EN ISO 23146:2016

SLOVENSKI STANDARD
01-junij-2016
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Fine ceramics (advanced ceramics, advanced technical ceramics) - Test methods for
fracture toughness of monolithic ceramics - Single-edge V-notch beam (SEVNB) method
(ISO 23146:2012)
Hochleistungskeramik - Prüfverfahren zur Bestimmung der Bruchzähigkeit
monolithischer Keramik - Verfahren für Biegeproben mit V-Kerb (SEVNB-Verfahren)
(ISO 23146:2012)
Céramiques techniques - Méthodes d'essai pour la détermination de la ténacité à la
rupture des céramiques monolithiques - Méthode sur éprouvette à entaille en V sur une
seule face (Méthode SEVNB) (ISO 23146:2012)
Ta slovenski standard je istoveten z: EN ISO 23146:2016
ICS:
81.060.30 Sodobna keramika Advanced ceramics
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 23146
EUROPEAN STANDARD
NORME EUROPÉENNE
April 2016
EUROPÄISCHE NORM
ICS 81.060.30 Supersedes CEN/TS 14425-5:2004
English Version
Fine ceramics (advanced ceramics, advanced technical
ceramics) - Test methods for fracture toughness of
monolithic ceramics - Single-edge V-notch beam (SEVNB)
method (ISO 23146:2012)
Céramiques techniques - Méthodes d'essai pour la Hochleistungskeramik - Prüfverfahren zur
détermination de la ténacité à la rupture des Bestimmung der Bruchzähigkeit monolithischer
céramiques monolithiques - Méthode sur éprouvette à Keramik - Verfahren für Biegeproben mit V-Kerb
entaille en V sur une seule face (Méthode SEVNB) (ISO (SEVNB-Verfahren) (ISO 23146:2012)
23146:2012)
This European Standard was approved by CEN on 18 March 2016.

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
© 2016 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 23146:2016 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
European foreword
The text of ISO 23146:2012 has been prepared by Technical Committee ISO/TC 206 “Fine ceramics” of
the International Organization for Standardization (ISO) and has been taken over as EN ISO 23146:2016
by Technical Committee CEN/TC 184 “Advanced technical ceramics” the secretariat of which is held by
DIN.
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 October 2016, and conflicting national standards shall
be withdrawn at the latest by October 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 CEN/TS 14425-5:2004.
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 23146:2012 has been approved by CEN as EN ISO 23146:2016 without any modification.

INTERNATIONAL ISO
STANDARD 23146
Second edition
2012-12-15
Fine ceramics (advanced ceramics,
advanced technical ceramics) — Test
methods for fracture toughness of
monolithic ceramics — Single-edge
V-notch beam (SEVNB) method
Céramiques techniques — Méthodes d’essai pour la détermination de
la ténacité à la rupture des céramiques monolithiques — Méthode sur
éprouvette à entaille en V sur une seule face (Méthode SEVNB)
Reference number
ISO 23146:2012(E)
©
ISO 2012
ISO 23146:2012(E)
© ISO 2012
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any
means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the
address below or ISO’s member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2012 – All rights reserved

ISO 23146:2012(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Apparatus . 2
6 Test piece preparation . 3
6.1 Number of test pieces . 3
6.2 Test-piece dimensions . 4
6.3 Preparing the V-notch by hand . 4
6.4 Preparing the V-notches by machine (optional) . 7
6.5 Determination of notch-root radius . 7
7 Test procedure . 8
7.1 Dimensions of test piece . 8
7.2 Flexural-strength test . 8
7.3 Measurement of notch depth . 9
7.4 Calculation of fracture toughness . 9
8 Precision and bias .11
9 Test report .11
Annex A (informative) Notch honing by machine .12
Annex B (informative) Interlaboratory evaluation of the SEVNB fracture toughness
test procedures .14
Annex C (informative) Corrections for effective crack length greater than notch depth .16
Bibliography .17
ISO 23146:2012(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 2.
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 document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 23146 was prepared by Technical Committee ISO/TC 206, Fine ceramics.
This second edition cancels and replaces the first edition (ISO 23146:2008), of which it constitutes a
minor revision.
iv © ISO 2012 – All rights reserved

