oSIST prEN ISO 4545-1:2022

Metallic materials - Knoop hardness test - Part 1: Test method (ISO/DIS 4545-1:2022)

ISO 4545-1:2017 specifies the Knoop hardness test method for metallic materials for test forces from 0,009 807 N to 19,613 N.
The Knoop hardness test is specified in this document for lengths of indentation diagonals ≥0,020 mm. Using this method to determine Knoop hardness from smaller indentations is outside the scope of this document as results would suffer from large uncertainties due to the limitations of optical measurement and imperfections in tip geometry. ISO 14577-1 allows the determination of hardness from smaller indentations.
A periodic verification method is specified for routine checking of the testing machine in service by the user.
Special considerations for Knoop testing of metallic coatings can be found in ISO 4516.

Metallische Werkstoffe – Härteprüfung nach Knoop – Teil1: Prüfverfahren (ISO/DIS 4545-1:2022)

Matériaux métalliques - Essai de dureté Knoop - Partie 1: Méthode d'essai (ISO/DIS 4545-1:2022)

ISO 4545-1:2017 spécifie la méthode d'essai de dureté Knoop pour les matériaux métalliques, pour des forces d'essai comprises entre 0,009 807 N et 19,613 N.
Le présent document spécifie l'essai de dureté Knoop pour les longueurs de diagonale d'empreinte ≥ 0,020 mm. L'utilisation de cette méthode pour déterminer la dureté Knoop d'empreintes plus petites ne fait pas partie du domaine d'application du présent document, car les résultats ainsi obtenus présenteraient des incertitudes élevées en raison des limitations du mesurage optique et des imperfections concernant la géométrie de la pointe. L'ISO 14577‑1 permet de déterminer la dureté des empreintes plus petites.
Une méthode de vérification périodique est spécifiée pour la vérification de routine, par l'utilisateur, de la machine d'essai utilisée.
Des considérations particulières pour les essais Knoop des revêtements métalliques sont disponibles dans l'ISO 4516.

Kovinski materiali - Preskus trdote po Knoopu - 1. del: Preskusna metoda (ISO/DIS 4545-1:2022)

General Information

• Status: Not Published
• Public Enquiry End Date: 03-Oct-2022
• ICS: 77.040.10 - Mechanical testing of metals
• Technical Committee: PKG - Testing of metallic materials
• Current Stage: 4020 - Public enquire (PE) (Adopted Project)
• Start Date: 05-Sep-2022
• Due Date: 23-Jan-2023
• Ref Project: prEN ISO 4545-1 - Metallic materials - Knoop hardness test - Part 1: Test method (ISO/DIS 4545-1:2022)

RELATIONS

• Revised: SIST EN ISO 4545-1:2018 - Metallic materials - Knoop hardness test - Part 1: Test method (ISO 4545-1:2017)
• Effective Date: 20-Oct-2021

Standards Content (sample)

SLOVENSKI STANDARD
oSIST prEN ISO 4545-1:2022
01-oktober-2022

Kovinski materiali - Preskus trdote po Knoopu - 1. del: Preskusna metoda (ISO/DIS

4545-1:2022)

Metallic materials - Knoop hardness test - Part 1: Test method (ISO/DIS 4545-1:2022)

Metallische Werkstoffe – Härteprüfung nach Knoop – Teil1: Prüfverfahren (ISO/DIS 4545

-1:2022)

Matériaux métalliques - Essai de dureté Knoop - Partie 1: Méthode d'essai (ISO/DIS

4545-1:2022)
Ta slovenski standard je istoveten z: prEN ISO 4545-1
ICS:
77.040.10 Mehansko preskušanje kovin Mechanical testing of metals
oSIST prEN ISO 4545-1:2022 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO 4545-1:2022
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oSIST prEN ISO 4545-1:2022
DRAFT INTERNATIONAL STANDARD
ISO/DIS 4545-1
ISO/TC 164/SC 3 Secretariat: DIN
Voting begins on: Voting terminates on:
2022-07-13 2022-10-05
Metallic materials — Knoop hardness test —
Part 1:
Test method
Matériaux métalliques — Essai de dureté Knoop —
Partie 1: Méthode d'essai
ICS: 77.040.10
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oSIST prEN ISO 4545-1:2022
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DRAFT INTERNATIONAL STANDARD
ISO/DIS 4545-1
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Voting begins on: Voting terminates on:
Metallic materials — Knoop hardness test —
Part 1:
Test method
Matériaux métalliques — Essai de dureté Knoop —
Partie 1: Méthode d'essai
ICS: 77.040.10
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oSIST prEN ISO 4545-1:2022
ISO/DIS 4545-1:2022(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

