Significance and Use

This practice provides a way to estimate the average grain size of polycrystalline materials. It is based on EBSD measurements of crystallographic orientation which are inherently quantitative in nature. This method has specific advantage over traditional optical grain size measurements in some materials, where it is difficult to find appropriate metallographic preparation procedures to adequately delineate grain boundaries.

1. Scope

1.1 This practice is used to determine grain size from measurements of grain areas from automated electron backscatter diffraction (EBSD) scans of polycrystalline materials.

1.2 The intent of this practice is to standardize operation of an automated EBSD instrument to measure ASTM G directly from crystal orientation. The guidelines and caveats of E112 apply here, but the focus of this standard is on EBSD practice.

1.3 This practice is only applicable to fully recrystallized materials.

1.4 This practice is applicable to any crystalline material which produces EBSD patterns of sufficient quality that a high percentage of the patterns can be reliably indexed using automated indexing software.

1.5 The practice is applicable to any type of grain structure or grain size distribution.

1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.7 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.

2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

ASTM Standards

E7 Terminology Relating to Metallography

E112 Test Methods for Determining Average Grain Size

E766 Practice for Calibrating the Magnification of a Scanning Electron Microscope

E1181 Test Methods for Characterizing Duplex Grain Sizes

E1382 Test Methods for Determining Average Grain Size Using Semiautomatic and Automatic Image Analysis

Keywords

backscattered electrons; backscatter diffraction; EBSD; Grain size; Kikuchi pattern; orientation map; SEM; scanning electron microscope;

ICS Code

ICS Number Code 71.040.50 (Physicochemical methods of analysis)

DOI: 10.1520/E2627-10

ASTM International is a member of CrossRef.

ASTM E2627