argon/co2 gas

[steve_morris]

i have a bottle of coogar 5 for my MIG welder

ive now acquired a TIG set. i will only be using it for mild steel (for now at least anyway). will the coogar 5 work or will i need pure argon?

 

[shenion]

Only pure argon or Ar/He mixes will work. Any CO2 or other gasses will quickly contaminate the tungsten.

 

[steve_morris]

looks like a mate i bought it off was wrong then, so much for it only needs pure argon for ali / stainless etc

oh well, the bottle is almost empty, looks like im only using MIG until then

as for contaminating the tungsten, would it effect the strength of the weld, or more just a visual thing / re-shaping the tungsten more often?

 

[matt1978]

Weld would be full of porosity (holes)

 

[steve_morris]

how exactly does the CO2 cause porosity problems with TIG but not MIG?

 

[hotrodder]

CO2 is dissociated (by the high temps) into CO and O, which then oxidises the tungsten. This'll happen immediatly. The tungsten will then spit tiny bits of itself into the weldpool and arc stability will disappear.

You don't have a (non consumable) tungsten with MIG which changes the picture quite a bit.

 

[steve_morris]

thanks

 

[roofman]

if the bottle is from Air Products ive got a large bottle of argon ile swap with you

 

[steve_morris]

its a BOC bottle. ive called supplier and they will swap it for a pure argon. only got 10 bar left, probably take 2-3 weeks to use that