Gerhard Fiedler <lists@connectionbrazil.com> wrote:
> Dave Tweed wrote:
> 
> > But what you're specifically proposing is that the elastic modulus of
> > the metal is a strong function of its temperature. I don't believe that
> > this is the case, at least not until you get close to its melting point.
> 
> I don't know that either, but I didn't (at least didn't mean to) propose
> that.
> 
> > As long as the modulus is reasonably constant, the strain will be
> > distributed monotonically throughout the metal, and all of it will
> > be in the direction of expansion, not contraction.
> 
> Expansion of each particle, yes.

Forget the particles. If you heat a hole, the material around the
circumference is going to expand, both circumferentially and radially.
Cooler material surrounding this will be subject to the radial expansion,
and since it is also elastic, will end up being compressed radially and
stretched circumferentially, to a degree that is related to the temperature
gradient.

The only way the hole can get smaller is if the material gets considerably
softer at high temperatures, or if something nonuniform occurs -- the hole
wasn't round to begin with, the edge buckles, or there's an anisotropic
component to the expansion. Any of these might apply to your blacksmiths.

-- Dave Tweed
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