Research on the dynamic process and defect formation in laser-arc hybrid welding of 12-mm thick AH36 steel

Laser-arc hybrid welding (LAHW) technology is a versatile and widely used method that has garnered significant attention, particularly in the thick plate welding required for shipbuilding. One of the most crucial parameters in LAHW is the laser-arc distance, which has a significant impact on the interaction between the laser and arc, especially in high-power laser and high-speed welding processes. As such, investigating the effects of laser-arc distance on the welding process is of great theoretical importance for both future research and industrial applications. This study utilizes high-speed photography to capture the welding process, focusing on how the laser-arc distance affects droplet transition and the stability of weld pool flow. Additionally, numerical simulations are used to explore the mechanisms underlying welding defect formation. The results indicate that an optimal laser-arc distance can produce a well-formed weld without significant defects. When the laser-arc distance (DLA) is too small, the coupling effect between the laser and arc becomes overly strong, causing unstable droplet transition and weld pool flow, which leads to defects such as spatter and undercutting. Conversely, when the laser-arc distance is too large, the coupling effect weakens, resulting in reduced weld reinforcement and the occurrence of porosity defects. The findings of this study offer valuable insights for optimizing welding parameters and improving weld quality in industrial applications of LAHW.