2024铝合金激光多次冲击诱导残余应力状态分布规律

采用高功率激光器多次冲击2024铝合金，用X射线衍射技术分析了冲击区域的残余应力，研究了冲击残余应力状态分布规律，并用其评价激光冲击强化效果。研究表明，随着冲击次数增加，塑变量及塑性应变梯度逐渐减小，测点是双向压应力状态，而4次冲击时，塑性应变梯度增大，光斑中心是单向压应力状态，其他点是双向压应力状态。当激光功率密度为2.8 GW/cm2时，3次冲击强化效果最佳，材料是二向压应力状态，残余最大主应力及应力强度的均值最大，方差最小，分布基本均匀，塑性应变梯度较小。

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.