The Influence of Laser Polishing Parameters on Surface Roughness of Additive Manufactured 316L Stainless Steel

Improving the surface roughness of metal additive manufactured parts is a challenging issue to further extend the usability and functionality of the manufactured parts. The metal extrusion additive manufacturing (MEX) process fabricates parts through layer-by-layer deposition followed by sintering, which often results in poor surface quality due to partially molten particles remaining on the surface. Laser polishing is a promising post-processing technique that reconstructs the work surface through a surface melting mechanism. This study investigates the influence of laser scanning speed and polishing environment on surface roughness improvement in the laser polishing of 316L stainless steel produced using MEX technology. The results show that polishing in an argon environment yields a smoother surface compared to polishing in air, although a deeper remelted layer was observed in the air environment. The effect of laser scanning speed on surface roughness followed different trends depending on the process environment. The minimum surface roughness (Sa) was achieved at a laser scanning speed of 200 mm/s in argon, reducing the Sa from 2.00 um to 0.37 um, representing an improvement of over 80%.