INTERNATIONAL ISO

STANDARD 6506-1

First edition
1999-09-01

Metallic materials — Brinell hardness

test —
Part 1:
Test method
Matériaux métalliques — Essai de dureté Brinell —
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Partie 1: Méthode d'essai
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ISO 6506-1:1999
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A Reference number
ISO 6506-1:1999(E)
ISO 6506-1:1999(E)

Contents

1 Scope ........................................................................................................................................................................ 1

2 Normative references .............................................................................................................................................. 1

3 Principles.................................................................................................................................................................. 1

4 Symbols and designations ..................................................................................................................................... 1

5 Testing machine....................................................................................................................................................... 3

6 Test piece ................................................................................................................................................................. 3

7 Procedure ................................................................................................................................................................. 3

8 Uncertainty of the results ....................................................................................................................................... 5

9 Test report ................................................................................................................................................................ 6

Annex A (informative) Procedure for periodic checks of the testing machines by the user............................... 7
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Annex B (normative) Minimum thickness of the test piece in relation to the mean diameter of indentation.... 8
(standards.iteh.ai)
Annex C (normative) Determination of the Brinell hardness for testing on flat surfaces ................................... 9
ISO 6506-1:1999
Bibliography ..............................................................................................................................................................
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© ISO 1999
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case postale 56 • CH-1211 Genève 20 • Switzerland
Internet iso@iso.ch
Printed in Switzerland

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© ISO ISO 6506-1:1999(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.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.

Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.

International Standard 6506-1 was prepared by the Technical Committee ISO/TC 164, Mechanical testing of metals,
Subcommittee SC 3, Hardness testing.

This first edition of ISO 6506-1 cancels and replaces ISO 6506:1981 and ISO 410:1982, of which it constitutes a
technical revision as follows:

 Deletion of the steel ball indenter.


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Integration of the table for the determination of Brinell hardness values for use in tests made on flat surfaces
(standards.iteh.ai)
(ISO 410:1982) into annex C of this part of ISO 6506.

 Deletion of the 2 mm ball indenter.

ISO 6506-1:1999
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 Addition of annex A concerning a procedure for periodic checks of the testing machines by the user.
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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

Annexes B and C form a normative part of this part of ISO 6506. Annex A is for information only.

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ISO 6506-1:1999(E) © ISO

Introduction

The force values in this part of ISO 6506 were calculated from kilogram force values. They were introduced before
the SI-system was adopted. It was decided to keep the values based on the old units for this part of ISO 6506 but
for the next revision it will be necessary to consider the advantage of introducing rounded values of test force and
possible consequences on the hardness scales.

Attention is drawn to the fact that in this part of ISO 6506, only the use of the hardmetal ball indenter is specified.

The designation of the Brinell hardness is HBW and should not be confused with the former designation HB, or HBS
when a steel ball indenter was used.

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INTERNATIONAL STANDARD © ISO ISO 6506-1:1999(E)

Metallic materials — Brinell hardness test —

Part 1:
Test method

1 Scope

This part of ISO 6506 specifies the method for the Brinell hardness test for metallic materials and is applicable up
to the limit of 650 HBW.

For specific materials and/or products, particular International Standards exist (i.e. ISO 4498-1).

2 Normative references

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The following normative documents contain provisions which, through reference in this text, constitute provisions of this
part of ISO 6506. For dated references, subsequent amendments to, or revisions of, any of these publications do not
(standards.iteh.ai)
apply. However, parties to agreements based on this part of ISO 6506 are encouraged to investigate the possibility of
applying the most recent editions of the normative documents indicated below. For undated references, the latest
edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid
International Standards. ISO 6506-1:1999
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ISO 4498-1, Sintered metal materials, excluding hardmetals — Determination of apparent hardness — Part 1:
Materials of essentially uniform section hardness.

ISO 6506-2:1999, Metallic materials — Brinell hardness test — Part 2: Verification and calibration of testing
machines.

3 Principles

An indenter (hardmetal ball with diameter D) is forced into the surface of a test piece and the diameter of the
indentation d left in the surface after removal of the force F is measured.

The Brinell hardness is proportional to the quotient obtained by dividing the test force by the curved surface area of
the indentation. The indentation is assumed to be spherical with a radius corresponding to half of the diameter of
the ball.

4 Symbols and designations

See Figure 1 and Table 1.

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ISO 6506-1:1999(E) © ISO

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Figure 1 — Principle of test

ISO 6506-1:1999
Table 1 — Symbols and designations
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Symbol 9b60-bfa435d94728/iso-6506-1-1999
Designation Unit
D Diameter of the ball mm
F Test force N
d Mean diameter of the indentation mm

 d1 + d 2 
d = 
 2 

d1, d2 Indentation diameters measured at 90° mm

h Depth of indentation mm

D − D2 − d 2
=
2
HBW Brinell hardness
Test force
= Constant ×
Surface area of indentation

2F
= 0,102 ×
(
pD D − D2 − d 2 )
0,102 ¥ F/D2 force-diameter ratio N/mm2

NOTE
1 1
Constant = = = 0,102
gn 9,806 65
gn = acceleration due to gravity

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© ISO ISO 6506-1:1999(E)

4.1 The Brinell hardness is denoted by HBW.

NOTE In former standards, in cases when a steel ball had been used, the Brinell hardness was denoted by HB or HBS.

4.2 The letters HBW are preceded by the hardness value and supplemented by an index indicating the test
conditions in the order:

a) the diameter of the ball, in millimetres;

b) a figure representing the test force (see Table 2);

c) the duration of application of test force, in seconds, if different from the specified time (see 7.5).

EXAMPLE 1 350 HBW 5/750 = Brinell hardness of 350 determined with a ball of 5 mm diameter and with a test force of
7,355 kN applied for 10 s to 15 s.

EXAMPLE 2 600 HBW 1/30/20 = Brinell hardness of 600 determined with a ball of 1 mm diameter and with a test force of
294,2 N applied for 20 s.

5 Testing machine

5.1 Testing machine, capable of applying a predetermined test force or forces within the range of 9,807 N to
29,42 kN in accordance with ISO 6506-2.

5.2 Indenter, a polished hardmetal ball, as specified in ISO 6506-2.

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5.3 Measuring device, as specified in ISO 6506-2.

NOTE
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A suggested procedure for periodic checks by the user is given in annex A.
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6 Test piece 9b60-bfa435d94728/iso-6506-1-1999
6.1 The test shall be carried out on a surface which is smooth and even, free from oxide scale, foreign matter and,
in particular, free from lubricants. The test piece shall have a surface finish that will allow an accurate measurement
of the diameter of the indentation.

6.2 Preparation shall be carried out in such a way that any alteration of the surface, for example due to heat- or
cold-working, is minimized.

6.3 The thickness of the test piece shall be at least eight times the depth of indentation. Values for the minimum
thickness of the test piece in relation to the mean diameter of indentation are given in annex B.

Visible deformation at the back of the test piece can indicate that the test piece is too thin.

7 Procedure

7.1 In general, the test is to be carried out at ambient temperature within the limits of 10 °C to 35 °C. Tests carried
out under controlled conditions shall be made at a temperature of (23 ± 5) °C.

7.2 The test forces given in Table 2 shall be used.

7.3 The test force shall be chosen so that the diameter of the indentation d lies between the values 0,24 D and
0,6 D.

The force-diameter ratio (0,102 ¥ F/D2) shall be chosen according to the material and the hardness test as indicated
in Table 3.

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ISO 6506-1:1999(E) © ISO

In order to test the largest representative area of the test piece, the diameter of the testing ball shall be chosen to be
as large as possible.

When the thickness of the test piece permits, a 10 mm diameter ball is preferred.

7.4 The test piece shall be placed on a rigid support. The contact surfaces shall be clean and free from foreign
matter (scale, oil, dirt, etc). It is important that the test piece lie firmly on the support so that displacement cannot
occur during the test.

7.5 Bring the indenter into contact with the test surface and apply the test force in a direction perpendicular to the
surface, without shock, vibration or overrun, until the applied force attains the specified value. The time from the
initial application of force to the time the full test force is reached shall not be less than 2 s nor greater than 8 s.
Maintain the test force for 10 s to 15 s. For certain materials, where a longer dwell time is required; this time shall be
applied with a tolerance of ± 2 s.

7.6 Throughout the test, the testing machine shall be protected from significant shock or vibration which can
influence the test result.

7.7 The distance from the edge of the test piece to the centre of each indentation shall be a minimum of two and a
half times the mean indentation diameter.

The distance between the centres of two adjacent indentations shall be at least three times the mean indentation
diameter.

Table 2 — Test forces for the different testing conditions

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Hardness symbol Ball diameter
PREVIEW
Force-diameter Nominal value of
(standards.iteh.ai) ratio test force
D 0,102 ¥ F/D2 F
ISO
mm 6506-1:1999 N/mm2 N
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HBW 10/3 000 10 30 29 420
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HBW 10/1 500 10 15 14 710
HBW 10/1 000 10 10 9 807
HBW 10/500 10 5 4 903
HBW 10/250 10 2,5 2 452
HBW 10/100 10 1 980,7

HBW 5/750 5 30 7 355

HBW 5/250 5 10 2 452
HBW 5/125 5 5 1 226
HBW 5/62,5 5 2,5 612,9
HBW 5/25 5 1 245,2

HBW 2,5/187,5 2,5 30 1 839

HBW 2,5/62,5 2,5 10 612,9
HBW 2,5/31,25 2,5 5 306,5
HBW 2,5/15,625 2,5 2,5 153,2
HBW 2,5/6,25 2,5 1 61,29

HBW 1/30 1 30 294,2

HBW 1/10 1 10 98,07
HBW 1/5 1 5 49,03
HBW 1/2,5 1 2,5 24,52
HBW 1/1 1 1 9,807

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© ISO ISO 6506-1:1999(E)

Table 3 — The force-diameter ratio for different metallic materials

Material Brinell hardness Force-diameter ratio

HBW 0,102 ¥ F/D2
N/mm2

Steel - Nickel alloys

30
Titanium alloys
Cast irona ⬍ 140 10
肁 140 30
⬍ 35 5
Copper and copper alloys 35 to 200 10
⬎ 200 30
⬍ 35 2,5
5
Light metals and their alloys 35 to 80 10
15
10
⬎ 80
15
Lead, tin 1
Sintered metal See ISO 4498-1

a
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For the testing of cast iron the nominal diameter of the ball shall be 2,5 mm,
5 mm or 10 mm. (standards.iteh.ai)
ISO 6506-1:1999
7.8 Measure the diameter https://standards.iteh.ai/catalog/standards/sist/b68590d5-4963-4c26-
of each indentation in two directions perpendicular to each other. The arithmetic mean
of the two readings shall be taken for the9b60-bfa435d94728/iso-6506-1-1999
calculation of the Brinell hardness.

NOTE For some testing machines, the following should be used:

 the average of a greater number of symmetrically placed measurements;

 an assessment of the projected indentation area into the material surface.

7.9 Table C.1 (see annex C) contains calculation tables which shall be used to determine the Brinell hardness for
tests on flat surfaces.

8 Uncertainty of the results

The uncertainty of results is dependent on various parameters which may be separated into two categories:

a) parameters dependent on the Brinell hardness testing machine (including the uncertainty of the verification of
the testing machine and on the calibration of the reference blocks);

b) parameters dependent on the application of the test method (variation of the operating conditions).

NOTE A complete evaluation of the uncertainty should be carried out according to the Guide to the Expression of
Uncertainty in Measurement [ 1]. Indicative values of the extended uncertainty at a confidence level of 95 % can be taken to be
equal to the maximum permissible error given in Table 2 of ISO 6506-2:1999.

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ISO 6506-1:1999(E) © ISO

9 Test report

The test report shall include the following information:

a) a reference to this International Standard, i.e. ISO 6506-1;

b) all details necessary for the complete identification of the test piece;

c) the test temperature if it is not within the limits (23 ± 5) °C;

d) the result obtained;

e) additional requirements outside the scope of this part of ISO 6506;

f) details of any occurrence which may have affected the result.

NOTE 1 There is no general process of accurately converting Brinell hardness into other scales of hardness or into tensile
strength. These conversions should therefore be avoided, unless a reliable basis for the conversion can be obtained by
comparative tests.

NOTE 2 It should be noted that for anisotropic materials, for example those which have been heavily cold-worked, there may
be a difference between the lengths of the two diameters of the indentation. The specification for the product may indicate
limits for such differences.

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© ISO ISO 6506-1:1999(E)

Annex A
(informative)

Procedure for periodic checks of the testing machines by the user

The indirect verification procedure is too time consuming and costly for routine checking. The following procedure is
recommended for this purpose.

Make at least one periodic check of the testing machine each day that it is used.

Before making the check, make at least two preliminary indentations to ensure that the test piece, indenter and anvil
are seated correctly. The results of these preliminary indentations should be ignored.

Make at least one hardness indentation on a reference block with approximately the same hardness as the material
being tested. If the difference between mean value of the hardness readings of the test material and the hardness of
the reference block are within the limits given in Table 2 of ISO 6506-2:1999, the machine may be regarded as
satisfactory. If not, an indirect verification should be performed.

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