Laser Powder Bed Fusion of 316L Stainless Steel: Effect of Laser Polishing on the Surface Morphology and Corrosion Behavior

Recently, laser polishing, as an effective post-treatment technology for metal parts fabricated by laser powder bed fusion (LPBF), has received much attention. In this paper, LPBF-ed 316L stainless steel samples were polished by three different types of lasers. The effect of laser pulse width on surface morphology and corrosion resistance was investigated. The experimental results show that, compared to the nanosecond (NS) and femtosecond (FS) lasers, the surface material's sufficient remelting realized by the continuous wave (CW) laser results in a significant improvement in roughness. The surface hardness is increased and the corrosion resistance is the best. The microcracks on the NS laser-polished surface lead to a decrease in the microhardness and corrosion resistance. The FS laser does not significantly improve surface roughness. The ultrafast laser-induced micro-nanostructures increase the contact area of the electrochemical reaction, resulting in a decrease in corrosion resistance.

Automated summary

In this study, the effect of laser pulse width on the surface morphology and corrosion resistance of LPBF-ed 316L stainless steel samples after laser polishing was investigated. The experimental results show that continuous wave (CW) laser polishing results in significant improvement in roughness and the best corrosion resistance. Nanosecond (NS) laser polishing leads to microcracks and decreased microhardness and corrosion resistance. Femtosecond (FS) laser polishing does not significantly improve roughness and results in decreased corrosion resistance due to ultrafast laser-induced micro-nanostructures increasing the contact area of the electrochemical reaction.