powder nozzle is used to create the shielding gas atmosphere, which ensures high geometric flexibility. Furthermore, specimen with high aspect ratio and hundreds of layers are manufactured, which represent typical features in additive manufacturing. T2 - ICALEO CY - Atlanta, USA DA - 22.10.2017 KW - Additive manufacturing KW - Ti-6Al-4V KW - Laser Metal Deposition PY - 2017 AN - OPUS4-42865 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Falkenberg, Rainer A1 - Charmi, Amir T1 - Virtual-lab-based determination of a macroscopic yield function for additively manufactured parts N2 - This work presents a method for the yield function determination of additively manufactured parts of S316L steel. A crystal plasticity model is calibrated with test results and used afterwards to perform so-called virtual experiments, that account for the specific process-related microstructure including crystallographic and morphological textures. These simulations are undertaken on a representative volume element (RVE), that is generated from EBSD/CT-Scans on in-house additively manufactured specimen, considering grain structure and crystal orientations. The results of the virtual experiments are used to determine an anisotropic Barlat yield function, that can be used in a macroscopical continuum-sense afterwards. This scale-bridging approach enables the calculation of large-scale parts, that would be numerically too expensive to be simulated by a crystal plasticity model. T2 - 3. Tagung des DVM-Arbeitskreises Additiv gefertigte Bauteile und Strukturen CY - Berlin, Germany DA - 07.11.2018 KW - Virtual experiments KW - Additive manufacturing KW - Anisotropy KW - Crystal plasticity KW - Scale-bridging PY - 2018 AN - OPUS4-46895 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hilgenberg, Kai T1 - EOS M300 as the heart of the QI living lab: Advancing with digital process chains N2 - This presentation shows how the connectivity of the EOS-M300/4 laser powder bed system is used to capture machine and process data as part of the living lab in QI Digital and how this can enable future digital quality assurance in additive manufacturing. T2 - AM Forum 2025 CY - Berlin, Germany DA - 17.03.2025 KW - Additive manufacturing KW - Quality assurance KW - QI Digital KW - Living lab PY - 2025 AN - OPUS4-62740 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Quosdorf, Heike T1 - A Digital Object Identifier for Additively Manufactured Parts as Open Source 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 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 show s the preprocessing steps that include computer tomography (CT) image capturing, feature segmentation and data distribution via CSV files. While all steps can be followed along in a Jupyter notebook with sample data, the software package includes functions to create and compare fingerprints, as well, as an application programming interface (API) for integration in existing software platforms. A quick showcase of our industry partners implementation of the algorithm as containerized micro service in their digital product passport (DPP) web solution PASS X proves the first successful technology transfer of this project. T2 - MSE Research Data Forum 2025 CY - Siegburg, Germany DA - 08.07.2025 KW - Open Science KW - Authentication KW - Unique identification KW - Digital fingerprint KW - X-ray Computed Tomography KW - Additive manufacturing KW - Open Source Software PY - 2025 AN - OPUS4-63904 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Geranmayeh, Ali T1 - Laser Metal Deposition of NiTi Shape Memory Alloys: Influence of Process Parameters on Thermal Profiles and Part Properties N2 - Laser Metal Deposition (LMD), a laser powder–directed energy deposition technology (LP-DED), offers unique flexibility for fabricating complex metallic components. Among candidate materials, Nitinol (NiTi) is particularly attractive due to its shape memory and superelastic properties, though its high sensitivity to processing conditions demands precise parameter control. In this work, prealloyed NiTi powder was deposited as single tracks, and process parameters were optimized using a Design of Experiments methodology. A Central Composite Design (CCD) was implemented with laser power, scan speed, and powder feed rate as inputs, while track’s height, width, aspect ratio, and dilution served as optimization responses. To address the strong susceptibility of NiTi to heat accumulation, hatch spacing was further optimized using a geometrically derived formula, enabling the use of maximum spacing while ensuring dense parts with smooth surfaces and minimal waviness. The presented framework establishes a systematic route for parameter optimization in NiTi LMD, offering practical guidelines for balancing densification and surface quality. T2 - WGF Assistant Seminar CY - Rechenberg-Bienenmühle, Germany DA - 10.09.2025 KW - Additive manufacturing KW - Shape memory alloys KW - Nitinol KW - Laser metal deposition KW - Design of experiments PY - 2025 AN - OPUS4-64164 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Linden, Anna T1 - AMVAD - Additive manufacturing for ventricular assist devices N2 - Some children are born with a univentricular heart, meaning their heart has only one pumping chamber instead of two. To improve circulation, patients often undergo the Fontan procedure, which reroutes blood flow — but this can put stress on other organs. In some cases, ventricular assist devices, or VADs, are used to support the heart’s pumping function. This involves an artificial pump connected directly to the patient's heart via silicone-based cannulas. Unique anatomical conditions introduce special challenges for cannula geometry. Additive manufacturing offers innovative solutions by enabling the production of personalized medical devices. The aim of the project is to develop the manufacturing workflow for the individualized cannula from digital imaging of the patient and customized design to additive manufacturing. Besides technical feasibility, validating the entire process is crucial for regulatory approval. The selection and testing of suitable additive manufacturing processes and biocompatible materials for individualized silicone cannulas, ensuring compliance with quality standards for high-risk medical products, will be presented. T2 - AMBER Spotlight On: 3D Printing meets Health & Biotech CY - Berlin, Germany DA - 16.09.2025 KW - Additive manufacturing KW - Medical device KW - Liquid silicone rubber PY - 2025 AN - OPUS4-64101 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Petrat, T. T1 - Embedding electronics into additive manufactured components using laser metal deposition and selective laser melting N2 - The paper deals with the integration of a light emitting diode (LED) into an additive manufactured metal component. Selective laser melting (SLM) and laser metal deposition (LMD) are used. The material used is the chrome-nickel steel 316L. The basic component is manufactured by means of SLM and consists of a solid body and an area with grid structure. The solid body includes a duct in the shape of a groove with a recess for the positioning of the power cable. The LED is embedded in the grid structure via an inlet from the solid body. In further processing, the groove is filled with LMD. Two strategies with different parameter combinations were investigated. It shows that a high energy input near the power cable leads to its destruction. By using multiple parameter combinations during the manufacturing process, this destruction can be prevented. There was a comparison of both strategies with regard to the necessary number of tracks and duration of welding time. T2 - LANE 2018 CY - Fürth, Germany DA - 03.09.2018 KW - Additive manufacturing KW - Condition monitoring KW - Process chain KW - Laser-metal-depositon KW - Selektive-laser-melting KW - Embedded electronics PY - 2018 AN - OPUS4-47947 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Evans, Alexander T1 - Introduction to AGIL N2 - An introduction to the Themenfeld Material project AGIL will be presented. The concept of the project, the work package structure and the material used within the project will be presented. T2 - 2nd