Enhanced microstructural control and mechanical performance of selective laser melted 2Cr13 martensitic stainless steel: The role of post-process heat treatment

Despite the growing industrial interest in selective laser melting (SLM) of stainless steels, the microstructural evolution mechanisms and microstructure-property relationships in SLM-fabricated 2Cr13 martensitic stainless steel remain insufficiently explored, hindering its optimized application.This study investigates the microstructure and mechanical properties of 2Cr13 martensitic stainless steel fabricated by selective laser melting (SLM), and the regulatory role of post-process heat treatment. Using optimized SLM parameters (180 W power, 620 mm/s scanning speed, 90° interlayer rotation), samples with 99.70 % relative density were prepared. As-built samples featured a martensite-dominated microstructure (with ∼6.3 % residual austenite and δ-ferrite), fine-grained regions in molten pools (prominent in the heat-affected zone), and excellent mechanical properties: 1673 ± 12 MPa ultimate tensile strength (UTS), and ∼9.28 % elongation(EL). Quenching at 950 °C–1050 °C showed 950 °C as optimal, fully transforming residual austenite and δ-ferrite into martensite without obvious grain growth, and achieving a peak hardness of 605.0 ± 7.3 HV_0.5. Tempering the 950 °C-quenched samples at 500 °C–700 °C induced (Fe, Cr)₂₃C₆ carbide nucleation, precipitation, and growth. Tempering at 500 °C yields balanced properties (1232 ± 5 MPa YS, 1429 ± 13 MPa UTS, ∼11.58 % EL). As the tempering temperature rose to 700 °C, UTS decreased to 861 ± 8 MPa, while elongation increased to ∼16.89 %.