Effect of selective laser melting process parameters on the microstructure and properties of a precipitation hardening stainless steel

In this paper, selective laser melting (SLM) was used to manufacture corrax stainless steel samples under different parameters. It was found that the SLMed samples were mainly composed by lots of fine marten-site (including cellular structure, cellular dendritic grains and blocky grains), and trace austenite. During SLM forming process, a large number of low-angle grain boundaries (LAGBs) and high-density disloca-tions were formed in the matrix. Meanwhile, the samples showed weak texture and no obvious prefer-ence orientation. Moreover, the relative density of all SLMed samples reached above 90%, and the relative density was above 97% when the laser energy density was 54.13-78.19 J.mm(-3). Under the optimal pro-cess parameters of P = 190 W, V = 1.1 m.s(-1), the relative density of sample reached above 99.52 +/- 0.09%, while the sample exhibited the best mechanical properties, including the highest microhardness (374. 2 +/- 6.5HV), yield strength (YS = 946 +/- 7.3 MPa), ultimate tensile strength (UTS = 1084 +/- 3 MPa) and elon-gation (EL = 17.64 +/- 0.18%). Moreover, the strengthening mechanisms of SLMed samples mainly included grain boundary strengthening, dislocation strengthening and precipitation strengthening, while disloca-tion strengthening played a dominant role. Besides that, the fracture mechanisms of SLMed samples belonged to ductile fracture, except for the samples prepared with laser energy density below 54.13 J.mm(-3). (C) 2021 The Authors. Published by Elsevier Ltd.

Automated summary

This study used selective laser melting to manufacture stainless steel samples and found that the samples were mainly composed of martensite and austenite, with excellent mechanical properties and relatively high relative density. The strengthening mechanisms included grain boundary strengthening, dislocation strengthening, and precipitation strengthening, with dislocation strengthening playing a dominant role. The fracture mechanisms were mainly ductile fracture for most samples.