Workshop on In situ Monitoring and Microstructure Development in Additive Manufacturing CY - Online meeting DA - 19.04.2021 KW - AGIL KW - Ageing KW - Additive manufacturing KW - Laser powder bed fusion PY - 2021 AN - OPUS4-54107 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 - Zerbst, Uwe A1 - Llavori, I. A1 - Hilgenberg, Kai T1 - Design methodology of vessel produced by L PBF stainless steel using representative specimens N2 - This work presents the preliminary results of an ongoing project with a double objective: on the one hand, the characterisation of the mechanical properties against fatigue damage of an additively manufactured 316 stainless steel produced by laser powder bed-based (L-PBF) technology; on the other hand, the implementation of numerical simulation techniques able to predict the mechanical behaviour of the material in order to optimise and reduce the design costs of vessels used in the chemical sector. The current state of the work developed in this research framework allows showing the first batch of experimental results of crack propagation rate (FCGR) and high cycle fatigue (HCF) tests. The geometry of the vessels studied presents three clearly differentiated regions, either in terms of thickness (11-15 mm) or concerning the inclination of the walls to the direction of manufacturing (0º - 45º). The experimental campaign carried out so far allows identifying the differences in behaviour when comparing different extraction locations around the vessel. This is due to the variations in thermal cycles that the deposited material undergoes during the manufacturing process. Therefore, this causes variations in the microstructure which lead to changes in the response of the material. In this work, these differences are analysed qualitatively and quantitatively from the results of FCGR and HCF, thus allowing to locate the regions with the highest risk in terms of structural integrity against fatigue. This preliminary phase together with the numerical simulation of the additive manufacturing process are key to achieving a reliable description and modelling of the material. The latter will make it possible to address the priority aim of this project, involving the manufacture of independent samples whose properties are representative of the original material extracted from the reference vessels. It is, therefore, a comprehensive methodology for the design of additively manufactured components based on the localised fatigue mechanical properties of representative specimens. T2 - ECF23, European Conference on Fracture 2022 CY - Funchal, Portugal DA - 27.06.2022 KW - Additive manufacturing KW - Steel 316L KW - Fracture Mechanics PY - 2022 AN - OPUS4-55240 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mohr, Gunther T1 - Towards component safety in laser powder bed fusion of metals N2 - The thermal history during additive manufacturing of complex components differs significantly from the thermal history of geometrically primitive test specimens. This can result in differences in properties that can lead to different material behavior. 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 - Additive Alliance CY - Hamburg, Germany DA - 05.03.2024 KW - Additive manufacturing KW - Heat accumulation KW - Laboratory specimens KW - In situ monitoring KW - Representative specimens KW - Thermal history PY - 2024 AN - OPUS4-60263 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Jonathan T1 - Visual surface structure analysis of high-resolution images from visual in-situ process monitoring in laser powder bed fusion N2 - Parameter studies are a common step in selecting process parameters for powder bed fusion of metals with laser beam (PBF-LB/M). Density cubes manufactured with varied process parameters exhibit distinguishable surface structures visible to the human eye. Industrial visual in-situ monitoring systems for PBF-LB/M currently have limited resolution and are incapable of reliably capturing differences in the surface structures. For this work, a 65 MPixel high resolution monochrome camera is integrated in an industrial PBF-LB/M machine together with a high intensity led bar. Post-exposure images are taken to analyze differences in light reflection on the specimen’s surface. The grey level co-occurrence matrix is used to quantify the in-situ measured visual surface structure of nickel-based super alloy IN939 density cubes. The properties of the grey level co-occurrence matrix correlate to the energy input and resulting porosity of specimens. Low energy samples with lack of fusion flaws show an increased contrast in the grey level co-occurrence matrix compared to specimens with an optimal energy input. The potential of high-resolution images as reference data in in-situ process monitoring in PBF-LB/M is discussed. T2 - 77th IIW Annual Assembly and International Conference CY - Rhodos, Greece DA - 06.07.2024 KW - Additive manufacturing KW - Powder bed fusion KW - In-situ monitoring KW - Image processing KW - Lack of fusion PY - 2024 AN - OPUS4-60688 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mohr, Gunther T1 - Development of representative test specimens by thermal history transfer in laser powder bed fusion N2 - The use of components manufactured by laser powder bed fusion (PBF LB/M) and subjected to fatigue loading is still hampered by the uncertainty about the homogeneity of the process results. Numerous influencing factors including the component’s geometry contribute to the risk of process instability and resulting inhomogeneity of properties. This drastically limits the comparability of different built parts and requires expensive full component testing. 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. Following this assumption, a strategy is developed to transfer the intrinsic preheating temperature as a measure of comparability of thermal histories from a region of interest of a complex component to a simple test specimen. This transfer concept has been successfully proved by the use of FEM-based macroscale thermal simulations, validated by calibrated infrared thermography. An adoption of the specimen manufacturing process by the adjustment of the inter layer times was established to manufacture specimens which are representatives of a specific region of a large-scale component in terms of the thermal history similarity criterion. The concept is schematically illustrated in Figure 1 and was demonstrated using a pressure vessel geometry from the chemical industry. T2 - 4th Symposium on Materials and Additive Manufacturing CY - Berlin, Germany DA - 12.06.2024 KW - Additive manufacturing KW - Thermal history KW - Laboratory specimens KW - In situ monitoring KW - Representative specimens PY - 2024 AN - OPUS4-60260 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schröpfer, Dirk 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-II/CIX CY - Munich, Germany DA - 06.03.2023 KW - Additive manufacturing KW - High strength steel KW - Residual stress PY - 2023 AN - OPUS4-59307 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Eissel, A. T1 - Modification of CoCr alloys to optimize of additively welded microstructures and subsequent surface finishing N2 - Due to increasing requirements relating to the efficiency of highly stressed components in turbine or plant construction, the use of cost-intensive, difficult to process materials is increasingly necessary today. In this context, cobalt-chromium alloys in particular are highly resistant to thermal and mechanical stress, as well as to corrosive and abrasive loads. Moreover, increasingly complex structures and the optimisation of resource efficiency also require additive manufacturing steps for the production or repair of components in many sectors. In order to realise a homogeneous and isotropic microstructure, alloy modifications are made to the alloy CoCr26Ni9Mo5W. For this purpose, hafnium and zirconium are added at 1 % and 0,33 % by mass each, as these elements are supposed to have a positive effect on the microstructure morphology. Plasma-Transferred-Arc is used for the welding tests. Wall structures are welded by multiple single-layer, overlapping welding beads on low-alloyed steel substrate (S355). The