Numerical simulation of GMA metal transfer phenomena including arc plasma

Abstract

MIG welding process contains arc plasma, metal transfer and weld pool phenomena. In this process, electrode wire melts by heat energy from the arc plasma, and molten metal at the wire tip deforms by various driving forces such as electromagnetic force, surface tension and arc pressure. Subsequently, the molten droplet detaches from the tip of wire and transfers to the base metal. The arc plasma shape changes together with the metal transfer behavior. In the present work, we constructed the unified model of metal transfer phenomena in which the interaction between the arc plasma and the metal drop was considered. In the numerical model developed, wire melting rate experimentally derived was provided as a function of arc current. But heat conduction and heat convection were not taken account in the metal.
The numerical result by the developed model could demonstrate transition of metal transfer mode from globular transfer to spray transfer with increase of current. It is found that spray transfer mode in higher current range is formed mainly by electromagnetic force directly acting on the molten metal. In case of low arc current, surface tension plays dominant role in globular transfer mode. Furthermore, the properties of droplet are strongly affected to determine the transfer mode.