Obvious improvement in electrochemical and long-term immersion corrosion resistance of AISI 420 martensitic stainless steel using laser shock peening

Effects of laser shock peening (LSP) on electrochemical and long-term immersion corrosion behaviors of AISI 420 martensitic stainless steel in 3.5 wt% NaCl solution were studied. Results indicated that LSP-induced corrosion resistant surface resulted in ∼98.1% decrease of passive current density and ∼89.5% increase of pitting potential. Furthermore, LSP-generated carbide decomposition and microstructure nanocrystallization contributed to the generation of Cr-rich passive film with better corrosion resistance. Owing to the inhibitory effect of nanocrystalline and compressive residual stress on corrosion propagation, LSP effectively inhibited the occurrence of rust even after 30 days’ immersion.