What gas for MIG on SS?

[Tee2]

I want to weld SS with my MIG and need some gas. I took a 40 tank to the local welding to get some gas. I was thinking of a Tri-mix. The guy told me that they didn't have a mix in a 40 but I could use argon. It has been a long time since I welded SS, but I thought argon was for AL. What should I look for?
Thanks

[diamondback]

Argon will work or argon 98 and CO2 2% will work as well. Both can give a good weld but the finish will be gray. Don't go over 5% CO2, the stainless codes don't allow it due to carbide precipitation.

The gas I like is a 88 argon 18 helium and 1 CO2. The finish on the weld will be the rose or straw color.

Make sure to check this information with the stainless mfg for the type. You didn't tell us if it was 304, 410 or anything else.

[Tee2]

I'll be welding SS 304 rod for a grill grate. Thanks.

[aametalmaster]

Tri Mix is the perferred text book gas. Argon will work but it won't wet out much it just lumps up with tall beads. 75/25 will work in a pinch also. If you can spring for another tank of tri mix thats prob the best way but the other 2 will work...Bob

[davedarragh]

I'll be welding SS 304 rod for a grill grate. Thanks.

You mean you'll be using "308" to join "304."

These are known as "18-8" steels.

Here's a suggestion, Blue Max FC-308L (dual shield) can be used with C-25 or 100% CO2. The wire is more expensive, but you already should have one of those 2 gases.

In your project (grill grate) one would think it would suffice.

One drawback, is, these FC SS wires are usually only available in 25/33# spools, .045 & 1/16" dia.

Dave