INTERNATIONAL STANDARD ISO 23146:2012(E)
Fine ceramics (advanced ceramics, advanced technical
ceramics) — Test methods for fracture toughness of
monolithic ceramics — Single-edge V-notch beam
(SEVNB) method
1 Scope
This International Standard specifies a method for the determination of the fracture toughness of
advanced technical ceramics. The procedure makes use of single-edge V-notched bars, which are loaded
in four-point bending until failure. It is applicable to monolithic ceramics with a grain size or major
microstructural feature size larger than about 1 µm.
The use of this International Standard for yttria tetragonal zirconia polycrystal material (Y-TZP) is not
recommended. The method might also be unsuitable for some other very tough or soft ceramics in which
a sharp crack does not form at the root of the V-notch.
2 Normative references
The following referenced documents are indispensable for the application 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 3611, Geometrical product specifications (GPS) — Dimensional measuring instruments; Micrometers
for external measurements — Design and metrological characteristics
ISO 7500-1, Metallic materials — Verification of static uniaxial testing machines — Part 1: Tension/compression
testing machines — Verification and calibration of the force-measuring system
ISO 14704, Fine ceramics (advanced ceramics, advanced technical ceramics) — Test method for flexural
strength of monolithic ceramics at room temperature
ISO 15732, Fine ceramics (advanced ceramics, advanced technical ceramics) — Test method for fracture
toughness of monolithic ceramics at room temperature by single edge precracked beam (SEPB) method
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 15732 apply.
4 Principle
This method of conducting a fracture toughness test is based on the preparation and fracture of bar
test pieces in which a sharp-tipped notch is machined. Using the technique of a reciprocating razor
blade and diamond paste, a narrow notch can be honed into a test piece using either a manual method
or a simple machine. Under well-controlled conditions, a notch-tip radius in the range of 1 µm to 20 µm
can be prepared depending on the grain size of the test material. For many materials, this is a close
approximation to a sharp crack, and the method has been found to give fracture toughness values
very close to those of other methods such as the single-edge precracked beam method (ISO 15732) or
the surface crack in flexure method (ISO 18756), provided that a sharp crack forms at the root of the
notch either during its preparation or during the subsequent fracture sequence. The method has the
advantage of simplicity of notch production compared with using a sharp-tipped diamond saw or a
diamond impregnated wire in which the tip radius is normally greater than 50 µm. The method is often
ISO 23146:2012(E)
easier to undertake compared with other methods of precracking and is applicable to a wider range of
materials outside the scope of these methods.
The method has been extensively researched (see the Bibliography) and has been evaluated in an ESIS
(European Structural Integrity Society)/VAMAS (Versailles Agreement on Advanced Materials and
Standards) round robin, the results of which are summarized in Annex B. This recommended practice is
based upon the ESIS/VAMAS SEVNB round robin.
The method may have some limitations for materials with grain sizes of less than 1 µm, for which
the assumption that the notch approximates to a sharp crack may not be valid (see Annex C). Users
should strive to minimize the notch-root radius in the test pieces. This International Standard places a
provisional criterion that the notch-root radius should be similar to or less than twice the average grain
size of the material.
The method is complementary to other methods of measuring fracture toughness described in ISO 15732
(single-edge precracked beam method), ISO 18756 (surface crack in flexure method), and ISO 24370
(chevron notch method); see the Bibliography.
5 Apparatus
5.1 Ordinary razor blades, preferably with a support along one edge but alternatively inserted in a
suitable holder.
NOTE 1 Razor blades thinner than about 0,2 mm are not ideal for this task unless stiffened by a support, such
as by gluing or screwing between two steel plates, leaving only about 2 mm of edge showing. A razor blade with a
tip angle of 30° or smaller is ideal.
NOTE 2 Although it is possible to machine the notches entirely by hand, the use of a simple device in which the
test pieces are mounted and in which a razor blade primed with diamond paste is moved in a reciprocating motion
across the mounted test pieces has a distinct advantage, as this provides controlled loading and directional
stability to the razor blade, and sharper notches are produced. An example is shown in Annex A.
5.2 Metallographic diamond paste, in a viscous organic carrier and of fine grain size, typically
1 µm to 3 µm.
5.3 Lubricant, a light lubricating oil for lubricating the razor blade, e.g. clock oil.
5.4 Test piece support, consisting of a flat plate or other suitable device for mounting test pieces
during notch honing.
5.5 Flexural-strength test fixture, preferably a four-point flexural-strength test fixture operating in
accordance with the requirements of ISO 14704, i.e. either 1/4-point flexure (preferred) or 1/3-point
flexure. Alternatively, a three-point flexural-strength test jig may also be used, but the alignment of the
V-notch with the central loading roller is more critical.
The test piece is supported on two bearing edges perpendicular to its length. The outer-support bearing
edges shall be parallel rollers of diameter 5,0 mm ± 0,2 mm and shall be capable of rolling outward on
flat support surfaces. Preferably, one of the rollers shall additionally be capable of rotating about an axis
parallel to the length of the test piece such that torsional loading is minimised. The two rollers shall
be positioned initially with their centres 40,0 mm ± 0,5 mm (1/4-point flexure) or 30 mm ± 0,5 mm
(1/3-point flexure) apart with their axes parallel to within 1°. The separation of the centres of the rollers
in their starting positions shall be measured to the nearest 0,1 mm with a travelling microscope. The
rollers shall be made from hardened steel or other hard material with a hardness greater than 40 HRC
(Rockwell C-scale). The rollers shall have a smooth burr-free surface finish with roughness less than
0,5 µm Ra and shall have a diameter uniform to ± 0,02 mm.
For four-point flexure, the two loading rollers are located at the 1/4-points (or 1/3-points), with an inner
span of 20 mm ± 0,2 mm (or 10 mm ± 0,2 mm for 1/3-point flexure) and are free to roll inwards. The
2 © ISO 2012 – All rights reserved

