Powder Variation and Mechanical Properties for SLM 17-4 PH Stainless Steel

Chemical composition and atomizing gas of powders may affect properties of 17-4 PH fabricated via selective laser melting (SLM) process. This study investigates 17-4 PH stainless steel powders with various atomizing gases and compositions within 17-4 PH specification range. Material characterization demonstrated differences in flowability between the powders, but all produced fully dense parts. The as-built phase composition varied widely, with samples from Ar-atomized powders ranging from a mostly martensitic grain structure to containing a significant amount of δ-ferrite depending on their composition, whereas samples from N2 atomized powder contained largely austenite phase. After solutionizing and H900 hardening all Ar atomized powders produced homogeneous microstructure and improved mechanical properties meeting AMS 17-4 PH specification. The N2 atomized powder produced a martensitic microstructure with retained austenite and only ultimate strength meeting AMS specification.