Cannot use straight argon for 403l Stainless?

Apr 22, 2005 2 Replies

Hello,



I was told by someone at Lincoln that I shouldn't use 100% Argon for 304L stainless. Is this absolutely correct or can I get away with it and at what cost?



I will be welding 1.5" schedule 40 SS pipe turbo exhaust. Yes, I am aware that better suited SS is available.



Also, just how mandatory is it to purge the pipe? It is not like I will be delivering milk through it.


Sounds like somebody got into the happy pills.

OK is this MIG or TIG. For TIG Pure argon is standard for all SS welds. You can use a Helium/Argon mix, but it is only "required" if doing heavy aluminum, dirty aluminum or heavy copper. The helium boost the heat in TIG.

For MIG, C25 (Argon 75%, CO2 25%) works OK, but you will get better results using a helium/argon/CO2 or oxygen/argon/CO2 tri-mix.

304L will work. 321 and 347 are far better.

By purging the pipe you prevent the oxidation of the interior surface while welding. If you don't purge then the welds will disintegrate from the inside. Rapidly!!!

Thanks a lot.! It is a TIG and believe it or not, it was a tech support from Lincoln who told me that I have to use Trimix or Argon / Oxygen mix.

I will purge.

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