焊接顺序对T形接头焊接残余应力场的影响

为了得到T形接头焊接顺序的优化方案,在确定合理的焊接热源形式以及建立有限元模型的基础上,利用单元死活技术从多道焊、分段焊与多层焊的角度对焊接顺序对T形接头焊接残余应力场的影响进行数值分析.对于多道焊来说,焊接残余拉应力出现在焊缝及其附近区域,且峰值出现在焊缝区域;相邻焊道之间采用首尾相接的方法得到的焊接残余拉应力峰值是最小的.对于分段焊来说,采用先焊两端后焊中间的方法不仅可以增加整个焊缝的焊接残余低应力区域;而且可以有效地降低先焊区域的焊接残余应力,降低效果与后焊焊段的焊接方向以及先焊焊段上的点到后焊焊段端部的距离有关.在多层焊的过程中,采用对称施焊的方法得到的焊接残余拉应力峰值是最小的.

INFLUENCE OF WELDING SEQUENCE ON WELDING STRESS OF T JOINT

In order to get the optimizing scheme of T type joint's welding sequence, the effect of welding sequence on welding residual stress field of T joint is simulated from the view of multibead welding, subsection welding and multilayer welding on the basis of ensuring reasonable welding heat source and establishing the finite model. For the multibead welding, the residual tensile stress appears in the weld and nearby while the maximum value appears in the weld. Moreover, the method of the different welding direction between adjacent beads during the multibead welding makes the residual tensile stress peak value minimum. The subsection welding in which the prior welding section is the two end section and the latter welding section is the middle section not only can increase the low stress region of weld, but also can effectively decrease welding residual stress of the prior welding section. Moreover, the decreasing effect of subsection welding is related to the welding direction of the latter welding section and the distance between one point of the prior welding section and the end of the latter section. In the multilayer welding process, the method of symmetry welding gets the minimum residual tensile stress.