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welding stainless with flux core mild steel wire???

34K views 17 replies 11 participants last post by  yazafoo 
#1 ·
hey guys, I'm a little green when it comes to welding. I have a lincoln pro core 100 amp wire feed. I have all of the parts to convert it to use gas, but the bottles are a little out of my price range right now. anyhow, my buddy has a buell with an aftermarket stainless exhaust. the rear pipe cracked and he wants to have it welded. what will happen if i use mild steel flux cored wire to repair it. I have been told that it could be very messy, and i know the weld will rust, but I want to know if it will hold. Although I've only been welding about a year, my welds are very nice so this is not one of my concerns. I'm confident that if it can be done, i can do it. I just want to be sure that i'd actually be helping the situation, rather than completely ruining his exhaust. Thanks in advance for the help.
 
#5 ·
'zactly.. tig welded with the ends capped and the inert gas piped into it... so the weld is covered from both sides with gas.

your filler rod has to match what the base metal is.. so stainless base = stainless filler.
 
#6 ·
thanks for the fast reply guys. i had a feeling it wouldn't work. if i bought stainless wire and a bottle, then could i use my mig?? what is the best gas mixture for welding a variety of metals? Do you need different gas for each of is there a mixture that covers a broad range of metals?
 
#8 · (Edited)
it's the headpipe about 6-8" down from where it attaches to the head. the crack is 2-3" and partially on a bend. maybe someone crafty could fabricate an external patch to cover the crack. then you could get to everything and make sure it's clean before welding. also, i'm not suggesting i would invest in the stainless wire and gas just to do a friend a favor. I'm just curious about what the correct way to do this is, and what some suitable alternatives may be. just lookin' for info to put in my memory bank.
 
#10 ·
Even though ugly I would opt for the patch. That's what first came into my mind also. Having the extra metal there act as a heat sink could help keep you from burning through and crystalizing the back side of the weld. Weld the patch on the vertical edges only and drill a hole at each end of the crack. Then a mig might be doable and actually have strength.
 
#13 ·
If you use gas for stainless use a 75/25 mix or stright argon. If the material is thin, keep a eye on your heat. once you burn through it wont stop. You could also put a little patch over the crack and weld around it. That would save it from re-cracking.
 
#14 ·
Whoever said cleaning the inside of the pipe is key has a real good pt. Carbon content has everything to do with steel and I have no idea how your welds would react to sipping on the carbon dust cocktail on the inside of those pipes. Clean it, research it and acquire the proper equipment and filler metals.
 
#16 ·
thanks for all the info. i don't think i'll be doing this repair. as much as i would like to help a friend, i think it would be better off in the hands of someone with more experience. thanks for all your help concrete guy.
 
#17 ·
I work for a welding supply company. You can mig weld stainless with good results as long as the weld joint is CLEAN and you use a stainless wire with the right shielding gas. A 75/25 argon/c02 or straight Argon gas will produce a weak weld joint. An A1025 shielding gas is your best bet. It's a tri-mix of Helium, Argon, CO2. For thin walled exhaust pipe I would use a maximum wire diam. of .023 and watch how much heat is burned into the piece as this will burn off the Helium and cause your weld to rust. I'm by no means a welding expert, but that's what I've done plenty of times in the past with great results.
 
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