CO2 Welding is a variation of GMAW. Here the inert gas is replaced by gas mixtures or carbon dioxide, which are chemically active. The carbon dioxide decomposes in the welding arc heat and oxygen is produced. To remove this, de-oxidants are employed in the welding wire. This produces a glassy layer of slag over the weld metal, which can melt off in the subsequent passes, or it can be brushed and removed. Argon +1 to 2 % O2 is used as shielding gas for alloy steels and stainless steels. Argon +3 to 5 % O2 is used as shielding gas for carbon steels and low alloy steels. CO2 alone is enough for carbon steels. CO2 Welding is replacing shielded metal arc welding in the fabrication of structural, pipes, automobile products storage tanks and machinery, etc.