SIST EN ISO 14577-2:2015

SLOVENSKI STANDARD
01-oktober-2015
1DGRPHãþD
SIST EN ISO 14577-2:2004
Kovinski materiali - Instrumentirano vtiskanje pri preskušanju trdote in drugih
lastnosti materialov - 2. del: Overjanje in kalibriranje preskuševalnih strojev (ISO
14577-2:2015)
Metallic materials - Instrumented indentation test for hardness and materials parameters
- Part 2: Verification and calibration of testing machines (ISO 14577-2:2015)
Metallische Werkstoffe - Instrumentierte Eindringprüfung zur Bestimmung der Härte und
anderer Werkstoffparameter - Teil 2: Prüfung und Kalibrierung der Prüfmaschinen (ISO
14577-2:2015)
Matériaux métalliques - Essai de pénétration instrumenté pour la détermination de la
dureté et de paramètres des matériaux - Partie 2: Vérification et étalonnage des
machines d'essai (ISO 14577-2:2015)
Ta slovenski standard je istoveten z: EN ISO 14577-2:2015
ICS:
77.040.10 Mehansko preskušanje kovin Mechanical testing of metals
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 14577-2
NORME EUROPÉENNE
EUROPÄISCHE NORM
July 2015
ICS 77.040.10 Supersedes EN ISO 14577-2:2002
English Version
Metallic materials - Instrumented indentation test for hardness
and materials parameters - Part 2: Verification and calibration of
testing machines (ISO 14577-2:2015)
Matériaux métalliques - Essai de pénétration instrumenté Metallische Werkstoffe - Instrumentierte Eindringprüfung
pour la détermination de la dureté et de paramètres des zur Bestimmung der Härte und anderer Werkstoffparameter
matériaux - Partie 2: Vérification et étalonnage des - Teil 2: Überprüfung und Kalibrierung der Prüfmaschinen
machines d'essai (ISO 14577-2:2015) (ISO 14577-2:2015)
This European Standard was approved by CEN on 16 April 2015.

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, 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: Avenue Marnix 17, B-1000 Brussels
© 2015 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 14577-2:2015 E
worldwide for CEN national Members.

Contents
Page
European foreword .3

European foreword
This document (EN ISO 14577-2:2015) 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 January 2016, and conflicting national standards shall be withdrawn at
the latest by January 2016.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 14577-2:2002.
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, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.
Endorsement notice
The text of ISO 14577-2:2015 has been approved by CEN as EN ISO 14577-2:2015 without any modification.

INTERNATIONAL ISO
STANDARD 14577-2
Second edition
2015-07-15
Metallic materials — Instrumented
indentation test for hardness and
materials parameters —
Part 2:
Verification and calibration of
testing machines
Matériaux métalliques — Essai de pénétration instrumenté pour la
détermination de la dureté et de paramètres des matériaux —
Partie 2: Vérification et étalonnage des machines d’essai
Reference number
ISO 14577-2:2015(E)
©
ISO 2015
ISO 14577-2:2015(E)
© ISO 2015, 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.
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Tel. +41 22 749 01 11
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copyright@iso.org
www.iso.org
ii © ISO 2015 – All rights reserved

