SIST EN ISO 14577-2:2004
(Main)Metallic materials - Instrumented indentation test for hardness and materials parameters - Part 2: Verification and calibration of testing machines (ISO 14577-2:2002)
Metallic materials - Instrumented indentation test for hardness and materials parameters - Part 2: Verification and calibration of testing machines (ISO 14577-2:2002)
Method of instrumented indentation test for hardness and materials parameters for metallic materials.
Metallische Werkstoffe - Instrumentierte Eindringprüfung zur Bestimmung der Härte und anderer Werkstoffparameter - Teil 2: Prüfung und Kalibrierung der Prüfmaschine (ISO 14577-2:2002)
In diesem Teil von ISO 14577 ist das Verfahren für die Prüfung und Kalibrierung von Prüfmaschinen für die instrumentierte Eindringprüfung nach ISO 14577-1 festgelegt.
Es ist ein direktes Verfahren zur Prüfung von Hauptfunktionen der Prüfmaschine und ein indirektes Verfahren, das für die Ermittlung der Abweichung der Prüfmaschine geeignet ist, festgelegt. Das indirekte Verfahren kann in Ergänzung zu der direkten Prüfung und für die regelmäßige Routineprüfung beim Anwender eingesetzt werden.
Wird eine Prüfmaschine auch für andere Prüfverfahren verwendet, muss sie für jedes Verfahren separat geprüft werden.
Für tragbare Prüfmaschinen ist dieser Teil von ISO 14577 sinngemäß anzuwenden.
Matériaux métalliques - Essai de pénétration instrumenté pour la détermination de la dureté et de parametres des matériaux - Partie 2: Vérification et étalonnage des machines d'essai (ISO 14577-2:2002)
L'ISO 14577-2 spécifie la méthode de vérification et d'étalonnage des machines d'essai destinées à la réalisation de l'essai instrumenté conformément à l'ISO 14577-1.
Elle décrit une méthode de vérification directe des fonctions principales de la machine d'essai et une méthode de vérification indirecte appropriée pour la détermination de la répétabilité de la machine d'essai.
L'ISO 14577-2 est également applicable aux machines d'essai transportables.
Kovinski materiali - Instrumentirano vtiskanje pri preskušanju trdote in drugih lastnosti materialov - 2. del: Overjanje in kalibriranje preskuševalnih strojev (ISO 14577-2:2002)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 14577-2:2004
01-marec-2004
Kovinski materiali - Instrumentirano vtiskanje pri preskušanju trdote in drugih
lastnosti materialov - 2. del: Overjanje in kalibriranje preskuševalnih strojev (ISO
14577-2:2002)
Metallic materials - Instrumented indentation test for hardness and materials parameters
- Part 2: Verification and calibration of testing machines (ISO 14577-2:2002)
Metallische Werkstoffe - Instrumentierte Eindringprüfung zur Bestimmung der Härte und
anderer Werkstoffparameter - Teil 2: Prüfung und Kalibrierung der Prüfmaschine (ISO
14577-2:2002)
Matériaux métalliques - Essai de pénétration instrumenté pour la détermination de la
dureté et de parametres des matériaux - Partie 2: Vérification et étalonnage des
machines d'essai (ISO 14577-2:2002)
Ta slovenski standard je istoveten z: EN ISO 14577-2:2002
ICS:
77.040.10 Mehansko preskušanje kovin Mechanical testing of metals
SIST EN ISO 14577-2:2004 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN ISO 14577-2:2004
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SIST EN ISO 14577-2:2004
EUROPEAN STANDARD
EN ISO 14577-2
NORME EUROPÉENNE
EUROPÄISCHE NORM
October 2002
ICS 77.040.10
English version
Metallic materials - Instrumented indentation test for hardness
and materials parameters - Part 2: Verification and calibration of
testing machines (ISO 14577-2:2002)
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: Prüfung und Kalibrierung der Prüfmaschine (ISO
machines d'essai (ISO 14577-2:2002) 14577-2:2002)
This European Standard was approved by CEN on 9 September 2002.
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 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 Management Centre has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,
Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2002 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 14577-2:2002 E
worldwide for CEN national Members.
