Hey guys, my welder is set up with ER70S-6 wire (Lincoln's L56), and an argon/co2 mix. Could I use this regular wire and gas to weld stainless steel exhaust tips to my tailpipes? I know I should be using stainless wire- but isn't that just for the best & strongest weld? I won't need "ultimate" strength out of the weld, just enough to keep the pipes from falling off. I really don't want to buy another bottle just to hold argon with. Thanks!

I'm fairly sure you can just use silver solder and an acetylene torch, and it would even look pretty good. Heat until the steel portion's good and cherry hot, and then touch the solder to the top of the pipe and it should run down around the whole seam on its own.

If you're set on welding it, I'm not 100% sure. I know the alloys are compatible, but whether you can weld stainless with regular wire is not something I'm 100% certain on. In theory I think you could do it for just an exhaust pipe, I think the strength issue comes into play because stainless can absorb a bit more heat than steel, but I don't have my book handy to look it up for you.

Mathius

it wouldn't be the right way to do it but you can stick it together with steel wire with carbon and stainless base metal. the gas isn't the right mix either for stainless welding but again what you're doing doesn't really matter. what you'd want to do if you were wemding any two disimaler metals that were compatable is to match the filler metal to the higher alloy. that is for stainless to carbon you'd use stainless filler. say for copper to steel you'd use something like ENiCu. tom if you're wondering i am a certified welder, ASME, AWS, and Mil-Spec as well as a dumbass.

I did it with an old crappy Craftsman welder. I welded 1/4" stainless to 1" sq. tube with flux core wire. I had to go real slow, but it worked, and still holds up well today.

You can weld mild steel and stainless together as easy if not easier with regular steel wire but... Even though its stainless you will eventually get dissimilar metal corosion and the stainless will corode. The strange thing is that the higher the purity of the stainless the more likely this will occur rapidly. As a confidence booster I welded some 3" mandrel bent 316 stainless onto my y-pipe with l-56 Lincoln wire ( normal stuff ) where in necked down to 2 1/2" right before the cat last spring and after a whole summer on it it looks to be holding up as well as any other weld on the exhaust.

Thanks for the scoop on the heat, Mathius. I don't have oxy/acet, just MIG... think I'd have to crank up the MIG and keep the puddle primarily on the stainless?

LOL, ede! I'm going to have to buy each one of those certifications of yours a beer if there's ever a national TGO gathering- then again... I owe a LOT of people beer... I'll probably be trailering a Keg. What's the right mix for stainless? Isn't it 100% argon? I wonder how much a small 20 cu/ft bottle costs... the only deal is that I really wouldn't be welding stainless at all... don't know if I can justify the cost of wire, a new gun liner, and a small bottle for a "possible" one-time-only weld job.

Johnsjj2, I wonder if flux core would be my best bet. It'd certainly be a hotter spark then the regular GMAW... which might compensate for that heat-absorbtion that Mathius talked about.

87roc, that works for s/s and carbon steel, too? Damn, I thought it was just for aluminum and steel. Glad to hear you welded the exhaust with L56 and it's still holding up; do you know what gas mix you used? Did you do anything special for the weld itself?

well tom lucky for you i don't drink. diet pepsi will work for me, and i own stock in pepsi. you won't ever get GMAW (mig) stainless to look very good even with a sound weld. as for gas argon will work as will a few mixed gases. for what you're doing don't worry about the gas it doesn'treally matter. if it really mattered you wouldn't want CO2 or c25 because of the carbon atoms in it. when stainless is welded you get what is called carbide precipation, basically carbon migrates to the weld or weld area. causes a lot of problems depending on the enviroment it's in. again for you it doesn't matter.

Used C25 and it worked okay. The "proper" gas to use is a matter of opinion round these parts. Straight argon or argon with 2 or 3% oxygen is what some very talented guys I know use for stainless.... aluminum and steel eh?

How hard is it to get that last cert?

What kind of problems? Like with brittleness?

Please excuse my ignorance on the subject too, I haven't even ever welded before. Just gotta find the time with my dad to learn. So for now I'm trying to learn what I can on my own

dumbass is sort of a life time achievement award

as for carbide precipitaion it'll cause corosion since all the corosive elements get bunched up in one place. if you're ever see stainless pipe in chemical service it's common to see the HAZ (heat effect zone, the area next to the weld) with gross errosion or metal lose because of a change in the metallurgical composition of the pipe, weld, and HAZ. for most practical applications here you can weld something and never look back, as long as sound welding pratices are followed and correct filler metal used.