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Homework Help: Iron-carbon alloy diagram

  1. Sep 16, 2006 #1
    What's the difference between the dotted lines and the regular lines on the iron-carbon alloy diagrams?
     
  2. jcsd
  3. Sep 16, 2006 #2

    Astronuc

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  4. Sep 17, 2006 #3
    Sorry! I made a mistake. It's called the continous cooling transformation diagram of iron-carbon alloy of euctectoid composition... I saw that in a book I'm reading called "Fundamentals of Materials Science and Engineering (2nd Edition)" by William D. Callister, Jr., and the diagrams are on page 444 and pg. 445...
     
  5. Sep 17, 2006 #4

    Astronuc

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    Using W. D. Callister's, "Material Science and Engineering, An Introduction", 6th Edition, I indentified an isothermal transformation diagram for iron-carbon of eutectoid composition. A = austenite (FCC), B = bainite, P = pearlite, and M = Martenite (BCT).

    I think the dashed lines are simply used to distinguish from other lines. There is one curvy dashed line between the fully A and fully P or B phases, and the dashed line simply shows the 50/50 boundary between A/P or A/B.

    Then there are two horizontal dashed lines which represent the 50% Martensitic transformation at 165°C and 90% M-transformation at ~130°C. The transformation from A to M requires starting with the heat at or above 727°C and rapidly quenching to the appropriate temperature (one of the horizontal lines).
     
  6. Sep 17, 2006 #5
    ok, thank you very much!
     
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