results show that the alloying elements hafnium and zirconium have a clear influence on the microstructure. Hardness measurements were also carried out. With each modification, the hardness is increased compared to the original material. The machining analyses show a reduction in cutting forces using ultrasonic assisted milling for high cutting speed and low feed rate. T2 - 2021 Intermediate meeting of C IX NF CY - Online meeting DA - 09.03.2021 KW - Alloy modification KW - Ultrasonic-assisted milling KW - Plasma-Transferred-Arc KW - Filler metal modification KW - Additive manufacturing PY - 2021 AN - OPUS4-52356 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Witte, Julien T1 - Additive Manufacturing of Iron Aluminides: Microstructure, Machinability, and Surface Integrity N2 - The increasing global focus on energy and resource efficiency has stimulated a growing interest in additive manufacturing. AM offers economic advantages and enables an efficient use of materials. However, AM components often require subsequent mechanical post-processing, such as machining (e.g. milling), to achieve the final contours or surfaces. This is a particular challenge due to the heterogeneous and anisotropic nature of AM structures, which affect machining and the resulting component properties. High-performance materials such as iron aluminide represent a promising alternative to conventional high-temperature materials with a significant economic advantage. However, the strength and hardness properties, which are advantageous for applications in highly stressed lightweight components, pose a challenge for economical machining in addition to the AM microstructure properties. The difficult-to-cut material causes accelerated tool wear and insufficient surface quality. This study shows that crack-free additive manufacturing of the three-component system of iron-nickel-aluminum is possible and advantages in terms of machinability compared to FeAl-AM components are achieved. The more homogeneous microstructure leads to a reduction in cutting forces, with positive effects on the machinability and optimized surface integrity. Ultrasonic assisted milling (USAM) offers great potential to address the major challenges posed by difficult-to-cut materials and additively manufactured weld structures. Therefore, this study focuses on assessing the transferability of previous positive results by USAM to the selected iron aluminide alloys. The machinability of the aluminides is analyzed by varying significant influencing variables in finish milling experiments and evaluated in terms of the loads on the tool and the resulting surface integrity. T2 - 77. IIW Annual International Conference CY - Rhodos, Greece DA - 07.07.2024 KW - Additive manufacturing KW - Surface-integrity KW - Iron-aluminide KW - Ultrasonic-assisted milling KW - Difficult-to-cut KW - Tool wear PY - 2024 AN - OPUS4-62027 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Witte, Julien T1 - Optimizing residual stresses in additively manufactured high-performance materials N2 - The integration of modern high-performance materials in combination with additive manufacturing (AM) has revolutionized the approach to lightweight construction across diverse applications. This study explores the synergy between these materials and additive manufacturing (AM), focusing on their unique properties to engineer resource-efficient structures. Despite these advancements, machining these hard-to-cut materials such as iron-aluminide for safety-critical components remains challenging due to increased tool wear and compromised surface integrity. This research focuses on overcoming these challenges through the application of ultrasonic-assisted milling (USAM), a hybrid machining process exhibiting significant potential. By incorporating ultrasonic oscillations along the milling tool axis, USAM minimizes tool and component surface loads, enhancing tool life and producing defect-free, homogeneous surfaces with reduced roughness parameters. This investigation centers on the influence of ultrasonic-assisted milling on residual material stresses, crucial for component performance under load. In contrast to conventional milling generating tensile stresses, USAM induces advantageous compressive residual stresses, potentially enhancing the component's crack resistance. The study employs experimental variations in ultrasonic amplitude during the machining process to identify optimal parameters for achieving maximum compressive stresses. In addition, the depth profile of these residual stresses on the surface is investigated, which provides more detailed insights into their distribution and possible effects. This research not only contributes to the evolving environment of innovative manufacturing technologies, but also places particular focus on the central role of residual stresses in the performance and reliability of safety-critical AM components. The results not only contribute to a better understanding of ultrasonic-assisted milling, but also provide crucial guidance for the design of components that can withstand the challenges of real-world applications. T2 - BMDK OvGU Magdeburg CY - Magdeburg, Germany DA - 19.06.2024 KW - Ultrasonic-assisted milling KW - Additive manufacturing KW - High-performance materials KW - Surface integrity KW - Residual stresses depth profile PY - 2024 AN - OPUS4-62025 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Eissel, A. T1 - Alloy modification for additive manufactured Ni alloy components Part I: Effect on microstructure and hardness N2 - Alloy 36 (1.3912), also known as “Invar”, is an alloy with 36% nickel. The alloy has a remarkably low thermal expansion coefficient in certain temperature ranges. Therefore, it is used in applications in which dimensional stability is critical, such as moulding tools for composite materials in aerospace and automotive applications. Moreover, increasingly complex structures and the optimisation of resource efficiency also require additive manufacturing steps for the production or repair of components. Additively manufactured components have a heterogeneous microstructure and anisotropic mechanical properties. In part I of this investigation, the initial alloy 36 is modified with the elements Ti, Zr and Hf up to a maximum of 0.33 wt.-%. The influence of the modification elements on the microstructure as well as on the hardness of the AM components is examined. Part II focusses on the effect of the alloy modifications on machinability as well as on the surface integrity of plasma-transferred-arc-welded (PTA) and finish milled invar components. The results show that PTA welding cause numerous finely distributed precipitates with high silicon content. T2 - 75th IIW Annual Assembly CY - Tokyo, Japan DA - 17.07.2022 KW - Alloy modification KW - Alloy 36 KW - Additive manufacturing PY - 2022 AN - OPUS4-55439 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maierhofer, Christiane T1 - Summary of in-situ monitoring in additive manufacturing - ProMoAM N2 - The quality of additively manufactured components is significantly influenced by the process parameters used during production. Thus, sensors and measuring systems are already commercially available for process monitoring, at least in metal-based additive manufacturing. However, it is not yet possible to detect defects and inhomogeneities directly or indirectly during the building process. The aim of the project ProMoAM is to develop spectroscopic and non-destructive testing methods for the in-situ evaluation of the quality of additively manufactured metal components in laser- or arc-based AM processes. In addition to passive and active methods of thermography, this includes optical tomography, optical emission spectroscopy, eddy current testing, laminography (radiography), X-ray backscattering, particle emission spectroscopy and photoacoustic methods. T2 - 2nd Workshop on In-situ Monitoring and Microstructure Development in Additive Manufactured Alloys CY - Online meeting DA - 19.04.2021 KW - In-situ monitoring KW - Additive manufacturing KW - Metals KW - Thermography PY - 2021 AN - OPUS4-52539 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Altenburg, Simon T1 - Towards hyperspectral in-situ temperature measurement in metal additive manufacturing N2 - The industrial use of additive manufacturing for the production of metallic parts with high geometrical complexity and lot sizes close to one is rapidly increasing as a result of mass individualisation and applied safety relevant constructions. However, due to the high complexity of the production process, it is not yet fully understood and controlled, especially for changing (lot size one) part geometries. Due to the thermal nature of the Laser-powder bed fusion (L-PBF) process – where parts are built up layer-wise by melting metal powder via laser - the properties of the produced part are strongly governed by its thermal history. Thus, a promising route for process monitoring is the use of thermography. However, the reconstruction of temperature information from thermographic data relies on the knowledge of the surface emissivity at each position on the part. Since the emissivity is strongly changing during the process due to phase changes, great temperature gradients, possible oxidation, and other potential influencing factors, the extraction of real temperature data from thermographic images is challenging. While the temperature development in and around the melt pool, where melting and solidification occur is most important for the development of the part properties. Also, the emissivity changes are most severe in this area, rendering the temperature deduction most challenging. A possible route to overcome the entanglement of temperature and emissivity in the thermal radiation is the use of hyperspectral imaging in combination with temperature emissivity separation (TES) algorithms. As a first step towards the combined temperature and emissivity determination in the L-PBF process, here, we use a hyperspectral line camera system operating in the short-wave infrared region (0.9 µm to 1.7 µm) to measure the spectral radiance emitted. In this setup, the melt pool of the L-PBF process migrates through the camera’s 1D field of view, so that the radiation intensities are recorded simultaneously for multiple different wavelength ranges in a spatially resolved manner. At sufficiently high acquisition frame rate, an effective melt pool image can be reconstructed. Using the grey body approximation (emissivity is independent of the wavelength), a first, simple TES is performed, and the resulting emissivity and temperature values are compared to literature values. Subsequent work will include reference measurements of the spectral emissivity in different states allowing its analytical parametrisation as well as the adaption and optimisation of the TES algorithms. An illustration of the proposed method is shown in Fig.1. The investigated method will allow to gain a deeper understanding of the L-PBF process, e.g., by quantitative validation of simulation results. Additionally, the results will provide a data basis for the development of less complex and cheaper sensor technologies for L-PBF in-process monitoring (or for related process), e.g., by using machine learning. T2 - 21st International Conference on Photoacoustic and Photothermal Phenomena CY - Bled, Slovenia DA - 19.06.2022 KW - Thermography KW - Additive manufacturing KW - L-PBF KW - Hyperspectral PY - 2022 AN - OPUS4-55152 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Eissel, A. T1 - Alloy modification for additive manufactured Ni alloy components Part I: Effect on microstructure and hardness N2 - Alloy 36 is an iron-based alloy with 36% nickel. It is used in applications in which dimensional stability is critical, such as molding tools for composite materials in aerospace and automotive applications. Moreover, increasingly complex structures and the optimisation of resource efficiency also require additive manufacturing steps for the production or repair of components. Additively manufactured components have a heterogeneous microstructure and anisotropic mechanical properties. In addition, the manufactured components require subsequent machining surface finishing due to the high requirements. Nickel iron alloys are difficult to machine. Additionally, inhomogeneous microstructure may lead to unstable cutting forces and conditions. Alloy modifications are made to the alloy 36. For this purpose, titanium, zirconium and niobium are added up to 1 % by mass each. Plasma-Transferred-Arc is used for the welding tests. The hardness profile is determined on the transverse section. The initial structure as well as the modifications have an austenitic structure. The microstructure of the modifications of Alloy 36 with 1% Ti and 1% Zr is not refined, instead the grain size increases. T2 - IIW C-II Intermediate meeting CY - Online meeting DA - 17.03.2022 KW - Alloy modification KW - Alloy 36 KW - Additive manufacturing PY - 2022 AN - OPUS4-56622 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Engelking, Lorenz T1 - Optimisation of surface residual stresses using hybrid milling processes for additive manufactured Nickel alloy components N2 - Ni alloys are cost intensive materials and generally classified as difficult-to-cut materials. However, machining of these materials is needed especially in case of alloy 36 (1.3912), which is commonly used in mould construction for the production of fibre-reinforced composites. With regard to repair, modification and manufacturing of such components, additive manufacturing offers significant economic advantages. Nevertheless, subsequent machining steps are needed to achieve the final component contour and defined surface conditions. Dependent on the material and machining process conditions, detrimental tensile residual stresses may be the result on the machined surface, having negative impact on the component performance and safety. Recent studies exhibited that hybrid machining processes, such as ultrasonic-assisted milling (USAM), are suitable for achieving favourable residual stress states at the surface of difficult-to-cut Ni-Cr alloys. In this investigation, wire arc additive manufactured (WAAM) specimens of alloy 36 were finish milled under different milling conditions. In addition to the machined surfaces condition and topology, the surface-near residual stresses were analysed using X-ray diffraction (XRD). Especially for low cutting speeds, significantly improved surface properties, roughness parameters and lower mechanical and microstructural degradations were found for the specimen machined with USAM compared to conventional milling. The improved surface integrity could furthermore be observed by a significant reduction of the tensile residual stresses in the surface boundary area. T2 - Bachelor-, Master-, Doktoranden-Kolloquium, Otto-von-Guericke-Universität Magdeburg CY - Magdeburg, Germany DA - 18.05.2022 KW - Surface integrity KW - Ultrasonic-assisted milling KW - Additive manufacturing KW - Ni alloy KW - Alloy 36 PY - 2022 AN - OPUS4-54908 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Robens-Radermacher, Annika T1 - Efficient cooling time optimization in Wire Arc Additive Manufacturing using a multi-layer reduced order model N2 - Additive manufacturing (AM) has transformed the industry by enabling the production of complex geometries and parts with customized properties. Among various AM techniques, wire arc additive manufacturing (WAAM) stands out due to its high deposition rate and low equipment cost. However, WAAM’s complex thermal history poses challenges for real-time simulation, essential for online process control and optimization. Consequently, experimental optimization remains the state-of-the-art approach. A critical parameter to optimize is the cooling phase duration, which prevents structural overheating, controls the molten pool size, and influences the mechanical properties of the final product. For efficient cooling time optimization, a fast-to-evaluate model of the temperature field during multi-layer deposition is necessary. This study proposes a reduced order model (ROM) using the proper generalized decomposition (PGD) method as a powerful tool to minimize computational effort. Given the moving heat source in WAAM processes, a mapping approach is employed to achieve a fully separated