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Steel cooling time?


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Hi, hope this is ok for me to ask. I’m a writer, and don’t know anything about blacksmithing.

Trying to find out how long it would take to cool molten steel to room temperature? The size would be a pool of it, roughly 1/2 an inch deep, 4 feet in diameter. Nothing being used to help speed the process, simply letting it sit.

Hope you guys don’t mind helping me out!

Thank you in advanced!

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Can't give you an exact answer since it will vary with the amount of convection generated by air currents and the radiative loss from the surface.  I hope there is someone here that has worked in a iron foundry.  Do you really mean room temperature or do you mean able to be handled by machinery or experienced labor?  If I saw such an object  I would come back in an hour  and spit on it.  If it sizzled I'd walk away for another hour and pour a cup of coffee on it and watch how it evaporated when I returned.  If it hung around for a while then would start thinking about how to move it.   The center would likely be hotter than the edges btw. So no answer but my expectation would be three hour based only on working in a hot mill.


By the way the heat radiating for that much molten steel would be intense and set fire to anything with in 5 feet of it that was combustible.  Unprotected people would get first and second degree burns any where near it. 

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Put your location in your profile. Then find a blacksmithing or organization near you and attend the meetings. In one day, you will have more answers than you have questions.

To directly try to answer your question, is the molten metal in the Great White North of Canada where - 20*F can be normal, or in the tropics where 100+ degrees is room temperature and normal? Is there a breeze or air movement. What type ground is under the metal? I can not give you a time, but in cooling the metal will hear the ground under the metal, and slow the cooling process.

Edited by Glenn
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  • 2 weeks later...

 In one day, you will have more answers than you have questions.

I'm inclined to disagree with you on the order of those words.  Then again, I got hooked as soon as I saw fire and smooshed steel.  Every time I go to the shop, or here, I answer a few of the questions I've been pondering, and leave with twice as many questions that are twice as in depth.  What's more, reading books on the topic compounds the problem even further, and has me using funny, old timey words for at least a week, thanks to characters like M.T. Richardsen, J.M. Drew, and John Lord Bacon.

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Welcome aboard Conner, glad to have you. If you'll put your general location in the header you might be surprised to find out how many of the IFI gang live within visiting distance.

I didn't miss it, you're a writer but I have a sort of traditional Frosty greeting for folk. ;)

To answer your question there are a number of factors to fill us in on. A pool of molten iron 1/2" deep x 48" dia. would take several hours on a melter floor. the refractory floor, that's the high temperature resistant liner in a furnace, would be hotter than the iron and it has a degree of insulative character.

Now if it were spilled/poured/leaked/etc. on a concrete floor you wouldn't have to wait for it to cool before you could walk across the spot. The temperature of the iron would cause the water molecularly locked in the set concrete to boil out explosively. Commonly called spalling and would splash and spray still molten iron for tens of feet at a minimum where large blobs would cause that concrete to spall.

How's THAT for a cool action scene?

If it were on a dirt, sand or gravel floor the moisture in the ground would boil out pretty quickly but not likely explosively. You still wouldn't want to get within say 10-15' without protective clothing.

If it were on a refractory floor, say fire brick it wouldn't explode if it weren't wet so it'd probably solidify in about 10 minutes +/-. Cool to room temperature? What's ambient? If it's the foundry probably an hour or so. If it's the living room at say 72f, give it several hours, 3 minimum and maybe as fast as 5. Again that would depend on the floor. If it were a dry dirt floor I'd vote for closer to 5 hours +. Of course if the floor weren't pretty refractory it wouldn't cool till the building went out and the ashes cooled.

So, how about telling us what the story's about. I don't know about these other lugs but I LOVE a good story, been known to write a few. My editing sucks though.

Frosty The Lucky.


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