Effect of laser shock peening on stress corrosion sensitivity of 304 stainless steel C-ring weld specimens

Abstract

As a new surface treatment technology, laser shock peening (LSP) can improve the corrosion resistance and fatigue performance of the metal surface with the help of a high-power density laser beam. In this work, 304 stainless steel C-ring weld specimens were treated with four laser power densities, and the effect of LSP on the surface properties of the specimens was investigated by microhardness measurement, grain size analysis and residual stress test. The research shows that LSP can improve the surface microhardness, produce grain refinement, and transform the residual tensile stress into residual compressive stress in the surface layer of 304 stainless steel. Electrochemical corrosion test and the constant strain corrosion test in boiling magnesium chloride solution were carried out. The results show that the crack initiation time of the C-ring weld specimens treated with LSP is significantly longer than that of the specimens without LSP. As the laser power density of LSP increases, the corrosion current density and the corrosion rate are decreased greatly, the polarization resistance is increased significantly, and the crack initiation time is increased evidently.