Measurement of Grain Size in Twinned FCC Metals

Grain Size Measurement

Types of Grain Sizes

  • Non-twinned(ferrite, BCC metals, Al)
  • Twinned FCC Metals (austenite)
  • Prior-Austenite (Parent Phase in Q&T Steels)

Intercept Grain Size Example: Single Phase Twinned Grain Structure

The 100X micrograph is that of a twinned FCC Ni-base superalloy, X-750, in the solution annealed and aged condition after etching with Beraha’s reagent which colored the grains. This is a much more difficult microstructure for intercept counting. The three circles measure 500 mm and P is 63 (intersections with twin boundaries are ignored).


The articles and presentations that can be down-loaded from this web site are based upon work done by GFV while employed at Bethlehem Steel (1967-1983), Carpenter Technology (1983-1996), Buehler Ltd. (1996-2009) and Struers (2009-Present) and from the authors consulting work for companies such as, Latrobe Steel, Scot Forge, etc., and from his litigation work. GFV's bylined articles appearing in various issues of the ASM Handbook series have been listed here courtesy of ASM International, Materials Park, Ohio.