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SIST EN ISO 14577-2:2004
EN ISO 14577-2:2002 (E)
CORRECTED 2003-03-05
Foreword
This document (EN ISO 14577-2:2002) has been prepared by Technical Committee ISO/TC 164
"Mechanical testing of metals" in collaboration with Technical Committee ECISS/TC 1 "Steel -
Mechanical testing", 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 April 2003, and conflicting national
standards shall be withdrawn at the latest by April 2003.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of
the following countries are bound to implement this European Standard: Austria, Belgium, Czech
Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg,
Malta, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom.
Endorsement notice
The text of ISO 14577-2:2002 has been approved by CEN as EN ISO 14577-2:2002 without any
modifications.
NOTE Normative references to International Standards are listed in Annex ZA (normative).
2
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SIST EN ISO 14577-2:2004
EN ISO 14577-2:2002 (E)
Annex ZA
(normative)
Normative references to international publications
with their relevant European publications
This European Standard incorporates by dated or undated reference, provisions from other
publications. These normative references are cited at the appropriate places in the text and the
publications are listed hereafter. For dated references, subsequent amendments to or revisions of
any of these publications apply to this European Standard only when incorporated in it by
amendment or revision. For undated references the latest edition of the publication referred to
applies (including amendments).
NOTE Where an International Publication has been modified by common modifications, indicated
by (mod.), the relevant EN/HD applies.
Publication Year Title EN Year
ISO 376 1999 Metallic materials - Calibration of EN ISO 376 2002
force-proving instruments used
for the verification of uniaxial
testing machines
ISO 3878 1983 Hardmetals - Vickers hardness EN 23878 1993
test
ISO 6508-2 1999 Metallic materials - Rockwell EN ISO 6508-2 1999
hardness test - Part 2:
Verification and calibration of
testing machines (scales A, B, C,
D, E, F, G, H, K, N, T)
ISO 14577-1 2002 Metallic materials - Instrumented EN ISO 14577-1 2002
indentation test for hardness and
materials parameters - Part 1:
Test method
ISO 14577-3 2002 Metallic materials - Instrumented EN ISO 14577-3 2002
indentation test for hardness and
materials parameters - Part 3:
Calibration of reference blocks
3
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SIST EN ISO 14577-2:2004
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SIST EN ISO 14577-2:2004
INTERNATIONAL ISO
STANDARD 14577-2
First edition
2002-10-01
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 14577-2:2002(E)
©
ISO 2002
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SIST EN ISO 14577-2:2004
ISO 14577-2:2002(E)
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ii © ISO 2002 – All rights reserved
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SIST EN ISO 14577-2:2004
ISO 14577-2:2002(E)
Contents Page
Foreword . iv
Introduction. v
1 Scope. 1
2 Normative references. 1
3 General conditions. 2
4 Direct verification and calibration . 2
5 Indirect verification . 11
6 Intervals between verifications. 13
7 Verification report/Calibration certificate . 13
Annex A (informative) Example of an indenter holder. 14
Annex B (normative) Procedures for determination of indenter area function . 15
Annex C (informative) Examples for direct verification of the displacement measuring system. 17
Annex D (informative) Examples for the documentation of the results of indirect verification . 18
Bibliography. 21
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SIST EN ISO 14577-2:2004
ISO 14577-2:2002(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.
The main task of technical committees is to prepare International Standards. 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.
Attention is drawn to the possibility that some of the elements of this part of ISO 14577 may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 14577-2 was prepared by Technical Committee ISO/TC 164, Mechanical testing of metals, Subcommittee
SC 3, Hardness testing.
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
Annex B forms a normative part of this part of ISO 14577. Annexes A, C and D are for information only.
iv © ISO 2002 – All rights reserved
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SIST EN ISO 14577-2:2004
ISO 14577-2:2002(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 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.
ISO 14577 has been written to allow a wide variety of post test data analysis.
© ISO 2002 – All rights reserved v
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SIST EN ISO 14577-2:2004
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SIST EN ISO 14577-2:2004
INTERNATIONAL STANDARD ISO 14577-2:2002(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.
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. The indirect method
shall be used in addition to the direct method and for the periodic routine checking of the testing machine in
service.
