Influence of welding sequences and boundary conditions on residual stress and residual deformation in DH36 steel T-joint fillet welds

• A combined experimental and numerical method is used to study DH36 steel T-joints. • The effects of successive vs. simultaneous welding on stress and deformation are clarified. • The magnitude and distribution of residual stress are studied using a thermo-elastic-plastic analysis method. • Optimal welding sequences and boundary conditions are recommended to minimize deformation. • Boundary conditions significantly affect transverse stress and deformation. This paper aims to investigate the influence of welding sequences and boundary conditions on welding-induced residual stress and residual deformation of DH36 steel T-joint fillet welds through experimental and numerical methods. A series of typical experiments of successive and simultaneous double-sided welding conditions are conducted to explore both the magnitude and distribution of temperature field, residual stress and residual deformation. Meanwhile, thermal elastic-plastic finite element analysis based on a double ellipsoidal heat source model is performed to investigate the heat transfer and deformation mechanism during the welding process. The influencing factors are further explored to determine and quantify the residual stress and residual deformation induced by different welding sequences and boundary conditions. There is generally well agreement between the experimental and numerical results in terms of temperature field, residual stress, residual deformation and molten pool morphology. The results show that the welding sequences have an important influence on the magnitude and distribution of residual stress and residual deformation. Continuous simultaneous double-sided welding can significantly reduce residual stress and residual deformation to obtain better-quality welds. Boundary conditions have a significant effect on the distribution and magnitude of residual deformation and little effects on residual stress. Tightening the ends of the flange plate with bolts during the welding process can significantly reduce the deformation.