Effect of geometry on the microstructural and tribological modifications of M50 steel induced by laser shock peening treatment

Abstract The effects of laser shock peening (LSP) on the microstructure, residual stress, hardness, and wear resistance of convex, flat and concave M50 steel were investigated by microstructure observation, residual stress detection, finite element method (FEM) numerical simulation, and mechanical property test. The results show that a dense layer with a certain depth is formed on the surface of M50 steel after LSP treatment, and lattice distortion and carbide precipitation occur. The residual compressive stress, hardness, and surface roughness were increased, which showed SUB < LSP-convex < LSP-flat < LSP-concave and the measured residual compressive stress agrees with the FEM simulation results. Compared with the SUB sample, the wear loss of the convex, flat, and concave models was reduced by 34.69%, 68.37%, and 71.43%, respectively. This is related to increased residual compressive stress, hardness, and carbide precipitation.