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INTERNATIONALSTANDARDISO6508-1Third edition2015-03-01Metallic materials — Rockwellhardness test —Part 1:Test methodMatériaux métalliques — Essai de dureté Rockwell —Partie 1: Méthode d’essaiReference numberISO 6508-1:2015(E) ISO 2015

ISO 6508-1:2015(E) COPYRIGHT PROTECTED DOCUMENT ISO 2015All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any formor by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without priorwritten permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country ofthe requester.ISO copyright officeCase postale 56 CH-1211 Geneva 20Tel. 41 22 749 01 11Fax 41 22 749 09 47E-mail copyright@iso.orgWeb www.iso.orgPublished in Switzerlandii ISO 2015 – All rights reserved

ISO 6508-1:2015(E) Contents PageForeword. iv12345678910Scope. 1Normative references. 1Principle. 1Symbols, abbreviated terms and designations. 1Testing machine. 4Test piece. 5Procedure. 5Uncertainty of the results. 7Test report. 7Conversions to other hardness scales or tensile strength values. 7Annex A (normative) Special HR30TSm and HR15TSm test for thin products. 8Annex B (normative) Minimum thickness of the test piece in relation to the Rockwell hardness. 9Annex C (normative) Corrections to be added to Rockwell hardness values obtained onconvex cylindrical surfaces.12Annex D (normative) Corrections to be added to Rockwell hardness C scale values obtainedon spherical test surfaces of various diameters.15Annex E (normative) Daily Verification Procedure.16Annex F (normative) Inspection of diamond indenters.19Annex G (informative) Uncertainty of the measured hardness values.20Annex H (informative) CCM - Working Group on Hardness.29Annex I (informative) Rockwell Hardness Measurement Traceability.30Bibliography. 33 ISO 2015 – All rights reserved iii

ISO 6508-1:2015(E) ForewordISO (the International Organization for Standardization) is a worldwide federation of national standardsbodies (ISO member bodies). The work of preparing International Standards is normally carried outthrough ISO technical committees. Each member body interested in a subject for which a technicalcommittee has been established has the right to be represented on that committee. Internationalorganizations, governmental and non-governmental, in liaison with ISO, also take part in the work.ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters ofelectrotechnical standardization.The procedures used to develop this document and those intended for its further maintenance aredescribed in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for thedifferent types of ISO documents should be noted. This document was drafted in accordance with theeditorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).Attention is drawn to the possibility that some of the elements of this document may be the subject ofpatent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of anypatent rights identified during the development of the document will be in the Introduction and/or onthe ISO list of patent declarations received (see www.iso.org/patents).Any trade name used in this document is information given for the convenience of users and does notconstitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformityassessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriersto Trade (TBT) see the following URL: Foreword - Supplementary informationThe committee responsible for this document is ISO/TC 164, Mechanical testing of metals, SubcommitteeSC 3, Hardness testing.This third edition cancels and replaces the second edition (ISO 6508-1:2005), which has beentechnically revised.ISO 6508 consists of the following parts, under the general title Metallic materials — Rockwell hardness test:— Part 1: Test method— Part 2: Verification and calibration of testing machines and indenters— Part 3: Calibration of reference blocksiv ISO 2015 – All rights reserved

INTERNATIONAL STANDARD ISO 6508-1:2015(E)Metallic materials — Rockwell hardness test —Part 1:Test method1 ScopeThis part of ISO 6508 specifies the method for Rockwell regular and Rockwell superficial hardness tests(scales and applicable range of application according to Table 1) for metallic materials and is applicableto stationary and portable hardness testing machines.For specific materials and/or products, other specific International Standards apply (for instance,ISO 3738-1 and ISO 4498).NOTEAttention is drawn to the fact that the use of tungsten carbide composite for ball indenters is consideredto be the standard type of Rockwell indenter ball. Steel indenter balls are allowed to continue to be used onlywhen complying with Annex A.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and areindispensable for its application. For dated references, only the edition cited applies. For undatedreferences, the latest edition of the referenced document (including any amendments) applies.ISO 6508-2:2015, Metallic materials — Rockwell hardness test — Part 2: Verification and calibration oftesting machinesISO 6508-3:2015, Metallic materials — Rockwell hardness test — Part 3: Calibration of reference blocks3 PrincipleAn indenter of specified size, shape, and material is forced into the surface of a test specimen under twoforce levels using the specific conditions defined in Clause 7. The specified preliminary force is appliedand the initial indentation depth is measured, followed by the application and removal of a specifiedadditional force, returning to the preliminary force. The final indentation depth is then measured andthe Rockwell hardness value is derived from the difference, h, in the final and initial indentation depthsand the two constants N and S (see Figure 1, Table 1 and Table 2) as:Rockwell hardness N hS(1)4 Symbols, abbreviated terms and designations4.1See Table 1, Table 2, Table 3, and Figure 1. ISO 2015 – All rights reserved 1

