Mechanism of laser-arc interaction of hybrid welding based on arc column layering

This study investigates the influence of laser-arc interaction on arc column layering to further elucidate the principles of laser-arc interaction. By employing high-speed camera imaging and spectral diagnostics, the effects of arc current on the delay of arc layering and the morphological changes in the inner and outer layers of the arc column during laser-MIG hybrid welding of aluminum alloy were examined. The findings reveal that the MIG arc exhibits a concentric double-layer structure, with the inner layer composed of metal vapor and the outer layer consisting of Ar plasma. The laser-arc interaction delays the formation of arc layered structure and induces expansion of the outer layer and contraction of the inner layer.

With the arc current range of 120-240A, the delay time of arc layering progressively decreases from 0.25 ms to 0 ms. At 240A, the layering delay phenomenon is completely eliminated. Concurrently, the diameter of the external Ar plasma expands to 1.04 times its original size, while the diameter of the internal metal vapor contracts to 0.89 times its original size. The study analyzes the mechanism of laser-arc interaction on the delay time of arc layering through changes in plasma characteristic parameters and the cooling effect of the laser on the arc. Additionally, by analyzing electromagnetic static pressure and electromagnetic contraction force, the mechanism by which arc current affects the morphological changes in the inner and outer layers of the arc is clarified, thereby deepening the understanding of the laser-arc hybrid welding mechanism.