How to identify cast iron

[chunkolini]

I have been asked to weld the for back on a chimnea, I've not seen it yet.
How do i telle the difference between cast iron and steel?
or will cast iron take mig welding?
it is a 'ten minute' job. I had better be as that all it is getting.

 

[chunkolini]

Spark test? I remember that being the way of doing it but what am I looking for?

 

[pedrobedro]

Spark test? I remember that being the way of doing it but what am I looking for?

The sparks are dull and don't travel far if you can make any. You surely have some definite steel there you can try first then do a comparison. You can try filing it as well. it is grey compared to steel which shows bright.

 

[gordon stephenson]

Hi Chunko, Red sparks as opposed to much lighter ones for steel,You could try a stainless mig weld, Only weld about an inch at a time ,then immediately give it a good peining with a hammer And Good luck.

 

[Bill Edwards]

If the sparks are a dull red it's cast iron.

Is the piece important, or should I say is the weld important? If it's not then you can try MIG, keep it cool by only doing a bit at a time.
If it matters you need mma with cast rods (high in nickel) and again keep it cool and peen it. When I say cool, if it's a big piece of metal do an entire inch at a time! Be able to comfortably keep your hand on it.

 

[Shedendman]

I'd rather braze to be honest,as you've not seen it you dont know weather its just cracked( being a chimnea its more likely) or theres a hole in it

 

[optima21]

Ive mig welded a cast iron exhaust clamp using stainless steel wire. it worked well......when I say worked, I mean it held, but when I tightened it up again, it broke somewhere else.

not sure where I first read about this, but someone may come along and say if it should or shouldn't work.

 

[WorkshopChris]

Do you have Tig, if so hit it high and fast just to get a pool. Then try to file cast will be like putting the file to a bit of glass.

If this chimnea has failed through heat then whatever you do it will probably go again. But if it failed through impact damage then you might be OK with a repair.

 

[sardine]

It will be Chinese recycled crud cast iron, naaaasssstttyyy !