Experimental research of distribution of residual stress state on 2024 aluminum alloy shocked by multiple lasers

2024 aluminum alloy samples were treated by multiple laser shock processing(LSP). Residual stresses of impact zone were analyzed by XRD. The distribution of residual stress state by multiple LSP was studied. The quality of laser shock processing was evaluated by the distribution of residual stress state. Experimental results show that plastic deformation and plastic strain gradient decreased with the increasing shock times, and the measured points were in two-direction compressive stress state. Plastic strain gradient was increased by 4 LSP impacts. The point center was in one-direction compressive stress state and the others were in two-direction compressive stress state. The quality of LSP was optimum by the laser power density of 2.8 GW/cm2 and 3 LSP impacts, with measured points in two-direction compressive stress state. In this condition, the mean values of maximum principal residual stresses and stress intensity were maximum, the variances of them were minimum, the distribution of them was uniform, and the plastic strain gradient was minimum.