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  • 1.
    Gruber, Samira
    et al.
    Fraunhofer Institute for Material and Beam Technology IWS, 01277, Dresden, Germany.
    Stepien, Lukas
    Fraunhofer Institute for Material and Beam Technology IWS, 01277, Dresden, Germany.
    Gerdt, Leonid
    Fraunhofer Institute for Material and Beam Technology IWS, 01277, Dresden, Germany.
    Lopez, Elena
    Fraunhofer Institute for Material and Beam Technology IWS, 01277, Dresden, Germany.
    Kieser, Jan
    Fraunhofer Institute for Material and Beam Technology IWS, 01277, Dresden, Germany.
    Brueckner, Frank
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development. Fraunhofer Institute for Material and Beam Technology IWS, 01277, Dresden, Germany.
    Leyens, Christoph
    Fraunhofer Institute for Material and Beam Technology IWS, 01277, Dresden, Germany; TUD Dresden University of Technology, Institute of Materials Science, 01069, Dresden, Germany.
    Bratt, Craig
    Fraunhofer USA—Center Midwest, Laser Applications Division, Plymouth, Michigan 48170, United States.
    Process development for laser powder bed fusion of GRCop-42 using a 515 nm laser source2023In: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 35, no 4, article id 042078Article in journal (Refereed)
    Abstract [en]

    Copper is widely used in high heat flux and electrical applications because of its excellent electrical and thermal conductivity properties. Alloying elements such as chromium or nickel are added to strengthen the material, especially for higher temperatures. Cu4Cr2Nb, also known as GRCop-42, is a dispersion-strengthened copper-chromium-niobium alloy developed by NASA for high-temperature applications with high thermal and mechanical stresses such as rocket engines. Additive manufacturing (AM) enables applications with complex functionalized geometries and is particularly promising in the aerospace industry. In this contribution, a parametric study was performed for GRCop-42 and the AM process laser powder bed fusion (PBF-LB/M) using a green laser source for two-layer thicknesses of 30 and 60 µm. Density, electrical conductivity, hardness, microstructure, and static mechanical properties were analyzed. Various heat treatments ranging from 400 to 1000 °C and 30 min to 4 h were tested to increase the electrical conductivity and hardness. For both layer thicknesses, dense parameter sets could be obtained with resulting relative densities above 99.8%. Hardness and electrical conductivity could be tailored in the range of 103-219 HV2 and 24%-88% International Annealed Copper Standard (IACS) depending on the heat treatment. The highest ultimate tensile strength (UTS) obtained was 493 MPa. An aging temperature of 700 °C for 30 min showed the best combination of room temperature properties such as electrical conductivity of 83.76%IACS, UTS of 481 MPa, elongation at break (A) at 24%, and hardness of 125 HV2.

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  • 2.
    Hendl, Julius
    et al.
    Institute of Materials Science, Technische Universität Dresden, Helmholtzstr. 7, 01069 Dresden, Germany; Fraunhofer—Institute for Material and Beam Technology (IWS—Dresden), Winterbergstraße 28, 01069 Dresden, Germany.
    Daubner, Sina
    Institute of Materials Science, Technische Universität Dresden, Helmholtzstr. 7, 01069 Dresden, Germany.
    Marquardt, Axel
    Institute of Materials Science, Technische Universität Dresden, Helmholtzstr. 7, 01069 Dresden, Germany; Fraunhofer—Institute for Material and Beam Technology (IWS—Dresden), Winterbergstraße 28, 01069 Dresden, Germany.
    Stepien, Lukas
    Fraunhofer—Institute for Material and Beam Technology (IWS—Dresden), Winterbergstraße 28, 01069 Dresden, Germany.
    Lopez, Elena
    Fraunhofer—Institute for Material and Beam Technology (IWS—Dresden), Winterbergstraße 28, 01069 Dresden, Germany.
    Brückner, Frank
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development. Fraunhofer—Institute for Material and Beam Technology (IWS—Dresden), Winterbergstraße 28, 01069 Dresden, Germany.
    Leyens, Christoph
    Institute of Materials Science, Technische Universität Dresden, Helmholtzstr. 7, 01069 Dresden, Germany; Fraunhofer—Institute for Material and Beam Technology (IWS—Dresden), Winterbergstraße 28, 01069 Dresden, Germany.
    In Situ CT Tensile Testing of an Additively Manufactured and Heat-Treated Metastable ß-Titanium Alloy (Ti-5Al-5Mo-5V-3Cr)2021In: Applied Sciences, E-ISSN 2076-3417, Vol. 11, no 21, article id 9875Article in journal (Refereed)
    Abstract [en]

