Effect of Scanning Speed on Surface Roughness and Mechanical Properties of 316L Stainless Steel Prepared by Selective Laser Melting

The 316L stainless steel part was prepared by the selective laser melting method at different scanning speeds. The effects of scanning speed on phase constitution, molten pool morphology, surface roughness, density, and mechanical properties of the part were investigated by phase analyses, metallographic microscopy, tensile test, Vickers hardness test, and surface roughness test. Results show that all specimens are successfully prepared at different scanning speeds (800 - 1200 mm/s). In addition, with increasing the scanning speed, the ratio of depth to width of molten pool without remelting is decreased, and the surface roughness is increased from 5.78 mu m to 22.79 mu m. The cracks appear at scanning speed of 800 mm/s, while the molten line shrinkage occurs when the scanning speed exceeds 1100 mm/s. When the scanning speed is 800 mm/s, specimens have relatively high porosity due to the overhigh laser input energy. When the scanning speed is 900 mm/s, the specimens have the optimal Vickers hardness (2401 MPa) and high relative density (99.2%).