Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Grain size

  1. Mar 7, 2010 #1


    User Avatar

    1) Hi just checking if the definition of grain size is the average size of grains in a metal expressed as average diameter. if it is not or if there is a more accurate definition could u define it for me.
    2) and if the formula N=2n-1 or is it N=2^(n-1)
    n being the number of grains per square inch at magnification of 100 diameters.
    or if i am completely wrong please tell me.

    thank you
  2. jcsd
  3. Mar 8, 2010 #2


    User Avatar
    Staff Emeritus
    Science Advisor

    Simple forumula is n = 2^(G - 1), or n = 2^(N - 1), where:
    n = the number of grains per square inch at 100X magnification, and
    G, N = the ASTM grain size number.

    See Complications---Different Measures of Size and
    Evolution of Test Methods E 112

    in http://www.metallography.com/grain.htm

    http://mse.iastate.edu/solidification/Courses/MatE443-Website/instructions/ASTM_grainsize.pdf [Broken]
    Last edited by a moderator: May 4, 2017
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook