Plasma Interaction and Dynamic Monitoring of Hybrid Laser-Arc Welding of Large-Length Continuous Welds in Large Cruise Ships

Abstract

Abstract Hybrid laser-arc welding, which combines the advantages of arc and laser welding, is a typical small heat input welding method for thin-walled structures like large cruise ships. In hybrid laser-arc welding, the interaction of the laser and arc plasma can improve the thermal efficiency of welding and reduce the plasma shielding effect in laser ablation. However, the length of welds in cruise ships is usually several meters long, making the shielding effect of plasma on laser far more complicated than that of short welds. The molten pool and plasma become inconsistent during the welding process of large-scale continuous welds due to thermal accumulation and parameter fluctuation, which increases the plasma’s shielding effect and may cause welding defects such as undercuts and poor shape. In this paper, large cruise structures with a length of 300 mm to 3000 mm were examined for welding quality consistency in the laser-arc hybrid welding process, and the mechanism of weld morphology change in continuous welding is revealed. A high-speed camera was used to capture images of the instantaneous plasma during the hybrid laser-arc welding of these large cruise ship structures. Various methods such as machine vision and SVR models were employed to analyze the dynamic characteristics of plasma and the plasma shielding effect during welding. Finally, the effect of weld length on plasma interaction during hybrid laser-arc welding was discussed. The results revealed that the dynamic changes of plasma were closely related to the length of welds. During continuous welding of a 3m-long seam, the maximum reduction rate of weld width can reach 26.8%. It is necessary to adjust the welding parameters during the welding process to ensure the quality of the weld when performing long-seam continuous welding. The use of high-speed cameras provides a straightforward and efficient approach to monitoring the plasma interaction during welding.