On Thu, 15 Nov 2018 23:20:25 +0000, Fredxx wrote:

On 15/11/2018 21:35, Cursitor Doom wrote:
On Thu, 15 Nov 2018 12:45:04 +0000, John Rumm wrote:

Most wire fed gas shield welding on steel uses CO2 as a primary
shielding gas rather than pure Argon or Helium. CO2 is classed as an
"Active" rather than an "Inert" gas, hence MAG rather than MIG.

Kind of struggling here to work out what use *any* non-inert gas would be
in a welding process. The very last thing you want is oxidisation!

It's normally for arc stability. It is normal to add a small amount of
CO2 to argon as pure argon has poor arc stability. O2/argon mixes are
for stability. Though only a couple of % of O2 is needed.

For MIG welding CO2 also aids penetration so mixes for thin material only have
around 5% CO2, those for thicker material around 20%

Argon mixes with CO2, even at the 5% level are for all practical purposes
incompatible with that required for TIG processes. But you can MIG weld with
pure argon, and some claim 100% CO2 works too.

What is very clear is not all ARC welding processes are the same, even with the
same base material.

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