Can you weld stainless steel with CO²?

**Vova** · 03-06-2008, 20:03

My Blitz Nur Spec fifty million pounds exhaust has a little crack at the weld in the rear section where it is hanging to the chassis, anyone else had this, it has done 20k KM now.

Anyway, the exhaust is stainless steel if I'm not mistaken (anyone confirm) and I have a CO² welding device.

I figured I need some SS-wire to feed it but do I also need different gas, like when welding aluminium?

Thanks

**bainsey00** · 03-06-2008, 20:05

not 100% but i weld stainless at work and sure we can only use argon as its tig welding (tunsten inert gas)

**whvn** · 03-06-2008, 20:06

edit.

**whvn** · 03-06-2008, 20:07

You can as long as you use argon/co2 mix, I did all my custom exhaust and manifold work with a small mig at home.

**Vova** · 03-06-2008, 20:08

Ok thanks, going to do that than. How did you found in difficulty terms to weld the ultrathin exhaust with a mig/co² ? Was it really difficult?

**whvn** · 03-06-2008, 20:12

To be honest I found it easier than normal steel, probably because its usually cleaner.
Just make sure you get the right gas and wire to suit the metals you are welding and you cant go wrong.

**Vova** · 03-06-2008, 20:17

Well I was referring morely to setting up the welder as the material is so thin. And about right gas..well I have a nearly full bottle of CO² so would be a bit expensive to get a new argon bottle just for the zorst..

**alanjuggler** · 03-06-2008, 20:18

i use an argon/co2 mix for SS - as above, i found it easier than mild steel to weld

i'm sure you could try co2, after all, the weld isn't really massively structural, i don't think it'll be as good a weld as an argon contained one, but it's not going to be the end of the world..

**bainsey00** · 03-06-2008, 20:25

i stand corrected and there goes my 4year apprenticeship owt the window

**fry** · 03-06-2008, 20:36

I welded some stainless plates onto the chassis with just co2 they went on fine and will probably be the only part of the chassis left in a years time

**Vova** · 03-06-2008, 20:51

Cheers guys, gonna give it a go this week

**96dennis96** · 03-06-2008, 23:04

i´ve welded ss a couple of times now and i usually did not use ss-wire. it´s still going strong after quite some abuse...

**TallPaul** · 03-06-2008, 23:40

I was going to TIG my Nur spec exhaust, but when I finally got round to taking it off, I only had access to a MIG. I used a normal mild steel set-up, standard wire & argosheild mixed gas with no problems. It welded very easily. I figured it keeps grounding out, so it'll wear through before it rusts through!

Although the weld doesn't look too pretty in the picture, it's totally gas tight. I added lots of extra weld to it to try & let the welds catch the speed humps, not the plate.

**Woodys13** · 04-06-2008, 02:39

I would use a CO2/argon mix gas for ss. Cant you get any acces to someone or somewhere that has a tig machine? imo (ive built stainless exhausts for a living) TIG would be the best option for a good weld on stainless

and the only option i'd consider myself

**Joematose** · 04-06-2008, 15:21

Just for a stupidity reference ....

I tried extending the stainless bracket on my frontpipe using a big old Arc welder with normal rods

what a mess

but I made it work

**diamondsink** · 04-06-2008, 15:47

The gas is to expel the oxygen from the weld. Will work with C02 but as said better with the proper Argon/C02 mix.

**TallPaul** · 04-06-2008, 21:23

I thought it was to prevent Nitrogen being absorbed by the weld? But I could well be wrong. I think the general term is "prevent impurities from the atmosphere" making the weld porous.

**Vova** · 04-06-2008, 21:36

As far as I was informed, the Argon mix is to keep oxygen away.

So I went to a TIG welder I knew today for a chat and we talked about whats best. He said that TIG'ing it wouldn't be much better than Argon/MIG'ing it. He told me that a TIG weld is pure, and doesn't contain any air bubbles (unseen with eye) like Argon and "CO²" often do, it used in chemical industry allot. He told me it just looks fancy and all and thats why people sometimes think its the ultimate weld, however its not technicly stronger than a properly weleded by Argon/MIG combo.

Than I told him I have a CO² and he told me that actually, I don't have CO², its just called CO² commonly but in fact is a Argon-mix gas! ..to my surprise, as I have been thinking all this time it was just CO², I almost used it once when wanting to freeze a certain something, lol.

Anyway, we concluded that my exhaust is fine if done with my Argonmix and ss-wire feed. He said you can even use the feed you have now but it will rust so not optimal however possible.

So its off to tha shop to get sum' ss-wire and let the welding commence!

Cheers for the help everyone!

**TallPaul** · 04-06-2008, 21:44

In terms of integrity, MIG & TIG are pretty similar in strength. The only real advantage of SS TIG is corrosion resistance- MIG uses mild steel filler wire, so it'll rust unless protected. I was under the impression TIG is "purer" if using neat Argon, but it's easier to weld with an Argon/CO2 gas due to the arc being more stable.
Pretty much as you've said!

**Fil** · 04-06-2008, 21:52

Originally Posted by tallpaul

In The only real advantage of SS TIG is corrosion resistance- MIG uses mild steel filler wire, so it'll rust unless protected.

I used stainless steel filler wire when I MIG welded some stainless brackets

You can also get aluminium filler wire for MIGing alu, and of course, mild steel wire for MIGing mild steel

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