A C02 gas metal arc welding (GMAW) process in which the metal transfer occurs below the surface of the base metal, Relatively high current and voltage are necessary for this welding technique, which is used only for mild steel applications. The welding current depends on the diameter of the wire; for example, a 1.14 mm (0.045 in.) diameter mild steel wire would be run at 400 to 425 amps and 35 to 37 volts. Under such conditions, the arc force digs a crater in the base metal which acts as a crucible for molten metal during welding. See GAS METAL ARC WELDING.