Hawk what gas?

[Wayne]

Hawk
I have been using Tri-Mix ( Helium Argon Carbon Dioxide ) for stainless wire. How does this compare to 98% Argon/2% Oxygen? I am wanting to set up for spray with mild steel wire and it would be nice if I could use one gas for both. Power is not a problem, I have a Deltaweld-452. At what metal thickness should I switch to .045 wire for mild steel? thanks for your help.
Wayne

[HAWK]

Wayne,

I have tried a few tri-mixes for stainless and would not turn my head for one over the 98AR/2%O2. The new "max" gases from Air Gas Mid America are nice and may have a small edge over the standard tried and true, but are expensive and availability can be an issue. You might check the SS filler manufacturer's recommendation, but I have always used 98% AR/2%O2 with the exception of testing the tri mixes. BTW: Some of the tri-mixes tend to separate and rolling the cylinders around the shop gets old fast!

I am one who tends to push the wire's limits. I think .045" filler for mild steel comes into play for stock over 1/2" thickness. I have used .035 up to 1.5" x 3" rectangular stock, but that is pushing the wire's limits to the max with out of position pulsed spray in multi-pass applications.

Given the amperage machine you have I would prefer the 92%Ar/8%CO2 for all around MIG. It will let you do short arc, globular transfer, and spray transfer with one gas. However, you still need a gas for stainless.

My only hesitation with using 98% Ar/2%O2 all the time for spray is what does the oxygen do to the filler as far as overall weld quality is concerned? I don't think it is a problem because it is primarily preheating the wire. I don't know how much oxygen is really be added to the weld if any. What do you think?

I do know I used the gas mix for spray on a lot of fabrication work for several years. The weldments were subjected to an abusive enviroment as far as impact and plain hard use are concerned. They have lasted well and still in service. I am speaking of high back hand carts constructed form 1/8" square tube and 1/4" steel plate.

[ASKANDY]

Wayne,

I believe the tri mix (HE,AR,Co2) is your best bet for short circuit SS. For spray, then go the 98%ar/2%O2. Not sure if I would go with the 92/8 for all around mig. I'm sure some people can get it to run well but I thought it gave me a higher, ropier bead with less penetration in short arc. I don't see a bunch of my distributors around here carry it as a stocking gas. Maybe that's just my area.
With the Deltaweld, you could use the high inductance setting to help wet out the puddle and that may be the difference. Anyway, I would love to hear your results if you go with the 92/8.

Good luck

Andy