Stargon SS

[Slamglide]

This gas is from Praxair. (Argon, carbon dioxide, nitrogen) mix. There replacement for Tri-mix. Anyone have any luck with this stuff. Welding 304 or 316 s/s. Having trouble finding the set up on my machine. Using a millermatic 251.

 

[TechnicAl]

Mixes containing Nitrogen are usually for certain specific grades, such as Duplex. I dont know this gas at all so I cant really comment but if your previous mix had helium it would be very different.

 

[hotrodder]

Here's the data sheet on it Al... http://www.praxair.com/~/media/North%20America/US/Documents/Specification%20Sheets%20and%20Brochures/Gases/P8785PXStargonSSdatasheet.ashx Unless i missed it there's no mention of the composition in that link, their catalogue describes it as >90% Ar, <10% CO2 and <10% N2 so nice tight specs The graphs in the first link put it slightly ahead of Ar + 2% CO2 for welding speed and bead appearance

You want to listen to TechnicAl (and Backpurge if/when he chips in) more than me but IIRC nitrogen is closer to argon with regards to arc voltage/ionisation potentials and thermal conductivity which kinda tallies with their claims about performance. Nitrogen promotes austenite, dunno what happens when it's combined with CO2

 

[TechnicAl]

I would have thought 10% CO2 would make SS black......5% can
I dont understand this at all

unless by < they mean 2% CO2 and are trying to hide the composition

and as Hotrodder say N2 promotes austenite which could result in hot cracking

 

[hotrodder]

I think they're probably trying to hide the composition, ignore the less than and more than symbols and the blend is 110%. Maybe it's the N2 content they want to keep quiet about? They claim 'controlled CO2 content' for low oxidising potential and reduced carbon pick up and it's more than 90% Ar... does, or could, N2 have much in the way of positive effects regarding arc stabilty/wetting etc compared to Ar?

 

[chunkolini]

110% by volume?
Wow.

 

[TechnicAl]

I think they're probably trying to hide the composition, ignore the less than and more than symbols and the blend is 110%. Maybe it's the N2 content they want to keep quiet about? They claim 'controlled CO2 content' for low oxidising potential and reduced carbon pick up and it's more than 90% Ar... does, or could, N2 have much in the way of positive effects regarding arc stabilty/wetting etc compared to Ar?

The cynic in me suspects the N2 has a positive effect on their profit

N is more plentiful than Ar

but thats just me being suspicious

 

[hotrodder]

Love it, speshial maths and a fellow cynical pill addict

 

[backpurge]

Agree with comments above, I know people do it, but you really should not be welding stainless steel with a gas containing more than 2.5% CO2 if you want to achieve quality welds. With regard N2 additions, as Al says these additions are common place when welding duplex (mainly TIG applications) but again you really don't want to be adding more than 2% as you can start to get micro pores forming especially in multi run joints. Having said all that Praxair are not going to release a product that doesn't work so would be very interested to hear from anyone actually using them