Tri mix gas for stainless steel MIG welding.

[Blondie_486]

Hello all,

For years I've been getting by doing repair welding on stainless exhaust systems using 308L wire and an 80/20 Argon CO2 mix. It does OK for repairs to stainless systems that have been in use for awhile and for installing new weld in catalytic converters.

Now I'm wanting to do a little better than just repairing. I have a couple of customers that want stainless cat back exhaust systems and I want to do a complete stainless system on my own truck. I want to incorporate a "no clamp" design and use gasketed flanges to make all exhaust connections.

I know you're supposed to use a tri-mix gas of Helium, Argon and CO2 unless you're spray welding. I want to have better appearing beads than what I can get now. My question is in what proportions should the gasses be?

Any help will be appreciated.
Thanks

Blondie

[H80N]

Blondie
the gas mix question is one where there is HUGE controversy... here is a link to one site with a lot of info on it..
good?? .. bad??? you decide...

http://www.weldreality.com/stainlesswelddata.htm

But it is an interesting read.. and will give points to ponder..
for me... I would Tig them ........
hope this helps
Heiti

[Blondie_486]

Heiti,

I'd TIG them too but alas no TIG welder yet. I have one at work but it'd take forever to take the stuff back and forth to work while fitting it all up. I'm trying to hook up on a TIG welder but it hasn't happened yet.

Thanks again for the link for the gasses.

Blondie

[bail76]

For a short circuit transfer a tri mix gas consisting of:
90% helium
7 1/2% argon
2 1/2% carbon dioxide
This will maintian the corrosion resistance of stainlees because its a mix that is 97% inert. Hope this helps.

[Charlie]

I've always used the traditional trimix for 302/303/304/316 and the "L" stuff in this range + some other stainless stuff. I've had good luck and the stuff electropolishes beautifully. However, the thinnest work is .080" and it goes up to 3/8". Occasionally had a spatter problem. I've read the Ed Craig article before and may change just for curiosity's sake. I don't know what type of stainless you're working with nor which gauge; methinks it may be a consideration in gas selection. Charlie

[HAWK]

Blondie_486,

If you are dead set on a tri-mix, take a look at the GOLD GAS offerings from Air Gas Mid America
http://airgas.com/documents/pdf/GOLDGASBRO.PDF

I have run a lot of stainless wire with 98%argon/2%oxygen with great results in short arc. It will also spray if you crank up the voltage.

[Blondie_486]

Hawk and everyone else,

I'm not dead set on anything at this point. From the article in the link Heiti left is seems that a 98/2 Argon and CO2 mix works too. I'm sure that a two gas mix is going to be cheaper than the three gas mix. I don't even know if any of the local suppliers have the tri mix yet. The thing is though the weather will be breaking soon and it'll be warm enough to work out in the garage and need to get ready to get some of this stuff going.

I'm looking at some TIG machines and Heiti also suggested in an e-mail that if I had a DC machine I could hook up a TIG torch to it and do scratch start TIG welding. But my stick machine is shot, I let a friend borrow it and when I got it back it didn't work any more. It was a cheap machine anyway, a Century that I picked up at Tractor Supply years ago. I have my eye on a couple of machines now I'm just waiting to see what I can get them for. One is a Miller SR-150, the other is a Hobart Cyber TIG like I used to use at the boiler factory and the shipyards. I'm leaning toward the Hobart as it has AC function where the Miller is strictly a DC machine. If I had the money I'd just go buy an Econo-TIG for now since it has both AC and DC capabilities. The guy with the Hobart hasn't made his mind up on price yet because it does need some work, it needs a coolant pump which shouldn't be too expensive, a torch, flow meter and he said the SCR's are bad in it and at the moment won't do AC functions but works on DC just fine. At any rate if I can get the machine cheap enough that it's worth fixing I'll go that route and TIG weld everything but I'm not counting on it and want to have a back up plan. My backup plan is to use the MIG machine I have and use the appropriate gas for it.

If money weren't the object I'd rather TIG most everything but it is a big obstacle at the moment so I have to try to work with what I have.

So has anyone used the 98/2 Argon CO2 mix to MIG stainless and if so how did it work?

Thanks
Blondie

[HAWK]

Blondie_486,

Good luck with your warmer weather ventures! I took a quick look back over the recommended shielding gases for GMAW with stainless and did not see 98AR/2CO2 listed as an option. If H80N listed it, then I am sure it is a viable option. I think your welds may be trap some moisture and possibly be on the cold side since there is no oxygen available to preheat your wire.

[Blondie_486]

Hawk,

H80N merely posted a link to the debate over which gas to use it wasn't necessarily his recommendation or opinion. Normally I either TIG or stick weld stainless but since I'll be doing this at home I have to try to make do with what I have on hand. I was just hoping someone had used the 98/2 mix and could relate their experience with it.

However I'm also going to check the availability of the tri mix this week with my suppliers and see what they can deliver, that'll probably be a major deciding factor too. You can't get what's not available.

Thanks for your input though.

Oh by the way I have found one local source that does stock the Optrel Satelite helmet but they want 275.00 for it and Indiana Oxygen Co. has them listed on ebay for 227.00 shipping included. That's a no brainer there but will look at the one at the local supplier and let them know what I can get it for on the net and see if they'll come close to price matching.

Thanks again for the help

Blondie

[cope]

Originally posted by Blondie_486
Hawk,


Oh by the way I have found one local source that does stock the Optrel Satelite helmet but they want 275.00 for it and Indiana Oxygen Co. has them listed on ebay for 227.00 shipping included. That's a no brainer there but will look at the one at the local supplier and let them know what I can get it for on the net and see if they'll come close to price matching.

Thanks again for the help

Blondie

Blondie, I bought a Jackson NexGen from IOC last weekend. Ordered it Saturday night and it got here Thursday. Nice people and good prices.