A comparative study on welding temperature fields,residual stress distributions and deformations induced by laser beam welding and CO2 gas arc welding

Welding-induced distortion in thin-plate structure is a serious problem which not only hinders the assembling process but also negatively affects the performance of product. Therefore, how to control welding deformation is a key issue both at design stage and at manufacturing stage. During welding process, there are a number of factors which can significantly affect manufacturing accuracy. Among these factors, the heat input is one of the largest contributors to the final deformation. Generally, when laser beam welding (LBW) is used to join parts the total heat input is far less than that used in a conventional welding method such as gas metal arc welding, so it is expected that LBW can significantly reduce welding distortion especially for thin-plate joints. As a fundamental research, we investigated the welding deformations in low carbon steel thin-plate joints induced by LBW and CO₂ gas arc welding by means of both numerical simulation technology and experimental method in the current study. Based on the experimental measurements and simulation results, we quantitatively compared the welding deformation as well as residual stress induced by LBW and those due to CO₂ gas arc welding. The results indicate that the out-of-plane deformation of thin-plate joint can be largely reduced if CO₂ gas arc welding method is replaced by LBW. Moreover, the numerical results indicate that the residual stresses induced by LBW are superior to those produced by CO₂ gas arc welding both in distribution and in magnitude.