Gas metal arc welding (GMAW), or Metal Inert Gas (MIG) welding was first patented in the USA in 1949 for welding aluminum. The arc and weld pool formed using a bare wire electrode was protected by helium gas, readily available at that time. CO² & argon CO² mixtures are known as metal active gas (MAG) processes. MIG is an attractive alternative to MMA, offering high deposition rates and high productivity.