焊接参数对Ti2AlNb合金电子束焊接接头焊缝形状和残余应力的影响

摘要

In order to estimate the residual stresses in Ti2AlNb alloy jointed by electron beam welding (EBW),a computational approach based on finite element method was developed.Meanwhile,experiments were carried out to verify the numerical results.The comparison between the simulation results and measurements suggests that the developed computational approach has sufficient accuracy to predict the welding residual stress distributions.The results show that the central area of the fusion zone suffers tensile stresses in three directions.When the other parameters remain unchanged,the focus current has great impact on the weld shape and size,and then affects the residual stress level significantly.Moreover,the thick plate full-penetrated EBW weld suffers near 1000 MPa tensile stress of Z-direction in the center of the fusion zone.The wider weld has lower tensile stress in Z-direction,resulting in lower risk for cracking.%采用有限元数值模拟方法预测Ti2AlNb合金电子束焊接接头的残余应力,并通过实验加以验证.对比模拟与实验结果,本文的数值计算方法具有良好的精度.结果 表明,焊缝中心区域呈现三向拉应力状态;其他焊接参数相同条件下,聚焦电流对焊缝形状及尺寸具有显著影响,从而影响焊接残余应力水平;对于Ti2AlNb合金厚板电子束熔透焊接头,焊缝中心具有1000 MPa左右的厚度方向应力;增大熔宽可降低厚度方向应力,进而降低接头裂纹倾向.