Types of Gas Used with Gas Metal Arc Welding

Argon…

Inert Gas… Cost effective gas shield… Produces smooth quiet are at low volts… Addition of 1% to 5% of active Hydrogen

will give better penetration and faster welding speed on stainless steel…

Helium…

Inert gas… Useful in welding thick section and

metals with high thermal conductivity…

More expensive than argon Requires high flow rates (2 to 2.5)

times that of argon…

Nitrogen…

Inert at room temperature Nitrogen combines with oxygen at arc

temperatures and becomes active… Unsuitable for majority of metals… Gives good results on copper… More cost affective than argon or

helium…

Carbon Dioxide CO2

CO2 is also used in its pure form in some MIG welding processes.  However, in some applications the presence of CO2 in the shielding gas may adversely affect the mechanical properties of the weld.