The indirect method of verification of the testing machine shall 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 normative documents contain provisions which, through reference in this text, constitute provisions of
this part of ISO 14577. For dated references, subsequent amendments to, or revisions of, any of these publications
do not apply. However, parties to agreements based on this part of ISO 14577 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 376:1999, Metallic materials — Calibration of force-proving instruments used for the verification of uniaxial
testing machines
ISO 3878, Hardmetals — Vickers hardness test
ISO 6508-2, Metallic materials — Rockwell hardness test — Part 2: Verification and calibration of testing machines
(scales A, B, C, D, E, F, G, H, K, N, T)
ISO 14577-1:2002, 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
1)
ISO Guide to the Expression of Uncertainty in Measurement (GUM)
1) Published in 1993; corrected and reprinted in 1995.
© ISO 2002 – All rights reserved 1
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SIST EN ISO 14577-2:2004
ISO 14577-2:2002(E)
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 the conditions laid down in
3.2 to 3.4
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 document and of ISO 14577-1 and, where applicable, ISO 14577-3. The testing
machine shall be protected from vibrations. For testing in the micro and nano ranges the testing machine shall also
be protected from air currents and temperature fluctuations. This influence shall be checked by repeated
measurements of the force/indentation depth curve.
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 would 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 The direct verification shall be carried out at a temperature of (23 ± 5) °C.
If a range of operating temperatures is required, then direct verification should be carried out at suitable points over
that range to determine the validity of the calibration as a function of temperature. If necessary, a calibration
correction function or a set of calibrations valid at specific operating temperatures may be determined.
4.1.2 The instruments used for verification and calibration shall be traceable to National Standards as far as
available.
4.1.3 Direct verification involves:
a) verification of the indenter;
b) calibration of the test force;
c) calibration of the displacement measuring device;
d) calibration of the machine compliance;
e) verification of the indenter area function, if the indentation depth is less than 6 µm;
f) verification of the testing cycle.
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SIST EN ISO 14577-2:2004
ISO 14577-2:2002(E)
4.2 Verification of the indenter
4.2.1 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
2)
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 geometrical values shall be measured and incorporated into the calibration certificate. The indenter
performance shall be verified periodically (see clause 6).
If the angle of the indenter deviates from the nominal value for an ideal geometry of the indenter, the average of the
certified angles for that indenter should be used in all applicable calculations, e.g. 0,2° error in the Vickers angle of
136° results in a 1 % systematic error in area.
The angle for pyramidal and conical indenters shall be measured within the indentation depth ranges given in
Table 1 (and illustrated in Figure 1). Indenters for use in the nano range and in the micro range (indentation depth
u 6 µm) shall have their area function calibrated over the relevant indentation depth ranges of use.
Table 1 — 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
1
h 200 120
2
Figure 1 — Illustration of measuring ranges given in Table 1
4.2.2 Vickers indenter
4.2.2.1 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 annex D in ISO 14577-1:2002.
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.
[1]
2) See ISO/IEC 17025 .
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SIST EN ISO 14577-2:2004
ISO 14577-2:2002(E)
4.2.2.2 The angle between the opposite faces of the vertex of the diamond pyramid shall be 136° ± 0,3°
(see Figure 2).
The angle shall be measured in the range between h and h (see Table 1 and Figure 1). The geometry and finish
1 2
of the indenter shall be controlled over the whole calibrated indentation depth range, i.e. from the indenter tip, h , to
0
the maximum calibrated indentation depth, h .
2
4.2.2.3 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°.
4.2.2.4 The four faces shall meet at a point. The maximum permissible length of the line of conjunction
between opposite faces is given in Table 2 (see also Figure 3).
4.2.2.5 The radius of the tip of the indenter shall not exceed 0,5 µm for the micro range (see Figure 4).
4.2.2.6 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 a verification by an atomic-force-microscope (AFM) is
recommended.
Table 2 — Maximum permissible length of the line of conjunction
Range of the indentation depth Maximum permissible length of the line of
conjunction
µm µm
h > 30 1
a
30 W h > 6 0,5
b
h u 6 u 0,5
a
This may 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
The correction of the shape of the indenter is taken into account, see C.2 in ISO 14577-1:2002.
