The process was first applied to the welding of aluminum using inert gases for shielding the arc and
the weld pool. The term MIG (Metal Inert Gas) welding has been a popular name for the process.
However, for joining of steels, it is common to have carbon dioxide and/or oxygen present in the
shielding gas mix. These two gases are not inert. Changing the proportions of carbon dioxide and
oxygen in the shielding medium can influence the chemical composition and therefore the properties of
the weld metal. The process therefore is sometimes referred to as Metal Active Gas (MAG) welding in
Europe. In North America, a more generic description “Gas Metal Arc Welding (GMAW) has been
adopted.
The equipment arrangement for the GMAW process is shown schematically in Figure 4.8. It
comprises a power source, electrode wire feeder and control system, the welding gun and a supply of
shielding gas.