Mechanism clarification of mitigating welding induced buckling by transient thermal tensioning based on inherent strain theory

Abstract

Welding induced buckling in thin plate structures significantly affects productivity and fabrication cost due to post-weld correction works. Transient thermal tensioning (TTT) as an in-process treatment was employed for mitigating welding induced buckling, and its mechanism was clarified by inherent strain theory. Butt welding experiment with 304 L stainless steel was conducted. A finite element (FE) model was established to examine thermal-mechanical response during the entire welding process. Computed results were validated by the measured out-of-plane welding distortion, which was obtained using a three-dimensional optical scanning system. Then, two additional heat sources on both sides of the welding line were applied to achieve TTT treatment with the established numerical model. Moreover, the influence of heating location on mitigating welding induced buckling was discussed. The results show that the maximum deflections along and perpendicular to welding direction were reduced by 82.6% and 74.7%, respectively. The heating location has a decisive influence on the mitigation of welding induced buckling, which should be kept away from the welding line with appropriate distance. The thermal stretching from additional heat sources enhances the self-constraint of the base material on the welding region during the cooling process, resulting in more tensile plastic strain generated to reduce welding inherent strain and tendon force.