M.I.G./M.A.G.S. Welding - Aplication Of Gases

The type of gas or gas mixtures employed in M.A.G.S. welding varies with the metal being joined. To some extent the gas is chosen to reduce costs, the inert gases being very expensive, but more often the gas is chosen for its effect on the arc characteristics, e.g. burn off rate, type of metal transfer and penetration. These important parameters play a large part in the selection of a shielding gas.

Here are some examples of shielding gases and their applications.

PURE ARGON 99.99% (Inert)
Supplied in peacock blue cylinders.

Applications:

Aluminium and its alloys
Magnesium and its alloys
Titanium and its alloys
Nickel and its alloys
Copper and its alloys
9% Nickel steels

Metal Transfer:

Spray and pulsed

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ARGON with 1-2% OXYGEN (Active)
Supplied in peacock blue cylinders with a black horizontal band around the middle, the oxygen content would also be indicated on the cylinder label.

Applications:

Stainless Steel

Metal transfer:

Dip, Spray and pulsed

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CARBON DIOXIDE (Co2) (Active)
This gas is supplied in liquid form in black cylinders, with a white vertical stripe indicating the siphon tube inside the cylinder. The oxygen content is high and this results in fierce arc charachteristics as the oxygen is burnt up and the arc voltage increases. This gas is rarely used today as it has been superseded by gas mixtures such as argon Co2 which combine the advantages of both gases.

Applications:

Low carbon steels
Low alloy steels

Metal transfer:

Dip and spray

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