SYMPOSIA PAPER Published: 01 January 1972

Practical Applications of Quantitative Metallography


An improved procedure based on the intercept method of measuring the grain size of single-phase microstructures has been developed that provides a quantitative description of the grain size yet is fast. The procedure combines the statistical advantage of using large numbers with the advantage of interpreting the data as a normal distribution, as verified by the chi square test. Application of the procedure to ferritic microstructures representative of best and worst case conditions indicates that accuracies on the order of 3 percent at a 95 percent confidence level can be achieved. In addition, the procedure is sensitive enough to distinguish a randomly mixed duplex grain structure. The measurements associated with a two-phase microstructure can be more precisely quantified through determination of volume fractions using a Pp measurement based on the use of an appropriate grid network, the coefficient of variation statistic, and the Poisson distribution. The analysis is demonstrated for an a priori system for which the percent accuracy and confidence level can be specified for the volume fraction measurement simply from calculation of the average value for Pp.

Author Information

Abrams, H
Homer Research Laboratories, Bethlehem Steel Corporation, Bethlehem, Pa.
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Developed by Committee: E04
Pages: 138–182
DOI: 10.1520/STP36848S
ISBN-EB: 978-0-8031-4610-5
ISBN-13: 978-0-8031-0095-4