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Thermal expansion of wire?

  1. Jul 21, 2011 #1
    thermal expansion of wire??

    hi ive got this 3mm iron-chromium-aluminium wire fixed at both ends, heated to approx 1000k (max 1200K) and suspended horizontally approx 1metre long.

    the wire it would appear has been extended by about 8mm, similar to what would be expected when its hot, only it stays this long when brought back down to room temperature!

    so my question is: why?! lol

    could it really be creep?

    thanks, mike
     
    Last edited: Jul 21, 2011
  2. jcsd
  3. Jul 24, 2011 #2
    Re: thermal expansion of wire??

    The wire probably stretched while it was hot and sagging down. If the wire stretched then it must also have gotten thinner.
     
  4. Aug 1, 2011 #3
    Re: thermal expansion of wire??

    Was it fixed under significant tension? If it was, then yes, it could be creep.

    Otherwise, it may depend on how it was cooled.
     
  5. Aug 1, 2011 #4
    Re: thermal expansion of wire??

    Creeping is absolutely normal for steel at 1000K, much more at 1200K. Even over a short time with a moderate load.

    Then, if your wire was new, you can have glowed it from some initial metallurgical state, like cold drawn. To decide what effect it was, just observe if the wire creeps further next time.
     
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