The most common protective gas is Argon(Ar), but mixes of argon and helium(He) is also used.
When welding stainless steel its often difficult to avoid incomplete penetration when using pure Argon. So by using a small percent of oxygen you overcome this disadvantage and stabilize the arc.
Helium mixes with argon gives you a hotter weld and are because of this used for thicker and heat avoiding materials such as copper and aluminium. When welding aluminium in normal thickness you usually use pure argon.
MAG-welding (Metal Active Gas) is metal arc welding with active protective gas for unalloyed and low alloyed steel.
Argon with a mix of carbon dioxide(Co2 2-25%) is the most common protective gas, also called “mixed-gas”. If you want high productivity you use a lower % of Co2 and for thicker materials you use a higher %.
Welding positions: Short arc; all positions. Spray arc; horizontal.
The equipment is the same for MIG-welding as for MAG-welding
