It seems HobbyWeld put a bit of O2 in their MIG mix. The question was about MIG/ MAG gasses. So what effect would that have?
All the mig mixes have about 2% oxygen, it makes the pool a bit more fluid (wetting) and helps with the stability of the arc
A lot of European mixes for MAG welding carbon steel are 2 component mixes of Ar and CO2 whereas in the UK we favour a 3 component mix with 2% O2 as said above
Most MAG (Metal Active Gas, the oxygen being an active agent in the mix) gas mixes have a bit of oxygen in them. MIG (Metal Inert Gas, usually Argon, Helium and CO2) gas for stainless hasn't got any.
Most of the Ar / CO2 mixes contain 2%O2........as far as Im aware its cheaper for the manufacturers as they dont have to remove it........some do special Oxygen free...but in reality its the Oxygen thats the ACTIVE part of the MAG name....Ive always worked on 1 Oxygen = 3CO2......so the 2% is like adding 6 parts CO2 so it makes it Argon 24% CO2........In America 75/25 is the common mix...without Oxygen
CO2 is an active component, MIG uses totally inert mixtures such as Ar and He (apart from “doped” mixtures which have ppm levels of O2)
With respect Al I was always led to believe 2 parts CO2 equaled 1 part O2 but it’s all smoke and mirrors to me to be honest!!
2% of oxygen is a tiny amount but adds a fair bit of arc energy and penetration and also adds a bit of cleaning
to be honest i wouldnt argue as it depends on thermodynamics (entropy) which are energy and temperature dependent.......theres a good chance there are settings where we are both correct...same for CO2 as it relies of dissociation into CO and O2......which again is dependent on settings / temperatures etc
Al, your comments about cost are mainly correct though, some companies use industrial grade argon which has around 2% O2 in it, whereas others make a true 3 part mix which uses high purity Ar plus O2 and CO2, all depends on how they are running their air separation units
8% is a really niche mix in the UK, ESAB developed their Purus wire to run with it, then realised only Air Liquide carry it as a standard mix and even then they want £50 odd quid a bottle! shame because that wire is brilliant
