Prediction of welding distortion and residual stress in a thin plate butt-welded joint

In automotive industry, thin plate parts are commonly used. During assembling process, welding technology is usually employed because of high productivity. Welding distortion often occurs in thin plate welded structures due to relatively low stiffness. The distortion causes problems not only in the assembling process but also in the final product quality. Therefore, prediction and reduction of welding deformation have become of critical importance. In this study, three-dimensional, thermo-elastic–plastic, large deformation finite element method (FEM) is used to simulate welding distortion in a low carbon steel butt-welded joint with 1 mm thickness. To compare with the large deformation theory, the small deformation theory is also used to simulate the welding deformation and welding residuals stress. Meanwhile, the characteristics of welding temperature field, plastic strain distribution and welding residual stress in thin welded plates are also examined numerically. Experiments are also carried out to measure the welding distortion in the thin plate butt-welded joint. By comparing the simulation results with the measurements, it is found that the results predicted by the thermo-elastic–plastic, large deformation FEM match the experimental values well. Moreover, using the inherent strains obtained by the thermo-elastic–plastic FEM, an elastic FEM is also employed to estimate welding deformation in the same butt-welded joint. Comparing the results simulated by the elastic FEM with those predicted by the thermo-elastic–plastic FEM, it is verified that the inherent strain method can effectively predict the welding deformation in the thin plate butt-welded joint with 1 mm thickness.