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

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

3 Terms and definitions .................................................................................................................................................................................... 1

4 Principle ........................................................................................................................................................................................................................ 1

5 Symbols and designations ......................................................................................................................................................................... 2

5.1 Symbols and designations used in this document .................................................................................................. 2

5.2 Designation of hardness number ........................................................................................................................................... 3

6 Testing machine....................................................................................................................................................................................................3

6.1 Testing machine ..................................................................................................................................................................................... 3

6.2 Indenter ......... .................................................................................................................................. .............................................................. 3

6.3 Diagonal measuring system ....................................................................................................................................................... 3

7 Test piece ..................................................................................................................................................................................................................... 4

7.1 Test Surface ............................................................................................................................................................................................... 4

7.2 Preparation ................................................................................................................................................................................................ 4

7.3 Thickness ..................................................................................................................................................................................................... 4

7.4 Support of unstable test pieces ................................................................................................................................................ 4

7.5 Metallic and other inorganic coatings ............................................................................................................................... 4

8 Procedure ....................................................................................................................................................................................................................5

8.1 Test temperature .................................................................................................................................................................................. 5

8.2 Test force ........................................................................................................................................... ........................................................... 5

8.3 Periodic verification .......................................................................................................................................................................... 5

8.4 Test piece support ................................................................................................................................................................................ 5

8.5 Focus on test surface ......................................................................................................................................................................... 5

8.6 Test force application ........................................................................................................................................................................ 6

8.7 Prevention of the effect of shock or vibration ............................................................................................................ 6

8.8 Minimum distance between adjacent indentations .............................................................................................. 6

8.9 Measurement of diagonal length ............................................................................................................................................ 7

8.10 Calculation of hardness value ................................................................................................................................................... 7

9 Uncertainty of the results .......................................................................................................................................................................... 7

10 Test report .................................................................................................................................................................................................................. 7

Annex A (normative) Procedure for periodic checking of the testing machine, diagonal

measuring system and the indenter by the user ............................................................................................................... 9

Annex B (informative) Uncertainty of the measured hardness values .......................................................................11

Annex C (informative) Knoop hardness measurement traceability ...............................................................................18

Annex D (informative) CCM — Working group on hardness ...................................................................................................22

Annex E (informative) Adjustment of Köhler illumination systems ...............................................................................23

Annex F (normative) Determining the Knoop hardness of metallic and other inorganic

coatings .......................................................................................................................................................................................................................24

Bibliography .............................................................................................................................................................................................................................28

iii
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oSIST prEN ISO 4545-1:2022
ISO/DIS 4545-1:2022(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 third edition cancels and replaces the second edition (ISO 4545-1:2017), which has been technically

revised.
The main changes compared to the previous edition are as follows:

— the scope is revised to include testing on metallic coatings and other inorganic coatings;

— add clause 7.5 Metallic and other inorganic coatings;
— add Annexe F to cover coatings specific requirements, to replace ISO 4516;
— update the references through the whole document.
A list of all parts in the ISO 4545 series can be found on the ISO website.
© ISO 2022 – All rights reserved
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oSIST prEN ISO 4545-1:2022
DRAFT INTERNATIONAL STANDARD ISO/DIS 4545-1:2022(E)
Metallic materials — Knoop hardness test —
Part 1:
Test method
1 Scope

This document specifies the Knoop hardness test method for metallic materials for test forces from

0,009 807 N to 19,613 N.

The Knoop hardness test is specified in this document for length of the long diagonal ≥0,020 mm.

Using this method to determine Knoop hardness from smaller indentations is outside the scope

of this document as results would suffer from large uncertainties due to the limitations of optical

measurement and imperfections in tip geometry. The Knoop hardness test specified in this document

is also applicable for metallic and other inorganic coatings. ISO 14577-1 allows the determination of

hardness from smaller indentations.

