Influence of Grain Size Distribution on Estimation of Mean Grain Size

Abstract

The influence of grain size distribution on the estimation of mean grain size has been investigated. A calculation of the mean grain size by the intercept (Heyn’s) or the planimetric (Jeffries’) method was carried out for a grain structure model. In the model, the grain shape and the grain diameter (equivalent volume diameter) D were reasonably set to be the tetrakai-decahedron and to have a log-normal distribution, respectively.
As the result of the calculation, the following equations are derived for the intercept and the planimetric methods;
(This article is not displayable. Please see full text pdf.)
\ oindentwhere D_g is the geometric mean grain diameter and σ_g is the geometric standard deviation for D. The calculated value by the intercept method, l_cal was in good agreement with the experimental value, \barl_ex. The mean grain sizes obtained experimentally revealed its clear dependence on σ_g, which corresponded well to that of the calculated sizes. These suggested that the grain size distribution should have a significant effect on the estimation of the mean grain size.