A Comprehensive 3-D Model on Gas Metal Arc Welding

A unified comprehensive model was developed to simulate the transport phenomena occurring during the gas metal arc welding process. An interactive coupling between arc plasma; melting of a continuously fed electrode; droplet formation, detachment, transfer, and impingement onto the workpiece under the influences of several competing forces including gravity, electromagnetic force, arc pressure, plasma shear stress, and surface tension; and weld pool dynamics all were considered. The transient distributions of current density, arc temperature, arc pressure, melt flow velocity and melt temperature in the droplet and in the weld pool were all calculated. Based on the unified model, the following investigations were conducted: 1) the effect of welding current on droplet generation, especially the use of pulsed current to achieve the one-droplet-per-pulse (ODPP) metal transfer; 2) the determination of dynamically stabled wire feed speeds for given welding conditions; 3) the effects of surface active elements (Marangoni effect) on the weld pool flow and solidified weld profile; 4) the fundamental mechanisms leading to the formation of ripples; 5) the issues associated with the beginning and the end of the welding (limited penetration and the formations of crater); 6) the deflection of arc plasma by an external magnetic field.