Metallic materials - Brinell hardness test - Part 2: Verification and calibration of testing machines (ISO 6506-2:2017)

This document specifies methods of direct and indirect verification of testing machines used for
determining Brinell hardness in accordance with ISO 6506-1 and also specifies when these two types of
verification have to be performed.
The direct verification involves checking that individual machine performance parameters fall within
specified limits whereas the indirect verification utilizes hardness measurements of reference blocks,
calibrated in accordance with ISO 6506-3, to check the machine’s overall performance.
If a testing machine is also to be used for other methods of hardness testing, it has to be verified
independently for each method.
This document is applicable to both fixed location and portable hardness testing machines. For
machines that are incapable of satisfying the specified force-time profile, the direct verification of force
and testing cycle can be modified by the use of Annex B.

Metallische Werkstoffe - Härteprüfung nach Brinell - Teil 2: Überprüfung und Kalibrierung der Prüfmaschinen (ISO 6506-2:2017)

Matériaux métalliques - Essai de dureté Brinell - Partie 2: Vérification et étalonnage des machines d_essai (ISO 6506-2:2017)

L'ISO 6506-2 :2017 spécifie des méthodes de vérifications directe et indirecte des machines d'essai utilisées pour la détermination de la dureté Brinell conformément à l'ISO 6506‑1 et spécifie également quand ces deux types de vérification doivent être réalisées.
La vérification directe implique de contrôler que les paramètres individuels de performance de la machine se situent à l'intérieur des limites spécifiées tandis que la vérification indirecte utilise des mesurages de dureté de blocs de référence, étalonnés conformément à l'ISO 6506‑3 pour contrôler la performance globale de la machine.
Si une machine d'essai est également utilisée pour d'autres méthodes d'essai de dureté, elle doit être vérifiée indépendamment pour chaque méthode.
L'ISO 6506-2 :2017 est applicable aux machines d'essai de dureté d'implantation fixe et portables. Pour les machines ne permettant pas de respecter le profil force-temps spécifié, la vérification directe de la force et du cycle d'essai peut être modifiée en utilisant l'Annexe B.

Kovinski materiali - Preskus trdote po Brinellu - 2. del: Preverjanje in umerjanje naprav za preskušanje (ISO 6506-2:2017)

Ta dokument določa metode neposrednega in posrednega preverjanja naprav za preskušanje, ki se uporabljajo za ugotavljanje trdote po Brinellu v skladu s standardom ISO 6506-1, ter določa tudi, kdaj je treba ti dve vrsti preverjanja izvesti.
Neposredno preverjanje vključuje preverjanje, da posamezni parametri delovanja naprave ne presegajo določenih mejnih vrednosti, medtem ko posredno preverjanje temelji na meritvah trdote referenčnih ploščic, umerjenih v skladu s standardom ISO 6506-3, da se preveri splošno delovanje naprave.
Če se naprava za preskušanje uporablja tudi za druge metode preskusa trdote, jo je treba preveriti posebej za vsako metodo.
Ta dokument se uporablja za nepremične in premične naprave za preskušanje trdote. Za naprave, ki ne morejo izpolnjevati določenega profila sila/čas, je mogoče neposredno preverjanje sile in preskusnega cikla spremeniti z uporabo dodatka B.

General Information

Status
Published
Public Enquiry End Date
29-Sep-2016
Publication Date
16-Jan-2019
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
15-Jan-2019
Due Date
22-Mar-2019
Completion Date
17-Jan-2019

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Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN ISO 6506-2:2019
01-marec-2019
1DGRPHãþD
SIST EN ISO 6506-2:2014
Kovinski materiali - Preskus trdote po Brinellu - 2. del: Preverjanje in umerjanje
naprav za preskušanje (ISO 6506-2:2017)
Metallic materials - Brinell hardness test - Part 2: Verification and calibration of testing
machines (ISO 6506-2:2017)
Metallische Werkstoffe - Härteprüfung nach Brinell - Teil 2: Überprüfung und Kalibrierung
der Prüfmaschinen (ISO 6506-2:2017)
Matériaux métalliques - Essai de dureté Brinell - Partie 2: Vérification et étalonnage des
machines d_essai (ISO 6506-2:2017)
Ta slovenski standard je istoveten z: EN ISO 6506-2:2018
ICS:
77.040.10 Mehansko preskušanje kovin Mechanical testing of metals
SIST EN ISO 6506-2:2019 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 6506-2:2019

