Laser cavitation processing of mild steel: Surface integrity, microstructure and stress corrosion performance

Abstract

Laser cavitation peening (LCP) is a new and effective technology for surface modification. The Q235 steel was processed by LCP and aluminum foil was employed as a coverage layer. Moreover, the Q235 steel was also treated by laser cavitation peening without a coverage layer (LCPwc). The surface integrity, microstructure, and stress corrosion behavior of Q235 steel processed by LCP and LCPwc were systemically studied. According to the experimental results, the mechanisms of LCP strengthening and stress corrosion performance of Q235 steel were revealed. The results indicate that LCP and LCPwc result in the surface plastic deformation of Q235 steel. The residual compressive stress is induced and microhardness is enhanced. On the surface layer of Q235 steel, the grains were refined and many dislocation structures produce. The impact of LCPwc and LCP enhances the yield strength and ultimate strength of Q235 steel, while the elongation decreases. The corrosion resistance and mechanical properties of Q235 steel are improved significantly after the processing of LCPwc and LCP. The Q235 after LCP processing has better mechanical properties while the LCPwc treatment makes the material have better anti-corrosion performance.