ASTM E92-2016 3837 Standard Test Methods for Vickers Hardness and Knoop Hardness of Metallic Materials《金属材料维氏硬度和努氏硬度的标准试验方法》.pdf

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1、Designation: E92 16Standard Test Methods forVickers Hardness and Knoop Hardness of MetallicMaterials1This standard is issued under the fixed designation E92; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last revision

2、.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon () 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 These test methods cover the determination of the

3、Vickers hardness and Knoop hardness of metallic materials bythe Vickers and Knoop indentation hardness principles. Thisstandard provides the requirements for Vickers and Knoophardness machines and the procedures for performing Vickersand Knoop hardness tests.1.2 This standard includes additional req

4、uirements in an-nexes:Verification of Vickers and Knoop Hardness Testing Machines Annex A1Vickers and Knoop Hardness Standardizing Machines Annex A2Standardization of Vickers and Knoop Indenters Annex A3Standardization of Vickers and Knoop Hardness Test Blocks Annex A4Correction Factors for Vickers

5、Hardness Tests Made onSpherical and Cylindrical SurfacesAnnex A51.3 This standard includes nonmandatory information in anappendix which relates to the Vickers and Knoop hardnesstests:Examples of Procedures for Determining Vickers andKnoop Hardness UncertaintyAppendix X11.4 This test method covers Vi

6、ckers hardness tests madeutilizing test forces ranging from 9.807 10-3N to 1176.80 N(1 gf to 120 kgf), and Knoop hardness tests made utilizing testforces from 9.807 10-3N to 19.613 N (1 gf to 2 kgf).1.5 Additional information on the procedures and guidancewhen testing in the microindentation force r

7、ange (forces 1kgf) may be found in Test Method E384, Test Method forMicroindentation Hardness of Materials.1.6 UnitsWhen the Vickers and Knoop hardness testswere developed, the force levels were specified in units ofgrams-force (gf) and kilograms-force (kgf). This standardspecifies the units of forc

8、e and length in the InternationalSystem of Units (SI); that is, force in Newtons (N) and lengthin mm or m. However, because of the historical precedent andcontinued common usage, force values in gf and kgf units areprovided for information and much of the discussion in thisstandard as well as the me

9、thod of reporting the test resultsrefers to these units.NOTE 1The Vickers and Knoop hardness numbers were originallydefined in terms of the test force in kilogram-force (kgf) and the surfacearea or projected area in millimetres squared (mm2). Today, the hardnessnumbers are internationally defined in

10、 terms of SI units, that is, the testforce in Newtons (N). However, in practice, the most commonly usedforce units are kilogram-force (kgf) and gram-force (gf). When Newtonunits of force are used, the force must be divided by the conversion factor9.80665 N/kgf.1.7 The test principles, testing proced

11、ures, and verificationprocedures are essentially identical for both the Vickers andKnoop hardness tests. The significant differences between thetwo tests are the geometries of the respective indenters, themethod of calculation of the hardness numbers, and thatVickers hardness may be used at higher f

12、orce levels thanKnoop hardness.NOTE 2While Committee E28 is primarily concerned with metallicmaterials, the test procedures described are applicable to other materials.Other materials may require special considerations, for example seeC1326 and C1327 for ceramic testing.1.8 This standard does not pu

13、rport 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:2C

14、1326 Test Method for Knoop Indentation Hardness ofAdvanced CeramicsC1327 Test Method for Vickers Indentation Hardness ofAdvanced CeramicsE3 Guide for Preparation of Metallographic SpecimensE6 Terminology Relating to Methods of Mechanical TestingE7 Terminology Relating to Metallography1These test met

15、hods are under the jurisdiction of ASTM Committee E28 onMechanical Testing and is the direct responsibility of Subcommittee E28.06 onIndentation Hardness Testing.Current edition approved Feb. 1, 2016. Published April 2016. Originallyapproved in 1952. Last previous edition approved in 2003 as E9282(2

16、003)2whichwas withdrawn July 2010 and reinstated in February 2016. DOI: 10.1520/E0092-16.2For 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 Summ

17、ary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1E29 Practice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE74 Practice of Calibration of Force-Measuring Instrumentsfo

18、r Verifying the Force Indication of Testing MachinesE140 Hardness Conversion Tables for Metals RelationshipAmong Brinell Hardness, Vickers Hardness, RockwellHardness, Superficial Hardness, Knoop Hardness, Sclero-scope Hardness, and Leeb HardnessE175 Terminology of MicroscopyE177 Practice for Use of

