1. file_not_found

    file_not_found New Member

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    Effects of lower internal temps on materials?

    Discussion in 'Research' started by file_not_found, Jan 16, 2018.

    Context isn't really important, but, just the title - I'd like to know what happens, say, if a block of steel's internal temperature is lowered to -100 degrees F. Or any material.

    It's easy to research extreme heat, for the most part, but not cold. You can't freeze something twice, but the properties of a solid still change as they get lower and lower. I just don't know what all exactly that entails for different materials. I'd love a chart or some kind of quick reference but everything I've found has been really dense and I'm having trouble. I just know that in general, things get more brittle? Uh...right?

    I'm not looking for a specific material, but rather a general idea. What happens to wood, brick, steel, or anything generic you can think of.

    And some oddball stuff. Could you freeze a human? Like actually turn someone into ice? I'm guessing you could because we're mostly water.

    Or, say you had a perfectly normal cityscape. If I dropped a block of some material that internally was -400F, how would that affect the surrounding air and area? How far do the effects go? Same for heat.

    I guess I don't have a specific question, but I hope I've given a good idea. Thank you for the help!
     
  2. file_not_found

    file_not_found New Member

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    Also, what are the negative effects of a person's internal temperature changing too rapidly - besides the temperature itself? Like if I raised an extremely hypothermic person's body temp to a normal 98F.
     
  3. OB1

    OB1 Senior Member

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    Thermal Shock I think? But as a first aider, you are trained to get the hypothermic temperature up as quickly as possible, otherwise the body will start to shutdown. I think it was explained to me thus; the blood goes to the vital organs for self preservation.


    It depends on the material, metal will certainly become brittle and if some sort of impact occurs it would shatter.
    Wood if you freeze doesn't actually change much in terms of its material properties I think, probably down to the anisotropy of the fibres. I am unsure about human tissue. Like you say we are mostly water. But I'd imagine that our cells and therefore tissue would become brittle and hence the body as a whole would be brittle.
     
  4. Kenosha Kid

    Kenosha Kid Active Member

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    The properties of materials, other than the obvious: temperature, don't change gradually as they get colder, but instead undergo what are called phase transitions. Different properties have different thresholds. Superconductivity for instance occurs in different materials at different temperatures or not at all. Significantly above those temperatures, or below them, they do not get more or less superconducting. It's only close to the threshold that interesting things happens.

    The temperature of a solid is the sum total of all of the modes if vibration (phonons) occurring within that solid, so cooling something down is like sucking the vibration out of a guitar string. So trivially what happens to steel as it cools is that it's internal vibrations are dampened.

    I don't know much about steel, but I know that at least some types will undergo a magnetic phase transition at certain temperature thresholds, suddenly affecting the elasticity of the material. You could have a look in that sort of area.
     
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  5. newjerseyrunner

    newjerseyrunner Contributor Contributor

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    Phase transitions for most materials happen close to absolute zero.

    As things cool, they shrink, so short answer for most rigid things that you mentioned is: it'll crack. If you heat an object in a non-uniform way, parts expand faster than other parts and put a lot of shear pressure on it. If you heat a cast iron pot up in the oven, then immediately run cold water over part of it, it will crack.

    This in true for most materials other than water. As objects with water in them freeze, water actually increases in size as it freezes, which causes great outwards pressure. Wood, if frozen quickly enough, will splinter, and humans would crack. In order to maintain in tact, an object with a lot of wood in it would need to be cooled gradually so that internal and external temperatures are the same. For example, if you dunked a body in liquid nitrogen, the outside would freeze very quickly, but the inside would remain warm for a while, so you'd create a tough outer shell. Once the inside also freezes, it'll put a lot of pressure on that shell and probably crack it.

    In terms of dropping cold objects in a city, how large of a cold object are you talking? Chefs use gallons of liquid nitrogen sometimes, which is in the negative hundreds.
     
  6. Kenosha Kid

    Kenosha Kid Active Member

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    There are almost countless phase transitions that occur far from zero, melting, evaporation, sublimation and ionization being the four obvious ones. Ferromagnetism will disappear at higher than room temperature for ferromagnetic materials. Metamorphic rock is due to crystallographic phase transitions at extremely high temperatures. Anything that conducts electricity will cease to do so at sufficiently high temperatures. For most stuff heavier than helium, most phase transitions occur well above 0K.
     
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  7. Iain Aschendale

    Iain Aschendale Potatoes again? Supporter Contributor

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    Look into cryogenic hardening, or cryo-treating, which was all the rage in the gun and blade community ten or fifteen years ago, it does interesting things to metal.
     
  8. JLT

    JLT Contributor Contributor

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    You might recall the investigation into the explosion of the space shuttle Challenger a few years back. The cause turned out to be an O-ring which, when exposed to freezing temperatures, became brittle and fragmented.

    But, as others have pointed out, it depends on the material. It might help to research the manufacturer's web site for the sort of information they have to file with the government on the tests that have been performed on a specific substance, or an engineering reference. Good luck!
     
  9. Cave Troll

    Cave Troll It's Coffee O'clock everywhere. Contributor

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    Well water expands when frozen, so all the cells would explode in a sense
    (At least most of them would). Your skin would probably crack and become
    brittle, and your organs would be as if shot by billions of tiny needles.
    So nothing good will come from freezing a person, since pretty much
    the only things that would 'survive' would be muscle, bone, and few other
    tissue types that don't rely heavily on water in their normal processes.
     
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