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welding cast iron
BenB - 4/12/11 at 05:48 PM

Is welding pig iron well.... a pig?
I'm not suggesting I try MIGing it (despite the info on MIGwelding.co.uk I don't fancy it much). But is it possible to do it? IE if I take my broken fireplace hearth to a pro welder (of which I no doubt there are loads in North West London ) are they just going to suck their teeth? Am I right thinking oxy-acetylene is the way forward?

PSpirine - 4/12/11 at 05:57 PM

You can stick-weld it pretty well. There are special rods you can buy for it (forget the name). They're not particularly expensive - about the same as any other rods IIRC.

The trick to welding it is if possible, heat the whole thing up in an oven as hot as possible (slowly), then weld, and let it cool down slowly.

Peteff - 4/12/11 at 05:59 PM

quote:
Originally posted by BenB
Am I right thinking oxy-acetylene is the way forward?


No, you might braze it with oxy-acetylene but I don't think you'll weld it. I think the only plausible way is stick welding with high Nickel rods with lots of pre heat and a long cool down period.

madteg - 4/12/11 at 06:13 PM

Pre heat stick weld with high content nickel rods and let cool.
If you need some rods let me know as i have some left over from a job and you find them very expensive.

zilspeed - 4/12/11 at 06:25 PM

I once had a mild steel elbow 1.5mm thick welded onto a cast iron exhaust manifold. He used stick to weld it, gas torch to heat the work, what he called "dissimmilar rods" and a deft touch. Welding mostly onto the cast, dipping slightly onto the mild steel bit.

A proper blacksmith will be able to do this job for you, just like the one I used.

trextr7monkey - 4/12/11 at 06:45 PM

I had some steering arms welded up as somone had cut the ends of the eyes off and MOT man wasn't happy, local engineering shop did them as above, £20 cash

steve m - 4/12/11 at 07:47 PM

I managed to weld up a rather split VW golf exhaust manifold with an Arc welder, a good few years ago,

I cut a deep v into the gap, and just kept going back an forth with the arc rods, untill the v was filled
wasnt a pretty job, but the car passed a couple of MOT's with the repair

Steve

Wheels244 - 4/12/11 at 07:56 PM

quote:
Originally posted by madteg
Pre heat stick weld with high content nickel rods and let cool.
If you need some rods let me know as i have some left over from a job and you find them very expensive.


+1

I like welding cast iron, bit of a challenge to prevent cracking
but get a lovely weld with the high nickel (dissimilar ) rods.
Plenty of preheat with a propane torch and don't try to do long runs at once.

austin man - 4/12/11 at 08:25 PM

I welded a cast manifold to a steel backplate, has done around 2k without problems I did pre heat the manifold prior to welding and would recommend using stick the Mig didn't seem to want to get the steel hot enough. The stick really created a pool of weld

BenB - 4/12/11 at 08:33 PM

Hmmmmmm. stick welding. Never done that!
Okay, at least I know what to ask the local welders when I find them thanks for the info!

fazerruss - 4/12/11 at 08:43 PM

Ive welded numerous bits of cast iron with mig p1ss easy. eg a cast collar on my pillar drill, drum ring gear on cement mixer.

snapper - 4/12/11 at 08:46 PM

As I understand it to Dow structural weld you need to heat the cast metal very hot.
For just joining cast good braze will do

The Black Flash - 4/12/11 at 08:50 PM

I Mig'd a cast bushing on my old lathe. Stuck it in the fire until it was red hot, ran through the house and out into the garage with it , and welded it up. Still fine a couple of years later. I'd want to get a professional in for anything critical, but for odd bits, doesn't see too bad.

MikeRJ - 4/12/11 at 08:52 PM

quote:
Originally posted by trextr7monkey
I had some steering arms welded up as somone had cut the ends of the eyes off and MOT man wasn't happy, local engineering shop did them as above, £20 cash


Steering arms will be forged steel, not cast iron.