    Additive manufacturing has been considered a suitable process for developing high-performance parts of medical or aerospace industries. The electron beam powder bed fusion process, EB-PBF, is a powder bed fusion process carried out in a vacuum, in which the parts are melted using a highly focused electron beam. The material class of metastable β-titanium alloys, and especially Ti-5Al-5Mo-5V-3Cr, show great potential for use as small and highly complex load-bearing parts. Specimens were additively manufactured with optimised process parameters and different heat treatments used in order to create tailored mechanical properties. These heat-treated specimens were analysed with regard to their microstructure (SEM) and their mechanical strength (tensile testing). Furthermore, in situ tensile tests, using a Deben CT5000 and a YXLON ff35 industrial µ-CT, were performed and failure-critical defects were detected, analysed and monitored. Experimental results indicate that, if EB-PBF-manufactured Ti-5553 is heat-treated differently, a variety of mechanical properties are possible. Regarding their fracture mechanisms, failure-critical defects can be detected at different stages of the tensile test and defect growth behaviour can be analysed.

  • 3.
    Moritz, Juliane
    et al.
    Technische Universität Dresden, Institute of Materials Science (IfWW), 01069, Dresden, Germany; Technology Field Additive Manufacturing and Surface Technologies, Fraunhofer Institute for Material and Beam Technology IWS, 01277, Dresden, Germany.
    Teschke, Mirko
    Chair of Materials Test Engineering (WPT), TU Dortmund University, 44227, Dortmund, Germany.
    Marquardt, Axel
    Technische Universität Dresden, Institute of Materials Science (IfWW), 01069, Dresden, Germany; Technology Field Additive Manufacturing and Surface Technologies, Fraunhofer Institute for Material and Beam Technology IWS, 01277, Dresden, Germany.
    Heinze, Stefan
    Technische Universität Dresden, Institute of Materials Science (IfWW), 01069, Dresden, Germany.
    Heckert, Mirko
    Technische Universität Dresden, Institute of Materials Science (IfWW), 01069, Dresden, Germany.
    Stepien, Lukas
    Technology Field Additive Manufacturing and Surface Technologies, Fraunhofer Institute for Material and Beam Technology IWS, 01277, Dresden, Germany.
    López, Elena
    Technology Field Additive Manufacturing and Surface Technologies, Fraunhofer Institute for Material and Beam Technology IWS, 01277, Dresden, Germany.
    Brueckner, Frank
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development. Technology Field Additive Manufacturing and Surface Technologies, Fraunhofer Institute for Material and Beam Technology IWS, 01277 Dresden, Germany.
    Walther, Frank
    Chair of Materials Test Engineering (WPT), TU Dortmund University, 44227, Dortmund, Germany.
    Leyens, Christoph
    Technische Universität Dresden, Institute of Materials Science (IfWW), 01069, Dresden, Germany; Technology Field Additive Manufacturing and Surface Technologies, Fraunhofer Institute for Material and Beam Technology IWS, 01277, Dresden, Germany.
    Influence of Two-Step Heat Treatments on Microstructure and Mechanical Properties of a β-Solidifying Titanium Aluminide Alloy Fabricated via Electron Beam Powder Bed Fusion2023In: Advanced Engineering Materials, ISSN 1438-1656, E-ISSN 1527-2648, Vol. 25, no 2, article id 2200931Article in journal (Refereed)
    Abstract [en]

    Additive manufacturing technologies, particularly electron beam powder bed fusion (PBF-EB/M), are becoming increasingly important for the processing of intermetallic titanium aluminides. This study presents the effects of hot isostatic pressing (HIP) and subsequent two-step heat treatments on the microstructure and mechanical properties of the TNM-B1 alloy (Ti–43.5Al–4Nb–1Mo–0.1B) fabricated via PBF-EB/M. Adequate solution heat treatment temperatures allow the adjustment of fully lamellar (FL) and nearly lamellar (NL-β) microstructures. The specimens are characterized by optical microscopy and scanning electron microscopy (SEM), X-ray computed tomography (CT), X-ray diffraction (XRD), and electron backscatter diffraction (EBSD). The mechanical properties at ambient temperatures are evaluated via tensile testing and subsequent fractography. While lack-of-fusion defects are the main causes of failure in the as-built condition, the mechanical properties in the heat-treated conditions are predominantly controlled by the microstructure. The highest ultimate tensile strength is achieved after HIP due to the elimination of lack-of-fusion defects. The results reveal challenges originating from the PBF-EB/M process, for example, local variations in chemical composition due to aluminum evaporation, which in turn affect the microstructures after heat treatment. For designing suitable heat treatment strategies, particular attention should therefore be paid to the microstructural characteristics associated with additive manufacturing.

