(西北工业大学 材料科学与工程学院，西安 710072)
摘 要: 采用ANSYS有限元分析软件，建立12 mm厚TC4钛合金平板电子束焊接温度场和应力场的三维有限元数值计算模型。模型采用圆锥体热源考虑电子束焊接时的小孔效应；材料的热学、力学性能参数随温度变化；相变和熔池内液体的对流散热通过比热和热导率的变化实现。计算结果表明：钛合金电子束焊接时，熔池呈典型的卵形分布。高值纵向残余拉应力集中分布在焊缝中心线两侧距焊缝中心线4 mm的区域内，平板内部出现接近材料屈服极限的局部三维残余拉应力状态。实验得到的焊缝宏观形貌和小孔释放法检测到的焊接残余应力对计算结果进行验证, 实验结果和计算结果吻合较好，证明了有限元模型的正确性。
关键字: 钛合金；电子束焊接；数值模拟；小孔法；残余应力
（School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China）
Abstract: A three dimensional finite element model used for calculating electron beam welding temperature and stress fields of 12 mm-thickness TC4 titanium alloy plate was developed through employing ANSYS software code. Cone body heat source model was chosen to simulate keyhole effect of electron beam welding. Temperature-dependent thermal and mechanical properties were used. Phase change and liquid convection in molten bath were simulated by the change of specific heat and heat conductivity. The results of the simulation show that the shape of the weld pool is typically oval. The longitudinal stresses with high value mainly lie in the region which extends a distance 4 mm away from the weld centerline. The phenomenon of local three dimensions residual tensile stresses, which are equivalent to the yield stress of the material, appears in the plate center. Macrograph of the fusion zone in the transverse section obtained from experiment and residual stresses determined by hole-drilling method are used to validate the simulated results. The experimental and numerical results are in sufficient overall agreement, which proves the validity of the finite element model.
Key words: titanium alloy; electron beam welding; numerical simulation; hole-drilling method; residual stress
