welding farmers copper/Copper Nickel? Cupro Nickel?

By mhill018 Date 10-14-2008 23:42

We recently fabed a pressure vessle out of copper nickel and the code was strictly tig because we hadnt qualified a mig yet. we just got an order for two more vessles and would like to qualify a mig. Any suggestions as to shielding gas? We run with a couple fronius' and will be using spray. Thickness is 1/2in. We ran with argon the other day but the bead just wouldnt wet out right. I was reading on a couple of sites that you should pre heat it? & run argon/helium mix? Any advice would be greatly appreciative. If you need more info just let me know

By defaced (**)

Date 10-15-2008 15:40

I've done some Inconel 625 cladding with pulse MIG and found that a tri-mix of He-Ar-CO2 worked well, but provided too much penetration for cladding, but for a structural application, it might work. I think something like 50-75% He, 1-2% CO2, and balance Ar would get you a bead that will wet and penetrate. If you've got a gas mixer, grab a bottle of 98-2 and a 100% He bottle and see what shakes out. You don't need much CO2, it's just there to stabilize the arc, you may find that you don't need it at all. The thing about Cu-Ni is that it's sluggish and with MIG it'll won't want to wet. Let me know what you end up using, I might have a project coming up that I could use pulse MIG on Cu-Ni.

By mhill018 Date 10-15-2008 22:33

thanks for the tips man, were gonna try some heli-star we got out back. i might not be exact but i think its like 65% AR, 33%HE, 2%CO2. i'll post again to let u know how it goes