In-situ formed graded microstructure and mechanical property of selective laser melted 15–5 PH stainless steel

In this work, we reported a novel in-situ formed graded microstructure in a selective laser melted (SLM) 15–5 PH stainless steel, and we investigated the processing-microstructure-property relationship systematically. We found that austenite and oxide volume fraction decreased with the build height, which were related to the in-situ thermal cycling and the heat accumulation in SLM. The result showed that the variations in oxide volume fraction led to a decreased yield strength along the height, and the high amount of austenite at the specimen bottom contribute to external plasticity and elongation. This work showed that the mechanical properties of precipitation hardening stainless steel can be manipulated by modifying the volume fraction of oxides and reverted austenite by the in-situ SLM thermal cycling. • An in-situ fabricated SLM 15–5 PH stainless steel with a graded microstructure was prepared. • The volume fractions of reverted austenite and oxide particles decrease with the build height. • The mechanism of graded microstructure formation in as-SLMed 15-5 stainless steel has been elucidated. • The influences of varied austenite and oxide volume fractions on mechanical properties have been investigated. • The ODS effect and stress-inducedphase transformation result in a strong and ductile as-SLMed 15–5 PH at specimen bottom.