Stainless question?

[JohnV]

Ok I am looking into welding up a custom exhaust for my car out of mandrel-bent alumized tubing...well thats the easy part....my question is I would like to weld a stainless steel muffler to this piping...what kind of wire/sheilding gas do I use??...currently I am running a .30 SuperArc L56 MIG welding wire on a Lincoln SP-135t with C25 as the sheilding gas...do I need to get a roll of stainless wire and use that??...or can I get away with what I am using right now?

Thanks for any info!...this site is awesome!

[Mike Sherman]

John, fusion welding of stainless directly to aluminum out. Bimetallic transition materials are available. These are made by rolling, explosion welding, friction welding, flash welding or hot pressure welding. What this means is you will have to purchase a tubular transition that has been made by one of the above mentioned processes. I would clamp it.

[JohnV]

Mike....maybe I should have explained a little better...its steel muffler piping with a aluminized coating to resist rusting...sorry for the confusion....how would I go about welding that to a stainless muffler?

Here is an example of the piping

Thanks!

[Brew]

If your wire is solid core, I'd just use the setup you already have. It will weld fine, but you may want to coat the weld and surrounding area with some sort of rust inhibitor. The galvanize paint that Eastwood sells or equivalent would be ideal.

[Roger]

Aluminized tubing is mild steel coated with aluminum. Weld with solid wire and shielding gas. With time pinholes first form in heat affected zone (HAZ) because welding burned off aluminum coating.
You can weld stainless steel to mild steel. Stainless steel wire or steel wire would work. Exhaust system is highly corrosive environment. Welding Steel to stainless steel will cause steel to sacrifice or deteriorate faster in HAZ.

Costly all stainless steel exhaust system is much better.

[Mike Sherman]

I see, I did not quite grasp what you had in mind. I would think you need to remove the aluminized coating first, which is going to allow that surface to oxidize faster ( as previously noted ). Welding of carbon steel to stainless steel is usually done with E309 or 310 in higher heat situations. A buttering pass on the carbon steel and then a pass to fuse the stainless and the buttered pass together is the correct way. This will be difficult on tube in your situation. As mentioned if you just want to stick it together, clean the aluminized material off and weld it with your mig. Not the best solution, but will definately work. Using all stainless is a good suggestion. Or as suggested earlier, clamp it.
Please let us know how you finally proceed and how it works.

[JohnV]

Well I am considering going the all stainless route also...I did some searching here and saw a post reffering to welding stainless with a MIG setup and they said that you could do it with C25 gas if you only had to make one pass and that it may reduce the rust resistant cababilities of the stainless in the area where you welded...I hate to say this but I was trying to keep this project as cheap as possible....so buying a bottle of tri-mix for just this project would out of the budget range....so if I could get away with C25 on the stainless I think I would do the stainless...whats your opinion?

By the way with the aluminized piping I was going to paint over it with a high heat/ceramic paint to ward off rust...since its under the car the only thing that will be visible will be the muffler so painting the piping is no big deal!

Thanks for all the help guys!

[Roger]

Go ahead and paint it but the real rust protection needs to be inside of tube to extend its life. Before aluminize exhaust tube they lasted about 3 years. With aluminized tube about 5 years and stainless 10 or more. That's with 20 to 30 thousand miles a year. That is also why I don't think it matters much if SS wire is used to weld SS to mild steel in exhaust system.

Another way is to weld on flanges then bolt it togeather.

[greginfinity]

Digging up an old thread... but I am in a similar situation right now and have a stainless muffler but am not sure I want to spend the $50+ on one 180 degree bend of 3" stainless. Aluminized is about half of this so would this really be so bad? I am using a Econotig if that helps, and it is on a summer driven car only (rarely sees rain too). Thanks.