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TY - THES AU - Bültmann, Jan Robert Zeno TI - Das Werkstoffverhalten von Stahl im Laser Powder Bed Fusion Prozess PB - Rheinisch-Westfälische Technische Hochschule Aachen VL - Dissertation CY - Aachen M1 - RWTH-2022-03889 SP - 1 Online-Ressource : Illustrationen, Diagramme PY - 2021 N1 - Veröffentlicht auf dem Publikationsserver der RWTH Aachen University 2022 N1 - Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2021 AB - The present thesis provides an overview of the steels that have been examined in scientific publications in the Laser Powder Bed Fusion process and the influence of various metallurgical and process-related phenomena on their anisotropic, mechanical properties in uniaxial tensile testing. The review of the literature and the investigations on three different, high-alloyed steels, the austenitic, high-manganese steel X30Mn22, the martensitic hardening tool steel X3NiCoMoTi18-9-5 and the stainless, austenitic steel X2CrNiMo17-12-2, reveal the mechanical behavior and the different characteristics of the anisotropy. Possible reasons and influences are determined. Microstructural features such as melt pool boundaries, dendrites, grain boundaries, gas pores, lack of fusion pores, cracks, inclusions, and crystallographic texture as well as surface roughness are mentioned and discussed as possible reasons for the anisotropy. A prominent texture and elongated grains parallel to the build-direction lead to higher strengths for the horizontally built specimens, but to higher elongations for the vertically built specimens. Lack of fusion pores are often crack starters and thus reduce ductility with an increasing building angle. Depending on their direction, cracks usually reduce the ductility of horizontally built specimens. Pores, inclusions, dendrites, and surface roughness contribute less to the anisotropy of the mechanical properties in the uniaxial tensile test. The influence of the alloying elements of the different steels has the greatest effect on the formation of cracks, gas pores and lack of fusion pores. The tendency to form cracks and gas pores depends, among other things, on the carbon content. Carbide forming elements reduce the influence of carbon. Silicon and chromium can also increase the risk of cracking. Sulfur and oxides increase the risk of lack of fusion pores. The microstructural features and thus the anisotropy itself can be specifically influenced by the process parameters including preheating temperature and scanning strategy. Additionally, post process heat treatments can also influence the anisotropy if they change the grain morphology, crystallographic texture, or lack of fusion pores LB - PUB:(DE-HGF)11 DO - DOI:10.18154/RWTH-2022-03889 UR - https://publications.rwth-aachen.de/record/844406 ER -