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Hot iron does not attract a magnet


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No.

The molten core (molten iron) is not attracted to a magnet, but because it's moving, it creates a magnetic field.

There's a difference.

A spinning aluminum disc creates a magnetic field in response to a magnet- the disc is not attracted to the magnet at rest, but when spinning, because it's conductive, creates magnetic eddy fields that then interact with the magnet.

The core moves and flows- the reason we've had magnetic pole reversals and why "Magnetic North" changes almost daily, and doesn't really line up with the axis of rotation- and as it moves, it sets up a magnetic field.

Doc.

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I can't answer the Earth's core question but this trait is useful to blacksmiths because that is when the carbon in a piece of steel goes into solution and the closed lattice molecule opens. In other words, loss of magnetism in a piece of steel signifies transformation to austenite with a minimum of grain growth. Raising the temperature further does not make for a harder better tool/blade - on the contrary, it increases grain growth. Quenching from this temperature will convert a great deal of the austenite to martensite, which is desireable for edgeholding, hardness and strength. Tempering is then required to properly finish the item but those temps is nowhere near the non-magnetic range.

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Hot iron does not attract a magnet.

Why?

Can this be useful to a blacksmith?


This can be quite usefull when working with tool steels. This is particularly true of eutectoid steels such as simple carbon steel of ~.83 carbon. The Eutectoid temp of the steel, in all the carbon atoms are in solution, is almost exactly the non magnetic point. for this reason 1084 is a very good blade steel because it makes it very very simple to heat treat, virtually no soak time is needed at all at that temp, so once your blade hits non-magnetic, you can immeditaly quench and know that you havent allowed grain growth, and that you are at the critical temp for quenching the steel.
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after reading more about this the thread should be "Hot Steel does not attract a Magnet"


Hot iron isn't magnetic either. The carbon content has nothing to do with whether it'll become non-magnetic or not, it's strictly a matter of the molecular structure's reaction to heat.

Also, there's lots of new theories about what's actually going on in the earth's core. That it's not liquid is pretty well accepted. (right now anyway. ;) ) One school of thought has the iron core kept a solid by the pressure with a smaller core of fissionables, fissioning in the very center. This being what's keeping earth's innards hot.

Frosty
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the best I've seen is as the Steel gets hotter the molecules speed up so fast they become non-magnetic...then again if the carbon goes into solution (being stuck in the iron molecule) it is different than steel or Iron at this point when we stop this process it becomes the Austenite...Austenite is non magnetic
see this paper http://rabi.phys.virginia.edu/HTW/supplements/knives_and_steel.pdf

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