MIG Welding 304 SS
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  1. #1
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    MIG Welding 304 SS

    I want to fabricate my own intercooler piping out of 304 SS, 16 gauge 2.5" piping. It would be a lot cheaper and much better fitting that buying an aluminum kit specifically for my car.

    My welding machine is a multiprocess, so I can TIG weld (I have a couple of torches) but I would need to get a new gas bottle along with filler rod, new tungsten, etc. Plus I don't have that much experience with TIG, I have a lot of experience with MIG so I'm for sure that I can make a much nicer looking weld with MIG.

    I have a bottle of C25 gas that I can use, would this suffice if I get 308L wire? I plan on polishing the whole thing afterwards so I'm not too worried about the look of the weld, as long as it won't be porous or anything. Would C25 be sufficient? And would .030" 308L be okay?

    Tweco Fabricator 181i

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  2. #2
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    Re: MIG Welding 304 SS

    1st person on WeldingWeb to have a scrolling signature!

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  3. #3
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    Re: MIG Welding 304 SS

    The last two paragraphs of this Lincoln article cover shielding gas questions.

    https://www.lincolnelectric.com/en-u...t-welders.aspx
    Dave J.

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  4. #4
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    Re: MIG Welding 304 SS

    Buy a rol of blue demon flux core SS and you could try both migging and tigging the tig torch with whatever gas....just for shiitzNgiggles.
    I've run maybe 3 lbs of the MIG on my 211. It lays down about like an electrode but is better on thin than an electrode !

  5. #5
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    Re: MIG Welding 304 SS

    Quote Originally Posted by Bonzoo View Post
    Buy a rol of blue demon flux core SS and you could try both migging and tigging the tig torch with whatever gas....just for shiitzNgiggles.
    I've run maybe 3 lbs of the MIG on my 211. It lays down about like an electrode but is better on thin than an electrode !

    Does it produce a lot of slag like regular flux core? I've used flux core a LOT on thin material, but I've never used it for stainless.

    Tweco Fabricator 181i

    "Always remember to be unique. Just like everyone else."

  6. #6
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    Re: MIG Welding 304 SS

    to give you a clear answer, Yes you can use MIG on 304 stainless no worries, but there are a few things to consider.

    First is that if you want your piping job to last you will need to back purge it, which will mean buying at least a small bottle of argon anyway, if you don't back purge it at all the inside of the tubing will oxidise heavily creating a large amount of chromium oxide, which is desirable on the surface of the steel, the chrome oxide is what makes stainless corrosion resistant, but it's only useful as a very thin surface layer, no back purge will turn most of the chrome in the stainless into chrome oxide, the result will firstly be much shallower penetration which will weaken your welds from the get go, but the oxidation will also make what's left of the welds very hard and brittle, so they will crack with prolonged vibration, such as anything connected to an engine and the weld will lose it's corrosion resistance as well, so it will rust.

    The other consideration is that you can't use C25 for stainless if you want to weld to remain as stainless steel, the carbon in the CO2 will bind with the Chromium to form chromium carbides, since the chromium is locked up in a chemical bond with the carbon which is inert it's not available to form a chemical bond with oxygen to form a chromium oxide layer on the surface, and so it will again rust, and the carbide crystals and make the metal more brittle as well, you'll know if this has happened because a magnet will stick to the weld, where as 304 is normally not magnetic at all, you want no more then 5% CO2 in your shielding gas for MIG stainless, you don't want to use pure argon either as a small amount of CO2 or oxygen is needed for good arc starting and stability, a cheap mix I like for light stainless is 97% argon 2% CO2 and 1% O2 (oxygen), but the "ideal" mix (IMO) is 90% helium, 7.5% argon, 2.5% O2, that mix is way overkill for what you're doing though.

    Interesting fact, even when TIG welding stainless, if you weld get's to hot the carbon in the steel can be consumed in the production of chrome-carbide as well, when the WPS and interpass temps havn't been followed on some of the pipe jobs i've worked on I've seen 304 stainless become magnetic and lose they're corrosion resistance simply from allowing the weld to get to hot.

