Ackattack1

iTrader: (7)

I'm thinking of making some exhaust modifications on my corvette and it will require welding of the stainless steel exhaust.

I have a millermatic 175 that has the capability of welding SS, but I'm new to welding.

What do I need.

Obviously stainless steel wire. Will my CO2/Argon mix gas work for this or do I need something else?

Also, how is welding SS? Trickier or more forgiving than mild steel. Any tips would be appreciated.

1fastWS6

iTrader: (3)

That gas will work fine, however, to get a better quality weld that won't oxidize later you'll need pure Argon gas. I built a bunch of stuff on my exhaust out of SS several years ago and now it looks slightly rusty around the weld, not bad but not like the rest of the tubing. Now that I think about it though, the OEM stainless is 409 series which will rust slightly anyway. The wire you buy will be 304/309 series which is non-metallic and won't rust. Other than that, it welds basically just like any other steel.

xfactor_pitbulls

iTrader: (16)

Yep I agree, welds up just like steel. No biggy.

Brandon

Ackattack1

iTrader: (7)

cool, thanks guys

LSxChevelle

iTrader: (4)

May have to have you show me some tricks once you're a pro...

Silver LT

If you have run a lot of regular wire, you might think about installing a new liner (and use it only for stainless). Would not want to have any of the regular wire coating contaminate the weld. A new contact tip would be a good idea too. As for wire, I use 308 (with argon gas) in my Miller 250 - a one pound spool (4" diameter) works great.

Another handy accessory, for all welding, is a felt wire cleaning pad, with wire lube. Should be available at any welding shop. The combination of the felt and the lube keeps the wire moving smoothly through the liner and cleans any junk off the wire.

xfactor_pitbulls

iTrader: (16)

Contamination between steel and SS is limited and not very hurtful in the applications he is talking about. A new liner and lube are always nice to use, but shouldnt be a necessity unless the liner is worn. If you were talking about swapping between aluminum and SS/steel it would be a different story.

Brandon

Npak

you can run a ss wire if ya want. but whos to be under ur car seeing all the welds anyways. just mild steel wire. some hobart excel arc 71 and clear coat the weld after u wire brush it. should be perfectly fine. itll all be nice if u can keep the heat down and keep a nice bead flowing. the clearcoat prevents the oxidiation.

jdustu

iTrader: (2)

it'll just rust from the inside out.....of course it'll do that anyways if you dont back purge with stainless

Silverback

Normal wire might leave a little copper dust in the liner, but nothing that will effect your weld… I like to blow the liner out with a blow gun any time I have a reason to disassemble/reload anyway.

C25 (25% CO2/75% Argon) which you’re probably using with mild steel will work OK with the stainless. The biggest thing you’ll probably see is that the stainless doesn’t wet out as well as mild steel does under the same conditions. Tri-mix will help that but it really isn’t worth it unless you’re doing a lot of it/doing food grade or similar welding.

Straight argon will NOT work.

For wire… well it depends… a lot of under car stainless ends up being 409, and something like some 409Ti wire would probably be the best, but the stuff is nearly impossible to get in smaller quantities/smaller diameters. 309/309L is the best at welding different grades together and probably the most flexible, will work for everything besides some of the more exotic higher grades that you won’t likely come across anywhere, and although it’s supposed to be much more common, it’s pretty rare for me to find it at any of the local welding shops… I don’t know why. In a pinch I usually end up grabbing some 308L, it’s not supposed to be as good at welding different grades together as the 309 (it’s pretty much designed to weld 304 together), but I haven’t had any real issues with it. It also is the right wire to weld on stuff like the typical 304 polished stainless exhaust tip…