The effects of selective laser melting (SLM) process parameters on the microstructure and mechanical properties of FeCrMnNi nitrogen-containing stainless steel

Abstract

The additive manufacturing of nitrogen-containing steels encounters significant challenges, including nitrogen loss and the formation of nitrogen pores, both of which detrimentally impact mechanical properties. This study fabricated FeCrMnNi nitrogen-containing stainless steel specimens using selective laser melting (SLM) technology. The effects of different process parameters (including laser power and scanning speed) on the nitrogen behavior, microstructure and mechanical properties of the specimens were systematically investigated. The results indicate that the nitrogen content in the as-deposited specimens was reduced compared to the original powder (0.32 %). The increase in energy density led to a gradual increase in nitrogen loss and a decrease in the porosity of the as-deposited specimens, which can be attributed to the combined effects of changes in melt pool size and solidification rate. A balanced performance was achieved at a laser power of 280 W and a scanning speed of 1200 mm/s, with 0.025 % porosity, 773.5 MPa tensile strength, and 37.25 % elongation. Less loss of nitrogen content and allowing the presence of fewer holes seem to result in better mechanical properties.