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  • 4.
    Moritz, Juliane
    et al.
    Institute of Materials Science (IfWW), Technische Universität Dresden, 01069, Dresden, Germany; Fraunhofer Institute for Material and Beam Technology IWS, 01277, Dresden, Germany.
    Teschke, Mirko
    Chair of Materials Test Engineering (WPT), TU Dortmund University, 44227, Dortmund, Germany.
    Marquardt, Axel
    Institute of Materials Science (IfWW), Technische Universität Dresden, 01069, Dresden, Germany; Fraunhofer Institute for Material and Beam Technology IWS, 01277, Dresden, Germany.
    Stepien, Lukas
    Fraunhofer Institute for Material and Beam Technology IWS, 01277, Dresden, Germany.
    López, Elena
    Fraunhofer Institute for Material and Beam Technology IWS, 01277, Dresden, Germany.
    Brueckner, Frank
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development. Fraunhofer Institute for Material and Beam Technology IWS, 01277 Dresden, Germany.
    Walther, Frank
    Chair of Materials Test Engineering (WPT), TU Dortmund University, 44227, Dortmund, Germany.
    Leyens, Christoph
    Institute of Materials Science (IfWW), Technische Universität Dresden, 01069, Dresden, Germany; Fraunhofer Institute for Material and Beam Technology IWS, 01277, Dresden, Germany.
    Influence of Electron Beam Powder Bed Fusion Process Parameters at Constant Volumetric Energy Density on Surface Topography and Microstructural Homogeneity of a Titanium Aluminide Alloy2023In: Advanced Engineering Materials, ISSN 1438-1656, E-ISSN 1527-2648, Vol. 25, no 15, article id 2201871Article in journal (Refereed)
    Abstract [en]

    In powder bed fusion additive manufacturing, the volumetric energy density E V is a commonly used parameter to quantify process energy input. However, recent results question the suitability of E V as a design parameter, as varying the contributing parameters may yield different part properties. Herein, beam current, scan velocity, and line offset in electron beam powder bed fusion (PBF-EB) of the titanium aluminide alloy TNM–B1 are systematically varied while maintaining an overall constant E V. The samples are evaluated regarding surface morphology, relative density, microstructure, hardness, and aluminum loss due to evaporation. Moreover, the specimens are subjected to two different heat treatments to obtain fully lamellar (FL) and nearly lamellar (NLγ) microstructures, respectively. With a combination of low beam currents, low-to-intermediate scan velocities, and low line offsets, parts with even surfaces, relative densities above 99.9%, and homogeneous microstructures are achieved. On the other hand, especially high beam currents promote the formation of surface bulges and pronounced aluminum evaporation, resulting in inhomogeneous banded microstructures after heat treatment. The results demonstrate the importance of considering the individual parameters instead of E V in process optimization for PBF-EB.

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  • 5.
    Moritz, Juliane
    et al.
    Institute of Materials Science (IfWW), Technische Universität Dresden, 01069 Dresden, Germany; Technology Field Additive Manufacturing and Surface Technologies, Fraunhofer Institute for Material and Beam Technology IWS, 01277 Dresden, Germany.
    Teschke, Mirko
    Chair of Materials Test Engineering (WPT), TU Dortmund University, 44227 Dortmund, Germany.
    Marquardt, Axel
    Institute of Materials Science (IfWW), Technische Universität Dresden, 01069 Dresden, Germany; Technology Field Additive Manufacturing and Surface Technologies, Fraunhofer Institute for Material and Beam Technology IWS, 01277 Dresden, Germanyterial and Beam Technology IWS, 01277 Dresden, Germany.
    Stepien, Lukas
    Technology Field Additive Manufacturing and Surface Technologies, Fraunhofer Institute for Material and Beam Technology IWS, 01277 Dresden, Germany.
    López, Elena
    Technology Field Additive Manufacturing and Surface Technologies, Fraunhofer Institute for Material and Beam Technology IWS, 01277 Dresden, Germany.
    Brueckner, Frank
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development. Technology Field Additive Manufacturing and Surface Technologies, Fraunhofer Institute for Material and Beam Technology IWS, 01277 Dresden, Germany.
    Walther, Frank
    Chair of Materials Test Engineering (WPT), TU Dortmund University, 44227 Dortmund, Germany.
    Leyens, Christoph
    Institute of Materials Science (IfWW), Technische Universität Dresden, 01069 Dresden, Germany; Technology Field Additive Manufacturing and Surface Technologies, Fraunhofer Institute for Material and Beam Technology IWS, 01277 Dresden, Germany.
    Locally Adapted Microstructures in an Additively Manufactured Titanium Aluminide Alloy Through Process Parameter Variation and Heat Treatment2023In: Advanced Engineering Materials, ISSN 1438-1656, E-ISSN 1527-2648, Vol. 25, no 2, article id 2200917Article in journal (Refereed)
    Abstract [en]

