1、Designation:E126801(Reapproved 2016)Standard Practice forAssessing the Degree of Banding or Orientation ofMicrostructures1This standard is issued under the fixed designation E1268;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the y
2、ear 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.INTRODUCTIONSegregation occurs during the dendritic solidification of metals and alloys and is aligned bysubsequent deformation
3、.Solid-state transformations may be influenced by the resulting microsegre-gation pattern leading to development of a layered or banded microstructure.The most commonexample of banding is the layered ferrite-pearlite structure of wrought low-carbon and low-carbonalloy steels.Other examples of bandin
4、g include carbide banding in hypereutectoid tool steels andmartensite banding in heat-treated alloy steels.This practice covers procedures to describe theappearance of banded structures,procedures for characterizing the extent of banding,and amicroindentation hardness procedure for determining the d
5、ifference in hardness between bands in heattreated specimens.The stereological methods may also be used to characterize non-bandedmicrostructures with second phase constituents oriented(elongated)in varying degrees in thedeformation direction.1.Scope1.1 This practice describes a procedure to qualita
6、tivelydescribe the nature of banded or oriented microstructures basedon the morphological appearance of the microstructure.1.2 This practice describes stereological procedures forquantitative measurement of the degree of microstructuralbanding or orientation.NOTE1Although stereological measurement m
7、ethods are used toassess the degree of banding or alignment,the measurements are onlymade on planes parallel to the deformation direction(that is,a longitudinalplane)and the three-dimensional characteristics of the banding or align-ment are not evaluated.1.3 This practice describes a microindentatio
8、n hardness testprocedure for assessing the magnitude of the hardness differ-ences present in banded heat-treated steels.For fully marten-sitic carbon and alloy steels(0.100.65%C),in the as-quenched condition,the carbon content of the matrix andsegregate may be estimated from the microindentation har
9、d-ness values.1.4 This standard does not cover chemical analytical meth-ods for evaluating banded structures.1.5 This practice deals only with the recommended testmethods and nothing in it should be construed as defining orestablishing limits of acceptability.1.6 The measured values are stated in SI
10、 units,which areregarded as standard.Equivalent inch-pound values,whenlisted,are in parentheses and may be approximate.1.7 This standard does not purport to address all of thesafety problems,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate
11、 safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2A370 Test Methods and Definitions for Mechanical Testingof Steel ProductsA572/A572M Specification for High-Strength Low-AlloyColumbium-Vanadium Structural St
12、eelA588/A588M Specification for High-Strength Low-AlloyStructural Steel,up to 50 ksi 345 MPa Minimum YieldPoint,with Atmospheric Corrosion ResistanceE3 Guide for Preparation of Metallographic SpecimensE7 Terminology Relating to Metallography1This practice is under the jurisdiction of ASTM Committee
13、E04 on Metallog-raphy and is the direct responsibility of Subcommittee E04.14 on QuantitativeMetallography.Current edition approved Jan.1,2016.Published April 2016.Originallyapproved in 1988.Last previous edition approved in 2007 as E1268 01(2007).DOI:10.1520/E1268-01R162For referenced ASTM standard
14、s,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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.
15、United States1 E140 Hardness Conversion Tables for Metals RelationshipAmong Brinell Hardness,Vickers Hardness,RockwellHardness,Superficial Hardness,Knoop Hardness,Sclero-scope Hardness,and Leeb HardnessE384 Test Method for Knoop and Vickers Hardness ofMaterialsE407 Practice for Microetching Metals a
16、nd AlloysE562 Test Method for Determining Volume Fraction bySystematic Manual Point CountE883 Guide for ReflectedLight Photomicrography3.Terminology3.1 DefinitionsFor definitions of terms used in thispractice,see Terminology E7.3.2 Definitions of Terms Specific to This Standard:3.2.1 banded microstructureseparation,of one or morephases or constituents in a two-phase or multiphasemicrostructure,or of segregated regions in a single phase orconstituent microstructure,into distinct layers parallel t