Does an Argon/CO₂ shielding gas lead to increased porosity in FCAW-G?

[Jack Ryan]

I've seen it reported that using an Ar/CO₂ shielding gas mix with FCAW-G can cause more porosity. For example:

You will find most of the time just less porosity when using CO₂ with many dual-shield wires
and
The lower the CO₂ percentage in the mix, the more worm-tracks reared their ugly heads.

I can't see why that would be - any thoughts?

Note that the wire being used is classified C/M, so both 100% CO₂ and an Ar/CO₂ mix are permitted.

Thanks
Jack

 

[Brad93]

I would consult the bible: Tubular Wire Welding by David Widgery

 

[Erie Fred]

I frequent a shop that runs a central gas supply, for both solid wire and flux core with gas.
Their mixer is set IIRC 82/18 or something, everyone is happy.

 

[Jack Ryan]

I would consult the bible: Tubular Wire Welding by David Widgery

Thanks Brad. I have read that and although I might have missed something, there is no mention of a correlation between increased Argon in the mix, and increased porosity - leave alone causation.

That book is pretty old now though, so perhaps something has changed. I probably just lack imagination, but I can't think of a mechanism that would cause it.

Jack

 

[Jack Ryan]

I frequent a shop that runs a central gas supply, for both solid wire and flux core with gas.
Their mixer is set IIRC 82/18 or something, everyone is happy.

Thanks for that.

It depends on the wire but C18 is pretty argon rich for most of them and if there was going to be increased porosity, they would know by now.

Jack

 

[Brad93]

When i was at ESAB, we ordered in 80/20 or 75/25 Ar/CO2 with no oxygen added for running 15.14 among other wires.

From BOC or Air Liquide that is a specialty gas for them!

MAG shielding gases here commonly have oxygen added in small concentrations to improve wetting if I remember correctly.

 

[Jack Ryan]

When i was at ESAB, we ordered in 80/20 or 75/25 Ar/CO2 with no oxygen added for running 15.14 among other wires.

From BOC or Air Liquide that is a specialty gas for them!

MAG shielding gases here commonly have oxygen added in small concentrations to improve wetting if I remember correctly.

It's pretty much the same here, although C10 (no O₂) seems to be stocked. I mostly use BOC gas - I haven't had anything to do with Air Liquide for years (no presence) and when I did, it was Liquid Air.

C25 is about as easy to get as E6010 electrodes.

Jack