Additive Fertigung
Filtern
Dokumenttyp
- Zeitschriftenartikel (18)
- Vortrag (15)
- Beitrag zu einem Tagungsband (7)
- Forschungsdatensatz (3)
Schlagworte
- Additive manufacturing (19)
- Additive Manufacturing (9)
- Laser powder bed fusion (9)
- Thermography (9)
- Heat accumulation (8)
- Infrared thermography (8)
- In situ monitoring (7)
- Process monitoring (6)
- Representative specimens (6)
- Thermal history (6)
- AISI 316L (5)
- Additive Manufacturing (AM) (5)
- Laboratory specimens (5)
- Laser Powder Bed Fusion (5)
- Laser Powder Bed Fusion (L-PBF) (5)
- Selective Laser Melting (SLM) (5)
- Additive Fertigung (4)
- Elastic modulus (4)
- Selective laser melting (SLM) (4)
- Shear modulus (4)
- Young's modulus (4)
- Additive manufacturing (AM) (3)
- Computed Tomography (3)
- In-situ process monitoring (3)
- Inter layer time (3)
- Laser powder bed fusion (L-PBF) (3)
- 3D printing (2)
- Aerosol measurements (2)
- Computed tomography (CT) (2)
- Data fusion (2)
- Fume (2)
- Keyhole porosity (2)
- Lack-of-fusion (2)
- Laser beam melting (LBM) (2)
- Laserstrahlschmelzen (2)
- Optical Tomography (2)
- Optical tomography (2)
- Particle gas emission (2)
- Plume (2)
- Process parameter optimization (2)
- Spatter (2)
- Ti-6Al-4V (2)
- Zwischenlagenzeit (2)
- 316L (1)
- AGIL (1)
- Bridging voids (1)
- Cellular substructure (1)
- Computed tomography (1)
- Convolutional neural networks (CNN) (1)
- Creep (1)
- Creep behavior (1)
- Defect detection (1)
- Design for Additive Manufacturing (DfAM) (1)
- Diffraction (1)
- Dwell-time (1)
- Electron backscatter diffraction (1)
- Emisssivity (1)
- Fatigue damage (1)
- Finite element method (1)
- Flaw detection (1)
- Heat treatment (1)
- High-resolution camera (1)
- Hybrid repair (1)
- IN 718 (1)
- IN718 (1)
- Image registration (1)
- In-situ Monitoring (1)
- In-situ Prozessüberwachung (1)
- In-situ monitoring (1)
- Inconel 718 (1)
- Inter-layer time (1)
- L-PBF (1)
- LPBF (1)
- Laser Powder Bed Fusion (LPBF) (1)
- Laser Powder Bed Fusion (PBF-LB/M) (1)
- Laser Powder Bed Fusion (PBF-LB/M, L-PBF) (1)
- Laser beam melting (1)
- Low-cycle fatigue (1)
- Machine learning (1)
- Melt pool depth (1)
- Microstructure (1)
- Neutron Diffraction (1)
- Online Process Monitoring (1)
- Online monitoring (1)
- PBF-LB/M/316L (1)
- Parabolic flight (1)
- Position detection (1)
- Ppreheating temperature (1)
- Preheating temperature (1)
- Process simulation (1)
- Reference data (1)
- Repair of gas turbine blades (1)
- Residual Stress (1)
- SWIR camera (1)
- SWIR thermography (1)
- Selective laser beam melting (1)
- Supportless (1)
- Temperature dependence (1)
- Tensile strength (1)
- Tensile testing (1)
- Time over threshold (1)
- Wärmeakkumulation (1)
- X-ray Diffraction (1)
- X-ray computed tomography (XCT) (1)
- infrared Thermography (1)
- µ-gravity (1)
Organisationseinheit der BAM
- 9 Komponentensicherheit (43)
- 9.6 Additive Fertigung metallischer Komponenten (29)
- 8 Zerstörungsfreie Prüfung (28)
- 8.0 Abteilungsleitung und andere (21)
- 8.5 Röntgenbildgebung (14)
- 9.3 Schweißtechnische Fertigungsverfahren (14)
- 5 Werkstofftechnik (12)
- 5.2 Metallische Hochtemperaturwerkstoffe (8)
- 5.1 Mikrostruktur Design und Degradation (7)
- 9.4 Integrität von Schweißverbindungen (3)
- 4 Material und Umwelt (2)
- 4.2 Material-Mikrobiom Wechselwirkungen (2)
- 8.3 Thermografische Verfahren (2)
- 1 Analytische Chemie; Referenzmaterialien (1)
- 1.6 Anorganische Referenzmaterialien (1)
- 5.0 Abteilungsleitung und andere (1)
- 5.4 Multimateriale Fertigungsprozesse (1)
- 8.4 Akustische und elektromagnetische Verfahren (1)