A periodic verification method is specified for routine checking of the testing machine in service by the

user.
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 4545-2:2017, Metallic materials — Knoop hardness test — Part 2: Verification and calibration of

testing machines

ISO 4545-3:2017, Metallic materials — Knoop hardness test — Part 3: Calibration of reference blocks

ISO 4545-4:2017, Metallic materials — Knoop hardness test — Part 4: Table of hardness values

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 https:// www .electropedia .org/
— ISO Online browsing platform: available at https:// www .iso .org/ obp
4 Principle

A diamond indenter, in the form of a rhombic-based pyramid with angles, α and β, between opposite

edges respectively equal to 172,5° and 130° at the vertex, is forced into the surface of a test piece

followed by measurement of the long diagonal, d, of the indentation remaining in the surface after

removal of the test force, F (see Figures 1 and 2).
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oSIST prEN ISO 4545-1:2022
ISO/DIS 4545-1:2022(E)
Figure 1 — Principle of the test and indenter geometry
Figure 2 — Knoop indentation

The Knoop hardness is proportional to the quotient obtained by dividing the test force by the projected

area of the indentation, which is assumed to be a rhombic-based pyramid, and having at the vertex the

same angles as the indenter.

NOTE As applicable, this test document has adopted hardness test parameters as defined by the working

group on hardness (CCM-WGH) under the framework of the International Committee of Weights and Measures

(CIPM) Consultative Committee for Mass and Related Quantities (CCM) (see Annex D).

5 Symbols and designations
5.1 Symbols and designations used in this document
See Table 1 and Figures 1 and 2.
Table 1 — Symbols and designations
Symbol Designation
F Test force, in newtons (N)
d Length of the long diagonal, in millimetres
d Length of the short diagonal, in millimetres

α Angle between the opposite edges of the long diagonal at the vertex of the diamond pyramid

indenter (nominally 172,5°) (see Figure 1)

β Angle between the opposite edges of the short diagonal at the vertex of the diamond pyramid

(nominally 130°) (see Figure 1)
V Magnification of the measuring system

NOTE Standard acceleration due to gravity, g = 9,806 65 m/s , which is the conversion factor from kgf to N.

To reduce uncertainty, the Knoop hardness can be calculated using the actual indenter angles α and β.

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oSIST prEN ISO 4545-1:2022
ISO/DIS 4545-1:2022(E)
Table 1 (continued)
Symbol Designation

c Indenter constant, relating projected area of the indentation to the square of the length of the

long diagonal
tan
Indenter constant, c= , for nominal angles α and β, c is approximately 0,070 28
2tan
Test force (kgf)
Knoop hardness
Projected area of indentation (mm )
1 Test force (N)
n Projected area of indentation (mm )
1 F
n cd
For the nominal indenter constant c ≈ 0,070 28,
Knoop hardness ≈×1,451

NOTE Standard acceleration due to gravity, g = 9,806 65 m/s , which is the conversion factor from kgf to N.

To reduce uncertainty, the Knoop hardness can be calculated using the actual indenter angles α and β.

5.2 Designation of hardness number
Knoop hardness, HK, is designated as shown in the following example.
6 Testing machine
6.1 Testing machine

The testing machine shall be capable of applying a predetermined force or forces within the desired

range of test forces, in accordance with ISO 4545-2.
6.2 Indenter

The indenter shall be a diamond in the shape of a rhombic-based pyramid, as specified in ISO 4545-2.

6.3 Diagonal measuring system
The diagonal measuring system shall satisfy the requirements in ISO 4545-2.
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oSIST prEN ISO 4545-1:2022
ISO/DIS 4545-1:2022(E)

Magnifications should be provided so that the diagonal can be enlarged to greater than 25 % but less

than 75 % of the maximum possible optical field of view. Many objective lenses are non-linear towards

the edge of the field of view.

NOTE A diagonal measuring system using a camera for measurement can use 100 % of the camera’s field of

view, provided it is designed to consider field of view limitations of the optical system.

