Mechanism investigation of the influence of the magnetic field on the molten pool behavior during laser welding of aluminum alloy

Abstract Magnetic field-assisted welding provides a promising approach to suppress defects and improve weld bead properties significantly. In this paper, a full factorial experiment was conducted to study the mechanism of the influence of the magnetic field on the weld profile of aluminum alloy laser welding. Furthermore, a three-dimensional numerical simulation model simultaneously considering the free surface of the keyhole, and the effect of the magnetic field is developed to reveal the mechanism of the influence of the magnetic field on the weld bead profile by analyzing molten pool behavior. It was found that the magnetic field can reduce the width of the weld bead while increasing the depth and middle width of the weld bead. The magnetic field distribution in the weld bead was numerically simulated and validated. The simulation results demonstrate that the liquid motion in the magnetic field can induce a Lorentz force in a direction opposite to the flow velocity. The magnetic field can suppress both the lower-to-upper region and center-to-edge molten flows of the molten pool, which reduces the heat transfer from the tip of the keyhole to the molten pool surface and from the center to the boundary of the molten pool. This can provide a concept to reveal the underlying mechanism of the influence of the magnetic field on the weld bead profile. This work could contribute to gain insight into the influence of a magnetic field on aluminum alloy laser welding.