Astm

Designation: E 112 – 96 (Reapproved 2004)e2

Standard Test Methods for

Determining Average Grain Size1
This standard is issued under the fixed designation E 112; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon(e) indicates an editorial change since the last revision or reapproval. This standard has been approved for use by agencies of the Department of Defense.

e1 NOTE—Reference (2) was editorially corrected in May 2006. e2 NOTE— Equation A1.9 was editorially corrected in November 2006.

INTRODUCTION

These test methods of determination of average grain size in metallic materials are primarilymeasuring procedures and, because of their purely geometric basis, are independent of the metal or alloy concerned. In fact, the basic procedures may also be used for the estimation of average grain, crystal, or cell size in nonmetallic materials. The comparison method may be used if the structure of the material approaches the appearance of one of the standard comparison charts. The intercept andplanimetric methods are always applicable for determining average grain size. However, the comparison charts cannot be used for measurement of individual grains. 1. Scope 1.1 These test methods cover the measurement of average grain size and include the comparison procedure, the planimetric (or Jeffries) procedure, and the intercept procedures. These test methods may also be applied to nonmetallicmaterials with structures having appearances similar to those of the metallic structures shown in the comparison charts. These test methods apply chiefly to single phase grain structures but they can be applied to determine the average size of a particular type of grain structure in a multiphase or multiconstituent specimen. 1.2 These test methods are used to determine the average grain size ofspecimens with a unimodal distribution of grain areas, diameters, or intercept lengths. These distributions are approximately log normal. These test methods do not cover methods to characterize the nature of these distributions. Characterization of grain size in specimens with duplex grain size distributions is described in Test Methods E 1181. Measurement of individual, very coarse grains in a finegrained matrix is described in Test Methods E 930. 1.3 These test methods deal only with determination of planar grain size, that is, characterization of the twodimensional grain sections revealed by the sectioning plane. Determination of spatial grain size, that is, measurement of the
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size of the three-dimensional grains in the specimen volume,is beyond the scope of these test methods. 1.4 These test methods describe techniques performed manually using either a standard series of graded chart images for the comparison method or simple templates for the manual counting methods. Utilization of semi-automatic digitizing tablets or automatic image analyzers to measure grain size is described in Test Methods E 1382. 1.5 These test methodsdeal only with the recommended test methods and nothing in them should be construed as defining or establishing limits of acceptability or fitness of purpose of the materials tested. 1.6 The measured values are stated in SI units, which are regarded as standard. Equivalent inch-pound values, when listed, are in parentheses and may be approximate. 1.7 This standard does not purport to address all ofthe 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. 1.8 The paragraphs appear in the following order:
Section Scope Referenced Documents Terminology Significance and Use Generalities of Application Sampling Test...