The resolution required of the diagonal measuring system depends on the size of the smallest

indentation to be measured, and shall be in accordance with Table 2. In determining the resolution of

the measuring system, the resolution of the microscope optics, the digital resolution of the measuring

scale and the step-size of any stage movement, where applicable, should be taken into account.

Table 2 — Resolution of the measuring system
Diagonal length
Resolution of the measuring
system
0,020 ≤ d < 0,080 0,000 4 mm
0,080 ≤ d 0,5 % of d
7 Test piece
7.1 Test Surface

The test shall be carried out on a polished surface, which is smooth and even, free from oxide scale and

foreign matter and, in particular, free from lubricants, unless otherwise specified in product standards.

The finish of the surface shall permit accurate determination of the diagonal length of the indentation.

7.2 Preparation

Surface preparation shall be carried out in such a way as to prevent surface damage, or alteration of the

surface hardness due to excessive heating or cold-working.

Due to the small depth of Knoop hardness indentations, it is essential that special precautions be taken

during preparation. It is recommended to use a polishing/electropolishing technique that is adapted to

the material to be measured.
7.3 Thickness

The thickness of the test piece, or of the layer under test, shall be at least 1/3 times the length of the

long diagonal length of the indentation. No deformation shall be visible at the back of the test piece after

the test.

NOTE The depth of the indentation is approximately 1/30 of the long diagonal length (0,033 d).

7.4 Support of unstable test pieces

For a test piece of small cross-section or of irregular shape, either a dedicated support should be used

or it should be mounted in a similar manner to a metallographic micro-section in appropriate material

so that it is adequately supported and does not move during the force application.

7.5 Metallic and other inorganic coatings

Annex F specifies additional procedures and requirements when determining the Knoop hardness of

metallic and other inorganic coatings.
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oSIST prEN ISO 4545-1:2022
ISO/DIS 4545-1:2022(E)
8 Procedure
8.1 Test temperature

The test is normally carried out at ambient temperature within the limits of 10 °C to 35 °C. If the test

is carried out at a temperature outside this range, it shall be noted in the test report. Tests carried out

under controlled conditions shall be made at a temperature of (23 ± 5) °C.
8.2 Test force

The test forces given in Table 3 are typical. Other test forces may be used. Test forces shall be chosen

that result in indentations with a long diagonal not less than 0,020 mm.
Table 3 — Typical test forces
Test force value, F
Hardness scale
N Approximate kgf equivalent
HK 0,001 0,009 807 0,001
HK 0,002 0,019 61 0,002
HK 0,005 0,049 03 0,005
HK 0,01 0,098 07 0,010
HK 0,02 0,196 1 0,020
HK 0,025 0,245 2 0,025
HK 0,05 0,490 3 0,050
HK 0,1 0,980 7 0,100
HK 0,2 1,961 0,200
HK 0,3 2,942 0,300
HK 0,5 4,903 0,500
HK 1 9,807 1,000
HK 2 19,613 2,000
Not an SI unit.
8.3 Periodic verification

The periodic verification defined in Annex A shall be performed within a week prior to use for each test

force used but is recommended on the day of use. The periodic verification is recommended whenever

the test force is changed. The periodic verification shall be done whenever the indenter is changed.

8.4 Test piece support

The test piece shall be placed on a rigid support. The support surfaces shall be clean and free from

foreign matter (scales, oil, dirt, etc.). It is important that the test piece lies firmly on the support so that

any displacement that affects the test result cannot occur during the test.
8.5 Focus on test surface

The diagonal measuring system microscope shall be focused so that the specimen surface and the

desired test location can be observed.

NOTE Some testing machines do not require that the microscope be focused on the specimen surface.

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oSIST prEN ISO 4545-1:2022
ISO/DIS 4545-1:2022(E)
8.6 Test force application

The indenter shall be brought into contact with the test surface and the test force shall be applied in a

direction perpendicular to the surface, without shock, vibration or overload, until the applied force

attains the specified value. The time from the initial application of the force until the full test force is

reached shall be 7 s .