Figure 2 — Angle of the Vickers diamond pyramid
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SIST EN ISO 14577-2:2004
ISO 14577-2:2002(E)
a
Line of conjunction
Figure 3 — Line of conjunction on the tip of the indenter, schematically
Figure 4 — Radius of the tip of the indenter
4.2.3 Berkovich, modified Berkovich and corner cube indenters
4.2.3.1 General
In practice there are two types of Berkovich pyramidal diamond indenters in common use. The Berkovich
[2]
indenter is designed to have the same surface area as a Vickers indenter at any given indentation depth. The
[3]
modified Berkovich indenter is designed to have the same projected area as the Vickers indenter at any given
indentation depth.
4.2.3.2 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 annex D in ISO 14577-1:2002.
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.
4.2.3.3 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).
4.2.3.4 The angle between the axis of the diamond pyramid and the three faces is designated α. The angle
between the three faces of the diamond pyramid shall be 60° ± 0,3° (see Figure 5).
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SIST EN ISO 14577-2:2004
ISO 14577-2:2002(E)
α = 65,03° ± 0,3° for Berkovich indenter
α = 65,27° ± 0,3° for modified Berkovich indenter
α = 35,26° ± 0,3° for corner cube indenters
Figure 5 — Angle of the Berkovich and corner cube indenters
4.2.3.5 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 an atomic-force-microscope
(AFM) should be carried out. For the nano range this measurement is recommended.
4.2.4 Hardmetal ball indenters
4.2.4.1 The characteristics of the hardmetal balls shall be the following:
hardness: the hardness shall be 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:
cobalt (Co) 5,0 % to 7,0 %
total carbides other than tungsten carbide 2,0 %
tungsten carbide (WC) balance
4.2.4.2 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 3), the ball shall not be used as an indenter.
Table 3 — 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
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SIST EN ISO 14577-2:2004
ISO 14577-2:2002(E)
4.2.5 Spherical tipped conical indenters
The characteristics of spherical tipped conical indenters shall be as given in Table 4 (see also Figure 6).
Table 4 — Tolerances for sphero-conical indenters
Feature Tolerance
R u 50 µm ± 0,25 R
av av
a
500 µm > R > 50 µm ± 0,1 R
av av
Cone included angle, 2 α
a
120° ± 5°
90° ± 5°
60° ± 5°
Cone flank angle α
60° ± 5°
45° ± 2,5°
30° ± 2,5°
NOTE Centerline of cone to centerline of mount is within 0,01 mm.
a
Rockwell diamond indenters (see ISO 6508-2) fulfill 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, thus:
0,5 u R(h)/R u 2
av
Indenters with a spherical tipped cone shape are useful for many applications. These indenters are normally made
from diamond but may also be made from other materials, e.g. ruby, sapphire or hardmetal. They are intended to
indent only with the spherical tip. If Hertzian contact mechanics are to be 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 reference
material with known properties.
Surface roughness Ra should be minimized. Roughness causes an uncertainty in the definition of the first contact
point in the actual area of contact 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 spherical cap h on a cone of included angle 2 α and radius R is given by:
s av
h = R [1 − sin(α)]
s av
In practice, there is a gradual transition from spherical cap to cone geometry which 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
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SIST EN ISO 14577-2:2004
ISO 14577-2:2002(E)
Figure 6 — Representation of the features of spherical indenters
4.3 Calibration of the test force
4.3.1 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 three times.
4.3.2 The test force shall be measured by a traceable method, e.g.:
a) measuring by means of an elastic proving-device in accordance with class 1 of ISO 376:1999;
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 maximum test force or 10 µN for the nano range.
4.3.3 The repeatability of the test force shall be within the tolerance of the nominal value of the test force as
given in Table 5.
Table 5 — Tolerances for test forces
Range of the test force Tolerances
N %
F W 2 ± 1,0
0,1 u F < 2 ± 1,5
a
0,001 u F < 0,1 ± 2,5
a
For the nano range the tolerance of ± 1 % is strongly recommended.
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SIST EN ISO 14577-2:2004
ISO 14577-2:2002(E)
4.4 Calibration of the displacement measuring device
4.4.1 The estimation capability required of the displacement measuring system depends on the size of the
smallest indentation depth to be measured. For the micro range this value is 0,2 µm, for the macro range W 2 µm.
The scale of the displacement measuring device shall be graduated to permit an estimation capability of
indentation depth in accordance with Table 6.
4.4.2 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 eac
...
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