representation of the temperature field. Building on the authors’ previous one-layer approach, this contribution extends the model to multiple layers through enhanced mapping and compression techniques. The compression reduces the total number of PGD modes as the number of layers increases. The extended mapping allows computations with a fixed mesh over the simulation time, in contrast to standard methods such as the element birth technique. For cooling time optimization, the cooling duration of each layer is incorporated as PGD variables, enabling time-efficient computation of the temperature field for varying cooling times. The developed ROM is applied to optimize the cooling time of a multiple layer example. Therefore a 5-10 layer wall structure is investigated using the austenitic stainless steel 1.4404 (AISI 316 L). The resulting cooling times and the efficiency of the approach are discussed. T2 - 12th European solid mechanics conference (ESMC) CY - Lyon, France DA - 07.07.2025 KW - Model order reduction KW - Proper generalized decomposition KW - Welding KW - Additive manufacturing KW - Optimzation PY - 2025 UR - https://esmc2025.sciencesconf.org/ AN - OPUS4-63855 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mishurova, Tatiana A1 - Serrano-Munoz, Itziar T1 - Multiscale residual stress analysis and synchrotron X-ray refraction of additively manufactured parts N2 - The overview of the activity of group 8.5 Micro-NDT (BAM, Belin, Germany) in the field of additively manufacturing material characterization will be presented. The challenges in the residual stress analysis of AM components are discussed on the basis on the show studies performed in BAM. Also, the synchrotron X-ray refraction technique, available in BAM, is presented, showing example of in-situ heating test of Al10SiMg AM material. T2 - Seminar at Grenoble INP, Science et Ingénierie des Matériaux et Procédés (SIMaP) CY - Grenoble, France DA - 01.07.2022 KW - Additive manufacturing KW - Residual stress KW - X-ray refraction KW - Computed tomography PY - 2022 AN - OPUS4-55232 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Serrano-Munoz, Itziar T1 - 3D imaging and residual stress analysis for AM Materials N2 - Metal Additive Manufacturing (AM) technologies such as Laser Powder Bed Fusion (LPBF) are characterized by layer wise construction, which enable advancements of component design, leading to potential efficiency and performance improvements. However, the rapid cooling rates associated with the process consequently leads to the generation of high magnitude residual stresses (RS). Therefore, a deep understanding of the formation of RS, the influence of process parameters on their magnitude and the impact on mechanical performance is crucial for widespread application. The experimental characterization of these RS is essential for safety related engineering application and supporting the development of reliable numerical models. Diffraction-based methods for RS analysis using high energy synchrotron X-rays and neutrons enable non-destructive spatially resolved characterization of both surface and bulk residual stresses in complex components. This presentation will provide an overview of recent research conducted by the BAM at large scale facilities for the characterization of residual stresses in LPBF metallic alloys. Special focus will be given to the challenges posed by textured LPBF materials for the reliable choice of the diffraction elastic constants (DECs), which is crucial to the accurate calculation of the level of RS. T2 - Seminar at LTDS, Ecole Centrale de Lyon CY - Lyon, France DA - 15.06.2023 KW - Residual stress KW - Additive manufacturing KW - Diffraction methods PY - 2023 AN - OPUS4-57808 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kempf, A. T1 - Influence of process-relevant parameters and heat treatments on the microstructure and resulting mechanical behavior of additively manufactured AlSi10Mg via Laser Powder Bed Fusion N2 - Within the group of additive manufacturing (AM) technologies for metals, laser powder bed fusion (L-PBF) has a leading position. Nevertheless, reproducibility of part properties has not reached sufficient maturity hindering the use for industrial applications especially for safety-relevant components. This article presents the results of various experimental tests performed with the aluminium alloy AlSi10Mg identifying reasons for the high deviations in mechanical properties. Herein, it is discussed how microstructure is influenced by different process parameters (laser power, scanning speed, energy density, building height) and how it can be adjusted by suitable post process heat treatments. The impact of resulting changes in microstructure is shown by monotonic tensile and cyclic fatigue tests considering specimens manufactured with different L-PBF machines. T2 - LiM 2021 CY - Online meeting DA - 21.06.2021 KW - Additive manufacturing KW - AlSi10Mg KW - Laser powder bed fusion PY - 2021 AN - OPUS4-53046 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Merz, Benjamin T1 - On the challenges of hybrid repair of gas turbine blades using laser powder bed fusion N2 - Additive manufacturing (AM) processes such as laser powder bed fusion (PBF-LB/M) are rapidly gaining popularity in repair applications. Gas turbine components benefit from the hybrid repair process as only damaged areas are removed using conventional machining and rebuilt using an AM process. However, hybrid repair is associated with several challenges such as component fixation and precise geometry detection. This article introduces a novel fixturing system, including a sealing concept to prevent powder sag during the repair process. Furthermore, a high-resolution camera within an industrial PBF-LB/M machine is installed and used for object detection and laser recognition. Herein, process related inaccuracies such as PBF-LB/M laser drift is considered by detection of reference objects. This development is demonstrated by the repair of a representative gas turbine blade. The final offset between AM build-up and component is analysed. An approximate accuracy of 160 μm is achieved with the current setup. T2 - LiM 2023 CY - Munich, Germany DA - 26.06.2023 KW - Laser powder bed fusion KW - Additive manufacturing KW - Hybrid repair KW - Position detection KW - High-resolution camera PY - 2023 AN - OPUS4-57837 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Eissel, A. T1 - Investigations on influencing the microstructure of additively manufactured Co-Cr alloys to improve subsequent machining conditions N2 - Co-Cr alloys are frequently used for highly stressed components, especially in turbine and plant construction, due to their high resistance to thermal and mechanical stress, as well as to corrosive and abrasive loads. Furthermore, they are classified as difficult-to-cut materials because of their high strength and toughness as well as their low thermal conductivity. However, for Co, an increased cost and supply risk can be observed in recent years. Therefore, additive manufacturing (AM) offers significant economic advantages due to higher material efficiency regarding repair, modification, and manufacturing of such components. Concerning inhomogeneity and anisotropy of the microstructure and properties as well as manufacturing-related stresses, a lot of knowledge is still necessary for the economic use of additive welding processes in SMEs. In addition, subsequent machining, particularly contour milling, is essential to generate the required complex contours and surfaces. Hence, additive and machining manufacturing processes need to be coordinated in a complementary way, especially due to additional challenges arising in milling of heterogeneous hard-to-cut microstructures. Recently, it has been shown that modern, hybrid cutting processes, such as ultrasonic-assisted milling (US), can improve the cutting situation. In this investigation, the Co-Cr initial alloy is additionally modified with Ti and Zr up to 1 wt.