SIlicone Bronze MIG Welding

[Ferrino]

I'm restoring a tubular steel chassis, which was originally bronze-welded/brazed using a torch and bronze filler. I've found a seam which has cracked and I'd like to find a way to repair it at home if possible. I've found a pro who says they can TIG it with silicone bronze, but it's PITA to transport it and there are no aesthetic considerations because this joint is hidden. I have a MIG welder that I use purely with steel wire, but have seen that silicone bronze wire is available. Do you see any reason why I couldn't use it in this application, where the new silicone bronze filler will be joining an existing brazed seam? Do I need to worry about compatibility of the silicone bronze MIG wire with the bronze previously used?

My other question concerns shielding gas - is it critical to use 100% argon or can I get away with the 75/25 Argon/CO2 mix I already have?

Thank you!

 

[oldbikedavey]

Try a test piece, and see how it goes.....
Nothing ventured, nothing gained !

 

[Hood]

My EWM specifies pure Argon or 97.5% Argon 2.5%CO2 for brazing, likely your 75/25 wouldn't be the best but as @oldbikedavey says you could always give it a try.
One thing however have you seen the price of CuSi wire? If you can load a 1Kg reel maybe not too bad but if you need bigger reels then it may be cheaper to get it Tig'd.

 

[Ferrino]

Thanks! I’ve bought a 2lb roll to give it a try. What would the impact of the C25 be or what should I be looking for in the weld to indicate the gas is inappropriate?

 

[Morrisman]

Why not just Mig it with steel wire, grind flush, nobody will ever know?

 

[Ferrino]

You can’t use steel MIG wire on top of bronze (at least I can’t).