    So short answer, if you MIG weld it, you need a different bottle of shielding back plus a bottle of argon for back purging.

    now, IF you want to use your C25 one option is to buy a small spool of DUEL SHIELD flux core wire, no it doesn't produce thick slag, but it's also fairly difficult to weld thin stuff with, the advange being no need to back purge as if it does melt through the slag will protect the back of the weld from oxygen, but as I said its easy to burn through with, but its also quite expensive.

    I'm sure you can find it in smaller spools somewhere, but an example https://weldingmart.com/lincoln-ultr...-4-e316lt0-1-4
    Last edited by ttoks; 08-04-2018 at 07:03 PM.

  7. #7
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    Re: MIG Welding 304 SS

    Quote Originally Posted by NotTheBest View Post
    Does it produce a lot of slag like regular flux core? I've used flux core a LOT on thin material, but I've never used it for stainless.
    Nooo . Nothink like I get when I mess with it with Hobart or Lincolns mild steel wire.
    Lemme look in my bookmarks for a vid real quick.

    OK this guy is flux with a strange CO2 mix Heavier metal


    Here the stuff I run once in a while for grill grates and brewery tanks. I use about 1/2-5/8 stickout. I think thats where his "ball is coming from ?" Get a can of anti spatter sprey
    Last edited by Bonzoo; 08-04-2018 at 07:20 PM.

  8. #8
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    Re: MIG Welding 304 SS

    Quote Originally Posted by NotTheBest View Post
    I want to fabricate my own intercooler piping out of 304 SS, 16 gauge 2.5" piping. It would be a lot cheaper and much better fitting that buying an aluminum kit specifically for my car.

    My welding machine is a multiprocess, so I can TIG weld (I have a couple of torches) but I would need to get a new gas bottle along with filler rod, new tungsten, etc. Plus I don't have that much experience with TIG, I have a lot of experience with MIG so I'm for sure that I can make a much nicer looking weld with MIG.

    I have a bottle of C25 gas that I can use, would this suffice if I get 308L wire? I plan on polishing the whole thing afterwards so I'm not too worried about the look of the weld, as long as it won't be porous or anything. Would C25 be sufficient? And would .030" 308L be okay?
    Backing up a step - I might not be totally following what you mean but Intercooler Piping to me means you are looking for heat transfer. SS has very poor conductivity, especially relative to aluminum, so you may want to reconsider your materials. Others have answered the questions on actually doing this much better than I could...
    -Dave
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  9. #9
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    Re: MIG Welding 304 SS

    Quote Originally Posted by davec View Post
    Backing up a step - I might not be totally following what you mean but Intercooler Piping to me means you are looking for heat transfer. SS has very poor conductivity, especially relative to aluminum, so you may want to reconsider your materials. Others have answered the questions on actually doing this much better than I could...
    I am almost certain he is talking about the pipework going from the turbo compressor outlet to the aluminium intercooler inlet, and from the intercooler outlet to the throttle body, stainless is 100% fine in terms of heat transfer in that situation, maybe he might lose 1% or maybe half a percent intake charge cooling efficiency as the piping isn't contributing as much to the cooling as if it was aluminium piping, but I highly doubt it will even be noticed, the purpose of the pipe is to get to air into the cooler and then into the throttle body, not to actually dissipate heat.
    Last edited by ttoks; 08-04-2018 at 08:06 PM.

  10. #10
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    Re: MIG Welding 304 SS

    When using dual shield fluxcore for this you have to make sure that all the slag is removed from inside. You wouldn't want pieces of slag getting sucked into your engine or blocking the IC. The good thing is that stainless slag usually pings of by itself, but there are always little pieces clinging on for dear life.
    If there are a lot of bends in the final product it might be a bit difficult to make sure that every little bit is removed.

    Eric
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  11. #11
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    Re: MIG Welding 304 SS

    Quote Originally Posted by E T View Post
    When using dual shield fluxcore for this you have to make sure that all the slag is removed from inside. You wouldn't want pieces of slag getting sucked into your engine or blocking the IC. The good thing is that stainless slag usually pings of by itself, but there are always little pieces clinging on for dear life.
    If there are a lot of bends in the final product it might be a bit difficult to make sure that every little bit is removed.

    Eric
    I see. I shouldn't have too many bends, most of them come in the kit already. But for some tighter bends I might need to do pie cuts. But I'll be sure to clean them very well before welding on the next section of the pie cut.

    Tweco Fabricator 181i

    "Always remember to be unique. Just like everyone else."

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