NOTE 1 The requirements for the time durations are given with asymmetric limits. For example, 7 s

indicates that 7 s is the nominal time duration, with an acceptable range of not less than 2 s (calculated as 7 s – 5 s)

to not more than 8 s (calculated as 7 s + 1 s).
The indenter shall contact the test piece at a velocity of ≤0,070 mm/s.

The duration of the test force shall be 14 s , except for tests on materials whose time-dependent

properties would make this an unsuitable range. For these tests, this duration shall be specified as part

of the hardness designation (see 5.2).

NOTE 2 There is evidence that some materials are sensitive to the rate of straining which causes changes in

the value of the yield strength. The corresponding effect on the termination of the formation of an indentation

can make alterations in the hardness value.
8.7 Prevention of the effect of shock or vibration
[1]

Throughout the test, the testing machine shall be protected from shock or vibration .

8.8 Minimum distance between adjacent indentations

The minimum distance between adjacent indentations and the minimum distance between an

indentation and the edge of the test piece are shown in Figure 3.

The minimum distance between the edge of the test piece and the centre of any indentation oriented

parallel to the edge of the test piece shall be at least 3,5 times the length of the short diagonal of the

indentation. The minimum distance between the edge of the test piece and the centre of any indentation

oriented perpendicular to the edge of the test piece shall be at least equal to the length of the long

diagonal of the indentation.

The minimum distance between the centres of two adjacent indentations, oriented side-by-side,

shall be at least 3,5 times the length of the short diagonal. For indentations oriented end-to-end, the

minimum distance between the centres of two adjacent indents shall be at least twice the length of the

long diagonal. If two indentations differ in size, the minimum spacing shall be based on the diagonal of

the larger indentation.
Figure 3 — Minimum distance for Knoop indentations
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oSIST prEN ISO 4545-1:2022
ISO/DIS 4545-1:2022(E)
8.9 Measurement of diagonal length

The length of the long diagonal shall be measured and used for the calculation of the Knoop hardness. For

all tests, the perimeter of the indentation shall be clearly defined in the field of view of the microscope.

Magnifications should be selected so that the diagonal can be enlarged to greater than 25 %, but less

than 75 % of the maximum possible optical field of view (see 6.3).

NOTE 1 In general, decreasing the test force increases the scatter of the results of the measurements. The

accuracy of the determination of the long diagonal length is unlikely to be better than ±0,001 mm.

NOTE 2 A helpful technique for adjusting optical systems that have Köhler illumination is given in Annex E.

If the shape of the indentation appears to be nonsymmetrical, divide the long diagonal into two

segments at the point of intersection with the short diagonal, and measure the length of each segment.

If the difference between the two segments is greater than 5 % of the length of the long diagonal, check

the parallelism between the supporting plane and the measuring plane of the specimen and eventually,

the alignment of the indenter to the specimen. Test results with deviations greater than 5 % should be

discarded.

This standard is not applicable to indentations having diagonal lengths ≤ 0,020 mm. Hardness

measurements requiring smaller indentation sizes can be made in accordance with ISO 14577-1,

ISO 14577 2 and ISO 14577-3 (see References [2] to [4]).
8.10 Calculation of hardness value

Calculate the Knoop hardness value using the formula given in Table 1. The Knoop hardness value can

also be determined using the calculation tables given in ISO 4545-4.
9 Uncertainty of the results
[5]

A complete evaluation of the uncertainty should be done according to JCGM 100: 2008 .

Independent of the type of sources, for hardness, there are two possibilities for the determination of the

uncertainty.

— One possibility is based on the evaluation of all relevant sources appearing during a direct calibration.

[6]
As a reference, a Euramet guideline is available.

— The other possibility is based on indirect calibration using a hardness reference block [below

abbreviated as CRM (certified reference material)] (see References [6] to [9]). A guideline for the

determination is given in Annex B.

It may not always be possible to quantify all the identified contributions to the uncertainty. In this case,

an estimate of type A standard uncertainty may be obtained from the statistical analysis of repeated

indentations into the test piece. Care should be taken if standard uncertainties of type A and B are

summarized, that the contributions are not counted twice (see JCGM 100: 2008, Clause 4).

10 Test report

The test report shall include the following information, unless otherwise agreed by the parties

concerned:
a) a reference to this document, i.e. ISO 4545-1;
b) all
...