Numerical simulation of coupled arc-droplet-weld pool behaviors during compound magnetic field assisted gas metal arc welding

A compound external magnetic field (EMF) can be used to prevent weld bead defects by controlling the metal transfer and arc behaviors during high-speed gas metal arc welding. A unified model containing the filler metal, arc, weld pool, and compound EMF was established to study the effect of the compound EMF on the welding process. The heat and mass transfer among the filler metal, arc, and weld pool under the action of the EMF was numerically analyzed. The simulation results showed that the high-temperature region in the molten pool was reduced and the temperature distribution was more uniform after the EMF was introduced. The speed of the forward liquid metal flow in the front of the molten pool increased due to the forward inclination of the filler metal and arc plasma, and a small metal bulge formed at the leading edge of the molten pool. Because of the periodic swing of the arc and the droplet, the transverse filling of the liquid metal strengthened. The generated additional electromagnetic force inside the weld pool was analyzed, and it had limited impact on the weld pool behavior.