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SIST EN ISO 6506-2:2019


EN ISO 6506-2
EUROPEAN STANDARD

NORME EUROPÉENNE

December 2018
EUROPÄISCHE NORM
ICS 77.040.10 Supersedes EN ISO 6506-2:2014
English Version

Metallic materials - Brinell hardness test - Part 2:
Verification and calibration of testing machines (ISO 6506-
2:2017)
Matériaux métalliques - Essai de dureté Brinell - Partie Metallische Werkstoffe - Härteprüfung nach Brinell -
2: Vérification et étalonnage des machines d'essai (ISO Teil 2: Überprüfung und Kalibrierung der
6506-2:2017) Prüfmaschinen (ISO 6506-2:2017)
This European Standard was approved by CEN on 10 December 2018.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and United Kingdom.





EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 6506-2:2018 E
worldwide for CEN national Members.

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SIST EN ISO 6506-2:2019
EN ISO 6506-2:2018 (E)
Contents Page
European foreword . 3

2

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SIST EN ISO 6506-2:2019
EN ISO 6506-2:2018 (E)
European foreword
This document (EN ISO 6506-2:2018) has been prepared by Technical Committee ISO/TC 164
"Mechanical testing of metals" in collaboration with Technical Committee ECISS/TC 101 “Test methods
for steel (other than chemical analysis)” the secretariat of which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by June 2019, and conflicting national standards shall be
withdrawn at the latest by June 2019.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 6506-2:2014.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 6506-2:2017 has been approved by CEN as EN ISO 6506-2:2018 without any
modification.


3

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SIST EN ISO 6506-2:2019

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SIST EN ISO 6506-2:2019
INTERNATIONAL ISO
STANDARD 6506-2
Fourth edition
2017-10
Metallic materials — Brinell
hardness test —
Part 2:
Verification and calibration of testing
machines
Matériaux métalliques — Essai de dureté Brinell —
Partie 2: Vérification et étalonnage des machines d'essai
Reference number
ISO 6506-2:2017(E)
©
ISO 2017

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SIST EN ISO 6506-2:2019
ISO 6506-2:2017(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2017, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2017 – All rights reserved

---------------------- Page: 8 ----------------------

SIST EN ISO 6506-2:2019
ISO 6506-2:2017(E)

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General conditions . 1
5 Direct verification . 2
5.1 General . 2
5.2 Measurement of the test forces . 2
5.3 Measurement of the properties of the indenter ball . 3
5.4 Calibration of the indentation diameter measuring system . 3
5.5 Verification of the testing cycle . 4
6 Indirect verification . 4
7 Intervals between verifications . 6
8 Verification report/calibration certificate . 6
Annex A (informative) Uncertainty of measurement of the verification results of the
hardness testing machine . 8
Annex B (normative) Verification of hardness testing machines that are incapable of
meeting the specified force/time profile .15
Bibliography .16
© ISO 2017 – All rights reserved iii

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SIST EN ISO 6506-2:2019
ISO 6506-2:2017(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, 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 of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial 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 of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the 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 not
constitute an endorsement.
For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 164, Mechanical testing of metals,
Subcommittee SC 3, Hardness testing.
This fourth edition cancels and replaces the third edition (ISO 6506-2:2014), which has been technically
revised.
The main changes compared to the previous edition are as follows:
— Clause 3 has been added;
— Table 3 has been modified.
A list of all parts in the ISO 6506 series can be found on the ISO website.
iv © ISO 2017 – All rights reserved

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SIST EN ISO 6506-2:2019
INTERNATIONAL STANDARD ISO 6506-2:2017(E)
Metallic materials — Brinell hardness test —
Part 2:
Verification and calibration of testing machines
1 Scope
This document specifies methods of direct and indirect verification of testing machines used for
determining Brinell hardness in accordance with ISO 6506-1 and also specifies when these two types of
verification have to be performed.
The direct verification involves checking that individual machine performance parameters fall within
specified limits whereas the indirect verification utilizes hardness measurements of reference blocks,
calibrated in accordance with ISO 6506-3, to check the machine’s overall performance.
If a testing machine is also to be used for other methods of hardness testing, it has to be verified
independently for each method.
This document is applicable to both fixed location and portable hardness testing machines. For
machines that are incapable of satisfying the specified force-time profile, the direct verification of force
and testing cycle can be modified by the use of Annex B.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 376, Metallic materials — Calibration of force-proving instruments used for the verification of uniaxial
testing machines
ISO 6506-1:2014, Metallic materials — Brinell hardness test — Part 1: Test method
ISO 6506-3, Metallic materials — Brinell hardness test — Part 3: Calibration of reference blocks
ISO 6507-1, Metallic materials — Vickers hardness test — Part 1: Test method
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at https://www.iso.org/obp
4 General conditions
Before a Brinell hardness testing machine is verified, the machine shall be checked to ensure that it is
properly set up in accordance with the manufacturer's instructions.
© ISO 2017 – All rights reserved 1