ISO 23146:2012(E)
rollers are free to rotate separately about an axis parallel to the length of the test piece to allow alignment.
For three-point flexure, the single loading roller, which need not rotate, shall be positioned centrally
between the outer-support rollers. The distances between the rollers shall be measured to the nearest
0,1 mm along the length of the specimen perpendicular to the direction of loading, using a travelling
microscope or other suitable device. The loading rollers in four-point flexure shall be symmetrically
positioned to within ± 0,1 mm. The arrangement for loading shall ensure that equal forces are applied
to the two loading rollers. The single loading roller in three-point flexure shall be centrally located to
within ± 0,2 mm.
5.6 Mechanical testing machine, capable of applying a force at a constant rate of displacement or
constant loading rate to the test piece in the flexural-strength test jig and of recording the force at which
the test piece fractures. The force measuring device shall be in accordance with ISO 7500-1 and shall have
an accuracy of ≤ 1 %.
NOTE The test facility can, with advantage, be equipped with a capability for recording the force/displacement
behaviour of the test piece, ideally a sensitive system directly contacting the test piece. Provided that the load-
train stiffness is sufficient, machine displacement recording can be adequate.
5.7 Ultrasonic cleaning bath, for cleaning the test pieces after notching, suitable for insertion of a
beaker or other receptacle containing solvent.
5.8 Calibrated micrometer, similar to the one in accordance with ISO 3611, but capable of being read
to a precision of 0,002 mm using a vernier or electronic readout.
5.9 Optical microscope, with calibrated magnifications over the range 50 × to 500 × , suitable for
observing the notch-tip shape, and fitted with photomicrographic facilities.
5.10 Notch-measuring device, a calibrated device for measuring the depth of the sawn notch after
fracture with a reading precision of 0,002 mm.
NOTE This can be achieved by the use of an appropriate travelling microscope, or a conventional metallurgical
microscope with calibrated stage movement, or a microscope with a calibrated micrometer eyepiece.
5.11 Drying oven, capable of maintaining 120 °C ± 5 °C for drying test pieces after cleaning.
5.12 Diamond slitting saw or slitting machine, capable of preparing a shallow notch in a set of test
pieces of width no more than 0,5 mm and depth of about 0,5 mm. See 6.3 for guidance.
6 Test piece preparation
6.1 Number of test pieces
At least seven test pieces shall be prepared for notching, of which five are required for testing and two
are dummy test pieces for protecting the others during notch preparation.
NOTE If a machine is used for preparing the V-notches, it might not be necessary to employ the dummy test
pieces to protect a test set of five test pieces.
Operators with no experience of preparing the sharp V-notches used in this method are highly
recommended to try out the technique and equipment first with surplus test pieces.
ISO 23146:2012(E)
6.2 Test-piece dimensions
Prepare bar test pieces of rectangular cross-section, preferably in accordance with the requirements
of ISO 14704. Figure 1 shows the shape and main dimensions of the test pieces prepared in accordance
with this International Standard.
NOTE 1 The chamfering or rounding requirements in ISO 14704 are not essential for the V-notch test, and
can be ignored.
NOTE 2 Other sizes of test pieces, e.g. (2 × 2,5 × > 25 mm), can optionally be used with appropriately sized
flexural-strength fixtures.
Key
L > 45 mm (1/4-point flexure) or > 35 mm (1/3-point flexure)
W 4,0 mm ± 0,2 mm
B 3,0 mm ± 0,2 mm
Figure 1 — Test piece dimensions in accordance with ISO 14704
6.3 Preparing the V-notch by hand
Mount the test pieces side by side on the test-piece support using an appropriate temporary adhesive, as
in Figure 2. Mount test pieces and dummies as close together as possible. Ensure that the top surfaces
of the test pieces are level. Draw a pencil line across the set of test pieces at the mid-point of their length
to indicate where the notch is to be prepared. Bending the test pieces while mounting on the holder is
to be avoided.
4 © ISO 2012 – All rights reserved