-% with the aim to enhance the homogeneity of the microstructure and, thus, the machinability. Hence the investigation includes finish milling tests of the AM components and the comparison of US and conventional machining. Both the modifications and the ultrasonic assistance exhibit a significant effect on the machining situation, e.g., US causes a higher surface integrity of the finish milled surfaces compared to conventional milling. T2 - International Congress on Welding, Additive Manufacturing and associated non destructive testing CY - Online meeting DA - 08.06.2022 KW - Co-Cr-alloy KW - Additive manufacturing KW - Ultrasonic-assisted milling KW - Surface integrity PY - 2022 AN - OPUS4-55431 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Engelking, Lorenz T1 - Alloy modification for additive manufactured Ni alloy components Part II: Effect on subsequent machining properties N2 - Alloy 36 (1.3912), also known as “Invar”, is an alloy with 36% nickel. It was developed in 1897 by Guillaume and stands out for its very low thermal expansion coefficient. It is classified as a difficult-to-cut material and is commonly used for the production of fiber-reinforced composites in the field of mold construction. Additive manufacturing (AM) offers many economic advantages regarding the repair, modification and manufacture of entire components. Subsequent machining of the AM components is necessary to account for complex structures, final contours or defined surfaces. This is usually done using a tool with a geometrically defined cutting edge, i.e., milling processes. Surface integrity is determined by metallurgical (e.g., microstructure of the subsurface), topological (e.g., surface defects, roughness) and mechanical (e.g., residual stresses) factors, which is crucial in terms of component safety and performance. Modern, hybrid cutting processes, such as ultrasonic-assisted milling (US), provide potentially improvement of the cutting situation of these components. In part I of this investigation, the initial alloy 36 is modified with the elements Ti, Zr and Nb up to a maximum of 1 wt.-%. The influence of the modification elements on the microstructure as well as on the hardness of the AM components is examined. Part II focusses on the effect of the alloy modifications on machinability as well as on the surface integrity of plasma-transferred-arc-welded (PTA) and finish milled invar components. The results show a significant positive influence of ultrasonic assistance on the resulting cutting force of both materials. The modification with 1% Ti shows a positive influence on the surface integrity, as the roughness of the conventional machining processes is lower compared to the initial alloy, which has to be confirmed in further experiments. T2 - IIW C-II Intermediate meeting CY - Online meeting DA - 17.03.2022 KW - Alloy modification KW - Ultrasonic-assisted milling KW - Plasma-Transferred-Arc KW - Surface integrity KW - Alloy 36 KW - Additive manufacturing PY - 2022 AN - OPUS4-54910 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Engelking, Lorenz T1 - Alloy modification for additive manufactured Ni alloy components Part II: Effect on subsequent machining properties N2 - Alloy 36 (1.3912), also known as “Invar”, is an alloy with 36% nickel. It was developed in 1897 by Guillaume and stands out for its very low thermal expansion coefficient. It is classified as a difficult-to-cut material and is commonly used for the production of fiber-reinforced composites in the field of mold construction. Additive manufacturing (AM) offers many economic advantages regarding the repair, modification and manufacture of entire components. Subsequent machining of the AM components is necessary to account for complex structures, final contours or defined surfaces. In part I of this investigation, the initial alloy 36 is modified with the elements Ti, Zr and Hf up to a maximum of 0.33 wt.-%. The influence of the modification elements on the microstructure as well as on the hardness of the AM components is examined. Part II focusses on the effect of the alloy modifications on machinability as well as on the surface integrity of plasma-transferred-arc-welded (PTA) and finish milled invar components. Machining tests were carried out, to investigate the influence of ultrasonic assistance and the effects of modification elements Ti, Zr and Hf on the occurring cutting forces, temperatures and resulting surface integrity of the AM components made of alloy 36 and their modifications. The results show a significant positive influence of ultrasonic assistance on the resulting cutting force as well as on the roughness of all materials investigated. T2 - 75th IIW Annual Assembly CY - Tokyo, Japan DA - 17.07.2022 KW - Alloy modification KW - Alloy 36 KW - Additive manufacturing KW - Ultrasonic-assisted milling KW - Surface integrity PY - 2022 AN - OPUS4-55432 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Engelking, Lorenz T1 - Effect of alloy modification for additive manufactured Ni alloy components on microstructure and subsequent machining properties N2 - Ni alloys are generally classified as difficult-to-cut materials and cost intensive. Additive manufacturing (AM) offers economic advantages. However, machining of these AM components is mandatory to create the final contour or surface. The inhomogeneous and anisotropic microstructure and properties of AM components causes an unstable cutting process. Moreover, undesirable tensile residual stresses are generated due to subsequent machining. In this investigation, the initial alloy 36 is modified with Ti and Nb up to 1.6 wt.-% and build-up welded via gas metal arc welding (GMAW) and plasma-transferred-arc (PTA). Then, finish-milling tests are carried out to investigate the influence of the modification as well as the cutting parameters on the resulting cutting force and the surface integrity. In addition, the conventional milling process (CM) is compared with the ultrasonic-assisted milling process (US), which has a significant influence on the machinability as well as on the surface integrity. T2 - Additive Fertigung – Werkstoffe – Prozesse – Wärmebehandlung 2022 CY - Bremen, Germany DA - 29.06.2022 KW - Additive manufacturing KW - Alloy 36 KW - Alloy modification KW - Ultrasonic-assisted milling KW - Surface integrity PY - 2022 AN - OPUS4-55429 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Treutler, K. T1 - Nickel-iron-alloy modification to enhance additively welded microstructure for subsequent milling N2 - The aerospace industry uses nickel-iron-alloys to create moulding tools for composite materials because of the low coefficient of thermal expansion. These tools have a large-sized and complex structure, making them cost-intensive and difficult to manufacture. Therefore, the focus is set on additive manufacturing, which can additionally enable the repair of components in order to eliminate local defects. However, the process usually results in a heterogeneous microstructure and anisotropic mechanical properties. As there is a high demand for a precise and exact fit of the precision moulds and thus the surface quality, the welded components must be subsequently machined. Nickel-iron alloys are difficult to machine and an inhomogeneous microstructure also leads to unstable cutting forces. Consequently, a refinement and homogenisation of the microstructure morphology is achieved through specific alloy modifications in order to stabilise and improve the subsequent machining process. Studies on the refinement of FeNi 36 based on vacuum arc melting furnaces are used as a starting point. Therefore, titanium and niobium are chosen as modification elements with a maximum 1 % weight percent and are added to nickel-iron base alloy. The elements are alloyed and build-up welded by using plasma-transferred-arc welding. The resulting microstructure morphology of the welded wall structure and the machining properties are then determined. Furthermore, the influence on the coefficient of thermal expansion is investigated in connection with the modification and the welding process itself. It can be shown that even small amounts of niobium have a significant influence on the structural morphology of the welded layers during plasma-transferred-arc welding. T2 - 2nd international Conference on Advanced Joining Processes 2021 CY - Sintra, Portugal DA - 21.10.2021 KW - Alloy modification