EN ISO 15653:2018
(Main)Metallic materials - Method of test for the determination of quasistatic fracture toughness of welds (ISO 15653:2018)
Metallic materials - Method of test for the determination of quasistatic fracture toughness of welds (ISO 15653:2018)
ISO 15653:2018 specifies methods for determining fracture toughness in terms of stress intensity factor (K), crack tip opening displacement or CTOD (δ) and experimental equivalent of the J-integral for welds in metallic materials (J).
ISO 15653:2018 complements ISO 12135, which covers all aspects of fracture toughness testing of parent metal and which needs to be used in conjunction with this document. This document describes methods for determining point values of fracture toughness. It should not be considered a way of obtaining a valid R-curve (resistance-to-crack-extension curve). However, the specimen preparation methods described in this document could be usefully employed when determining R-curves for welds. The methods use fatigue precracked specimens which have been notched, after welding, in a specific target area in the weld. Methods are described to evaluate the suitability of a weld for notch placement within the target area, which is either within the weld metal or within the weld heat-affected zone (HAZ), and then, where appropriate, to evaluate the effectiveness of the fatigue crack in sampling these areas.
Metallische Werkstoffe - Prüfverfahren zur Bestimmung der quasistatischen Bruchzähigkeit von Schweißnähten (ISO 15653:2018)
Diese Internationale Norm legt Verfahren zur Bestimmung der Bruchzähigkeit mit dem K–Konzept (Spannungsintensitätsfaktor), dem CTOD-Konzept (Rissspitzenöffnungsverschiebung, δ) und dem J Integralkonzept (experimentelles Äquivalent für das J-Integral) für Schweißungen an metallischen Werkstoffen fest.
Diese Internationale Norm ist ein Zusatz zu ISO 12135, die alle Aspekte der Bruchzähigkeitsprüfung von Grundwerkstoffen abdeckt und in Verbindung mit diesem Dokument verwendet werden muss. Diese Internationale Norm beschreibt Verfahren für die Bestimmung von Einzelwerten der Bruchzähigkeit. Sie sollte nicht zur Bestimmung einer R-Kurve (Risswiderstandskurve) herangezogen werden. Dies betrifft nicht die in dieser Internationalen Norm beschriebene Methodik zur Probenpräparation, die auch bei der Bestimmung von R-Kurven von Schweißungen hilfreich eingesetzt werden könnte. Im vorliegenden Verfahren werden Proben mit Ermüdungsrissen verwendet, die nach dem Schweißen in einen definierten Bereich der Schweißnaht eingebracht werden. Dabei handelt es sich entweder um das Schweißgut oder die Wärmeeinflusszone (WEZ) der Schweißnaht. Es wird eine Methodik beschrieben, die die Effektivität der realisierten Kerblage für Ermüdungsrisseinbringung und Prüfung nachweist.
Matériaux métalliques - Méthode d'essai pour la détermination de la ténacité quasi statique à la rupture des soudures (ISO 15653:2018)
ISO 15653:2018 spécifie des méthodes permettant de déterminer la ténacité à la rupture en termes de facteur d'intensité de contrainte (K), d'écartement à fond de fissure, CTOD (δ) et d'équivalent expérimental de l'intégrale pour les soudures dans les matériaux métalliques (J).
ISO 15653:2018 complète l'ISO 12135, qui couvre tous les aspects des essais de ténacité à la rupture du métal de base et qui doit être utilisée conjointement avec le présent document. Ce document décrit des méthodes de détermination des valeurs ponctuelles de la ténacité à la rupture. Elle ne doit pas être considérée comme étant une méthode permettant d'obtenir une courbe R valide (résistance à la propagation de fissure). Cependant, les méthodes de préparation des éprouvettes décrites dans la présente Norme internationale peuvent être employées utilement lors de la détermination des courbes R pour les soudures. La présente méthode utilise des éprouvettes préfissurées par fatigue qui ont été entaillées, après soudage, dans une surface cible spécifique de la soudure. Les méthodes sont décrites pour évaluer l'adaptabilité d'une soudure à l'emplacement des entailles dans la surface cible qui se trouve soit dans la zone fondue soit dans la zone de soudure affectée thermiquement (ZAT) puis, en cas de besoin, pour évaluer l'efficacité de la fissuration par fatigue lors de la traversée de ces surfaces.
