[SEL] OT quesiton about cast iron

[Steve W.]

Bill Dickerson wrote:
> Assume automotive parts here in these questions:
> 
> 
> A. Is the cast in exhaust manifolds different than the cast in, say, an
> engine block or heads?

Yes it is a different composition. Blocks have more nickel and silicon 
than manifolds.

> 
> B. If different, are they higher or lower nickel content?

Manifolds are lower nickel content than the blocks.

> 
> C. Can one gauge nickel content by "the spark test", taking a grinder to it
> and watching the pattern and color of the sparks?

Yes, BUT not without a LOT of practice.

> 
> D. Is it easier or harder to weld an exhaust manifold than an engine block
> or head?

When new they are about the same except the thinner walls on the 
manifolds make them easier to burn through, and stress cracking is 
harder to prevent.

When used Manifolds get BRITTLE and tend to shrink from the constant 
thermal cycling. Blocks tend to relax and are usually easier to weld as 
they age IF you bake them to drive out any oil/coolant.

I don't even attempt to weld some manifolds, Instead I braze them or 
replace them.

> 
> 
> Thanks.
> 
> 
> Bill
> Runnells, Iowa, USA
> 


-- 
Steve W.
Near Cooperstown, New York

Pacifism - The theory that if they'd fed
Jeffrey Dahmer enough human flesh,
he'd have become a vegan.