ASTM_E_1181_-_02_2015.pdf

Designation:E118102(Reapproved 2015)Standard Test Methods forCharacterizing Duplex Grain Sizes1This standard is issued under the fixed designation E1181;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.INTRODUCTIONTest methods are well established for the determination of average grain size,and estimation oflargest grain size,in products assumed to contain a single log-normal distribution of grain sizes.Thetest methods in this standard are set forth to characterize grain size in products with any otherdistributions of grain size.The term“duplex grain size”is chosen to describe any of these other distributions of grain size,because of its common usage and familiarity.However,the use of that term does not imply that onlytwo grain size distributions exist.These test methods are equally aimed at describing the nature of the deviation from a singlelog-normal distribution of grain sizes,and at describing with reasonable accuracy the distributions ofsizes that actually exist.1.Scope1.1 These test methods provide simple guidelines for decid-ing whether a duplex grain size exists.The test methodsseparate duplex grain sizes into one of two distinct classes,then into specific types within those classes,and providesystems for grain size characterization of each type.1.2 UnitsThe values stated in SI units are to be regardedas standard.No other units of measurement are included in thisstandard.1.3 This standard may involve hazardous materials,operations,and equipment.This standard does not purport toaddress all of the safety concerns associated with its use.It isthe responsibility of the user of this standard to consultappropriate safety and health practices and determine theapplicability of regulatory limitations prior to its use.2.Referenced Documents2.1 ASTM Standards:2E3 Guide for Preparation of Metallographic SpecimensE7 Terminology Relating to MetallographyE112 Test Methods for Determining Average Grain SizeE407 Practice for Microetching Metals and AlloysE562 Test Method for Determining Volume Fraction bySystematic Manual Point CountE883 Guide for ReflectedLight PhotomicrographyE930 Test Methods for Estimating the Largest Grain Ob-served in a Metallographic Section(ALA Grain Size)2.2 ASTM Adjuncts:Comparison Chart for Estimation of Area Fractions33.Terminology3.1 Definitions:3.1.1 All terms used in these test methods are either definedin Terminology E7,or are discussed in 3.2.3.2 Definitions of Terms Specific to This Standard:3.2.1 bands or banding in grain size,alternating areas ofsignificantly different grain sizes.These areas are usuallyelongated in a direction parallel to the direction of working.3.2.2 grain sizeequivalent in meaning to the average of adistribution of grain sizes.3.2.3 necklace or necklace structureindividual coarsegrains surrounded by rings of significantly finer grains.3.2.4 topologically varyingvarying nonrandomly,in somedefinable pattern;that pattern may be related to the shape of thespecimen or product being examined.4.Summary of Test Method4.1 These test methods provide means for recognizing thepresence of duplex grain size.The test methods separate duplex1These test methods are under the jurisdiction of ASTM Committee E04 onMetallography and are the direct responsibility of Subcommittee E04.08 on GrainSize.Current edition approved Oct.1,2015.Published November 2015.Originallyapproved in 1987.Last previous edition approved in 2008 as E118102(2008)1.DOI:10.1520/E1181-02R15.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3This comparison chart shows different area percentages of light grains amongdark grains.Available from ASTM Headquarters.Order Adjunct:ADJE1181.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 grain sizes into two classes(randomly varying,and topologi-cally varying),and define specific types of duplex grain sizeswithin these classes.The test methods provide means forestimating area fractions occupied by distinct grain sizes,andoffer existing standard methods(Test Methods E112,TestMethods E930)for determining grain size in specific identifiedareas.The test methods provide for reporting of specific,distinctive information for each type of duplex grain size.And,as an alternative,the test methods offer a procedure forstatistically determining the distribution of all the grain sizespresent in a duplex grain size specimen.5.Significance and Use5.1 Duplex grain size may occur in some metals and alloysas a result of their thermomechanical processing history.Forcomparison of mechanical properties wit