ISO 14577-2:2015(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 General conditions . 1
3.1 Preparation . 1
3.2 Functional installation . . 1
3.3 Indenter . . 2
3.4 Application of the test force . 2
4 Direct verification and calibration . 2
4.1 General . 2
4.2 Calibration of the test force . 2
4.3 Calibration of the displacement measuring device . 3
4.4 Verification and calibration of the machine compliance . 4
4.4.1 General. 4
4.4.2 Procedure . 4
4.5 Calibration and verification of the indenter . 5
4.5.1 General. 5
4.5.2 Vickers indenter . 5
4.5.3 Berkovich, modified Berkovich, and corner cube indenters . 7
4.5.4 Hard metal ball indenters . 8
4.5.5 Spherical tipped conical indenters . 9
4.6 Verification of the indenter area function .10
4.6.1 General.10
4.6.2 Procedure .10
4.7 Verification of the testing cycle .10
5 Indirect verification .11
5.1 General .11
5.2 Procedure .12
6 Intervals between calibrations and verifications .14
6.1 Direct verification and calibration .14
6.2 Indirect verification .15
6.3 Routine checking .15
7 Verification report/Calibration certificate .15
Annex A (informative) Example of an indenter holder .16
Annex B (normative) Procedures for determination of indenter area function .17
Annex C (informative) Examples for the documentation of the results of indirect verification .19
Annex D (normative) Machine compliance calibration procedure .21
Bibliography .25
ISO 14577-2:2015(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 second edition cancels and replaces the first edition (ISO 14577-2:2002), which has been
technically revised.
ISO 14577 consists of the following parts, under the general title Metallic materials — Instrumented
indentation test for hardness and materials parameters:
— Part 1: Test method
— Part 2: Verification and calibration of testing machines
— Part 3: Calibration of reference blocks
— Part 4: Test method for metallic and non-metallic coatings
iv © ISO 2015 – All rights reserved

ISO 14577-2:2015(E)
Introduction
Hardness has typically been defined as the resistance of a material to permanent penetration by
another harder material. The results obtained when performing Rockwell, Vickers, and Brinell tests are
determined after the test force has been removed. Therefore, the effect of elastic deformation under the
indenter has been ignored.
ISO 14577 (all parts) has been prepared to enable the user to evaluate the indentation of materials by
considering both the force and displacement during plastic and elastic deformation. By monitoring the
complete cycle of increasing and removal of the test force, hardness values equivalent to traditional
hardness values can be determined. More significantly, additional properties of the material, such as
its indentation modulus and elasto-plastic hardness, can also be determined. All these values can be
calculated without the need to measure the indent optically. Furthermore, by a variety of techniques, the
instrumented indentation test allows to record hardness and modulus depth profiles within a, probably
complex, indentation cycle.
ISO 14577 (all parts) has been written to allow a wide variety of post test data analysis.
INTERNATIONAL STANDARD ISO 14577-2:2015(E)
Metallic materials — Instrumented indentation test for
hardness and materials parameters —
Part 2:
Verification and calibration of testing machines
1 Scope
This part of ISO 14577 specifies the method of verification and calibration of testing machines for
carrying out the instrumented indentation test in accordance with ISO 14577-1:2015.
It describes a direct verification method for checking the main functions of the testing machine and an
indirect verification method suitable for the determination of the repeatability of the testing machine.
There is a requirement that the indirect method be used in addition to the direct method and for the
periodic routine checking of the testing machine in service.
It is a requirement that the indirect method of verification of the testing machine be carried out
independently for each test method.
This part of ISO 14577 is also applicable for transportable testing machines.
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 3878, Hardmetals — Vickers hardness test
ISO 14577-1:2015, Metallic materials — Instrumented indentation test for hardness and materials
parameters — Part 1: Test method
ISO 14577-3, Metallic materials — Instrumented indentation test for hardness and materials parameters —
Part 3: Calibration of reference blocks
3 General conditions
3.1 Preparation
The machine shall be designed in such a way that it can be verified.
Before verification and calibration of the testing machine, it shall be checked to ensure that the conditions
laid down in 3.2 to 3.4 are met.
3.2 Functional installation
The testing machine shall be configured to operate in compliance with and shall be installed in an
environment that meets the requirements of this part of ISO 14577, ISO 14577-1:2015, and, where
applicable, ISO 14577-3. The testing machine shall be protected from vibrations. For testing in the
ISO 14577-2:2015(E)
micro and nano ranges, the testing machine shall also be protected from air currents and temperature
fluctuations.
The influence of environment on the data, i.e. the noise floor, shall be estimated by performing a low force
(e.g. equivalent to the usual initial contact force) indentation on a CRM and analysing the displacement
over time. The force variability is the indent stiffness (obtained from force removal curve) multiplied
by the standard deviation of the displacement once any background drift in mean displacement has
been subtracted. These uncertainties shall then be included in the total combined uncertainty tests as
calculated in ISO 14577-1:2015, Clause 8 and Annex H.
3.3 Indenter
In order to get repeatable measurements of the force/indentation depth data set, the indenter holder
shall be firmly mounted into the testing machine.
The indenter holder should be designed in such a way that the contribution to the overall compliance is
minimized (see Annex A).
3.4 Application of the test force
The test force shall be applied and removed without shock or vibration that can significantly affect the
test results. It shall be possible to verify the process of increasing, holding, and removal of the test force.
4 Direct verification and calibration
4.1 General
4.1.1 Direct verification and calibration shall be carried out at the constant temperature of use, typically
10 °C to 35 °C, but preferably in the range (23 ± 5) °C. If a range of operating temperatures is required, then
direct calibration and verification should be carried out at suitable points over that temperature range
to determine the calibration validity as a function of temperature. If necessary, a calibration correction
function or a set of calibrations valid at specific operating temperatures can be determined.
4.1.2 The instruments used for direct calibration and verification shall be traceable to National
Standards as far as available.
4.1.3 Direct verification and calibration involves
a) calibration of the test force,
b) calibration of the displacement measuring device,
c) verification and calibration of the machine compliance,
d) verification of the indenter,
e) calibration and verification of the indenter area function, if the indentation depth is less than 6 µm, and
f) verification of the test cycle.
4.2 Calibration of the test force
4.2.1 Each range of force used shall be calibrated over the whole force range for both application and
removal of the test force. A minimum of 16 evenly distributed points in the test force range shall be
calibrated, i.e. 16 during application and 16 during removal of the test force. The procedure shall be
repeated at least three times and the average calibration value shall be used. The maximum difference in
calibration values shall not exceed half of the tolerances given in Table 1.
2 © ISO 2015 – All rights reserved

