Laser shock peening-induced carbide evolution and remarkable improvement in electrochemical and long-term immersion corrosion resistance of 2Cr12NiMoWV martensitic stainless steel

Abstract

Influences of laser shock peening (LSP) with different coverage layers on the electrochemical and long-term immersion corrosion behaviors of 2Cr12NiMoWV martensitic stainless steel in 3.5 wt% NaCl solution were studied. Results suggested that LSP-induced corrosion resistant surface resulted in ~84.8 % diminution of corrosion density and ~ 84.4 % decrease of passive current density as well as much higher pitting potential. Furthermore, LSP-generated carbide decomposition, matrix nanocrystallization and surface segregation of Cr contributed to the generation of Cr-rich passive film with better corrosion resistance. Due to the inhibitory effect of matrix nanocrystallization and compressive residual stress on corrosion propagation, LSP greatly reduced the size and number of the corrosion pits even after 30 days' immersion in NaCl solution.