ASTM_B_294_-_10.pdf

Designation:B29410Standard Test Method forHardness Testing of Cemented Carbides1This standard is issued under the fixed designation B294;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.1.Scope1.1 This test method covers the hardness testing of ce-mented carbides by use of a Rockwell hardness tester perform-ing tests in the Rockwell HRA scale(regular scale,diamondindenter,10 kgf(98.07 N)preliminary test force,and 60 kgf(588.4 N)load)in the range of Rockwell 80 HRA and above.Also covered are the procedures for the testing and selection ofdiamond indenters,the management and traceability of the fourlevels of standardized test blocks,and the making and calibra-tion of Primary,Secondary,and Working standardized testblocks.1.2 The Rockwell hardness tester is a convenient andreliable means of measuring the hardness of cemented car-bides.A hardness value is obtained easily,but it is subject toconsiderable error unless certain precautions are observed.1.3 The latest version of Test Methods E18 shall be fol-lowed except where otherwise indicated in this test method.1.4 The values stated in SI units are to be regarded asstandard except that force and length values associated with theRockwell hardness testers will comply with E18 with forcevalues specified as N(kgf)and indenter length values specifiedas mm.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-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2E18 Test Methods for Rockwell Hardness of Metallic Ma-terialsE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with Specifications2.2 ISO Standards:3ISO/IEC 17011 Conformity AssessmentGeneral Require-ments for Accreditation Bodies Accrediting ConformityAssessment BodiesISO/IEC 17025 General Requirements for the Competenceof Testing and Calibration Laboratories3.Significance and Use3.1 Rockwell hardness testing is one of the more importantmethods used to evaluate cemented carbides.For composi-tional groups of cemented carbides,hardness is an indication ofwear resistance and toughness.Lower hardness grades usuallyindicate less wear resistance but greater toughness.For aspecific grade of cemented carbide,hardness is an indication ofthe metallurgical quality of the material.In no case is Rockwellhardness testing the only test method to be considered inevaluating cemented carbides.4.Apparatus4.1 TesterAll hardness tests shall be performed using aRockwell hardness tester that meets the requirements definedin the latest version of Test Method E18 except whereotherwise indicated in this test method.Testers shall complywith the requirements of Annex A3 of this test method.4.2 ScaleAll tests shall be performed using the carbideRockwell HRA scale(a carbide diamond indenter,10 kgf(98.07 N)preliminary force,and 60 kgf(588.4 N)total testforce.4.3 Effect of VibrationThe Rockwell hardness testershould be located in a vibration-free area in order to avoiderroneous results.If this is not possible,the tester shall bemounted so as to minimize vibrations,since vibrations tend tocause erratic readings.4.4 IndenterThe indenters used shall conform to therequirements defined in Annex A2 of this test method.4.5 AnvilsSelect an anvil suitable for the specimen to betested.The test piece should be supported rigidly,with the test1This test method is under the jurisdiction of ASTM Committee B09 on MetalPowders and Metal Powder Products and is the direct responsibility of Subcom-mittee B09.06 on Cemented Carbides.Current edition approved May 1,2010.Published June 2010.Originallyapproved in 1954.Last previous edition approved in 2009 as B294 09(2009).DOI:10.1520/B0294-10.2For 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 American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 surface perpendicular to the line of travel of the indenter.Forthe best accuracy,flat test pieces should be tested on a flat spotanvil of approximately 6-mm diameter.The surface of the anvilthat contacts the sample should have a Rockwell hardness of atleast 58 HRC,and shall be polished smooth and be free of pitsand heavy scratches that could affect the test results.Themounting surface of the anvil support and the mating surface ofthe anvil