[Chips O'Toole]

Now that I've managed to repair a cast iron motor casing with MIG, I have a new question which is related: can I replace missing cast iron fragments with stainless and weld them to cast iron using MIG? It seems like it should work.

Imagine this scenario: I have something made of cast iron, and a piece gets broken off. The piece can't be fixed, or it gets lost. Can I go in and "tin" the broken edge of the object with stainless MIG wire, make a stainless piece to replace the lost part, and weld the new part to the stainless I built up using MIG?

It seems like it ought to work, and if if did, I would think maybe a weld with cast iron on one side would be easier to create successfully than a weld with cast iron on both sides.

This would be a neat trick to have handy, since cast iron has a way of breaking, and the chunks that come off are not always suitable to be reattached.

[Poland308]

Depends on how much stress they will see. They will tend to break off at the weld point.

Edit. Heat stress will cause it to break free as well. SS expands at a diferent rate than cast so repeated heat cycles will also cause it to break free

[Chips O'Toole]

So if I tried it at all, best to stick to things that stay cool.

[weldin mike 27]

Find a scrap piece of cast iron and shape a piece that is what you want. You'll be in a lot better shape than with stainless. (easier to cut and grind as well.

[Tommy2069]

i would just go back with a piece of black iron. why put stainless?if you must put stainless i sugest useing 309 or 316 wire or rods. but een so if it sees any kinda of bind it's gonna crack.now we use nickel cadium rods to weld on our drill headssome of the teeth and jets are cast iron we have never had any break off after we welded them and they do see alot of stress but those rods ain't cheap.we also use them to do build up work on our water pumps after a while we get washout holes and just plain old wear out grooves i fill them in with the nickel rods and their good to go .

[Poland308]

He was using mig only. With SS wire.

[AndersK]

Not that I have tried but wouldn't silicon bronze work for this?

[Tommy2069]

He was using mig only. With SS wire.

missed that part.well i don't think it's gonna hold up much.lol

[Olivero]

I have TIG welded stainless to cast and it will hold but that's TIG, MIG I have no idea.

I always try to go parent metal to parent metal with the correct rod to join them so if you can do that, I would.

[Chips O'Toole]

A couple of days ago, I saw something interesting on a show about restoring military tanks. If I understood it correctly, they were welding cast parts back together. The tank they were working on had some very big castings. One of the guys who was doing the work said he was going to make it authentic. He said he was going to use stainless filler, just like the factory did.

He would have been talking about what? Maybe 1942? I guess cast iron and stainless filler are not a new combination.

[Chips O'Toole]

I have already been corrected. I am told cast tank turrets were tool steel, not iron.