Kovinski materiali - Preskusna metoda za ugotavljanje kvazistatične lomne žilavosti zvarnih spojev (ISO 15653:2018)
Ta dokument določa metode za ugotavljanje lomne žilavosti glede na koeficient lomne žilavosti (K), premik vrha odprtja razpoke ali CTOD (δ) ter preskusni ekvivalent integrala J zvarnih spojev v kovinskih materialih (J).
Ta dokument dopolnjuje standard ISO 12135, ki obravnava vse vidike preskušanja lomne žilavosti glavne kovine in ga je treba uporabljati skupaj s tem dokumentom. Ta dokument opisuje metode za ugotavljanje točkovnih vrednosti lomne žilavosti. Ne sme se ga upoštevati kot način pridobivanja veljavne krivulje R (krivulja odpornosti na raztezanje razpoke). Vendar bi lahko metode za pripravo preskušancev, opisane v tem dokumentu, uporabili pri ugotavljanju krivulj R za zvarne spoje. Pri metodah se uporabljajo utrujeni napokani preskušanci, ki so po varjenju bili zarezani na določenem ciljnem mestu zvarnega spoja. Opisane so metode za oceno primernosti izvedbe zareze na ciljnem mestu zvarnega spoja, ki je na zvarni kovini ali območju, na katerega vpliva toplota (HAZ), in nato oceno učinkovitosti utrujene razpoke pri vzorčenju teh območij, kjer je to ustrezno.
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-oktober-2018
1DGRPHãþD
SIST EN ISO 15653:2011
.RYLQVNLPDWHULDOL3UHVNXVQDPHWRGD]DXJRWDYOMDQMHNYD]LVWDWLþQHORPQH
åLODYRVWL]YDUQLKVSRMHY ,62
Metallic materials - Method of test for the determination of quasistatic fracture toughness
of welds (ISO 15653:2018)
Metallische Werkstoffe - Prüfverfahren zur Bestimmung der quasistatischen
Bruchzähigkeit von Schweißnähten (ISO 15653:2018)
Matériaux métalliques - Méthode d'essai pour la détermination de la ténacité quasi
statique à la rupture des soudures (ISO 15653:2018)
Ta slovenski standard je istoveten z: EN ISO 15653:2018
ICS:
25.160.40 Varjeni spoji in vari Welded joints and welds
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EN ISO 15653
EUROPEAN STANDARD
NORME EUROPÉENNE
January 2018
EUROPÄISCHE NORM
ICS 25.160.40 Supersedes EN ISO 15653:2010
English Version
Metallic materials - Method of test for the determination of
quasistatic fracture toughness of welds (ISO 15653:2018)
Matériaux métalliques - Méthode d'essai pour la Metallische Werkstoffe - Prüfverfahren zur
détermination de la ténacité quasi statique à la rupture Bestimmung der quasistatischen Bruchzähigkeit von
des soudures (ISO 15653:2018) Schweißverbindungen (ISO 15653:2018)
This European Standard was approved by CEN on 10 November 2017.
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, Serbia, 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: Rue de la Science 23, B-1040 Brussels
© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 15653:2018 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
European foreword
This document (EN ISO 15653:2018) has been prepared by Technical Committee ISO/TC 164
"Mechanical testing of metals" in collaboration with Technical Committee CEN/TC 121 “Welding and
allied processes” 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 July 2018, and conflicting national standards shall be
withdrawn at the latest by July 2018.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 15653:2010.
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, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 15653:2018 has been approved by CEN as EN ISO 15653:2018 without any modification.