KW - Ultrasonic-assisted milling KW - Nickel-iron-alloy KW - Additive manufacturing KW - Plasma transferred arc welding PY - 2021 AN - OPUS4-53635 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Joining processes for components in hydrogen technologies: Current need and future importance N2 - This presentation gives an overview on the importance of joining processes for component fabrication in hydrogen technologies. For that reason, the current need and future research and developement activites are highlighted for the three technological fields: hydrogen storage, transport and use (in terms of the emerging field of additive manufacturing). Finally, some remarks are given for necessary changes in the standardization. T2 - IIW Intermediate Meeting, Comm. II-A "Welding Metallurgy" CY - Online meeting DA - 17.03.2022 KW - Hydrogen KW - Welding KW - Research KW - Review KW - Additive manufacturing PY - 2022 AN - OPUS4-54488 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wandtke, Karsten T1 - Consideration of manufacturing-related stresses and cold crack avoidance in high-strength steels WAAM components N2 - High-strength steels offer great potential in weight-optimised modern steel structures. Additive manufacturing processes, such as Wire Arc Additive Manufacturing (WAAM), enable near-net-shape manufacturing of complex structures and more efficient manufacturing, offering significant savings in costs, time, and resources. Suitable filler materials for WAAM are already commercially available. However, the lack of knowledge or technical guidelines regarding welding residual stresses during manufacturing and operation in connection with cold cracking risk limit their industrial application significantly. In a project of BAM and TU Chemnitz, the influences and complex interactions of material, manufacturing process, design and processing steps on residual stress evolution are investigated. By developing process recommendations and a special cold cracking test, economic manufacturing, and stress-appropriate design of high-strength steel WAAM components are main objectives. The present study focuses on determining the influence of heat control (interpass temperature, heat input, cooling time) and the design aspects of the components on the hardness and residual stresses, which are analysed by X-ray diffraction. Defined reference specimens, i.e., hollow cuboids, are automatically welded with a special WAAM solid wire. The influences of wall length, wall thickness and wall height on the residual stresses are analysed. Geometric properties can be selectively adjusted by wire feed and welding speed but cannot be varied arbitrarily. This was addressed by adapted build-up strategies. The results indicate a significant influence of the heat control and the wall height on the residual stresses. The interpass temperature, wall thickness and wall length are not significant. These analyses allow recommendations for standards and manufacturing guidelines, enabling a safe and economic manufacturing of high-strength steel components. T2 - European Steel Technology and Application Days CY - Düsseldorf, Germany DA - 14.06.2023 KW - DED-arc KW - Additive manufacturing KW - Heat control KW - High-strength filler metals KW - Residual stress PY - 2023 AN - OPUS4-57691 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Witte, Julien T1 - Optimizing residual stresses in additively manufactured high-performance materials N2 - The integration of modern high-performance materials in combination with additive manufacturing (AM) has revolutionized the approach to lightweight construction across diverse applications. This study explores the synergy between these materials and additive manufacturing (AM), focusing on their unique properties to engineer resource-efficient structures. Despite these advancements, machining these hard-to-cut materials such as iron-aluminide for safety-critical components remains challenging due to increased tool wear and compromised surface integrity. This research focuses on overcoming these challenges through the application of ultrasonic-assisted milling (USAM), a hybrid machining process exhibiting significant potential. By incorporating ultrasonic oscillations along the milling tool axis, USAM minimizes tool and component surface loads, enhancing tool life and producing defect-free, homogeneous surfaces with reduced roughness parameters. This investigation centers on the influence of ultrasonic-assisted milling on residual material stresses, crucial for component performance under load. In contrast to conventional milling generating tensile stresses, USAM induces advantageous compressive residual stresses, potentially enhancing the component's crack resistance. The study employs experimental variations in ultrasonic amplitude during the machining process to identify optimal parameters for achieving maximum compressive stresses. In addition, the depth profile of these residual stresses on the surface is investigated, which provides more detailed insights into their distribution and possible effects. This research not only contributes to the evolving environment of innovative manufacturing technologies, but also places particular focus on the central role of residual stresses in the performance and reliability of safety-critical AM components. The results not only contribute to a better understanding of ultrasonic-assisted milling, but also provide crucial guidance for the design of components that can withstand the challenges of real-world applications. T2 - European Conference on Surface Integrity 11 CY - Prague, Czech Republic DA - 03.06.2024 KW - Ultrasonic-assisted milling KW - Additive manufacturing KW - High-performance materials KW - Surface integrity KW - Residual stresses depth profile PY - 2024 AN - OPUS4-62026 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Treutler, Kai T1 - Additive Manufacturing of Iron Aluminides: Microstructure, Machinability, and Surface Integrity N2 - The increasing global focus on energy and resource efficiency has stimulated a growing interest in additive manufacturing. AM offers economic advantages and enables an efficient use of materials. However, AM components often require subsequent mechanical post-processing, such as machining (e.g. milling), to achieve the final contours or surfaces. This is a particular challenge due to the heterogeneous and anisotropic nature of AM structures, which affect machining and the resulting component properties. High-performance materials such as iron aluminide represent a promising alternative to conventional high-temperature materials with a significant economic advantage. However, the strength and hardness properties, which are advantageous for applications in highly stressed lightweight components, pose a challenge for economical machining in addition to the AM microstructure properties. The difficult-to-cut material causes accelerated tool wear and insufficient surface quality. This study shows that crack-free additive manufacturing of the three-component system of iron-nickel-aluminum is possible and advantages in terms of machinability compared to FeAl-AM components are achieved. The more homogeneous microstructure leads to a reduction in cutting forces, with positive effects on the machinability and optimized surface integrity. Ultrasonic assisted milling (USAM) offers great potential to address the major challenges posed by difficult-to-cut materials and additively manufactured weld structures. Therefore, this study focuses on assessing the transferability of previous positive results by USAM to the selected iron aluminide alloys. The machinability of the aluminides is analyzed by varying significant influencing variables in finish milling experiments and evaluated in terms of the loads on the tool and the resulting surface integrity. T2 - Intermediate Meeting of IIW CY - Online meeting DA - 13.03.2024 KW - Additive manufacturing KW - Surface-integrity KW - Iron-aluminide KW - Ultrasonic-assisted milling KW - Difficult-to-cut KW - Tool wear PY - 2024 AN - OPUS4-62294 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mohr, Gunther T1 - On the limitations of small cubes as test coupons for process