Simulation on Keyhole Behavior and Pore Control in Pulsed Laser Induced Arc Welding Process of Magnesium Alloy

The keyhole behavior of low-power pulsed laser induced arc welding of magnesium alloys constitutes an essential factor in the formation of porosity defects. An in-depth exploration of the keyhole behavior represents a theoretical breakthrough for eliminating porosity and enhancing weld quality. This is a significant focus for investigating defect control approaches. A model of the gas-liquid interface during the keyhole formation process of low-power pulsed laser induced arc welding of magnesium alloys is established herein. The influence of welding parameters on the evolution of keyholes was investigated through experiments. This study aims to clarify the evolution of keyhole morphology and the delayed closing mechanism in pulsed laser induced arc welding. The results indicate that the laser excitation current and arc current are the primary factors influencing keyhole depth and delayed closing time, respectively. On this basis, the correlation system of process parameters, mechanical factors, and keyhole behavior parameters was established. By combining experiments and simulations, the process threshold for controlling porosity defects of the weld was obtained. The threshold can be determined by considering the following conditions: the laser excitation current is less than 190 A and the arc current is greater than 85 A. This method can effectively prevent the formation of weld porosity.