View Full Version : Silver solder cast iron?

Michael Az
03-27-2004, 06:45 PM
I need to attach a small square of steel to a small piece of cast iron and need to know if silver solder will work. I've never tried welding cast iron and only have a mig anyway.
Thanks for the help!

03-27-2004, 07:20 PM
My one attempt at it, years ago, wasn't terribly successful, but I think it's possible. For some reason I have the idea that there's a different flux...but I may be making that up.

G.A. Ewen
03-27-2004, 08:11 PM
I'm not sure that you can get cast iron clean enough for silver solder. 99% nickel electrode and a stick welder will do the job in most cases.

03-27-2004, 08:35 PM
micheal, you have to grind the surface of the cast iron to be silver brazed with a coarse wheel so you leave grooves, then wire brush it and then clean it with something like crc lectromotive, then coat with flux and heat till flux melts, wire brush again, reflux and tin with silver, have the steel piece fluxed ahead of time and place on Cast iron and heat till they bond.


[This message has been edited by irnsrgn (edited 03-27-2004).]

Forrest Addy
03-27-2004, 09:14 PM
My exterience has leac me to fine bead blasting the cast iron to remove the surface carbon.

The flux attacks the cast iorn surface without producing the heavy black discoloration and silver wets it immediately on contact at temperature.

Michael Az
03-27-2004, 10:43 PM
Thanks everybody for the replys. Sounds like the job could be a little touchy so maybe I should just braze them together. I'm not up to snuff on this though, could I heat one of the pieces and layer it with braze, then place the other piece on it and then bring them up to temp?
Thanks again

03-28-2004, 12:19 AM
Brazing of cast iron is common practice; the keys to that are clean materials, plenty of flux and enough heat. Hard to judge how much heating power you need without seeing the parts. Arc welding of steel to cast iron with is easy to do if you use the right rod material which is high nickel. I imagine you can get MIG wire that works but it might not be worth the cost of a roll if you are only doing one small part.

03-28-2004, 12:20 AM
I wonder if you can attach the steel with screws and skip the welding.

03-28-2004, 01:28 AM
If you try welding cast iron preheat to at least 250 degrees to avoid cracking problems. Use a tiger torch or the oven.

Michael Az
03-28-2004, 11:54 AM
Cass, I might very well do that, use screws and forget the welding, solderiing.
Evan, thanks for the remind about preheating cast iron.