TC4钛合金激光焊缝形貌与残余应力数值分析

针对激光深熔焊特点,采用均匀体热源模型、双椭球热源模型和组合热源模型,对TC4钛合金CO₂激光深熔焊的焊缝形貌和残余应力进行了数值模拟与试验.结果表明,在进行激光深熔焊焊缝形貌与残余应力数值计算中,应根据激光焊接热输入选择激光热源模型,并提出了均匀热源模型适合较大热输入,双椭球热源模型适合中等热输入,而组合热源模型适合较小热输入的选择原则;组合热源模型和双椭球热源模型均能体现热输入随深度的递减变化,焊缝轮廓呈现圆锥形和钉子形;均匀体热源的上下表面的残余应力分布基本一致,而双椭球热源和组合热源模型的下表面残余应力明显低于上表面.

Numerical research on weld bead geometry and residual stresses with different heat source models in laser welding of TC4 titanium alloy

According to the features of laser deep penetration welding,three heat models of uniform heat source,double ellipsoidal heat source and the combined heat source were used to study numerically the weld bead geometry and residual stresses in CO₂ laser welding of TC4 titanium alloy.The results show that the heat source model in calculation should be selected according to the energy input.Then an approach to select the heat source model was proposed that the uniform heat source should be used under the condition of the greater energy input,the double ellipsodial heat source is suitable for medium energy input and the combined heat source fits for smaller energy input.Both the double ellipsodial heat source and the combined heat source can indicate the decrease of heat input with depth,and the estimated weld bead geometry as circular cone shape or nail shape.The residual stresses on top and back sides are similar when the uniform heat source is used,but the larger residual stress exists on the top surface than that on back surface when the double ellipsodial and combined heat sources are used.