Grain Radius Notes
Experimental data on grain sizes often are based on measurements known as the intercept length. The intercept length can be defined as the distance between two opposed, adjacent grain boundary intersection points on a test line segment that crosses the grain at any location due to random placement of the test line. Finding these length can be done through a count of the number of grains intercepted by a test line or the number of grain boundary intersections with a test line, per unit length of test line. This then allows for the calculation of the mean lineal intercept length, , following Mendelson (1969),
A more through discussion on the intercept method can be found in ASTM ASTMI (2015).