Mig welding wire can be aluminum welding wire, stainless steel welding wire or other alloy wire specially for mig welding processes. Solid wire MIG welding: Metal inert gas (MIG) welding was first patented in the USA in 1949 for welding aluminium. The arc and weld pool formed using a bare wire electrode was protected by helium gas, readily available at that time. From about 1952 the process became popular in the UK for welding aluminium using argon as the shielding gas, and for carbon steels using CO 2 . CO 2 and argon-CO 2 mixtures are known as metal active gas (MAG) processes. MIG is an attractive alternative to MMA, offering high deposition rates and high productivity.