1、Designation:A24717Standard Test Method forEvaluating the Microstructure of Graphite in Iron Castings1This standard is issued under the fixed designation A247;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A
2、 number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope1.1 This test method covers the classification of graphit
3、e incast irons in terms of type,distribution,and size by visualcomparison to reference photomicrographs.This test method isintended to be applicable for all iron-carbon alloys containinggraphite particles,and may be applied to gray irons,malleableirons,compacted graphite irons,and the ductile(nodula
4、r)irons.1.2 The reference photomicrographs included in this testmethod are in no way to be construed as specifications.In anappropriate specification for a specific material where graphitemicrostructure is an important consideration,this test methodmay be used as a reference to concisely define the
5、graphitemicrostructure required.1.3 These reference photomicrographs are offered primarilyto permit accurate reporting of microstructures of cast ironsand to facilitate the comparison of reports by different labora-tories or investigators.1.4 The values stated in SI units are to be regarded asstanda
6、rd.No other units of measurement are included in thisstandard.1.5 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-bi
7、lity of regulatory limitations prior to use.1.6 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the Wo
8、rld Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2E3 Guide for Preparation of Metallographic Specimens2.2 ASTM Adjuncts:Iron Casting Graphite Microstructure Rating Chart(WallChart)33.Summary of Test Method3.1 The reference micrographs included
9、in this standardform the basis for classification.Characteristic features ofgraphite particle shape and distribution are designated bynumerals and letters.Type,distribution,and size of observedgraphite are compared with the idealized microstructures in thestandard charts and rated accordingly as clo
10、sely as possible tothe equal or similar microstructures in the charts.4.Significance and Use4.1 The comparison of observed graphite particles with thestructures shown in the charts give only purely descriptiveinformation on the type,distribution,and size of the graphite inthe sample being evaluated.
11、It does not indicate,except in avery broad way,the origin of the graphite or the suitability ofthe iron-carbon alloy for a particular service.5.Test Specimens or Samples5.1 The preferred sample is a section cut from an actualcasting that is being evaluated at a location agreed uponbetween the manufa
12、cturer and purchaser.When this isimpractical,a test lug or projection often can be appended tothe casting and sawed or broken off to be used as the testsample.If neither of these methods is convenient,microstruc-tural test coupons,such as those recommended by the Cast Iron1This test method is under
13、the jurisdiction of ASTM Committee A04 on IronCastings and is the direct responsibility of Subcommittee A04.21 on Testing.Current edition approved July 1,2017.Published July 2017.Originally approvedin 1941.Last previous edition approved in 2016 as A247 16a.DOI:10.1520/A0247-17.2For referenced ASTM s
14、tandards,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.ADJA0247A.Original adju
15、nct produced in 2010.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDeve
16、lopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.1 Research Committee(5R)of the American Foundry Society4shall be cast from metal representative of the castings poured.6.Polishing6.1 Grinding and polishing may follow the usual acceptedmetallographic procedures as covered in Guide E3,except thatcare must be taken that the graphite is retained at the polishedsurface and not torn or dragged out.Use of diam