Enhancing all-position weldability and weld quality via an innovative laser-GMAW hybrid welding technique with copper liner

The change in welding position results in varied effects of gravity on the weld pool behavior. Conventional welding methods face difficulties when adjusting to welding in different positions. To address these challenges, a novel all-position welding technology, laser-GMAW hybrid welding with copper liner (CL), was introduced. CL serves a dual purpose. First, from flat to vertical welding, it supports the weld pool across various positions, thereby preventing root sagging or burn-through defects at the root of the weld in this range. Second, it facilitates accelerated weld pool solidification and inhibits its downward movement during vertical to overhead welding positions, forming the back continuous reinforcement. To quantitatively analyze the impact of CL on the temperature field during welding, finite element software was employed in this study. Moreover, the study also explored the effects of the size of the forming groove, welding current, and laser power on the weld appearance during overhead welding. As a result, with constant welding parameters, ideal welds with continuous back reinforcement were successfully achieved at five representative positions within the 0-180 degrees range.