Spatter behavior for 316L stainless steel fabricated by selective laser melting in a vacuum

A 316L stainless steel [SS316L] plate was fabricated by selective laser melting (SLM) in a vacuum. SS316L has excellent properties such as a high corrosion resistance and hardness, but forming complicated structures is challenging due to difficulties working the material. Although SLM can fabricate complicated shapes because it builds a 3D material layer-by-layer from a powder, some issues have yet to be resolved, including dimensional accuracy, surface finishes, surface roughness, processing time, and mechanical properties such as hardness. Another issue is irradiating a metal powder by a laser generates spattering. Spattering results in an insufficient input energy to the powder bed because the laser is absorbed by the spatter particles. Consequently, technology to suppress the amount of spatter for SLM processes is needed. In this study, to clarify the mechanism of the spatter-free process, SS316L is fabricated by SLM and the powder behavior during laser irradiation is observed by a high-speed video camera. The amount of spatter depends on the input energy of the laser. At a laser fluence of 20 kJ/cm(2), the amount of spatter is minimized and the surface roughness on the fabricated sample improves from 30 mu m to 3.5 mu m .