ISO 14577-2:2015(E)
4.2.2 The test force shall be measured by a traceable method, for example, the following:
a) measuring by means of an elastic proving-device in accordance with class 1, or better of, ISO 376;
b) balancing against a force, accurate to within ±0,2 % applied by means of calibrated masses with
mechanical advantage;
c) electronic balance with a suitable accuracy of 0,1 % of the minimum calibrated test force or 10 µg
(0,1 µN) for the nano range.
For each measured point used for calibration, the difference between the measured and the nominal test
force shall be within the tolerances given in Table 1.
Table 1 — Tolerances for test forces
Range of the test force
Tolerances
F
%
N
F ≥ 2 ±1,0
0,001 ≤ F < 2 ±1,0
a
F < 0,001 ±2,5
a
For the nano range, a tolerance of ±1 % is strongly recommended.
4.3 Calibration of the displacement measuring device
4.3.1 The resolution required of the displacement measuring system depends on the size of the smallest
indentation depth being measured. For the micro range, this value is by definition h = 0,2 µm; for the
macro range it is typically ≥2 µm.
The scale of the displacement measuring device shall be graduated to permit a resolution of indentation
depth measurement in accordance with Table 2.
4.3.2 The displacement measuring device shall be calibrated on the testing machine for every range
used by means of a suitable method and a corresponding system. The device shall be calibrated at a
minimum of 16 points in each direction evenly distributed throughout its travel. The procedure shall be
repeated three times.
The following methods are recommended for the measurement of the relative displacement of the
indenter: laser interference method, inductive method, capacitive method, and piezotranslator method.
For each measured point used for calibration, the difference between the measured and the nominal
displacement shall be within the tolerances given in Table 2.
Table 2 — Resolution and tolerances of the displacement measuring device
Resolution of the displacement
Range of application measuring device Tolerances
nm
Macro ≤100 1 % of h
Micro ≤10 1 % of h
a
Nano ≤1 2 nm
a
For the nano range, a tolerance of <1 % of h (indentation depth) is strongly recommended.
4.3.3 Changes in temperature are commonly a dominant source of displacement drift. To minimize
thermally induced displacement drift, the temperature of the instrument shall be maintained such that the
displacement drift rate remains constant over the time period of one calibration cycle. The drift rate shall
ISO 14577-2:2015(E)
be measured during, immediately before, or immediately after each calibration cycle, e.g. by monitoring
displacement during a suitable hold period. The displacement calibration data shall be corrected for
thermal drift and the product of variation in drift rate and the duration of one calibration cycle shall be
less than the tolerance given in Table 2. The drift rate uncertainty shall be included in the displacement
calibration uncertainty calculation.
4.4 Verification and calibration of the machine compliance
4.4.1 General
See Annex D and ISO 14577-1:2015, Annex C.
This verification and calibration shall be carried out after the test force and the displacement measuring
system have been calibrated in accordance with 4.2 and 4.3.
4.4.2 Procedure
The calibration and verification of machine compliance is carried out by the measurement of indentation
modulus at a minimum of five different test forces. Method 3 as described in Annex D is recommended.
In all cases, a suitable Certified Reference Material (CRM) shall be mounted into the instrumented
indentation test system in the same way as future test samples will be mounted. This is to ensure that
the CRM provides a faithful reproduction of each particular total machine compliance.
The compliance of the testing machine can be affected by the particular construction and mounting of an
indenter and also the method used to mount a sample. For instance, mounting in plastics (e.g. PVC) can
introduce an extra compliance into the measurement loop. The verification and calibration of machine
compliance should be performed using the indenter that will be used for subsequent measurements.
For indentation depths, h > 6 µm, it is not necessary to take into account the real contact area function.
c
For the verification and calibration of the machine compliance, a reference material with certified
indentation modulus, independent from the indentation depth, shall be used. A material with a high
ratio of EH/ (such as tungsten) is recommended. The range for the test force is defined by the
IT IT
minimum test force that correlates to 6 µm indentation depth and the maximum possible test force of
the testing machine. Large indentation depths have the advantage that errors in the area function are
likely to be smaller; however, care shall be taken that the test is not biased by pile-up in the reference
material. The measured compliance of the indentation shall then be compared with the calculated
compliance for the indentation using the certified value of modulus. To recalibrate machine compliance,
the product of the applied force and the detected difference in machine compliance is applied to the
displacement data to refine the estimate of contact depth and, therefore, the machine compliance
estimate at each force. This process is iterated until self-consistent values of machine compliance and
contact depth are reached.
For indentation depths, <6 µm, the method above shall be applied, except that the actual area of contact,
as calculated from the calibrated indenter area function, shall be used to calculate the contact compliance
using the certified modulus of the CRM.
In many nano and micro range instruments, the machine compliance value is independent of force.
However, if this is not the case, then a machine compliance function can be determined using the above
procedure but a wider range of forces. The range for the test forces is defined by the indentation depths,
>0,5 µm, and the maximum test force of the testing machine or the maximum test force for which no
unusual test piece response (e.g. pile-up of metals or cracking of ceramics or glasses) occurs.
If the machine compliance is recalibrated, then an indirect validation shall be performed before use.
The calibration procedures detailed in Annex D require the use of reference materials (see ISO 14577-3)
that shall be isotropic and homogeneous. It is assumed that the indentation modulus and Poisson’s ratio
are independent of the indentation depth.
4 © ISO 2015 – All rights reserved

