Study on arc characteristics and weld appearance of laser-twin-arc-GTAW hybrid welding

Laser twin-arc GTAW（LTA-GTAW） process has been developed by using the synergic interaction effects of laser and a coupled arc in a weld pool to achieve higher energy efficiency. In this study, bead-on-plate welding was conducted on 8-mm-thick Q235B workpieces to investigate the variation of hybrid arc profile, the influence of hybrid arc profile on weld forming, microstructure and mechanical properties of the joint during the LTA-GTAW process. The influence of Laser-GTAW and LTA-GTAW methods on weld surface appearance, heat input per unit length, and weld metal microstructure were also demonstrated systematically. The LTA-GTAW can make the distribution of arc energy more reasonable in welding depth and width. When defocus is 0, I_f is 330 A, Ib is 240 A, laser power is 2.4 kW, and spacing between heat sources of tungsten electrode is 10 mm, the weld shape is better. Compared with LaserGTAW, LTA-GTAW can achieve lower heat input at the same penetration depth, and the microstructure of the weld is refined. The tensile strength of the welded joint is 121.8% of the base material, and the fracture mode of the welded joint is ductile fracture, the comprehensive mechanical properties are better.