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SIST EN ISO 6506-2:2019
ISO 6506-2:2017(E)

Especially, it should be checked that:
a) the mount holding the ball-holder slides correctly in its guide;
b) every ball-holder with a ball used during the calibration is firmly held in the mount;
c) the test force is applied and removed without shock, vibration, or overrun and in such a manner
that the readings are not influenced; and
d) if the indentation diameter measuring system is integrated into the machine,
— the change from removing the test force to measuring mode does not influence the diameter
measurements,
— the illumination does not affect the diameter measurements, and
— the centre of the indentation is in the centre of the field of view, if necessary.
5 Direct verification
5.1 General
5.1.1 Direct verification should be carried out at a temperature of (23 ± 5) °C. If the verification is
made outside this temperature range, this shall be reported in the verification report.
5.1.2 The instruments used for verification shall be traceable to the SI.
5.1.3 Direct verification involves:
a) measurement of the test forces;
b) measurement of the diameter, hardness, and density of the indenter ball;
c) calibration of the indentation diameter measuring system; and
d) measurement of the testing cycle.
For each of the above items, direct verification also includes assessment of the results against the
specified tolerances.
5.2 Measurement of the test forces
5.2.1 Each test force shall be measured within the working range of the testing machine. When the
force is applied in open-loop mode by a lever or other system employing a mechanical advantage, this
shall be done at no fewer than three positions of the indenter uniformly spaced throughout its range of
movement during testing.
5.2.2 Three measurements shall be made for each force at each position of the indenter. Immediately
before each measurement is taken, the indenter shall be moved in the same direction as during testing.
5.2.3 The force shall be measured by one of the following two methods:
— by means of a force-proving instrument in accordance with ISO 376 Class 1 or better;
— by balancing against a force, accurate to ±0,2 %, applied by means of calibrated masses or another
method with the same accuracy.
2 © ISO 2017 – All rights reserved

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SIST EN ISO 6506-2:2019
ISO 6506-2:2017(E)

5.2.4 Each measurement of a force shall be within ±1,0 % of the nominal test force [see Formula (A.2)],
as defined in ISO 6506-1.
5.3 Measurement of the properties of the indenter ball
5.3.1 The indenter consists of a ball and an indenter holder. The verification applies only to the ball.
5.3.2 For the purpose of verifying the size and the hardness of the balls, a minimum of two balls,
selected at random from a batch, shall be tested. Each sampled ball shall be verified for size and hardness
and then discarded.
5.3.3 The balls shall be polished and free from surface defects.
5.3.4 The user shall either measure the balls to ensure that they meet the following requirements or
shall obtain balls from a supplier certifying that the following conditions are met.
5.3.4.1 The diameter shall be determined by taking the mean value of not less than three single values
of diameter measured at different positions on the ball. No single value shall differ from the nominal
diameter by more than the tolerance given in Table 1.
Table 1 — Tolerances for the different ball diameters
Ball diameter Tolerance
mm mm
10 ±0,005
5 ±0,004
2,5 ±0,003
1 ±0,003
5.3.4.2 The characteristics of the tungsten carbide composite balls shall be as follows.
a) Hardness: The hardness shall be not less than 1 500 HV, when determined in accordance with
ISO 6507-1. The tungsten carbide composite ball can be tested directly on its spherical surface or
by sectioning the ball and testing on the ball interior.
3
b) Density: ρ = (14,8 ± 0,2) g/cm .
The density can be determined from the sampled balls, prior to hardness testing, or from the whole
batch. The following chemical composition is recommended:
— tungsten carbide (WC): balance;
— total other carbides: 2,0 %;
— cobalt (Co): 5,0 % to 7,0 %.
5.4 Calibration of the indentation diameter measuring system
5.4.1 For systems where the indentation diameter is measured directly, the scale of the system
shall be graduated to permit estimation of the diameter to within ±0,5 %. The indentation diameter
measuring system shall be calibrated for every objective lens and for each incorporated line scale, in
two perpendicular measurement axes (if applicable), by measurements made on a standard scale at
a minimum of four intervals, arranged centrally in the field of view, for each working range. For each
measurement, the magnitude of the difference between the measured and reference values shall not be
greater than 0,5 % [see Formula (A.4)].
© ISO 2017 – All rights reserved 3