ISO 14577-2:2015(E)
4.5 Calibration and verification of the indenter
4.5.1 General
The indenter used for the indentation test shall be calibrated. Evidence that the indenter complies with
the requirements of this part of ISO 14577 shall be fulfilled by a calibration certificate from a qualified
calibration laboratory and evidence from the most recent indirect verification that the indenter area
function has not changed. The latter shall be provided using the verification methods described in
Annex B and suitable certified reference materials. All specified indenter geometry parameters shall be
measured and incorporated into the calibration certificate.
If the angle of the indenter deviates from the nominal value for an ideal geometry of the indenter, the
average of certified angles for that indenter should be used in all applicable calculations at depths h > 6 µm.
NOTE A 0,2° error in the Vickers angle of 136° (2α) results in a 1 % systematic error in area.
Indenters for use in the nano range and in the micro range, indentation depth <6 µm, shall have their
area function calibrated over the relevant indentation depth ranges of use. The indenter performance
shall be verified periodically (see Clause 6).
Where non-diamond indenters are used, the values of elastic modulus and Poisson ratio shall be obtained
and used instead of the diamond values in the appropriate analyses.
The angle for pyramidal and conical indenters shall be measured within the indentation depth ranges
given in Table 3 and illustrated in Figure 1.
Table 3 — Values for the measuring ranges for the angle of pyramidal and conical indenters
Dimensions in micrometres
Indentation depth Macro range Micro range
h 6 0,2
h 200 Specified max. indentation depth
Figure 1 — Illustration of measuring ranges given in Table 3
4.5.2 Vickers indenter
4.5.2.1 The four faces of the right square-based diamond pyramid shall be smooth and free from surface
defects and contaminants. For notes on cleaning of the indenter surface, see also ISO 14577-1:2015, Annex D.
The surface roughness of the indenter has a similar effect on measurement uncertainty as test piece
roughness. When testing in the nano range, the indenter surface finish should be taken into consideration.
ISO 14577-2:2015(E)
4.5.2.2 The angle between the opposite faces of the vertex of the diamond pyramid shall be 136° ± 0,3°
(see Figure 2) (α = 68,0° ± 0,2°).
The angle shall be measured in the range between h and h (see Table 3 and Figure 1). The geometry
1 2
and finish of the indenter shall be controlled over the whole calibrated indentation depth range, i.e. from
the indenter tip, h , to the maximum calibrated indentation depth, h .
0 2
4.5.2.3 The angle between the axis of the diamond pyramid and the axis of the indenter holder (normal
to the seating surface) shall not exceed 0,5°.
4.5.2.4 The four faces shall meet at a point. The maximum permissible length of the line of conjunction
between opposite faces is given in Table 4 (see also Figure 3).
4.5.2.5 The radius of the tip of the indenter shall not exceed 0,5 µm for the micro range (see Figure 4).
4.5.2.6 The verification of the shape of the indenter shall be carried out using microscopes or other
suitable devices.
If the indenter is used for testing in the micro or nano range, verification by a closed loop controlled
atomic-force-microscope (AFM) should be carried out. For the nano range, this measurement is
strongly recommended.
Table 4 — Maximum permissible length of the line of conjunction
Maximum permissible length
Range of the indentation depth
of the line of conjunction
µm
µm
h > 30 1
a
30 ≥ h > 6 0,5
b
h ≤ 6 ≤ 0,5
a
This can be assumed to have been achieved when there is no detectable conjunction when the indenter is verified by
an optical microscope at 400 × magnification.
b
This shall be included when the correction of the shape of the indenter is taken into account; see ISO 14577-1:2015,
C.2.
Figure 2 — Angle of the Vickers diamond pyramid
6 © ISO 2015 – All rights reserved