ISO 23146:2012(E)
Key
1 mounting plate
2 dummy test pieces
3 test pieces for testing
4 pencil line as a guide for introducing a diamond-sawn starter notch
Figure 2 — Mounting procedure for the set of test pieces
Mount the holder on a diamond saw. Saw a starter notch along the pencil line of width ≤ 0,5 mm. The
notch should have the same depth of about 0,5 mm over its entire length. Figure 3 shows a schematic
arrangement for sawing. After sawing, clean the holder, test pieces, and especially the notch.
Dimensions in millimetres
a) Test pieces arranged on the test piece support
b) Machining a starter notch with a thin diamond saw blade
Key
A tensile surface
B holder
C diamond saw blade
D sawn notch
X dummy test pieces
Figure 3 — Schematic diagrams for sawing
NOTE 1 It is helpful if the thickness of the diamond saw blade is only a little larger than the thickness of the
razor blade used for notch honing. Otherwise, the razor-blade tip might skate over the surface of the pre-sawn
notch and it might be difficult to start polishing the V-notch. V-shaping the saw-blade tip can help if available saw
blades are significantly thicker than the razor blades.
Fix the test-piece holder in a vice or other suitable clamp. Fill the starter notch with the fine diamond
paste as shown in Figure 4 a).
ISO 23146:2012(E)
To protect the fingers, place a razor blade in a holder or apply a heavy self-adhesive tape as shown in
Figure 4 b). Put the exposed edge of
...