核电用特厚SA508-3钢板焊接过程模拟分析

Simulation Analysis of Welding Process of SA508-3 Steel Thick Plate for Nuclear Power

为了得到核电SA508-3钢焊件上各区域热循环曲线及残余应力分布规律,采用有限元软件,通过提出改进的子结构算法,减少模型非线性计算的节点总数,使模拟更加接近真实的厚板焊接过程。模拟结果表明:离热源越近的节点峰值温度越高,冷却速度越快,焊缝上任意节点的热循环曲线基本一致;厚板焊后残余变形关于焊缝中心对称;焊缝外表面的横向残余应力既有压应力,也有拉应力,焊缝内表面为较高的横向拉应力,纵向一直保持较高的残余拉应力,且占主导地位,使得焊件危险部位在沿着焊接方向的焊缝中心附近。

According to the new material which was SA508-3 steel for nuclear power, based on finite element numerical simulation, three-dimensional finite element model was established, and finite element model of 100 mm steel plate was established, and the substructure method was adopted which reduce the nonlinear calculation of the total nodes number to simulate more close to the real thick wall plate welding process and accurately predict temperature field and residual stress distribution rule of welding process. It is found that the node has a different cooling rate which has different distance from the weld centerline, the closer distance to heat source, the faster cooling rate is; welding residual deformation of thick plate is Symmetrical about weld seam center. The outside weld surface has compressive residual stress and tensile stress, the inside weld surface has higher transverse tensile stress, and reached the maximum at the weld center line, the longitudinal residual stress of the weld and near area is tensile stress, and the maximum tensile stress is more than the maximum compressive stress which became dominant to reaches the yield strength of material into the plastic and result in the weldment dangerous position appear the center line of welds along the welding direction.