ISO 14577-2:2015(E)
Key
a line of conjunction
Figure 3 — Line of conjunction on the tip of the indenter — Schematic
Figure 4 — Radius of the tip of the indenter
4.5.3 Berkovich, modified Berkovich, and corner cube indenters
4.5.3.1 In practice, there are two types of Berkovich pyramidal diamond indenters in common use. The
Berkovich indenter (see Reference [5]) is designed to have the same surface area as a Vickers indenter at
any given indentation depth. The modified Berkovich indenter (see Reference [11]) is designed to have
the same projected area as the Vickers indenter at any given indentation depth.
4.5.3.2 The three faces of the triangular based diamond pyramid shall be smooth and free from surface
defects and from contaminations. For notes on cleaning of the surface, see also ISO 14577-1:2015, Annex D.
The surface roughness of the indenter has a similar effect on measurement uncertainty as does test
piece roughness. When testing in the nano range, the indenter surface finish should be taken into
consideration.
4.5.3.3 The radius of the tip of the indenter shall not exceed 0,5 µm for the micro range and shall not
exceed 0,2 µm for the nano range (see Figure 4).
4.5.3.4 The angle between the axis of the diamond pyramid and the three faces is designated α. The
angle between edges of the triangular base of the diamond pyramid shall be 60° ± 0,3° (see Figure 5).
ISO 14577-2:2015(E)
Key
a
α = 65,03° ± 0,30° for Berkovich indenter
α = 65,27° ± 0,30° for modified Berkovich indenter
α = 35,26° ± 0,30° for corner cube indenters
Figure 5 — Angle of the Berkovich and corner cube indenters
4.5.3.5 The verification of the shape of the indenter shall be carried out using microscopes or
suitable devices.
If the indenter is used for testing in the micro and nano range, a measurement by a closed-loop
controlled atomic-force-microscope (AFM) should be carried out. For the nano range, this measurement
is strongly recommended.
4.5.4 Hard metal ball indenters
4.5.4.1 The characteristics of the hard metal balls shall be the following:
— hardness:   not less than 1 500 HV 10, when determined in accordance with ISO 3878;
3 3
— density:   ρ = 14,8 g/cm ± 0,2 g/cm .
The following chemical composition is recommended:
a) cobalt (Co):   5,0 % to 7,0 %;
b) total carbides other than tungsten carbide:   2,0 %;
c) tungsten carbide (WC):   balance.
4.5.4.2 The balls shall have a certified geometry. Batch certification methods are sufficient. The
certificate shall show the diameter of the average value of at least three measured points of different
positions. If any value differs from the permissible values of the nominal diameter (see Table 5), the ball
(and/or the batch) shall not be used as an indenter.
8 © ISO 2015 – All rights reserved

