> > change has occurred in the area around the hole.  This why =

> I said heat =

> > the hole to 500C.  (Strength starts dropping at 220C.)
> =

> Hm... steel isn't really a "simple" material :)
> =

> Look at this:
> http://www.mace.manchester.ac.uk/project/research/structures/s
> trucfire/materialInFire/Steel/HotRolledCarbonSteel/thermalProp
> erties.htm
> =

> All throughout this discussion, we assumed a rather constant =

> thermal expansion coefficient (I think you call it COTE). But =

> according to this, around room temperature it seems to be =

> close to 0, and grows with temperature. =

> =

> There is a phase change around 700=B0C, but even before and =

> after that it doesn't behave that linearly as we assumed. =

> ("Linearly" would be a constant COTE.)
> =

> > The steel will deform, and thus the hole may get smaller.  But it =

> > won't shrink evenly, it'll collapse, and remain that way =

> once the heat =

> > is removed.
> =

> This is what I've been trying to say. The shrinking of the =

> hole -- if it happens -- would probably be a plastic effect, =

> not an elastic effect.
> =

> Gerhard


The hole doesn't shrink in that case.  It becomes a funny shape, just how
funny is a bit unpredictable.  Plastic deformation has already been
mentioned, and dismissed with "so what?".  You could heat it up even more
until it melts and closes up the hole.  Or just thump it with a hammer.

I remain unconvinced that heating up the hole causes it to contract  :)

Tony


-- =

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