19、the Terms Precision and Bias inASTM Test MethodsE384 Test Method for Knoop and Vickers Hardness ofMaterialsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 ISO Standards:3ISO 6507-1 Metallic MaterialsVickers hardness TestPart 1: Test MethodISO/IEC 1

20、7011 Conformity AssessmentGeneral Require-ments for Accreditation Bodies Accrediting ConformityAssessment BodiesISO/IEC 17025 General Requirements for the Competenceof Testing and Calibration Laboratories3. Terminology and Equations3.1 Definitions of TermsFor the standard definitions ofterms used in

21、 this test method, see Terminology E6 andTerminology E7.3.1.1 indentation hardness, nthe hardness as evaluatedfrom measurements of area or depth of the indentation made byforcing a specified indenter into the surface of a material underspecified static loading conditions.3.1.2 Knoop hardness number,

22、 HK,nthe calculated resultfrom a Knoop hardness test, which is proportional to the testforce applied to the Knoop indenter divided by the projectedarea of the permanent indentation made by the indenter afterremoval of the test force.3.1.2.1 DiscussionThe projected area of the permanentindentation ma

23、de by the Knoop indenter is calculated basedpartly on the measured length of the long diagonal of theprojected area of the indentation.3.1.3 Knoop hardness test, nan indentation test in which aKnoop rhombic-based pyramidal diamond indenter havingspecified edge angles, is forced under specified condi

24、tions intothe surface of the test material, and, after removal of the testforce, the length of the long diagonal of the projected area ofthe indentation is measured to calculate the Knoop hardnessnumber.3.1.4 Vickers hardness number, HV,nthe calculated resultfrom a Vickers hardness test, which is pr

25、oportional to the testforce applied to the Vickers indenter divided by the surfacearea of the permanent indentation made by the indenter afterremoval of the test force.3.1.4.1 DiscussionThe surface area of the permanent in-dentation made by the Vickers indenter is calculated basedpartly on the measu

26、red mean length of the two diagonals of theprojected area of the indentation.3.1.5 Vickers hardness test, nan indentation test in whicha Vickers square-based pyramidal diamond indenter havingspecified face angles is forced under specified conditions intothe surface of the test material, and, after r

27、emoval of the testforce, the lengths of the two diagonals of the projected area ofthe indentation are measured to calculate the Vickers hardnessnumber.3.2 Definitions of Terms Specific to This Standard:3.2.1 standardization, nto bring in conformance to aknown standard through verification or calibra

28、tion.3.2.2 microindentation hardness test, na hardness test,normally in the Vickers or Knoop scales, using test forces inthe range of 9.807 10-3to 9.807 N (1 to 1000 gf).3.2.3 macroindention hardness test, na hardness test usingtest forces normally higher than 9.807 N (1 kgf). Macroinden-tation test

29、s include Vickers, Rockwell and Brinell.NOTE 3Use of the term microhardness should be avoided because itimplies that the hardness, rather than the force or the indentation size, isvery low.3.2.4 scale, na specific combination of indenter (Knoop orVickers) and the test force (kgf).3.2.4.1 DiscussionF

30、or example, HV 10 is a scale definedas using a Vickers indenter and a 10 kgf test force and HK 0.1is a scale defined as using a Knoop indenter and a 100 gf testforce. See 5.10 for the proper reporting of the hardness leveland scale.3.2.5 as-found condition, nthe state of the hardness ma-chine as ref

31、lected by the initial verification measurements madeprior to performing any cleaning, maintenance, adjustments orrepairs associated with an indirect verification.3.2.6 hardness machine, na machine capable of perform-ing a Vickers or Knoop hardness test.3.2.7 hardness testing machine, na Vickers or K

32、noophardness machine used for general testing purposes.3.2.8 hardness standardizing machine, na Vickers orKnoop hardness machine used for the standardization ofVickers or Knoop hardness test blocks.3.2.8.1 DiscussionA hardness standardizing machine dif-fers from a hardness testing machine by having

33、tighter toler-ances on certain parameters.3.3 Equations:3.3.1 The average dof a set of n diagonal length measure-ments d1, d2, , dnis calculated as:d5d11d211dnn(1)where each of the individual diagonal measurements d1, d2, dnis the mean of the two diagonal length measurements inthe case of a Vickers