ISO 14577-2:2015(E)
Table 5 — Tolerances for ball indenters
Dimensions in millimetres
Ball diameter Tolerance
10 ±0,005
5 ±0,004
2,5 ±0,003
1 ±0,003
0,5 ±0,003
4.5.5 Spherical tipped conical indenters
The characteristics of spherical tipped conical indenters shall be as given in Table 6 (see also Figure 6).
Table 6 — Tolerances for sphero-conical indenters
Feature Tolerance
R ≤ 50 µm ±0,25 R
av av
a
500 µm > R > 50 µm ±0,1 R
av av
Cone included angle, 2α
a
120° ±5°
90° ±5°
60° ±5°
Cone flank angle, α
60° ±5°
45° ±2,5°
30° ±2,5°
NOTE Centreline of cone to centreline of mount is within 0,01 mm.
a
Rockwell diamond indenters (see ISO 6508-2) fulfil this requirement.
The instantaneous radius of curvature, R(h), of the spherical cap at any indentation depth, h, measured
from the point of first contact shall not vary by more than a factor of two from the average radius, R ,
av
as given by the condition in Formula (1):
0,5 ≤ |R(h)/R | ≤ 2 (1)
av
Indenters with a spherical tipped cone shape are useful for many applications. These indenters are
normally made from diamond but can also be made from other materials, e.g. ruby, sapphire, or hardmetal
(WC-Co cemented carbide). They are intended to indent only with the spherical tip. If Hertzian contact
mechanics are being used to interpret the indentation response, the value used for the indenter radius
is critical. It is, therefore, recommended that the shape of each indenter be determined directly by a
suitable measurement system, or indirectly by indentation into a certified reference material.
Surface roughness, Ra, should be minimized. Roughness causes an uncertainty in the actual area of
contact and in the definition of the first contact point of the indenter with the test piece. Asperities have
radii of contact vastly different from the average radius of the spherical cap and, therefore, behave very
differently. If possible, the Ra of the diamond surface should be less than 1/20 of the usual indentation
depth for an indenter.
NOTE Geometry suggests that the depth of the spherical cap, h , on a cone of included angle, 2α, and radius,
s
R , is given by Formula (2):
av
h = R [1 − sin(α)] (2)
s av
ISO 14577-2:2015(E)
In practice, there is a gradual transition from spherical cap to cone geometry that is hard to specify. Given this and
the uncertainties in R and α allowed (see Table 4), caution should be exercised whenever the depth exceeds 0,5 h .
av s
Figure 6 — Representation of the features of spherical indenters
4.6 Verification of the indenter area function
4.6.1 General
See ISO 14577-1:2015, Annex C.
4.6.2 Procedure
Procedures for the determination of indenter area function are given in Annex B.
The direct verification of the indenter area function consists of a comparison of the measured indenter
area function with a documented indenter area function determined for the newly certified and
calibrated indenter.
NOTE The indenter area function and machine compliance correction can be determined simultaneously
using an iterative procedure and multiple reference materials (see Reference [8]).
If the difference in area between the measured and certified area functions (obtained as described in
Annex B and expressed at each measured indentation depth as a percentage of the original certified area
value) exceeds 30 % at any indentation depth in the range of calibration of an indenter, that indenter
shall be discarded.
4.7 Verification of the testing cycle
The testing cycle (application of the test force, holding of the maximum test force, and removal of the
test force) shall be measured with a tolerance of 0,1 s. The duration of each part of the testing cycle shall
meet the requirements of ISO 14577-1:2015.
10 © ISO 2015 – All rights reserved

