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Hall Petch Equation

  1. Apr 15, 2016 #1
    What is the Hall Petch equation. When I Google (images) I get::

    σy = σo + ky / √d


    σy = σo + ky d1/2

    In the first ky is divided by √d and in the second multiplied by √d.

    The second equation is in a study book I have.

    Am I making a math error? Thanks.
    Last edited: Apr 15, 2016
  2. jcsd
  3. Apr 16, 2016 #2


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    Gold Member

    I saw from different references that is ##\sigma_{y}= \sigma_{0}+k_{y}d^{-\frac{1}{2}}##
  4. Apr 16, 2016 #3
    Yes, the minus sign should be there. :-)
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