高强埋弧焊接圆钢管多层多道焊接数值模拟

Numerical simulation of high-strength submerged arc welded circular steel tubes with multi-layer and multi-pass welding

摘要:

为研究高强埋弧焊接圆钢管纵向残余应力分布规律及影响因素,考虑了高强钢材非线性物理材料属性和焊接过程中的相变潜热,以均匀热源模型模拟第一道次熔化极气体保护焊（GMAW）热源,以双椭球热源模型模拟第二、三道次埋弧焊（SAW）热源,通过单元生死功能模拟焊缝生长过程,并在焊接荷载步间不断修正钢管与空气热传递的表面积,对3道次焊接工艺进行了热-结构耦合瞬态分析并根据拓展的有限元模型研究了焊接方向、道间温度、焊接速度对纵向残余应力分布的影响。与试验对比表明:有限元模型可对焊接纵向残余应力进行预测并为焊接工艺提供建议。高强埋弧焊接圆钢管纵向残余应力分布形式为:焊缝附近残余拉应力接近钢管屈服,随着距焊缝距离增大转变为残余压应力最大值后再次变为残余拉应力。焊接工艺建议:第一和第三道次焊接方向相同而第二道次反向,GMAW焊接速度为4 mm/s,SAW焊接速度为6 mm/s,在冷却时间成本可控范围内道间温度应控制在最低。

Abstract:

To investigate the distribution of longitudinal residual stress and influencing factors of high-strength submerged arc welded circular steel tubes, the nonlinear physical properties of high-strength steel and the latent heat of phase change during the welding process were considered. The uniform heat source model was used to simulate the gas metal arc welding (GMAW) heat source of the first pass, and the double ellipsoid heat source model was used to simulate the submerged arc welding (SAW) heat sources of the second and third passes. The element life and death function was applied to simulate the weld growth process, and continuously modify the surface area of the heat transfer between steel tube and air between the welding load steps. The thermal-structural coupling transient analysis of the three-pass welding process was carried out, and the influences of welding direction, interpass temperature, and welding speed on the distribution of longitudinal residual stress were discussed according to the extended finite element model. Comparison with the test results shows that the finite element model could predict the welding longitudinal residual stress and provide suggestions for the welding process. The longitudinal residual stress distribution pattern of the high-strength submerged arc welded circular steel tube was: the residual tensile stress near the weld was close to the yield of the steel tube, and as the distance from the weld increased, it changed to the maximum value of the residual compressive stress and then became the residual tensile stress again. The welding process is recommended as follows: the first and third passes have the same welding direction but the second pass is reversed, the welding speeds of GMAW and SAW are 4 and 6 mm/s respectively, and the interpass temperature should be kept to a minimum value within the controllable range of the cooling time cost.