Coupled simulation of plume–keyhole interaction in laser deep penetration welding

During laser deep penetration welding, a complex multiphase interaction significantly affects the welding process. Although the effects of plume particles on keyhole behaviour have been examined experimentally, the underlying mechanisms remain insufficiently validated. This study developed a Rand function-based plume model to describe the dynamic attenuation of laser energy by plume particles, coupled with a multi-physics simulation of keyhole dynamics. Considering plume effects, the average keyhole depth decreased by 13%, and the probability of keyhole bottom collapse increased by 12%. Bubbles resulting from keyhole collapse were positioned further from the keyhole bottom, and easier to cause porosity defects. The simulations also revealed enhanced molten pool surface expansion. This study successfully validated the effect of laser-induced plume on keyhole instability through simulation.