Laser surface remelting to restore corrosion resistance in sulfide-compromised austenitic stainless steels

Abstract

This study investigates the impact of laser surface remelting (LSR) on enhancing the corrosion resistance of 316L stainless steel (SS), focusing on the mitigation of manganese sulfide (MnS) inclusions. Optimized LSR parameters, including an energy density of 2000 J/cm² and power levels of 150 W and 300 W, effectively modify and solubilize coarse and acicular MnS inclusions, leading to a refined and homogeneous microstructure. The remelted samples exhibit a thicker, uniform chromium-oxygen-rich passive layer, particularly Cr₂O₃, significantly enhancing resistance to pitting corrosion. Electrochemical analyses, supported by the Power Law model and polarization curves, reveal that LSR improves passive film properties, with high resistivity values (ρ_δ) indicating superior electrochemical performance. The elemental redistribution of key alloying elements such as chromium and molybdenum further reduce micro-galvanic coupling effects. The results emphasize the synergistic effects of higher energy densities and power levels in restoring the corrosion resistance of the surface to be able forming protective passive films with increased uniformity and thickness. By demonstrating the ability to recover and optimize corrosion resistance, LSR emerges as a transformative surface engineering strategy for advancing material performance in environments prone to aggressive corrosion, providing valuable insights for demanding industrial applications.