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MIG welding stainless???

3K views 27 replies 15 participants last post by  Fraser 
#1 ·
I have to weld some stainless to repair a friends boat lift. There is enough welding to be done that I don't want to bother someone with a TIG, and I don't own one. Before Google tells me what to do, I will ask you guys.
Is 80/20 shielding gas ok? Similar diameter wire to what I would use for mild steel? Same tips? Any precautions? This will be a structural part- any thoughts on imbrittlement? 3/16" plate to 3/16" 2x3 box tube. Thanks in advance.
 
#2 ·
I'm not an expert, however I know you need to use a different shielding gas. We just went through this a month ago. For the life of me I can't remember what it was that we bought though. Outside of that and obviously wire we didn't change anything and it worked just fine.
 
#10 ·
In non cosmetic projects, I've just used er70s-6 mild steel wire with regular shielding gas. I'm not sure if this would meet your needs in a marine application but it will permanently attach two pieces of stainless together. If I want pretty welds I Always TIG. I've used shielded stainless wire before with pretty good results but I think you have to use a different polarity than mild wire. It's been a while I'm not sure.
 
#25 · (Edited)
Stainless flux core still needs shielding gas, it just allows you to use a different mix of gas. It's sometimes called dual shielding.
IIRC solid stainless wire shouldn't be used with more than 5% co2 because the stainless grabs the carbon and that is what causes porosity. The flux core can use gas with more co2 in the mix.
 
#27 · (Edited)
We use .035 308L stainless wire at work and 98/2% gas. Run it hot and lots of wire with a good welder. I weld stainless all the time at work, shoot me a message if you have any questions.

Edit: also keep your gun feed line as straight on with the welder as possible. Stainless wire likes to "birds nest" up inside the welder. It's very sensitive wire.
 
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