Argon 5/2. Is a mix of gases (93% Argon with 5% Carbon Dioxide and 2% Oxygen). Used in Mig welding, mainly of mild steel.
In small amounts, there is evidence that the Oxygen can improve the stability of the arc and reduce the tension of the molten metal. Argon 5/2 provides arc stability, puddle control and reduces spatter compared to pure Oxygen. The improved weld quality and reduced clean up makes Argon 5/2 a preferable choice of gas for MIG welding.