An improved simulation of temperature field in VPPA-GMAW of Al-Cu-Mg alloy

The thermal properties with consideration of the phase transitions were established to simulate the temperature field of the paraxial variable polarity plasma arc (VPPA)-gas metal arc welding (GMAW) hybrid welding. A variable combined heat source model was developed to describe the heat transfer process of hybrid welding. The effects of different energy ratios of hybrid welding on the weld pool geometries and penetration depth were investigated. An appropriate increase in the VPPA welding power could improve the depth-to-width ratio of weld beads, to achieve deep-penetration welding. Experiments were performed to measure weld geometries, and the weld pool was captured in situ by a high-speed camera to verify the developed finite element model. The calculated results were in good agreement with the experimental results. The adapted matching of the VPPA and GMAW powers was determined by the numerical simulation to optimize the hybrid welding process, resulting in high-quality butt welds.