Effect of scanning speed and laser power on formability, microstructure, and quality of 316L stainless steel prepared by selective laser melting

Selective Laser Melting (SLM) prepared 316L stainless steel has been widely deployed in academia and industry today. This paper studied the influence of laser power (50-450 W) and scanning speed (1000-2800 mm/s) on formability, hardness, microstructure, internal and external quality, and porosity of the built, and further analyzed the internal relationship between input energy density and them. The results revealed that high laser power needs to match high scanning speed to obtain better formability; that is, appropriate energy density was the fundamental guarantee of formability. Besides, high energy density will lead to a smaller ratio of width and height (W/H) and a larger area of the molten pool. And the cellular grain's size increased significantly from 181 to 1615 nm, with the energy density increasing from 26.8 to 750.0 J/mm3. In addition, the sample's quality was also related to the energy density. And the porosity variation trend was similar to that of surface roughness, indicating a strong correlation between internal quality and surface quality.