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  1. #1
    Join Date
    Mar 2008
    Posts
    14

    Pure Argon or Argon/CO2/O2 for Stainless MIG ??

    Hi People,
    I have a small job to do for a mate in stainless and normally would do this with TIG but its a shedload of tricky corner welds and I wanted to use MIG. It doesn't really matter what it looks like but strength is the main issue so .....

    I have pure Argon I use for TIG and “SpeedShield 5/2” – Argon/CO2/Oxygen" I use for MIG.

    Which of these is better for stainless MIG ???

    Thanks for any advice.

  2. #2
    Join Date
    Sep 2003
    Location
    Clark County, NV
    Posts
    5,258
    Funny. The supplier says to use the straight Argon for MIG stainless: https://www.speedgas.com.au/product/argon/

    BUT, you'll find most say the bead profile will be too high.

    I've done a lot of stainless, but most of it was stick. I did a very little stainless MIG a long time ago. We used the expensive tri-mix (He/Ar/CO2) and that last CO2 component is less than 3%, but supposedly helps a lot, as does the large He component.

    I have a stainless job coming into the shop soon. Fortunately with enough lead time to learn how to ride that bike again before pumping out the production. I'll experiment myself with the "wrong" gasses just to find out for myself what happens, but I plan to switch to tri-mix if I decide to MIG it.

  3. #3
    Join Date
    Mar 2009
    Posts
    267
    SpeedShield 5/2 is 93%argon, 5%co2 and 2% oxygen, well according to Google anyway. I've welded a bunch of stainless with 90%argon 10%co2 and had good results, so I'd go with the SpeedShield.
    "never argue with an idiot; he'll bring you down to his level, and win by experience"

  4. #4
    Join Date
    Mar 2008
    Posts
    14
    Quote Originally Posted by IcedVolvo View Post
    Hi People,
    I have a small job to do for a mate in stainless and normally would do this with TIG but its a shedload of tricky corner welds and I wanted to use MIG. It doesn't really matter what it looks like but strength is the main issue so .....

    I have pure Argon I use for TIG and “SpeedShield 5/2” – Argon/CO2/Oxygen" I use for MIG.

    Which of these is better for stainless MIG ???

    Thanks for any advice.
    Just wanted to post my experience with using the Ar/CO2/O2 mix with stainless:

    1: had to use higher voltage than expected
    2: wire is very stiff, so keep your gun lead as straight as possible
    3: with mild steel can clamp to the bench, but with stainless worked much better with clamp on material!
    4: could achieve spray transfer but didn't penetrate well
    5: welds were sooty on the outside but clean after brushing
    6: ok penetration, steel bent in vice with no weld failure
    7: a little easy to remove spatter after weld (did the stainless have some coating on it ????)
    7: not as pretty as TIG but much faster and easy for repetitive/tricky positions

    thanks for replies :-)

    20170327_121117.jpg

  5. #5
    Join Date
    Nov 2004
    Location
    marin co. ca.
    Posts
    2,201

    My Choice

    Tri gas all da way.

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