ISO 6508-1:2015(E) Table 1 — Rockwell Regular scalesRockwell Hardness Type of indenter ADiamond coneBHRBWBall 1,587 5 mmEHREWBall 3,175 mmHHRHWCDFGKHRCHRDDiamond coneDiamond cone98,07 N98,07 NS588,4 N0,002 mm980,7 N0,002 mm980,7 N98,07 NHRKWBall 3,175 mm98,07 N980,7 N98,07 NApplicablerange of application (RockwellConstantRegularNhardness scales)10010 to 100 HRBW0,002 mm13070 to 100 HREW1001000,002 mm1301,471 kN 0,002 mm130588,4 N20 to 95 HRA1301,471 kN 0,002 mm98,07 NFullRange0,002 mm588,4 N98,07 N98,07 NBall 3,175 mmF1,471 kN 0,002 mmBall 1,587 5 mmBall 1,587 5 mmScalingConstant98,07 NHRFWHRGWTotalforce0,002 mm13020a to 70 HRC40 to 77 HRD60 to 100 HRFW30 to 94 HRGW13080 to 100 HRHWFullRangeConstantApplicablerange of application (Rockwell Superficialhardness scales)40 to 100 HRKWaThe applicable range of application can be extended to 10 HRC if the surfaces of the diamond cone and spherical tip arepolished for a penetration depth of at least 0,4 mm.Table 2 — Rockwell Superficial scalesRockwell HardnessSuperficial symbolhardnessUnitscale15N30N45N15T30T45TType tF0FS147,1 N0,001 mm100147,1 N0,001 mm100HR15NDiamond cone29,42 NHR15TWBall 1,587 5 mm29,42 NHR30NHR45NHR30TWHR45TWDiamond coneDiamond coneBall 1,587 5 mmBall 1,587 5 mm29,42 N294,2 N29,42 N294,2 N29,42 N441,3 N29,42 N441,3 N0,001 mm0,001 mm0,001 mm0,001 mmN10010010010070 to 94 HR15N42 to 86 HR30N20 to 77 HR45N67 to 93 HR15TW29 to 82 HR30TW10 to 72 HR45TWScales using indenter balls with diameter 6,350 mm and 12,70 mm may also be used, if specified in theproduct specification or by special agreement. See ASTM E 18 for additional scales using these ball sizes.NOTE 1For certain materials, the applicable range of application might be narrower than those indicated.NOTE 2The numbers representing the test forces were originally based on units of kgf. For example, the totaltest force of 30 kgf has been converted to 294,2 N.2 ISO 2015 – All rights reserved

ISO 6508-1:2015(E) Table 3 — Symbols and abbreviated nary test forceNScaling constant, specific to the scalemmF1Additional test force (total force minus preliminary force)FTotal test forceSNFull range constant, specific to the scalehPermanent depth of indentation under preliminary test force after removal ofadditional test force (permanent indentation depth)HRARockwell Regular hardness 100 HRCHRDHRBWHREWHRFWRockwell Regular hardness 130 HRGWHRHWHRKWHRN4.2h0, 002N-mmh0, 002Rockwell Superficial hardness 100 HRTWNh0, 001The following is an example of the designation of Rockwell hardness.EXAMPLE70HR30 TWindication of type of ball used, W Tungsten carbidecompositeRockwell scale symbol (see Tables 1 or 2)Rockwell hardness symbolNOTE 1 Previous versions of this part of ISO 6508 allowed the use of steel indenter balls, which requiredthe suffix S.NOTE 2For the HR30TSm and HR15TSm scales defined in Annex A, a capital S and a lower-case m is usedindicating the use of steel indenter balls and a diamond spot specimen holder. ISO 2015 – All rights reserved 3

ISO 6508-1:2015(E) YF0F 0 F 1F05617428377KeyX timeY indenter position1 indentation depth by preliminary force, F02 indentation depth by additional test force, F13 elastic recovery just after removal of additional test force,F145678permanent indentation depth, hsurface of specimenreference plane for measurementposition of indenterindentation depth vs. time curveFigure 1 — Rockwell principle diagram5 Testing machine5.1 Testing machine, shall be capable of applying the test forces for some or all of the Rockwellhardness scales as shown in Table 1 and Table 2, performing the procedure defined in Clause 7, andcomplying with all of the requirements defined in ISO 6508-2:2015.5.2 Spheroconical diamond indenter, shall be in accordance with ISO 6508-2:2015, with anincluded angle of 120 and radius of curvature at the tip of 0,2 mm. Diamond indenters shall be certifiedfor use for either— only the regular Rockwell diamond scales,— only the superficial Rockwell diamond scales, or— both the regular and the superficial Rockwell diamond scales.5.3 Ball indenter, shall be tungsten carbide composite in accordance with ISO 6508-2:2015, with adiameter of 1,587 5 mm or 3,175 mm (see Note 1 and Note 2)NOTE 1Ball indenters normally consist of a spherical ball and a separate appropriately designed holder. Singlepiece spherically tipped indenters are allowed, provided that the surface of the indenter that makes

SC 3, Hardness testing. This third edition cancels and replaces the second edition (ISO 6508-1:2005), which has been technically revised. ISO 6508 consists of the following parts, under the general title Metallic materials — Rockwell hardness test: — Part 1: Test method — Part 2: Verification and calibration of testing machines and indenters — Part 3: Calibration of reference blocks iv .