INTERNATIONAL ISO
STANDARD 15653
Second edition
2018-01
Metallic materials — Method of test
for the determination of quasistatic
fracture toughness of welds
Matériaux métalliques — Méthode d'essai pour la détermination de la
ténacité quasi statique à la rupture des soudures
Reference number
ISO 15653:2018(E)
©
ISO 2018
ISO 15653:2018(E)
© ISO 2018
All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
Published in Switzerland
ii © ISO 2018 – All rights reserved
ISO 15653:2018(E)
Contents Page
Foreword .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and units . 3
5 Principle . 3
6 Choice of specimen design, specimen orientation and notch location .4
6.1 Classification of target area for notching . 4
6.2 Specimen design . 4
6.3 Specimen and crack plane orientation . 4
7 Pre-machining metallography. 8
7.1 Microstructural assessment of macrosections . 8
7.2 Additional requirements for heat-affected zone tests . 9
8 Machining. 9
8.1 Tolerances on specimen dimensions . 9
8.2 Notch placement for through-thickness notched specimens .10
8.3 Notch placement for surface-notched specimens.10
8.4 Notch machining .11
9 Specimen preparation .16
9.1 Fatigue precracking .16
9.2 Side grooving .16
10 Test apparatus, requirements and test procedure .16
11 Post-test metallography .16
11.1 General .16
11.2 Through-thickness notched specimens .17
11.2.1 Sectioning .17
11.2.2 Assessment .17
11.3 Surface-notched specimens .17
11.3.1 Sectioning .17
11.3.2 Assessment .17
11.4 Assessment of pop-in .17
12 Post-test analysis .20
12.1 Choice of tensile properties .20
12.2 Determination of fracture toughness .21
12.2.1 K .
Ic 21
12.2.2 δ . 21
12.2.3 J . 22
12.2.4 Shallow-notched bend specimen .22
12.3 Qualification requirements .23
12.3.1 General.23
12.3.2 Weld-width-to-crack-ligament ratio .23
12.3.3 Crack front straightness .23
12.3.4 Symbols used to identify fracture toughness values .25
12.3.5 Through-thickness notched specimens .25
12.3.6 Surface-notched specimens .25
13 Test report .26
Annex A (informative) Examples of notch locations .27
Annex B (informative) Examples of pre-test and post-test metallography .29
ISO 15653:2018(E)
Annex C (informative) Residual-stress modification and precracking technique .31
Annex D (normative) Assessment of pop-in .35
Annex E (informative) Shallow-notched bend specimen testing.42
Bibliography .45
iv © ISO 2018 – All rights reserved
ISO 15653:2018(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 4, Toughness testing — Fracture (F), Pendulum (P), Tear (T).
This second edition of ISO 15653 cancels and replaces the first edition (ISO 15653:2010), which has
been technically revised.
The main changes compared to the previous edition are as follows:
— new formulae for the calculation of single-point determination of CTOD (12.2.2) have been added;
— introduction for reverse bending in C.3 has been added;
— assessment of pop-in in D.1 has been clarified;
— new formula for the calculation for single-point determination of CTOD in shallow notched specimens
in E.4 has been added.
INTERNATIONAL STANDARD ISO 15653:2018(E)
Metallic materials — Method of test for the determination
of quasistatic fracture toughness of welds
1 Scope
This document specifies methods for determining fracture toughness in terms of stress intensity factor
(K), crack tip opening displacement or CTOD (δ) and experimental equivalent of the J-integral for welds
in metallic materials (J).
This document complements ISO 12135, which covers all aspects of fracture toughness testing of parent
metal and which needs to be used in conjunction with this document. This document describes methods
for determining point values of fracture toughness. It should not be considered a way of obtaining a valid
R-curve (resistance-to-crack-extension curve). However, the specimen preparation methods described
in this document could be usefully employed when determining R-curves for welds. The methods use
fatigue precracked specimens which have been notched, after welding, in a specific target area in the
weld. Methods are described to evaluate the suitability of a weld for notch placement within the target
area, which is either within the weld metal or within the weld heat-affected zone (HAZ), and then, where
appropriate, to evaluate the effectiveness of the fatigue crack in sampling these areas.
