This study examined the effects of laser shock peening (LSP) and LSP without protective coating (LSPwC) on the microstructure and corrosion behavior of 304L stainless steel using cyclic polarization testing. LSP enhanced corrosion resistance under mild sensitization (650 °C; 5 h) by inducing compressive stress and increasing dislocation density, stabilizing the passive film. Limited improvement was observed under severe sensitization (650 °C; 24 h). Deformation-induced martensite detected by XRD was attributed to mechanical polishing, not LSP. In contrast, LSPwC reduced corrosion resistance across all conditions due to Fe-rich surface oxides that impaired passivation.
Chiang et al. (Fri,) studied this question.