Finite element analysis of residual stress distribution in a thick plate joined using two-pole tandem electro-gas welding

A computational approach considering moving heat sources was introduced to predict the residual stress distribution produced by electro-gas welding (EGW) joints. Considering the two-pole tandem of EGW, a finite element analysis (FEA) was suggested to evaluate the thermal behavior of EGW applied to a joint of ultra-thick plates. Based on a thermo-mechanical FEA, the profiles of the residual stresses are investigated for EH40 thermo-mechanical control process (TMCP) steel plates with a thickness of 80 mm. In order to simulate the weaving motion of two weldment poles, a quasi-steady heat flux model is introduced based on Goldak's double ellipsoidal heat source model. The X-ray diffraction methods were used to measure the residual stress field on the surface treated by chemical polishing. The residual stress profiles determined by the FEA and measurement showed quite good agreement, as regards the values both peaks and of the profile. Residual stresses relieved by post-weld treatments, particularly by ultrasonic peening and toe grinding, is also presented.