parameter optimization in laser powder bed fusion of metals 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. Development of material and machine specific process parameters is commonly based on results acquired from small cubic test coupons of about 10 mm edge length. Such cubes are usually used to conduct an optimization of process parameters to produce dense material. The parameters are then taken as the basis for the manufacturing of real part geometries. However, complex geometries go along with complex thermal histories during the manufacturing process, which can significantly differ from thermal conditions prevalent during the production of simply shaped test coupons. This may lead to unexpected and unpredicted local inhomogeneities of the microstructure and defect distribution in the final part and it is a root cause of reservations against the use of additive manufacturing for the production of safety relevant parts. In this study, the influence of changing thermal conditions on the resulting melt pool depth of 316L stainless steel specimens is demonstrated. A variation of thermo-graphically measured intrinsic preheating temperatures was triggered by an alteration of inter layer times and a variation of cross section areas of specimens for three distinct sets of process parameters. Correlations between the preheating temperature, the melt pool depth, and occurring defects were analyzed. The limited expressiveness of the results of small density cubes is revealed throughout the systematic investigation. Finally, a clear recommendation to consider thermal conditions in future process parameter optimizations is given. T2 - Icaleo 2023 CY - Chicago, IL, USA DA - 16.10.2023 KW - Additive manufacturing KW - Heat accumulation KW - Thermal history KW - In situ monitoring KW - Representative specimens KW - Thermography PY - 2023 AN - OPUS4-58656 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mohr, Gunther T1 - On critical shifts of the process window due to heat accumulation in laser powder bed fusion N2 - Safety-critical applications of products manufactured by laser powder bed fusion (PBF-LB/M) are still limited to date. This is mainly due to a lack of knowledge regarding the complex relationship between process, structure, and resulting properties. The assurance of homogeneity of the microstructure and homogeneity of the occurrence and distribution of defects within complexly shaped geometries is still challenging. Unexpected and unpredicted local inhomogeneities may cause catastrophic failures. The identification of material specific and machine specific process parameter windows for production of fully dense simple laboratory specimens is state of the art. However, the incorporation of changing thermal conditions that a complexly shaped component can be faced with during the manufacturing process is often neglected at the stage of a process window determination. This study demonstrates the tremendous effect of changing part temperatures on the defect occurrence for the broadly used stainless steel alloy AISI 316L. Process intrinsic variations of the surface temperature are caused by heat accumulation which was measured by use of a temperature adjusted mid-wavelength infrared (MWIR) camera. Heat accumulation was triggered by simple yet effective temporal and geometrical restrictions of heat dissipation. This was realized by a variation of inter layer times and reduced cross section areas of the specimens. Differences in surface temperature of up to 800 K were measured. A severe development of keyhole porosity resulted from these distinct intrinsic preheating temperatures, revealing a shift of the process window towards unstable melting conditions. The presented results may serve as a warning to not solely rely on process parameter optimization without considering the actual process conditions a real component is faced with during the manufacturing process. Additionally, it motivates the development of representative test specimens. T2 - The 76th IIW annual assembly and international conference on welding and joining CY - Singapore DA - 16.07.2023 KW - Additive manufacturing KW - Laser powder bed fusion KW - Laboratory specimens KW - Process parameter optimization KW - Heat accumulation KW - Keyhole porosity KW - Infrared thermography PY - 2023 AN - OPUS4-58023 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Engelking, Lorenz T1 - Optimisation of surface residual stresses using hybrid milling processes for additive manufactured Ni alloy components N2 - Ni alloys are cost intensive materials and generally classified as difficult-to-cut materials. However, machining of these materials is needed especially in case of alloy 36 (1.3912), which is commonly used in mould construction for the production of fibre-reinforced composites. With regard to repair, modification and manufacturing of such components, additive manufacturing offers significant economic advantages. Nevertheless, subsequent machining steps are needed to achieve the final component contour and defined surface conditions. Dependent on the material and machining process conditions, detrimental tensile residual stresses may be the result on the machined surface, having negative impact on the component performance and safety. Recent studies exhibited that hybrid machining processes, such as ultrasonic-assisted milling (USAM), are suitable for achieving favourable residual stress states at the surface of difficult-to-cut Ni-Cr alloys. In this investigation, wire arc additive manufactured (WAAM) specimens of alloy 36 were finish milled under different milling conditions. In addition to the machined surfaces condition and topology, the surface-near residual stresses were analysed using X-ray diffraction (XRD). Especially for low cutting speeds, significantly improved surface properties, roughness parameters and lower mechanical and microstructural degradations were found for the specimen machined with USAM compared to conventional milling. The improved surface integrity could furthermore be observed by a significant reduction of the tensile residual stresses in the surface boundary area. T2 - ICRS11, 11th International Conference on Residual Stresses CY - Nancy, France DA - 27.03.2022 KW - Surface integrity KW - Ultrasonic-assisted milling KW - Additive manufacturing KW - Ni alloy KW - Alloy 36 PY - 2022 AN - OPUS4-54904 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Strobl, Dominic T1 - Reduced Order Model with Domain Mapping for Temperature Field Simulation of Wire Arc Additive Manufacturing N2 - Additive manufacturing (AM) has revolutionized the manufacturing industry, offering a new paradigm to produce complex geometries and parts with customized properties. Among the different AM techniques, the wire arc additive manufacturing (WAAM) process has gained significant attention due to its high deposition rate and low equipment cost. However, the process is characterized by a complex thermal history, dynamic metallurgy, and mechanical behaviour that make it challenging to simulate it in real-time for online process control and optimization. In this context, a reduced order model (ROM) using the proper generalized decomposition (PGD) method is proposed as a powerful tool to overcome the limitations of conventional numerical methods and enable the real-time simulation of the temperature field of WAAM processes. Though, the simulation of a moving heat source leads to a hardly separable parametric problem, which is handled by applying a novel mapping approach. Using this procedure, it is possible to create a simple separated representation of the model, also allowing to simulate multiple layers. In this contribution, a PGD model is derived for the WAAM procedure simulating the temperature field. A good agreement with a standard finite element method is shown. The reduced model is further used in a stochastic model parameter estimation using Bayesian inference, speeding up calibrations and ultimately leading to a calibrated real-time simulation. T2 - SIM-AM 2023 CY - Munich, Germany DA - 26.07.2023 KW - Additive manufacturing KW - Reduced Order Model PY - 2023 AN - OPUS4-58253 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -