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, I_b 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 Laser-GTAW, 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.