Numerical simulation of heat and mass transient behavior during WAAM overlapping deposition with external deflection magnetic field

During the magnetic controlling wire arc additive manufacturing (WAAM) process, the external magnetic field directly influences the arc shape and the molten pool flow, which can further affect the morphology of the deposition layer and the overlapping flatness. This study introduced an external deflection magnetic field (EDM) with longitudinal and deposition direction components into the WAAM process. A numerical simulation model of the coupling of the arc and the molten pool was established on the basis of a weak coupling method. The numerical simulation model was utilized to investigate the effect of the EDM field on the heat and mass transfer behaviors in the WAAM overlapping deposition process. The results showed that the EDM field generated an additional electromagnetic force in the welding arc and molten pool with circumferential and single-side lateral components. The additional electromagnetic force drove the arc plasma to the rear of the molten pool and the side of the solidified weld bead simultaneously, which resulted in more heat and electromagnetic force concentrated on the gap of the overlapping beads. An asymmetric circumferential rotating vortex appeared in the molten pool, which drove the melted metal to fill the gap of the overlapping beads and improved the overlapping flatness.