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 12135:2016, Metallic materials — Unified method of test for the determination of quasistatic fracture
toughness
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 12135 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at https://www.iso.org/obp
3.1
stretch zone width
SZW
increase in crack length associated with crack tip blunting, i.e. prior to the onset of unstable crack
extension, pop-in ( 3.3) or slow stable crack extension, and occurring in the same plane as the fatigue
precrack
3.2
target area
intended fatigue crack tip position within the weld metal (3.7) or HAZ (3.9)
3.3
pop-in
abrupt discontinuity in the force versus displacement record, featured as a sudden increase in
displacement and, generally, a sudden decrease in force, subsequent to which displacement and force
increase to above their values at the initiation of the discontinuity
ISO 15653:2018(E)
3.4
local compression
controlled compression applied to specimens in the thickness direction on the unnotched ligament
prior to fatigue cracking using hardened steel platens
Note 1 to entry: See Annex C.
3.5
welding
operation in which two or more parts are united by means of heat, friction, pressure or all three of
these, in such a way that there is continuity in the nature of the metal between these parts
Note 1 to entry: Filler metal, the melting temperature of which is of the same order as that of the parent metal,
may or may not be used.
3.6
weld
union of pieces of metal made by welding (3.5)
3.7
weld metal
all metal melted during the making of a weld (3.6) and retained in the weld
3.8
parent metal
metal to be joined by welding (3.5)
3.9
heat-affected zone
HAZ
zone in the parent metal that is metallurgically affected by the heat of welding (3.5)
3.10
fusion line
FL
junction between the weld metal (3.7) and the parent metal (3.8) heat-affected zone
3.11
weld positional
WP
target position for the fatigue crack tip, defined with respect to a reference line
Note 1 to entry: See Figure A.1 for examples.
3.12
specific microstructure
SM
target microstructure for the fatigue crack tip
Note 1 to entry: See Figure A.2 for examples.
3.13
specimen blank
specimen prepared from weld metal (3.7) plus parent metal (3.8) prior to notching
3.14
post-weld heat treatment
heat treatment applied after welding (3.5) for the purpose of reducing residual stresses or modifying
weld (3.6) properties
2 © ISO 2018 – All rights reserved
ISO 15653:2018(E)
4 Symbols and units
For the purposes of this document, the symbols and units given in Table 1 apply in addition to those in
ISO 12135.
Table 1 — Symbols and units
Symbol Unit Designation
d , d mm Lengths of microstructural features associated with pop-in.
1 2
h mm Effective weld width, defined as shortest distance between fatigue crack tip and
weld fusion line within the central 75 % of the thickness (see Figures 13 and 14).
HV10 Vickers hardness using 10 kg force.
N Normal to welding direction.
P Parallel to welding direction.
Q Weld thickness direction.
R MPa 0,2 % offset yield strength of parent metal at the temperature of the fracture test.
p0,2b
R MPa 0,2 % offset yield strength of weld metal at the temperature of the fracture test.
p0,2w
R MPa Tensile strength of parent metal at the temperature of the fracture test.
mb
R MPa Tensile strength of weld metal at the temperature of the fracture test.
mw
s mm Distance between crack tip and target area measured in the crack plane
(see Figure 12).
s mm Distance between crack tip and target area measured perpendicular to the
crack plane (see Figure 12).
V mm Crack mouth opening displacement at notch edge in bend specimen and that at
load line in compact specimen.
V mm Displacement measured by clip gauge mounted on knife edges.
g
V mm Displacement measured with the double clip gauge arrangement described
g1
in E.3 and illustrated in Figure E.1.
V mm Displacement measured with the double clip gauge arrangement described
g2
in E.3 and illustrated in Figure E.1.
X Direction parallel to primary grain flow of parent metal.
Y Direction transverse to primary grain flow and to thickness of parent metal.
Z Direction through thickness of parent metal.
