Enhancement of corrosion resistance of 304L stainless steel treated by massive laser shock peening

Abstract

The effects of laser shock peening (LSP) on the pitting corrosion behaviour of austenite stainless steel in an acid chloride environment are investigated in this work. The results reveal that LSP treatment improves the pitting corrosion resistance of 304L stainless steel, resulting in a higher pitting potential and a lower metastable pitting nucleation rate of larger pits. However, the augmented effect is only significant in the case of massive LSP impacts. The effects of LSP on microstructure, surface morphology, residual stress, and chemical composition of the surface are studied and analyzed. The significant compressive residual stress and grain refinement on the surface of 304L stainless steel treated by massive LSP impacts are attributed to the enhancement of pitting corrosion resistance, as the former helps minimize microcracks between the intermetallic and matrix metals, and the latter allows for forming a thicker inner layer supplied by Cr2O3 in the passive film.