heat conduction in a red hot rod ?

I don't know if this is the right place to ask this question, but if it's not please point me to the correct group.

Back in the fifties I recall heating the end of a 20 inch long piece of 1 inch cold rolled steel bar stock in a blacksmith forge to red hot. On several occasions, instead of hammering the piece on an anvil I would plunge it into the water because someone asked me to do something else. On these occasions I noticed that the end that I was holding would seem to get much hotter faster when plunged versus when hammering on the piece. For some reason the heat traveled to the part I was holding faster when plunged versus being forged. Is there a scientific reason for what happened or has my memory deceived me? tnx

Reply to
Henry Kolesnik
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It seems possible to me that as you stick the hot steel into the quench tank, that the water right at the top gets pretty hot. Water has some heat capacity, so it will retain a bunch of that heat. Then you stick the rod much further down, and the steel right by your hand is now in a localized bath of near-boiling water. This could heat the steel right by your hand somewhat. Also, when I quench a long rod, it usually generates some steam, and the steam itself warms my hand somewhat. Perhaps the steam warming your hand gave you the impression of warmth and your brain interpreted it a little bit as your hand being warmed by the rod and not the steam, and perhaps the rod was in fact warmed some by the local hot water at the top of the quench tank. At any rate, I do not believe that the act of wetting one end will change the thermal conductivity properties of a CRS rod.

Grant Erwin Kirkland, Washington

Reply to
Grant Erwin

I'm new at this stuff here but I think that what you are mentioning might be due to the heat rising through the rod. when you hammer you are holding the rod cross ways, but when you quench you tip the rod down and allow the heat to rise through the metal. I only mention this because I have seen that orientation of my work piece has an effect on how my tempering colors run.

Live forever or die trying.

WhenTheWifeLetsMe

Reply to
WhenTheWifeLetsMe

In a solid, heat travels equally in all directions. 'Heat' only _rises_ in a fluid medium. There it's the heated portions of the medium that rise due to buoyancy caused by their lowered density. Convection.

You are heating the work in a fluid medium (air/flame) it's the heated gas on the outside of the work that is subject to convection and you are seeing the result of that in the way the colors run.

There are exceptions to the general statements I've made (water and soapstone spring to mind), but iron is not one of them.

-- Carl West snipped-for-privacy@comcast.net

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Reply to
Carl

Well, I learned something else new to me here. Not a suprise really. This is why I love reading this group. Everyone is really helpfull and most are VERY knowledgable.

Thank you for correcting my assumption

Live forever or die trying.

WhenTheWifeLetsMe

Reply to
WhenTheWifeLetsMe

Grant I agree and my mind must have been playing tricks. I thught perhaps the atomic structure had changed from BFC to BCC or something exoteric like that that was a phenomena I didn't know about. I have given and letting it rest. Thanks to all for all the opinions.

Reply to
Henry Kolesnik

Yes.

If you consider the atomic nature. A like thing for magnets. If the hot end is cooled - the heat is still in the rod, just the end is now cooler. However the electrons are vibrating like all ever - jitter bug due to a hot foot. With this agitation, the atoms near - act alike and you hand gets warm.

The hot rod is now pounded. Random jitter is no longer the case and there are distinct shock waves and barriers slow or prevent heat flow (jitter bugging with the neighbor). :-)

Magnetism is similar - the poles (atoms again) are aligned to a certain percentage based on the field and the metal it is in. If struck, the compass points spin on their axis and end up every which way.

Martin

Reply to
Martin H. Eastburn

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