BT20钛合金激光焊接残余应力场及热处理研究

采用小孔释放法和数值模拟从对比的角度研究了B他0钛合金激光焊接和TIG焊接残余应力场的分布特点，并从理论上进行了分析。研究结果表明：在热影响区，激光焊接残余应力比TIG焊接残余应力小；但在焊缝及熔合线上，激光焊残余应力比TIG焊的大。这主要与激光焊接线能量小，塑性变形区窄有关。控制和消除激光焊接残余应力更具重要意义。经真空热处理后，激光焊接焊缝的针状马氏体转变为等轴细晶组织，焊接残余应力显著降低。

Study on Residual Stress Field in Laser Beam Welding Joints of BT20 Titanium Alloy and Its Heat Treatment

Hole drilling method and numerical simulation were used to analyze the distributions of the residual stress in welding joints for BT20 titanium alloy, which were welded by laser beam and TIG. Some discussions about the difference of the residual stress between laser welding and TIG welding are given. The result shows that in heat-affected zone (HAZ), the values of laser welding residual stress are lower than that of TIG welding residual stress, but are bigger in bead and fusion line. The main reason is that the speed of laser welding is very fast and the plastic zone is considerably narrow. The control and removal of residual stress are more significant. After vacuum heat treatment, the acicular martensite become fine and the residual stress relieve effectively.