Effect of the Absorption Layer on the Microstructure and Mechanical Properties of M50 Steel by Laser Shock Peening

By means of laser shock peening (LSP) for 1–6 times, microstructure observation, hardness, rotating bending fatigue performance tests, and the influence of the absorption layer on the LSP effect of the M50 steel has been studied. The results show that, after LSP with an absorption layer of aluminum foil or black tape, carbide fracture and pit damage occurred on the surface of the sample, and the damage degree gradually increased with the increase of shock times. The hardness was increased by 9.3% and 7.8%, and the residual stress was increased by 37.5% and 36.1%, respectively. The rotating bending fatigue limit strength of the steel increased by 45.9% and 44.5%. LSP effectively improves the fatigue performance of steel.