(a) Using the intercept method determine the mean intercept length, in millimeters, of the...

(a) Using the intercept method determine the mean intercept length, in millimeters, of the specimen whose microstructure is shown in Figure 4.15b; use at least seven straight-line segments.

(b) Estimate the ASTM grain-size number for this material.

Figure 4.15 (b) Photomicrograph of the surface of a polished and etched polycrystalline specimen of an iron–chromium alloy in which the grain boundaries appear dark, 100×. [Photomicrograph courtesy of L. C. Smith and C. Brady, the National Bureau of Standards, Washington, DC (now the National Institute of Standards and Technology, Gaithersburg, MD.)]