采用热-弹-塑性有限元计算模拟了Ti2AlNb合金电子束焊的温度场和应力场.为了准确反映熔透型电子束焊接的特点,对旋转高斯曲面体热源模型进行了改进.研究结果表明:采用改进的热源模型能准确地模拟穿透型电子束焊焊缝横截面轮廓;残余应力的模拟结果与实验结果吻合较好,证明了有限元模型的正确性;Ti2AlNb合金电子束焊后残余应力以纵向拉应力为主,且集中分布在距焊缝中心线3 mm的区域内;横向残余应力在表面附近区域呈压应力,内部呈拉应力,表面横向压应力是由焊缝纵向和厚度方向的收缩导致的;焊缝内部出现三向拉应力的状态.
A 3D thermal elastic-plastic finite element model was developed to predict welding residual stresses induced by full-penetration electron beam welding of Ti2AlNb alloy.Rotary-Gauss body heat source model was modified to reflect the full-penetration weld.The results show that the cross section profiles of the weld seam simulated with the modified heat source model agree well with the experimental results.The residual stress distribution also has a good agreement between the numerical and experimental results,which proves the validity of the finite element model.The longitudinal tensile stresses plays a major role in the welded joint of Ti2AlNb alloy and the region of residual stresses distribution is very narrow within a distance 3 mm away from the weld centerline.Compressive transverse stress is observed on the top and bottom surfaces while tensile transverse stress at the center of the weld,and the discrepancy is ascribed to the longitudinal and normal contracting of the weld.In addition,the phenomenon of local three dimensions residual tensile stresses appears in the plate center.
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