Numerical simulation of metal transfer in pulsed-MIG welding

Abstract

Pulsed currents of various shapes have been employed to control the metal transfer phenomena. In the present study, a simulation model including both the arc plasma and the metal transfer is constructed, and their behaviors in pulsed-MIG arc welding are numerically investigated. When the peak current is set to 450 A and the peak time is set to 1.5 ms, only a single droplet is transferred per pulse. The numerical model can indicate the metal transfer and arc plasma behavior depending on the pulse shape. The temperature of the arc plasma increases rapidly at the early phase of the peak time, and consequently, the temperature of the wire electrode increases. After that, a large amount of the metal vapor generates from the wire tip, and the arc temperature decreases. These behaviors are periodic and can be controlled through the pulse shape. In addition, the appropriate pulse frequency depends on the surface tension of the wire electrode. This result shows that balance of the surface tension and the electromagnetic force is important to determine the droplet behavior. Therefore, in controlling the welding process, it is important to consider the properties of both the welding power source and the welding material.