This test method is based upon the stereological principle that a grid with a number of regularly arrayed points, when systematically placed over an image of a two-dimensional section through the microstructure, can provide, after a representative number of placements on different fields, an unbiased statistical estimation of the volume fraction of an identifiable constituent or phase (1, 2, 3).

This test method has been described (4) as being superior to other manual methods with regard to effort, bias, and simplicity.

Any number of clearly distinguishable constituents or phases within a microstructure (or macrostructure) can be counted using the method. Thus, the method can be applied to any type of solid material from which adequate two-dimensional sections can be prepared and observed.

A condensed step-by-step guide for using the method is given in Annex A1.

1. Scope

1.1 This test method describes a systematic manual point counting procedure for statistically estimating the volume fraction of an identifiable constituent or phase from sections through the microstructure by means of a point grid.

1.2 The use of automatic image analysis to determine the volume fraction of constituents is described in Practice E1245.

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

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

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

E3 Guide for Preparation of Metallographic Specimens

E7 Terminology Relating to Metallography

E407 Practice for Microetching Metals and Alloys

E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method

E1245 Practice for Determining the Inclusion or Second-Phase Constituent Content of Metals by Automatic Image Analysis

Keywords

Metallographic analysis/inspection; Point count; Systematic manual point count; Volume change;

ICS Code

ICS Number Code 77.040.99 (Other methods of testing metals)

Citing ASTM Standards

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