Selective Laser Melting of a Fe–Cr–Ni–Al–Mo Precipitation Hardening Stainless Steel: Process Parameter Optimization and Control of Microstructure and Properties

Fe–12Cr–9Ni–1.75Al–1.65Mo precipitation hardening stainless steel (PHSS) is being prepared using selective laser melting (SLM) technology, and then solution treatment, direct aging, and solution aging treatment heat‐treat are being conducted subsequently. Effects of the SLM printing process and heat‐treat on relative density, mechanical properties, and microstructural evolution of PHSS are systematically investigated. The density of the as‐printed sample reached 99.49% (laser power 260 W, scanning speed 1000 mm s −1 ). After solution treatment, austenite almost completely transforms into martensite, simultaneously accompanied by organizational coarsening. After aging treatment, there is no significant change in the microstructure, and nanoscale NiAl phase precipitates are obtained. The strength of direct aging samples and solid solution aging samples is greatly improved, exhibiting good comprehensive mechanical properties. In comparison to grain refinement and dislocation strengthening, precipitation strengthening caused by the nanoscale NiAl phase emerges as the dominant contributor.