Gas metal arc welding is a semi-automatic or automatic arc welding process that uses a welding gun through which a continuous and consumable wire electrode and a shielding gas is fed. A constant voltage, direct current power source is most commonly used with GMAW, but constant current systems, as well as alternating current, can be used. It was originally developed for aluminum in the 1940s, but its high welding speed has led to its use in welding steel, especially in industries such as the automobile industry. Photo credit: William M. Plate Jr., U.S. Air Force |