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采用热-弹塑性三维有限元法研究激光熔透焊接 Ti6Al4V 合金的残余应力,并采用小孔法测量焊接残余应力以和计算结果进行比较。有限元计算时,建立了以焊缝形貌尺寸为参数的统一锥形热源模型来模拟不同热输入时的焊接温度场,并讨论了边界条件和有限元网格大小的确定。研究结果表明:采用焊缝轮廓尺寸作为热源参数能准确模拟焊缝横截面轮廓;钛合金激光熔透焊接的纵向残余应力分布梯度陡;在焊件表面和内部残余应力分布趋势不同,采用小孔法测量的残余应力分布和计算的焊接件内部残余应力分布相似。
The residual stress of laser penetration welding of Ti6Al4V alloy was studied by the thermo-elasto-plastic three-dimensional finite element method. The welding residual stress was measured by the pinhole method and compared with the calculated results. In the finite element calculation, a uniform pyramid heat source model was established to simulate the welding temperature field under different heat input. The boundary conditions and the finite element mesh size were discussed. The results show that the profile of welded seam can accurately simulate the cross-sectional profile of weld seam. The gradient of residual stress distribution in laser welded titanium alloy is steep. The distribution of residual stress on the surface and internal of weldment is different, The residual stress distribution measured by the method is similar to the calculated residual stress distribution inside the weldment.