This summer Im going to be making a custom 2.5" stainless steel exhaust for my car. The only problem is that Ive never welded with stainless wire before. Ive welded stainless steel using steel wire though. Ive done MIG, Stick, and Oxyfuel (cutting, welding, brazing, and machine cutting). The exhaust will be done with a Millermatic 125 mig welder and .030" wire. Im just looking for some advice with welding stainless- is it any different from mild steel? If so, what do I need to do differently? Thanks!

Also, the machine im using is 75% Argon, 25% CO2. Ive been told that I should use pure argon. Can I get away with the mix?

 

I'd recommend either pure argon or a trimix for stainless...Pure argon would be plenty for doing an exhaust.

 

What would happen if I used the 75/25 mix? I dont own the welding machine, and would have to buy a bottle of argon.

 

good info

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Sirfallsalot243 &raquo;</TD></TR><TR><TD CLASS="quote">What would happen if I used the 75/25 mix? I dont own the welding machine, and would have to buy a bottle of argon.</TD></TR></TABLE>

The metal loses some of its stainless properties.
Correct me if i'm wrong plz

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Ludster &raquo;</TD></TR><TR><TD CLASS="quote">

The metal loses some of its stainless properties.
Correct me if i'm wrong plz</TD></TR></TABLE>

Yep, i just looked it up. If I use a mix, the stainless welds will rust. Looks like im gonna have tog et a bottle of argon.

Another question- is there anything different about welding stainless, as far as the technique goes? Does the bead run the same, or do I need to do anything different than Mig welding steel?

 

Weld stainless hot (hot enough to weld it fast) And fast. Your heat effected zone will be smaller then. It welds just like mild cold rolled steel. Just have to be careful with the heat because you will cook the chromium right out of the metal. And then get sugaring and all the stupid stuff you don't wan.t

 

Right - you are going to have to move a bit quicker than you are used to with mild. Practice a while on scrap to get it down. Once you get into the groove its not too complicated, just have to get used to the pace. Start to lollygag and you will blow it out or cook it a bit.

Best of luck with your project.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jaydmcrx &raquo;</TD></TR><TR><TD CLASS="quote">Weld stainless hot (hot enough to weld it fast) And fast. Your heat effected zone will be smaller then. It welds just like mild cold rolled steel. Just have to be careful with the heat because you will cook the chromium right out of the metal. And then get sugaring and all the stupid stuff you don't wan.t</TD></TR></TABLE>

Yeah and you know...haul ***

It's not that much harder than mild steel. It's a bit cantankerous at times but not so bad that's it's like an entirely different process.

 

Thanks for all the help guys. I should have a good peice of metal to practice with once I cut off the extra for the muffler and resonator to go on. Anyone know a good place to get a bottle of argon? Should I buy a bottle, and have it filled, or rent one? The places that rent the bottles out charge $100 deposit or so, and Ive heard that you dont get that back. I can get a 20CF bottle for around $60, and have it filled for like $35. What do you suggest?

 

bump

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Sirfallsalot243 &raquo;</TD></TR><TR><TD CLASS="quote">Anyone know a good place to get a bottle of argon? Should I buy a bottle, and have it filled, or rent one?</TD></TR></TABLE>

Any decent welding supply store will have Argon. I bought a bottle because I use it for both stainless and for aluminum.

 

Whats that run?

 

you cant use the 75-25 cuz that too much c02 co2 is carbon you dont want to add carbon to a stainless joint.... if its not to hard for your to get ahold of use a tri mix gas that uses less than 5% c02 that is just enought to stablize the weld to short circut on the stainless instead of spray transfering it.....

 

if you just uses strait argon you will not be able to get into a short circuit mode.... i doubt that you want your welds being super hot while welding thiner tubing.........

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Ryan111987 &raquo;</TD></TR><TR><TD CLASS="quote">if you just uses strait argon you will not be able to get into a short circuit mode.... i doubt that you want your welds being super hot while welding thiner tubing.........</TD></TR></TABLE>

Can you further explain? Ive been told by most to use straight argon.

 

You can weld the stainless with 75/25, but it would be better with 100 argon or a stainless trimix. The trimix is a bit salty though if you are only going to make your exhaust and that is it. If you have a good welding store in your area, try and get a .030-.035 flux core stainless wire, it runs much smoother and gives you added insurance of keeping out the impurities. I personally use Addifix 942 or the 932, but it is expensive. If you are on a strict budget, use the 75/25 and 308/308L wire. If you can get the flux core that would be better because it keeps your spatter down tremendously too. What material are you using? 304?

 

This is the piping kit I am using:

http://kteller.biz/prodtype.as...y=cat

And will be using an SNL twin loop muffler (www.jdmcircle.com) Im still open for suggestions for the resonator.

If I use a fluxcore wire, I wont need gas, correct? Im all about spending a little more money if it will make better welds. That way I dont have to worry about renting a bottle.

 

You will still need a shielding gas. Many times people call it a "dual shield", because you use a gas and the flux cored wire. The Addifix wire that I use it about $30 per pound. I usually buy it in 10lb or 30lb spools. I absolutely love this wire. But, like I said earlier, your local welding supplier may be able to get you something cheaper. Lincoln, Harris-welco, Anchor, Crown Alloy, may make a flux core stainless wire.

 

So I should use a fluxcore stainless wire with straight argon gas?

 

Buy some 308 stainless wire and a bottle of argon.