中文摘要：

利用高功率重复率Nd：YAG激光对TC4钛合金电子束焊缝进行了冲击强化处理，研究了激光冲击强化处理过程中改变激光功率密度对电子束焊缝残余应力分布和表面层硬度的影响．试验结果表明，当激光脉冲能量为45．9J时，激光光斑直径Ф9mm，残余应力基本不发生变化，而激光光斑直径小于Ф3mm，焊缝残余应力分布变化显著，并随着激光光斑直径的减小，残余压应力的数值增大更加明显．当激光冲击的功率密度大于18GW／cm^2时，激光冲击强化处理使电子束焊缝区的残余应力改变明显，改善了焊缝残余应力的分布；当激光冲击的功率密度大于12GW／cm^2时，激光冲击强化处理使电子束焊缝区的表面层硬度明显改变，改善了焊缝区域硬度的分布，有利于提高TC4钛合金焊缝区的机械性能．

英文摘要：

The surface of TC4 titanium alloy welding line by electron beam welding （EBW） was processed by high power Q-switched and repetition-rate Nd ： YAG laser. Effects of laser power density on residual stress and micro-hardness of the TC4 alloy welding line by laser shock processing （LSP） were analyzed. The results show that residual stresses remain unchanged for laser power 45.9 J, spot diameter Ф9 mm. For laser power 45.9 J, spot diameter less than Ф3 mm, the distribution of residual stress in EBW obviously alters, and residual stresses increase with decreasing spot diameter. When laser power density is greater than 18 GW/cm^2, residual stresses of EBW line are changed, which improves residual stress distribution. When laser power density is greater than 12 GW/cm^2, the surface micro-hardness of EBW line alters. Mechanical properties of TC4 titanium alloy welding line will be improved by LSP.