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Pure Argon or Argon/CO2/Oxygen for SS MIG

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Pure Argon or Argon/CO2/Oxygen for SS MIG

Postby icedvolvo » Wed Mar 15, 2017 11:03 pm

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

Which of these is better for stainless MIG ???

Thanks for any advice.
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Re: Pure Argon or Argon/CO2/Oxygen for SS MIG

Postby Edgewalker » Thu Mar 16, 2017 12:07 am

What do you mean by "tricky corner weld?"

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Re: Pure Argon or Argon/CO2/Oxygen for SS MIG

Postby icedvolvo » Thu Mar 16, 2017 1:44 am

Edgewalker wrote:What do you mean by "tricky corner weld?"

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Lots and lots of 10mm x 1.2mm box butted onto 6mm plate ... not hard but just painful ...
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Re: Pure Argon or Argon/CO2/Oxygen for SS MIG

Postby Edgewalker » Thu Mar 16, 2017 1:50 am

http://m.lincolnelectric.com/en-us/supp ... etail.aspx

Some good info here.

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Re: Pure Argon or Argon/CO2/Oxygen for SS MIG

Postby Edgewalker » Thu Mar 16, 2017 1:54 am

I'm guessing you want short- circuit transfer. I would have never guessed 90helium/7.5argon/2.5Co2. Never mig welded stainless myself.

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Re: Pure Argon or Argon/CO2/Oxygen for SS MIG

Postby weldin mike 27 » Thu Mar 16, 2017 3:55 am

Pure argon isn't used for anything except Aluminium. Other metals need a certain amout of active gas/ gasses to get the punch into the arc.
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Re: Pure Argon or Argon/CO2/Oxygen for SS MIG

Postby cj737 » Thu Mar 16, 2017 5:56 am

I've used 100% CO for stainless MIG personally. But, I'd probably still use TIG and 100% Ar and fuse weld that corners. One beautiful thing about stainless, its strong as can be once welded if the fit up is good. Get your heat right, large cup, and stroke!

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Re: Pure Argon or Argon/CO2/Oxygen for SS MIG

Postby Otto Nobedder » Thu Mar 16, 2017 6:57 pm

icedvolvo wrote: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 my pure Argon I use for TIG and my “SpeedShield 5/2” – Argon/CO2/Oxygen" I use for MIG.

Which of these is better for stainless MIG ???

Thanks for any advice.


Use the "speedshield" mix. Pure argon is very difficult to get a decent weld in stainless mig, even in flat position.

Yes, the ideal gasses are the helium mix mentioned above, and 98/2 Ar/O2, but your existing mix will perform far better than straight argon.

Steve S
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Re: Pure Argon or Argon/CO2/Oxygen for SS MIG

Postby icedvolvo » Thu Mar 16, 2017 7:39 pm

Otto Nobedder wrote:
icedvolvo wrote: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 my pure Argon I use for TIG and my “SpeedShield 5/2” – Argon/CO2/Oxygen" I use for MIG.

Which of these is better for stainless MIG ???

Thanks for any advice.


Use the "speedshield" mix. Pure argon is very difficult to get a decent weld in stainless mig, even in flat position.

Yes, the ideal gasses are the helium mix mentioned above, and 98/2 Ar/O2, but your existing mix will perform far better than straight argon.

Steve S


Thank u sir, that is the answer I was looking for :-) If I cant do it properly I will revert to TIG but these structures are 4m long and difficult to get into "nice" positions for TIG, so a "point and shoot any angle" MIG is my easy method
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Re: Pure Argon or Argon/CO2/Oxygen for SS MIG

Postby icedvolvo » Mon Mar 27, 2017 1:20 am

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 straight
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: small amounts of spatter after welding: was the stainless coated in something organic or was it the CO2 ???
8: not as pretty as TIG but much faster and easy for repetitive/tricky positions

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