Simulation and experimental studies on process parameters, microstructure and mechanical properties of selective laser melting of stainless steel 316L

Abstract

SLM process parameters such as laser power, scanning speed, layer thickness and hatch spacing play a crucial role in the quality of the processed product. In order to find the parameters suitable for SLM process, a finite element model was established to simulate the distribution of temperature field of selective laser melting (SLM) stainless steel 316L (SS316L) parts. After finite element simulation, the optimum factor levels for SLM processing SS316L were as follows: laser power of 100–200 W, scanning speed of 500–1500 mm/s, hatch spacing of 0.04–0.12 mm, and layer thickness of 0.03–0.06 mm. Then, based on a series of experiments, different laser energy densities were divided into three regions corresponding to three melting mechanisms: the partial melting zone (37.88–75.76 J/mm3), the full melting zone (75.76–151.52 J/mm3), and the over-melting zone (larger than 151.52 J/mm3). The surface roughness, density, microstructure and mechanical properties of the SLM SS316L were strongly dependent on the laser energy density. The results showed that an excellent SS316L part with a relative density higher than 99.66% and good mechanical properties could be obtained at a laser energy density of 119.05 J/mm3 with a laser powder of 200 W, a scanning speed of 700 mm/s, a hatch spacing of 0.08 mm and a layer thickness of 0.03 mm.