ASTM_A_892_-_09_2014e1.pdf

Designation:A89209(Reapproved 2014)1Standard Guide forDefining and Rating the Microstructure of High CarbonBearing Steels1This standard is issued under the fixed designation A892;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.1NOTEUnits statement was inserted in Section 1.5 editorially in October 2014.1.Scope1.1 This guide covers the description of carbide structures inannealed high carbon bearing steels.1.2 Included is a guide for rating steel specimens by agraded series of photomicrographs showing the incidence ofcertain conditions.1.3 The reference photomicrographs are graded illustrationsof annealed carbides categorized by size,network,and lamellarcontent(shape).1.4 This guide is to facilitate communication and descrip-tion of microstructure.It does not establish limits of accept-ability.Such limits are a matter of agreement between user andproducer.1.5 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.6 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2E3 Guide for Preparation of Metallographic SpecimensE407 Practice for Microetching Metals and AlloysE1245 Practice for Determining the Inclusion or Second-Phase Constituent Content of Metals by Automatic ImageAnalysis2.2 ASTM Adjuncts:Photomicrographs for Defining and Rating the Microstruc-ture of High Carbon Bearing Steels33.Apparatus3.1 In order to adequately compare the structure of aspecimen with the photomicrographs,it will be necessary toview a properly prepared sample at 1000 magnification withgood resolution.4.Specimen Preparation4.1 Samples that represent a portion of the cross section ofthe material shall be prepared using the practices described inGuide E3.The size of the sample shall be negotiated betweenthe user and the producer.It may be a full cross section butshould not be too large for practical handling in the polishingoperation.4.2 The properly polished specimens shall be etched in asuitable etchant which will clearly delineate the annealedcarbide structure of the material being examined as describedin Practice E407.Nital(2%)will frequently be an adequateetchant for routine examination.When critical or detailedanalysis of structures is required,the recommended etchant isPicral(saturated).5.Description5.1 The reference photomicrographs(available in ASTMAdjunct ADJA08923)are arranged into three categories,asfollows:carbide size(CS),carbide network(CN),and lamellarcontent(LC).5.2 Six photomicrographs for each category are providedand are identified by category and number,for example,CS1-CS6,CN1-CN6,and LC1-LC6.Higher numbers indicatea larger number or greater degree of severity of the categorybeing rated.1This guide is under the jurisdiction of Committee A01 on Steel,Stainless Steeland Related Alloys and is the direct responsibility of Subcommittee A01.28 onBearing Steels.Current edition approved Oct.1,2014.Published October 2014.Originallyapproved in 1988.Last previous edition approved in 2009 as A892 09.DOI:10.1520/A0892-09R14E01.2For 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.3Available from ASTM International Headquarters.Order Adjunct No.ADJA0892.Original adjunct produced in 2009.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.2.1 Actual counted number of carbides per 400 m2determined from the carbide size series of photomicrographs isas follows(reported counts are the average of three measure-ments):CS1 508CS2 419CS3 324CS4 234CS5 165CS6 1156.Procedure for Evaluation6.1 Using an optical metallograph and a magnification of1000,examine a properly prepared and etched specimen.Select a field which is representative of the category to begraded and compare it to the photomicrographs which are partof this method.The rating will be the number of that photo thatmost closely resembles the appearance of the specimen.Aseparate field may be used for each category or a single fieldmay be rated for more than one category.An example rating isCS4,CN2,LC1.6.2 As an alternate method,the rating of carbide size byautomatic image analysis shall be conducted in accordancewith Practice E1245.The rating shall be defined by thefollowing equation:Rating5 6.78882 4.59241026!*nA(1)where:nA=number of carbides per mm2.The results shall be rou