Thermal field distribution and residual mechanical effects of welded spherical joints strengthened by laser welding

To investigate the temperature effects induced by laser welding reinforcement method for hollow spherical joints and their influence on the mechanical performance of joints, a comprehensive series of temperature measurement experiments and numerical analyses was conducted. Precise temperature measurement data were obtained using thermocouples and infrared thermal imagers under various laser welding power and speed conditions. Based on the characteristics of hollow spherical joints, a modified Gaussian heat source model was developed. On this basis, a comprehensive investigation was conducted into the thermal residual stresses generated during the welding process, and the mechanisms by which these residual stresses impact the bearing capacity of welded joints are analyzed. The results show that the maximum welding temperature increases with welding power and decreases with welding speed. Temperatures progressively decrease outwards from the weld, and the heat-affected zone within both the sleeve and stiffener welding areas is remarkably confined. Furthermore, the modified Gaussian heat source model accurately describes the laser welding reinforcement process, with numerical simulation results demonstrating excellent agreement with experimental results. Due to the small magnitude of temperature-induced residual strain and deformation, the resulting residual mechanical effects have a negligible impact on the joint's static bearing capacity. It is concluded that laser welding reinforcement is a feasible solution for hollow spherical joints.