so, i've been searching around for some info on shield gas for TIG on
stainless. i found a few consistent recommendations, but which one and why?
i do notice that most recommend little or no CO2.
i'm welding 16-20ga. 304 SS using 308L filler via TIG process.
98% Argon / 2% CO2
75% Argon / 25% CO2
96% Argon / 3% CO2 / 1% Hydrogen
98% Argon / 2% Oxygen
90% He / 7.5% Ar / 2.5% CO2
With austenitic stainless TIG use can use Ar/Hydrogen.
The gas is sold as such for TIG stainless, certainly here in the UK.
I know as a metallurgist who has worked on hydrogen in welds that
austenitic (Cr-Ni) stainless has properties to hydrogen far removed
from that of carbon steels by thousands of times and overall, it is
very highly immune to hydrogen cracking.
Hydrogen will intensify the arc. More penetrative I think but
certainly faster run rate. In reality you must be able to use it all
day every day for mild steel, though I've never seen mention of that.
The hydrogen will actually clean the tungsten - as it is a reducing
Any mixture with oxygen or CO2 has to be an absolute no-no for TIG -
it would oxidise away the tungsten
can you suggest a helium/argon mix for doing 16-20ga. 304-321? i would like
to keep gas costs down but at the same time if i'm gonna use helium then i
would like a mix that the welds will benefit from.
Yes, it's similar to using helium with aluminum welding. It adds more energy
to the weld, makes the stainless puddle appear a bit wetter, (flows better)
the arc starting is better, and travel speed can increase. At work we have
every weld station a bottle of argon and a bottle of 98/2 % argon/hydrogen.
Using "Y" valves I can select either bottle as my shielding gas, without
While you can get mixtures as high as 7% hydrogen, I've found over the years
that 2% works good.
I am writing this from home, that's why my "from" name is different.
can 98% argon / 2% hydrogen also be used on aluminum? i ask because i
would like to only have 1 tank for now.
anyone experience the hydrogen igniting? i ask because of my recent
issue with my torch cup acting like a blow torch for half-a-second
right after my arc starts (while using 2% lanthanated tungsten).
Ernie's 1st response to me on this is that my argon may have hydrogen
Aluminium / aluminum blowholes with hydrogen. I assume, thinking from
first principles, that that means no Ar/H2 for Al. ???
On solidification, any hydrogen in the Al melt is rejected out of
solution and blowholes the solidifying metal.
About the only metal immune to hydrogen is austenitic stainless steel.
Ar/2%H2 - flammability - surely none at all?