Ed Huntress wrote:

Invar, IIRC, is a special cast-iron alloy that has a near-zero coefficient
of thermal expansion. Moore Special Tool used it for the heads of their jig
grinders.

I wasn't aware that it had special hardening properties. Are you sure you
aren't thinking of its freedom from thermal expansion, in use?

No, I'm not that sure. But I know, that there do exist special steels
that do not change their sizes (or _very_ little) if hardened. They are
used for stamp and die making. Roechling has them (among others). And I
_think_ they are called invar, but have no source at hand to verify
that.

OK, I did a quick Google. Invar is not cast. But also I didn't find that
property of not changing it's size when hardened. But still it doesn't
change it's size over a big temerature range. It's mostly used for
gauges.

Anyone has a name at hand?


Nick
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