钛合金厚板电子束焊接残余应力模拟研究

Numerical Simulation of Residual Stress for Electron Beam Welding of Thick Titanium Alloy

采用有限元软件深入分析了钛合金厚板电子束焊接接头的温度场和应力场,考虑了装配间隙的影响,基本掌握了残余应力的分布规律。结果表明:残余应力主要集中在焊缝及HAZ位置,超出该区域后,应力迅速下降。试件内部厚度方向残余拉应力较大,最大值在650 MPa左右,不可忽视。横向残余应力在焊缝的上下表面处均为压应力,与传统的电弧填丝焊后应力状态相反。相比于不留装配间隙,当间隙不超过0.1 mm时,残余应力基本不变。焊后最大等效应力接近材料屈服强度,需要采取优化焊接工艺或者消应力处理等方法,避免叠加工作应力后导致的结构失效问题。

The temperature and stress fields of electron beam welded joint in thick titanium alloy were analyzed by using finite element software considering different assembly gap conditions, and the distribution of residual stress was basically mastered. The result shows that residual stress is mainly concentrated in the welded and HAZ, then, the stress decreases rapidly beyond this area. The residual stress in the thickness direction of the specimen is too large to ignore, and the maximum tensile stress is around 650 MPa. The transverse residual stress is compressive stress on the upper and bottom surface of welding seam, which is contrary to the stress state of traditional arc welding. Compared with no assembly gap, when the clearance is less than 0.1 mm, the residual stress basically maintains invariable. After welding, the maximum equivalent stress is closed to the yield strength of base metal, so it is necessary to optimize welding process or stress elimination treatment to avoid structural failure caused by superimposed working stress.