SS with a mig??
 

Hey guys well i mostly do mild steal welding i dont do much if any stainless. Well last night my buddy needed to have his down pipe shortened and rewelded. And by needed more or less just really wanted it done lol. Well anyways he tells me he has stainless wire and what not so i tell him ill give it a shot.

Comes by and the wire he brings all the lables are ripped off the spool so im not 100% sure but im guess its .035 -.040 seemed pretty thick it was silver so i assumed it was the right stuff. Do a few test passes and just threw slag everywhere. I got it down some but i was constantly fighting with the burning threw or throwing slag everywhere. Welded his dp together didnt look great but wasnt anything horrible at the same time, just a good amount to slag.

Now is this mostly because of the heavier gauge wire or just because this was more or less something that should have been done with a tig. Im still pretty new to welding but would like to learn for my self for next time.

O and im using a Lincoln 175hd.

Were you using Argon?

You need trimix to short circuit ss. You can spray it with 98/2 but it's not recommened on thin stuff like you are welding.

Try Trimix gas(every gas supplier knows what this is)
0.035 308 wire (pick a brand)

I like around 18v 160-180ipm for thin stuff.

I was using the c25 forgot to add that. But yea i figured i was missing a few steps they way things were turning out LOL.

I'm guessing that by slag, you mean "spatter"? Or soot maybe?

Thing you have to remember is, stainless has to be welded using a non-active gas, such as Argon or Helium. If you have over 2% of active gas in your gas mix, you will contaminate the stainless.

Chances are, you have a CO2, or CO2/Argon mix in your setup right now. (Or at least I hope you do!)

Post some pics, it would be helpful for advice!

Hope that helps!

Edit : typed this out before any other replies, and just came back to the PC and hit submit.

CO2 is an active gas, and with 25%, you are contaminating it.

yep that c25 will jack a stainless weld UP. I love it when people at the shop forget to change the bottle. It's only slightly less horrible than when they forget to change their wire :(

Yea i dont have any pics but every thing you guys are saying makes perfect sense to me. It was a 2am spur of the moment kinda thing lol. But i do know for next time thanks guys.

with bare wire mig on stainless you need really good quality wire. Or it will run like shit no matter what you do. It's not cheap but worth every penny.