Assessment of Some Methods for Grain Size Measurement

Due to the fact that grain size measurement in metallic materials is of great importance, five well known and established grain size measurement methods were compared for accuracy and time consumption, i. e.: comparison method, intercept method, planimetric method (by Jeffries), planimetric delineation method performed in semiautomatic manner and automatic method (commercial software by ZEISS). For that purpose standard low-carbon ferritic steel (W. NR. 1.0360), austenitic steel (W. NR. 1.4404) with two different grain sizes (denoted as A and B) and nodularized grey cast iron (EN-JS 1082) were chosen. It was discerned that the comparison method represents the fastest solution for the grain size measurement but it is limited in precision and applicability in two phase materials. The automatic (commercially available software) method was proved to be unreliable, while the intercept method or one of the planimetric methods is the most reasonable choice when higher accuracy is required.