Welding stainless with straight CO2

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I need to do some MIG on stainless, but can't afford to pick up another bottle right now. If I'm running straight CO2, am I better off using ER70S6 or 308L? I can pick up a 2lb spool of 308L for $20, and if it will be any more corrosion resistant when running CO2 vs standard MIG wire I'll do it, but if there's no advantage I'll just run the 70S6. So, anyone try 308L with CO2?Lincoln 175HD
Reply:You shouldn't weld your stainless with 100% CO2.  you'll ruin the corrosion resistance of the weld, regardless of which filler metal you use.  If you don't care about the corrosion resistance, then ER70S6 will work just as well.  Assuming you're welding 304 stainless steel, when I say this.  That said, you do have some risk of cracking depending on how much dilution you get with the stainless base metal when you use mild steel filler.If you can't won't get the proper shielding gas, see if you can borrow some stainless flux cored wire from someone.  Some of the some of the stainless fluxcored wires can be run with 100% CO2; I think.Or better yet, buy some appropriate stick rod, and use that instead of the wrong filler and shielding gas.Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:We recently qualified a wps at work that uses 100% Co2 with stainless fluxcore. The inside of a boiler could care less if it's all shiny and purity.
Reply:Originally Posted by Showdog75We recently qualified a wps at work that uses 100% Co2 with stainless fluxcore. The inside of a boiler could care less if it's all shiny and purity.
Reply:I could probably go for a bottle of C25 but I just don't do enough stainless to be worth buying a bottle for that. Would that do any better?Or maybe I'll take the time to TIG it, I'd been hoping I wouldn't have to spend that much time.Lincoln 175HD
Reply:You need trimix, not C25 for stainless mig.  Pure Argon for SS Tig.TA Arcmaster 300CM3XMT 304S22P12 suitcase feederX-Treme 12VSOptima pulserTA161SMaxstar 150STLHypertherm PM45OP setupStihl 020AVP, 039, 066 Magnum
Reply:MIght as well use a wire coat hanger, complete with the paint/varnish still on it, as filler if you are thinking of using straight CO2 with solid wire filler.Do it right or don't bother.If the part is made of stainless and you actually want it to remain stainless, then that means using stainless filler and the appropriate shielding gas.  For short-circuit transfer mode GMAW, that usually means using tri-mix.  For spray mode GMAW, that may be some 98-2 argon-oxygen.Or just use GTAW with 100% argon.  The best laid schemes ... Gang oft agley ...
Reply:Any thing above 5percent co2 with mig with make the weld brittle found out when I grabbed wrong bottle for pulsing 316l one day