Welding Cast Iron

SHOOT ME. I heard it was a pain in the a, but I didn't think it was this bad (especially not being able to preheat and slow cool)

I'm using 1/8" 7018, and basically going a half an inch tops at a time, beating the slag and cleaning then letting it cool.

Starting to think I should have gotten some nickel 55.....

Anybody have any you know pointers?:doh:

Use nickle rod, preheat the whole thing and weld it all at once. Then bury it in a box full of sand to cool down overnight.

I tried that once with a 7018 before I really had any idea how to weld. Didn't work at all.

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Nickel and heat, slow cool ftw

Is this something that you can preheat in an oven or something? Theres a different method you can use if it has bearings in it or its part of something big or you can't preheat the whole thing for whatever reason, but its slow and tedious and difficult to get right.

like whats been said nickle rod and heat.

7018 rod is garbage for cast. Nickel is the meal ticket.

A bucket of rice or sand works good for cooling. Definitely preheat as much as you can.

PALCO 808 if you're dead set on stick welding it

Very best way to weld cast is with a gas torch, a good flux and cast iron rod.

Thanks for the pointers, I've been on the road for the last week and a half. It's part of the exhaust on an old massey 175, that won't budge and I really didn't feel like bustin' bolts in the manifold because its a Cast 90 that bolts to manifold for the stack. So I can preheat "sort of". Just the whole slow cooling thing, I haven't touched it since I finished it, but I'm pretty sure it's just going to crack with that 7018, plus I think I had it too hot too many times.

If you really want to weld it solid, you should really use Oxy Acetylene and a applicable filler material that would be suitable for the base metal and service applications. Pre and Post weld heating is a must but using a non arc welding process would help to keep the temperature fluxes not as severe. When you arc weld you create a highly non equilibrium state and by using the oxy/acc process you will more uniformity heat the parts up. Cooling rate is the other important side to that equation. Most of the time you can use a pure nickel rod (ERNi-Cl). The high nickel content allows for better contraction with out cracking when everything solidifies and then during subsequent post welding cooling. If the part is subject to some high stresses then the weld becomes much more critical and using a traditional arc welding process might not work.

I'll post up some pictures a little later on, been working so much here lately haven't had much time to do anything.

These old farmers bring busted stuff into my shop all the time. I always abrasive blast the two parts(if possible) then grind out a "V" as deep as possible without affecting the fit-up.
Pre heat with Oxy-Act or even propane if it isn't too large, then heli-arc with NI-99 filler rod. I usually just re-heat a few times after welding, each time heating a little less, let it air cool for about an hour.
Never had any come back and have even clamped a test piece and hit it with a big azz hammer to see how well it held. The part broke beside the weld, not in it.

Can it be brazed? If so, grind a decent V into it and grind around the V, then pre heat until there is a moderate glow, lay your brass and then throw it in the sand box so it cools slower and has a lesser chance of warping. depending on the part, some machining may be needed.

Lots of good info here. I have never had to weld cast iron. But now I have an idea how to.

How I did my turbine housing for my wastegate was simply preheat the entire part in an oven to 400 or as hot as it would get to get it pretty even and warm throughout then put the torch to it to heat it further. Got the whole housing to about 800 then slowly hot tacked the pipe to the housing (mig). Washed it out with a tig torch and slowly brought it back down with the oven then to a sand bucket for final cooling... Not the best method I know but still holding to this day

You can tig it just clean real well and use nickel rod

Any update on how this turned out?


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