34、indentation, or is the long diagonal lengthmeasurement in the case of a Knoop indentation.3.3.2 The repeatability R in the performance of a Vickers orKnoop hardness machine at each hardness level, under the3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New Yo

35、rk, NY 10036, http:/www.ansi.org.E92162particular verification conditions, is determined from n diago-nal measurements made on a standardized test block as part ofa performance verification. The repeatability is estimated as thepercent range of n diagonal measurements with respect to themeasured ave

36、rage hardness value as:R 5 100 3Sdmax2 dmindD(2)where:dmax= the longest diagonal length measurement made on thestandardized test block,dmin= the shortest diagonal length measurement made onthe standardized test block, andd= the average (see 3.3.1)ofthen diagonal lengthmeasurements made on the standa

37、rdized test block.3.3.3 The error E in the performance of a Vickers or Knoophardness machine at each hardness level, relative to a standard-ized reference value, is calculated as a percent error determinedas:E 5 100 3Sd2 drefdrefD (3)where:d= the average (see 3.3.1)ofn diagonal length measure-ments

38、made on a standardized test block as part of aperformance verification, anddref= the certified diagonal length reported for the standard-ized test block.4. Significance and Use4.1 Vickers and Knoop hardness tests have been found to bevery useful for materials evaluation, quality control of manu-fact

39、uring processes and research and development efforts.Hardness, although empirical in nature, can be correlated totensile strength for many metals, and is an indicator of wearresistance and ductility.4.2 Microindentation hardness tests extend testing to mate-rials that are too thin or too small for m

40、acroindentationhardness tests. Microindentation hardness tests also allowspecific phases or constituents and regions or gradients toosmall for macroindentation hardness testing to be evaluated.Recommendations for microindentation testing can be found inTest Method E384.4.3 Because the Vickers and Kn

41、oop hardness will revealhardness variations that may exist within a material, a singletest value may not be representative of the bulk hardness.4.4 The Vickers indenter usually produces essentially thesame hardness number at all test forces when testing homoge-neous material, except for tests using

42、very low forces (below25 gf) or for indentations with diagonals smaller than about 25m (see Test Method E384). For isotropic materials, the twodiagonals of a Vickers indentation are equal in length.4.5 The Knoop indenter usually produces similar hardnessnumbers over a wide range of test forces, but

43、the numbers tendto rise as the test force is decreased. This rise in hardnessnumber with lower test forces is often more significant whentesting higher hardness materials, and is increasingly moresignificant when using test forces below 50 gf (see Test MethodE384).4.6 The elongated four-sided rhombo

44、hedral shape of theKnoop indenter, where the length of the long diagonal is 7.114times greater than the short diagonal, produces narrower andshallower indentations than the square-based pyramid Vickersindenter under identical test conditions. Hence, the Knoophardness test is very useful for evaluati

45、ng hardness gradientssince Knoop indentations can be made closer together thanVickers indentations by orienting the Knoop indentations withthe short diagonals in the direction of the hardness gradient.5. Principle of Test and Apparatus5.1 Vickers and Knoop Hardness Test PrincipleThe gen-eral princip

46、le of the Vickers and Knoop indentation hardnesstest consists of two steps.5.1.1 Step 1The applicable specified indenter is broughtinto contact with the test specimen in a direction normal to thesurface, and the test force F is applied. The test force is held fora specified dwell time and then remov

47、ed.5.1.2 Step 2For the Vickers hardness test, the lengths ofthe two diagonals are measured and the mean diagonal lengthis calculated, which is used to derive the Vickers hardnessvalue. For the Knoop hardness test, the length of the longdiagonal is measured, which is used to derive the Knoophardness

48、value.5.1.3 Most materials will exhibit some elastic recoverywhen the indenter is removed after the loading cycle. However,for the purposes of calculating the hardness results from theindentation diagonal lengths, it is assumed that the indentationretains the shape of the indenter after the force is

49、 removed. InKnoop testing, it is assumed that the ratio of the long diagonalto the short diagonal of the indentation is the same as for theindenter.5.2 Testing MachineThe testing machine shall support thetest specimen and control the movement of the indenter into thespecimen under a preselected test force, and should have a lightoptical microscope to select the desired test location and tomeasure the size of the indentation produced by the test. Theplane of the surface of the test specimen should be perpendicu-lar to the axis of the i