ISO 14577-2:2015(E)
5 Indirect verification
5.1 General
Indirect verification should be carried out at the temperature of use by means of reference blocks
calibrated in accordance with ISO 14577-3, or within the temperature at for which the calibration of the
reference blocks is valid, typically (23 ± 5) °C. Indirect verification using a reference material shall be
made to ensure the direct verification is valid and that no damage or contamination has occurred to the
indenter tip.
Before measuring on the reference block, it is recommended to inspect and clean the indenter first using
the procedure recommended in ISO 14577-1:2015, Annex D. If the results of these initial indentations
indicate the presence of contamination or damage, then the indenter should be cleaned again before
further trial indents are made. If after further cleaning, indentation into the reference material still
indicates the presence of contamination or damage, then inspection with an optical microscope at
a magnification of 400x is recommended. Detection of sub-microscopic damage or contamination is
possible using appropriate microscopy of indents or the indenter. Where damage is detected, the
indenter shall be replaced.
For an indirect validation decision tree, see Figure 7. The procedures for the determination of the
machine compliance, C , and the area function, A (h ), calibration/verification shall be implemented
F p c
before a new indenter is used. If, after applying the currently valid correction for machine compliance
and indentation area function (obtained using a variable epsilon and a radial displacement correction,
ISO 14577-1:2015, Annex I), a measured value from a reference block deviates from the certified value
of the test piece by more than the maximum permissible amount of the limits specified in Table 7 (see
Note 2) and repetition of the procedure using a newly verified and certified indenter and valid machine
compliance correction corresponding to that indenter) also fails to reproduce the certified value, the
testing machine shall be serviced and a full, direct calibration be performed.
NOTE 1 The use of control charts is a sensitive way to determine changes in performances before a control
limit is breached (see Annex C).
ISO 14577-2:2015(E)
Figure 7 — Flow chart of decisions and actions to taken for indirect verification
NOTE 2 A reference indenter is a calibrated indenter used infrequently and only for checking the instrument
and test indenter performance through indirect validation comparison.
5.2 Procedure
5.2.1 The indirect verification shall be carried out at least at the two test forces most frequently used.
For tests with indentation depths <6 µm, this provides some verification of the contact area function.
Indirect verification should be carried out on at least two reference blocks (CRMs) whose certified values
12 © ISO 2015 – All rights reserved

ISO 14577-2:2015(E)
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