Effect of He-Ar shielding gas composition on the arc physical properties of laser-arc hybrid fillet welding: numerical modeling

A three-dimensional numerical model of laser-arc hybrid plasma for aluminum alloy fillet joints is developed in this study. This model accounts for the geometric complexity of fillet joints, the physical properties of shielding gases with varying He-Ar ratios, and the coupling between arc plasma and laser-induced metal plume. The accuracy of the model is validated using a high-speed camera. The effects of varying He contents in the shielding gas on both the temperature and flow velocity of hybrid plasma, as well as the distribution of laser-induced metal vapor mass, were investigated separately. The maximum temperature and size of arc plasma decrease as the He volume ratio increases, the arc distribution becomes more concentrated, and its flow velocity initially decreases and then sharply increases. At high helium content, both the flow velocity of hybrid plasma and metal vapor are high, the metal vapor is concentrated on the right side of keyhole, and its flow appears chaotic. The flow state of arc plasma is most stable when the shielding gas consists of 50% He + 50% Ar.