    Electron beam powder bed fusion (PBF-EB/M) has been attracting great research interest as a promising technology for additive manufacturing of titanium aluminide alloys. However, challenges often arise from the process-induced evaporation of aluminum, which is linked to the PBF-EB/M process parameters. This study applies different volumetric energy densities during PBF-EB/M processing to deliberately adjust the aluminum contents in additively manufactured Ti–43.5Al–4Nb–1Mo–0.1B (TNM-B1) samples. The specimens are subsequently subjected to hot isostatic pressing (HIP) and a two-step heat treatment. The influence of process parameter variation and heat treatments on microstructure and defect distribution are investigated using optical and scanning electron microscopy, as well as X-ray computed tomography (CT). Depending on the aluminum content, shifts in the phase transition temperatures can be identified via differential scanning calorimetry (DSC). It is confirmed that the microstructure after heat treatment is strongly linked to the PBF-EB/M parameters and the associated aluminum evaporation. The feasibility of producing locally adapted microstructures within one component through process parameter variation and subsequent heat treatment can be demonstrated. Thus, fully lamellar and nearly lamellar microstructures in two adjacent component areas can be adjusted, respectively.

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  • 6.
    Selbmann, Alex
    et al.
    Fraunhofer Institute for Material and Beam Technology IWS, Dresden 01277, Germany.
    Gruber, Samira
    Fraunhofer Institute for Material and Beam Technology IWS, Dresden 01277, Germany.
    Propst, Martin
    Institute of Aerospace Engineering, TUD Dresden University of Technology, Dresden 01602, Germany.
    Dorau, Tim
    Institute of Aerospace Engineering, TUD Dresden University of Technology, Dresden 01602, Germany.
    Drexler, Robert
    Fraunhofer Institute for Material and Beam Technology IWS, Dresden 01277, Germany.
    Toma, Filofteia-Laura
    Fraunhofer Institute for Material and Beam Technology IWS, Dresden 01277, Germany.
    Mueller, Michael
    Institute of Materials Science, TUD Dresden University of Technology, Dresden 01069, Germany.
    Stepien, Lukas
    Fraunhofer Institute for Material and Beam Technology IWS, Dresden 01277, Germany.
    Lopez, Elena
    Fraunhofer Institute for Material and Beam Technology IWS, Dresden 01277, Germany.
    Bach, Christian
    Institute of Aerospace Engineering, TUD Dresden University of Technology, Dresden 01602, Germany.
    Brueckner, Frank
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development. Fraunhofer Institute for Material and Beam Technology IWS, Dresden 01277, Germany.
    Leyens, Christoph
    Fraunhofer Institute for Material and Beam Technology IWS, Dresden 01277, Germany; Institute of Materials Science, TUD Dresden University of Technology, Dresden 01069, Germany.
    Process qualification, additive manufacturing, and postprocessing of a hydrogen peroxide/kerosene 6 kN aerospike breadboard engine2024In: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 36, no 1, article id 012027Article in journal (Refereed)
    Abstract [en]

    This contribution addresses the complete process chain of an annular aerospike breadboard engine fabricated by laser powder bed fusion using the nickel-based superalloy Inconel® 718. In order to qualify the material and process for this high-temperature application, an extensive material characterization campaign including density and roughness measurements, as well as tensile tests at room temperature, 700, and 900 °C, was conducted. In addition, various geometric features such as triangles, ellipses, and circular shapes were generated to determine the maximum unsupported overhang angle and geometrical accuracy. The results were taken into account in the design maturation of the manifold and the cooling channels of the aerospike breadboard engine. Postprocessing included heat treatment to increase mechanical properties, milling, turning, and eroding of interfaces to fulfill the geometrical tolerances, thermal barrier coating of thermally stressed surfaces for better protection of thermal loads, and laser welding of spike and shroud for the final assembly as well as quality assurance. This contribution goes beyond small density cubes and tensile samples and offers details on the iterations necessary for the successful printing of large complex shaped functional parts. The scientific question is how to verify the additive manufacturing process through tensile testing, simulation, and design iterations for complex geometries and reduce the number of failed prints.

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