Numerical analysis and verification of residual stress in T joint of S355 steel

T joint is a widely used welding form. The welding deformation and residual stress produced during the welding process affect the integrity and reliability of the resultant structure. In this study, S355 low alloy steel was used as test material, and the thermal-mechanical coupling characteristics of multi-layer welding were combined with SYSWELD finite element software to calculate the residual welding stress of T joint. The residual welding stress of multi-layer welding T joint with tangent tube and sheet was measured using X-ray diffraction method. The results showed that the numerical simulation was in good agreement with the experimental findings. With respect to the transverse residual stress, the maximum residual stress appeared near the weld toe. The transverse stress perpendicular to the weld direction represented the tensile stress at the weld center as well as the tensile stress at the tube surface far from the weld. Regarding longitudinal residual stress, the maximum residual stress also appeared near the weld toe, and its value was highest at the center of the weld, but decreased along the direction perpendicular to the weld. These results can serve as useful guide for actual welding design.