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SIST EN ISO 6506-2:2019
ISO 6506-2:2017(E)

5.4.2 For systems where the indentation diameter is calculated from a measurement of projected
area, the system shall be calibrated for every objective lens by measurements of a range of at least four
standard circular reference images covering the range of areas measured. The maximum error shall not
exceed 1 % of the area.
5.4.3 All systems shall also be verified by making measurements of certified reference indentations,
such as those on hardness reference blocks calibrated in accordance with ISO 6506-3. For each ball size,
at least four indentations, covering the working range of diameters, shall be measured by each objective
lens. During these measurements, the type of illumination shall remain unchanged. No mean measured
diameter shall differ from the certified mean diameter of the reference indentation by more than 0,5 %.
5.5 Verification of the testing cycle
5.5.1 The testing cycle is to be verified by the testing machine manufacturer at the time of manufacture
and when the testing machine undergoes repair which might have affected the testing cycle. Verification
of the testing cycle at other times is as specified in Table 4.
5.5.2 The testing cycle shall be verified to conform with the testing cycle defined in ISO 6506-1, taking
into account any uncertainty
...

SLOVENSKI STANDARD
oSIST prEN ISO 6506-2:2016
01-september-2016
Kovinski materiali - Preskus trdote po Brinellu - 2. del: Preverjanje in umerjanje
naprav za preskušanje (ISO/DIS 6506-2:2016)
Metallic materials - Brinell hardness test - Part 2: Verification and calibration of testing
machines (ISO/DIS 6506-2:2016)
Metallische Werkstoffe - Härteprüfung nach Brinell - Teil 2: Überprüfung und Kalibrierung
der Prüfmaschinen (ISO/DIS 6506-2:2016)
Matériaux métalliques -- Essai de dureté Brinell -- Partie 2: Vérification et étalonnage des
machines d_essai (ISO/DIS 6506-2:2016)
Ta slovenski standard je istoveten z: prEN ISO 6506-2
ICS:
77.040.10 Mehansko preskušanje kovin Mechanical testing of metals
oSIST prEN ISO 6506-2:2016 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
oSIST prEN ISO 6506-2:2016

---------------------- Page: 2 ----------------------
oSIST prEN ISO 6506-2:2016
DRAFT INTERNATIONAL STANDARD
ISO/DIS 6506-2
ISO/TC 164/SC 3 Secretariat: DIN
Voting begins on: Voting terminates on:
2016-04-28 2016-07-27
Metallic materials — Brinell hardness test —
Part 2:
Verification and calibration of testing machines
Matériaux métalliques — Essai de dureté Brinell —
Partie 2: Vérification et étalonnage des machines d’essai
ICS: 77.040.10
ISO/CEN PARALLEL PROCESSING
This draft has been developed within the International Organization for
Standardization (ISO), and processed under the ISO lead mode of collaboration
as defined in the Vienna Agreement.
This draft is hereby submitted to the ISO member bodies and to the CEN member
bodies for a parallel five month enquiry.
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
To expedite distribution, this document is circulated as received from the
IN ADDITION TO THEIR EVALUATION AS
committee secretariat. ISO Central Secretariat work of editing and text
BEING ACCEPTABLE FOR INDUSTRIAL,
composition will be undertaken at publication stage.
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 6506-2:2016(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
©
PROVIDE SUPPORTING DOCUMENTATION. ISO 2016

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oSIST prEN ISO 6506-2:2016
ISO/DIS 6506-2:2016(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2016, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2016 – All rights reserved

---------------------- Page: 4 ----------------------
oSIST prEN ISO 6506-2:2016
ISO/DIS 6506-2:2016(E)
Contents Page
Foreword . iv
1 Scope. 1
2 Normative references . 1
3 General conditions . 1
4 Direct verification. 2
4.1 General . 2
4.2 Measurement of the test forces . 2
4.3 Measurement of the properties of the indenter ball . 2
4.4 Calibration of the indentation diameter measuring system. 3
4.5 Verification of the testing cycle . 4
5 Indirect verification. 4
6 Intervals between verifications . 6
7 Verification report/calibration certificate . 6
Annex A (informative) Uncertainty of measurement of the verification results of the
hardness testing machine . 8
A.1 General . 8
A.2 Direct verification of the hardness testing machine. 8
A.2.1 Measurement of the test forces . 8
A.2.2 Calibration of the indentation diameter measuring system. 10
A.2.3 Measurement of the indenter ball. 12
A.2.4 Measurement of the testing cycle . 12
A.3 Indirect verification of the hardness testing machine. 12
A.4 Budget of uncertainty of measurement . 13
Annex B (normative) Verification of hardness testing machines that are incapable of
meeting the specified force/time profile . 15
B.1 Procedure . 15
Bibliography. 16