Additively manufactured components are characterized by heterogeneous mechanical properties due to variations of the microstructure, flaws and residual stresses resulting from the inhomogeneous fabrication process. The large number of influencing factors poses a further challenge in understanding the correlation between material properties, process parameters and component geometry. Therefore, the qualification of components based on witness specimens produced within the same job is questionable. This work aims to present a new strategy for the characterization of PBF-LB/M components based on representative specimens. The key assumption is the feasibility of a transfer of the thermal history from a component to a specimen. It is assumed that similar material properties are determined for components and specimens produced adopting a similar thermal history. After the definition of a region of interest in the component, a combination of thermal analyses by means of finite elements and in-situ experimental determination of the thermal history through infrared thermography is used to produce test coupons with a similar thermal history. The effectiveness of the procedure is demonstrated on a pressure vessel for applications in the chemical industry.
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.
Die thermische Historie beim additiven Aufbau von komplexen Realkomponenten und geometrisch primitiven Prüfkörpern unterscheidet sich signifikant. Daraus können Eigenschaftsunterschiede resultieren, die zu unterschiedlichem Materialverhalten führen können. In diesem Vortrag wird das Konzept repräsentativer Probekörper eingeführt, das eine Übertragung thermischer Historien von komplexen Geometrien auf einfache Geometrien ermöglicht und hierdurch zu einer besseren Vergleichbarkeit der Werkstoffeigenschaften führen soll.
Development of representative test specimens by thermal history transfer in laser powder bed fusion
(2024)
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.
This study investigates the room‐ and high‐temperature (650 °C) tensile and low‐cycle‐fatigue behavior of Inconel 718 produced by laser powder bed fusion (PBF‐LB/M) with a four‐step heat treatment and compares the results to the conventional wrought material. The microstructure after heat treatment is characterized on different length scales. Compared to the wrought variant, the elastic and yield properties are comparable at both test temperatures while tensile strength, ductility, and strain hardening capacity are lower. The fatigue life of the PBF‐LB/M variant at room temperature is slightly lower than that of the wrought material, while at 650 °C, it is vice versa. The cyclic stress response for both material variants is characterized by cyclic softening, which is more pronounced at the higher test temperature. High strain amplitudes (≥0.7%) at room temperature and especially a high testing temperature result in the formation of multiple secondary cracks at the transitions of regions comprising predominantly elongated grain morphology and columns of stacked grains with ripple patterns in the PBF‐LB/M material. This observation and pronounced crack branching and deflection indicate that the cracks are controlled by sharp micromechanical gradients and local crystallite clusters.
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.
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.
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.
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.
This article reports temperature-dependent elastic properties (Young’s modulus, shear modulus) of three alloys measured by the dynamic resonance method. The alloys Ti-6Al-4V, Inconel IN718, and AISI 316 L were each investigated in a variant produced by an additive manufacturing processing route and by a conventional manufacturing processing route. The datasets include information on processing routes and parameters, heat treatments, grain size, specimen dimensions, and weight, as well as Young’s and shear modulus along with their measurement uncertainty. The process routes and methods are described in detail. The datasets were generated in an accredited testing lab, audited as BAM reference data, and are hosted in the open data repository Zenodo. Possible data usages include the verification of the correctness of the test setup via Young’s modulus comparison in low-cycle fatigue (LCF) or thermo-mechanical fatigue (TMF) testing campaigns, the design auf VHCF specimens and the use as input data for simulation purposes.