[TheForge] Welding cast iron

[Ries Niemi]

On Dec 6, 2005, at 11:04 AM, Bruce Freeman wrote:

> Okay, idea time:
>
> I've long wondered (having no practical experience in the matter AT 
> ALL) whether the problems in welding cast iron were due to the 
> graphite (carbon).  Folks sometimes say that the stuff has absorbed 
> oil or grease.  Well, castings CAN be porous, but it strikes me that 
> if grease were the problem with welding cast iron, then it would be 
> more of a problem in welding steel.  (You don't want a lot of junk on 
> steel, but you don't need perfect cleanliness - the grease will burn 
> off.)
>
> But graphite would burn off less readily, and more would be exposed as 
> you melted the mother metal.
>
> So if graphite is the problem, how can you get rid of it?
>
> So I looked up graphite on the web and found that it's soluble in 
> something * molten iron!    This suggests that a pure iron electrode 
> might be a good candidate for welding cast iron.
>
> This is all by guess and by golly.  I'd be interested if anyone has 
> ever tried it.
>
> Bruce
> NJ
Never tried a pure iron electrode- but my guess is that it wouldnt stay 
pure iron for long, and thats where your troubles would start. I have 
had good success with both nickel rod and with silicon bronze tig 
brazing with cast iron.
And I can vouch for the fact that both cast iron and cast aluminum are 
a lot harder to weld when dirty than mild steel. With almost any 
welding process, apply enough amps to steel, and the crud burns off.
But with cast iron or cast aluminum, by the time you put in enough heat 
to burn off the oil, you are looking at a puddle.
Aluminum bell housings are particularly bad.

Ries Niemi
Industrial Artist

http://www.RiesNiemi.com