Effect of Powder Chemical Composition on Microstructures and Mechanical Properties of L-PBF Processed 17-4 PH Stainless Steel in the As-Built and Hardened-H900 Conditions
Post-build heat treatments such as solutionizing and precipitation hardening are recommended for selective laser melting (SLM) processed components to achieve a homogeneous microstructure. In this study, the effect of powder elemental composition on microstructures and mechanical properties of SLM processed 17-4 PH was studied in the as-built and precipitation hardened (H900) condition without prior solutionizing. Microstructural characterization demonstrated that H900 increased martensite phase composition for samples from powder with low chromium to nickel equivalent (Creq/Nieq) value, whereas no significant difference was observed for the samples from powders with high Creq/Nieq value. None of the specimens exhibited austenite reversion and strain hardening behavior in the as-built and H900 conditions. Low Creq/Nieq specimen exhibited higher yield and tensile strengths, and microhardness from H900, which are comparable to H900 wrought sample. However, no significant improvement in total elongation was observed other than uniform elongation for low Creq/Nieq specimen.