© ISO 2016 – All rights reserved iii

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oSIST prEN ISO 6506-2:2016
ISO/DIS 6506-2:2016(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national
standards bodies (ISO member bodies). The work of preparing International Standards is normally
carried out through ISO technical committees. Each member body interested in a subject for which a
technical committee has been established has the right to be represented on that committee.
International organizations, 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 of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial 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 of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the 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 not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO's adherence to the WTO principles in the Technical
Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 164, Mechanical testing of metals,
Subcommittee SC 3, Hardness testing.
This fourth edition cancels and replaces the third edition (ISO 6506-2:2014), which has been technically
revised.
ISO 6506 consists of the following parts, under the general title Metallic materials — Brinell
hardness test:
— Part 1: Test method
— Part 2: Verification and calibration of testing machines
— Part 3: Calibration of reference blocks
— Part 4: Table of hardness values
iv © ISO 2016 – All rights reserved

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oSIST prEN ISO 6506-2:2016
DRAFT INTERNATIONAL STANDARD ISO/DIS 6506-2:2016(E)

Metallic materials — Brinell hardness test — Part 2:
Verification and calibration of testing machines
1 Scope
This part of ISO 6506 specifies methods of direct and indirect verification of testing machines used for
determining Brinell hardness in accordance with ISO 6506 1, and also specifies when these two types of
verification has to be performed.
The direct verification involves checking that individual machine performance parameters fall within
specified limits whereas the indirect verification utilizes hardness measurements of reference blocks,
calibrated in accordance with ISO 6506 3, to check the machine’s overall performance.
If a testing machine is also to be used for other methods of hardness testing, it has to be verified
independently for each method.
This part of ISO 6506 is applicable to both fixed location and portable hardness testing machines. For
machines that are incapable of satisfying the specified force-time profile, the direct verification of force
and testing cycle can be modified by the use of Annex B.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 376, Metallic materials — Calibration of force-proving instruments used for the verification of uniaxial
testing machines
ISO 6506-1:2014, Metallic materials — Brinell hardness test — Part 1: Test method
ISO 6506-3, Metallic materials — Brinell hardness test — Part 3: Calibration of reference blocks
ISO 6507-1, Metallic materials — Vickers hardness test — Part 1: Test method
3 General conditions
Before a Brinell hardness testing machine is verified, the machine shall be checked to ensure that it is
properly set up in accordance with the manufacturer's instructions.
Especially, it should be checked that
a) the mount holding the ball-holder slides correctly in its guide,
b) every ball-holder with a ball used during the calibration is firmly held in the mount,
c) the test force is applied and removed without shock, vibration, or overrun and in such a manner
that the readings are not influenced, and
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ISO/DIS 6506-2:2016(E)
d) if the indentation diameter measuring system is integrated into the machine,
 the change from removing the test force to measuring mode does not influence the diameter
measurements,
 the illumination does not affect the diameter measurements, and
 the centre of the indentation is in the centre of the field of view, if necessary.
4 Direct verification
4.1 General
4.1.1 Direct verification should be carried out at a temperature of (23 ± 5) °C. If the verification is
made outside this temperature range, this shall be reported in the verification report.
4.1.2 The instruments used for verification shall be traceable to the SI.
4.1.3 Direct verification involves
a) measurement of the test forces,
b) measurement of the diameter, hardness, and density of the indenter ball,
c) calibration of the indentation diameter measuring system, and
d) measurement of the testing cycle.
For each of the above items, direct verification also includes assessment of the results against the
specified tolerances.
4.2 Measurement of the test forces
4.2.1 Each test force shall be measured within the working range of the testing machine. When the
force is applied in open-loop mode by a lever or other system employing a mechanical advantage, this
shall be done at no fewer than three positions of the indenter uniformly spaced throughout its range of
movement during testing.
4.2.2 Three measurements shall be made for each force at each position of the indenter. Immediately
before each measurement is taken, the indenter shall be moved in the same direction as during testing.
4.2.3 The force shall be measured by one of the following two methods:
— by means of a force-proving instrument in accordance with ISO 376 Class 1 or better;
— by balancing against a force, accurate to ±0,2 %, applied by means of calibrated masses or another
method with the same accuracy.
4.2.4 Each measurement of a force shall be within ±1,0 % of the nominal test force (see Formula A.2),
as defined in ISO 6506-1.
4.3 Measurement of the properties of the indenter ball
4.3.1 The indenter consists of a ball and an indenter holder. The verification applies only to the ball.
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4.3.2 For the purpose of verifying the size and the hardness of the balls, a minimum of two balls,
selected at random from a batch, shall be tested. Each sampled ball shall be verified for size and
hardness and then discarded.
4.3.3 The balls shall be polished and free from surface defects.
4.3.4 The user shall either measure the balls to ensure that they meet the following requirements or
shall obtain balls from a supplier certifying that the following conditions are met.
4.3.4.1 The diameter shall be determined by taking the mean value of not less than three single
values of diameter measured at different positions on the ball. No single value shall differ from the
nominal diameter by more than the tolerance given in Table 1.
Table 1 — Tolerances for the different ball diameters
Ball diameter Tolerance
mm mm
10 ±0,005
5 ±0,004
2,5 ±0,003
1 ±0,003
4.3.4.2 The characteristics of the tungsten carbide composite balls shall be as follows:
a) Hardness: The hardness shall be not less than 1 500 HV, when determined in accordance with
ISO 6507-1. The tungsten carbide composite ball can be tested directly on its spherical surface or
by sectioning the ball and testing on the ball interior.
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b) Density: ρ = (14,8 ± 0,2) g/cm .
The density can be determined from the sampled balls, prior to hardness testing, or from the whole
batch. The following chemical composition is recommended:
— tungsten carbide (WC): balance;
— total other carbides: 2,0 %;
— cobalt (Co): 5,0 % to 7,0 %.
4.4 Calibration of the indentation diameter measuring system
4.4.1 For systems where the indentation diameter is measured directly, the scale of the system shall
be graduated to permit estimation of the diameter to within ±0,5 %. The indentation diameter
measuring system shall be calibrated for every objective lens, and for each incorporated line scale, in
two perpendicular measurement axes (if applicable), by measurements made on a standard scale at a
minimum of four intervals, arranged centrally in the field of view, for each working range. For each
measurement, the magnitude of the difference between the measured and reference values shall not be
greater than 0,5 % (see Formula A.7).
4.4.2 For systems where the indentation diameter is calculated from a measurement of projected area,
the system shall be calibrated for every objective lens by measurements of a range of at least four
standard circular reference images covering the range of areas measured. The maximum error shall not
exceed 1 % of the area.
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4.4.3 All systems shall also be verified by making measurements of certified reference indentations,
such as those on hardness reference blocks calibrated in accordance with ISO 6506-3. For each ball size,
at least four indentations, covering the working range of diameters, shall be measured by each objective
lens. During these measurements, the type of illumination shall remain unchanged. No mean measured
diameter shall differ from the certified mean diameter of the reference indentation by more than 0,5 %.
4.5 Verification of the testing cycle
4.5.1 The testing cycle is to be verified by the testing machine manufacturer at the time of
manufacture and when the testing machine undergoes repair which might have affected the testing
cycle. Verification of the testing cycle at other times is as specified in Table 4.
4.5.2 The testing cycle shall be verified to conform with the testing cycle defined in ISO 6506-1, taking
into account any uncertainty associated with the timing measurements.
5 Indirect verification
5.1 Indirect verification should be carried out at a temperature of (23 ± 5) °C by means of reference
blocks calibrated in accordance with ISO 6506-3. If the verification is made outside of this temperature
range, this shall be reported in the verification report.
The test and bottom surfaces of the reference blocks and the surfaces of indenters shall not contain any
additives or corrosion products.
5.2 The testing machine shall be verified for each test force and for each size of ball used. For each test
force, at least two reference blocks shall be selected from the hardness ranges specified in Table 2 (for
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0,102 × F/D = 30) and Table 3 (for other force-diameter indices).
The two reference blocks shall be taken from different hardness ranges, if possible.
5.3 If this indirect verification is not the one immediately following a direct verification, the reference
indentation on each reference block shall be measured, with the same type of illumination that was
u
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