Δa mm Maximum length of brittle crack extension (beyond SZW; see 3.1) associated with
pop
pop-in.
λ mm Length of specific microstructure measured in pre-test or post-test metallography
(see Figure B.2).
5 Principle
This document specifies procedures for the determination of fracture toughness on notched-plus-
fatigue-cracked specimens taken from welds. It pertains to situations where the fatigue crack tip is
a) located in relation to a weld feature of interest, referred to as “weld positional” (WP), and
b) specifically located within a microstructure of interest, referred to as “specific microstructure” (SM).
Metallographic examination of the weld is used to confirm that the target weld feature and/or
microstructure is indeed present at the crack tip and in sufficient quantity for testing.
Specimen geometry and notch orientation are chosen, and a fatigue crack then extended from the
specimen's notch tip into the target weld feature or microstructure by applying a controlled alternating
force to the specimen. The purpose of the test is to determine weld fracture toughness in the absence
of significant residual welding stresses. To achieve this and to produce a straight-fronted fatigue crack,
ISO 15653:2018(E)
modifications to the fatigue precracking procedure may be required. These modifications are usually
necessary when testing as-welded or partially stress-relieved welds.
The fracture toughness test is performed and evaluated in accordance with ISO 12135, but subject to
additional requirements of this test method regarding post-test analysis (see 12.2.1, 12.2.2 and 12.2.3)
and qualification (see 12.3).
Post-test metallography is often required to make certain that the crack tip was located in the target
weld feature and/or microstructure and to determine the significance of pop-ins.
The sequence of operations is summarized in Figure 1.
6 Choice of specimen design, specimen orientation and notch location
6.1 Classification of target area for notching
A specimen selected for weld positional (WP) testing is intended to test a defined weld region with
respect to a reference position (e.g. the weld metal centreline).
A specimen selected for specific microstructure (SM) testing is intended to sample a specific
microstructure along the whole or part of the crack front length within the central 75 % of the specimen
thickness.
NOTE Some examples of WP and SM notch locations are given in Annex A.
WP weld metal centreline notch locations sampling predominantly grain-refined regions may give
misleading (overly high) values of fracture toughness for misaligned two-pass and parallel multi-pass
welds. For these welds, it is recommended that the SM notch locations shown in Figures A.2 d) and e),
respectively, be used.
6.2 Specimen design
Specimen design shall be of compact or single-edge-notched bend configuration as defined in
ISO 12135 and may be plain-sided or side-grooved. Bend specimens notched into the plate thickness
(see Figures 2, 3 and 4, parent metal specimens XY and YX and weld metal specimens NP and PN) are
referred to as through-thickness notched specimens, while those notched into the planar surface of the
plate (see Figures 2, 3 and 4, parent metal specimens XZ and YZ and weld metal specimens NQ and PQ)
are referred to as surface-notched specimens.
NOTE Tolerances on weld specimen dimensions are less stringent than those for testing parent metal
(see 8.1).
Test specimens shall have the dimension B or W (see Figure 5) equal to the full thickness of the parent
metal adjacent to the weld to be tested (excluding weld overfill).
Testing of sub-sized (i.e. B or W < full thickness in directions Q for weld and Z for parent metal in
Figures 2, 3 and 4) and/or side-grooved specimens is permitted, but shall be properly identified as such
in the test report. Results from sub-sized and/or side-grooved specimens may differ from those from
full-thickness specimens owing to size effects and/or different microstructural regions being tested.
6.3 Specimen and crack plane orientation
Specimen and crack plane orientation relative to the weld and parent metal working directions shall be
defined using the identification system described in Figures 2, 3 and 4.
4 © ISO 2018 – All rights reserved
ISO 15653:2018(E)
Choose target area
Choose specimen size
and geometry
Choose notch
orientation
Speciic
microstructure, SM
Weld positional, WP
Pre-test
metallography
Yes Can SM be No
tested?
Prepare blank
Mark notch location
Notch
Modify
Yes
residual stesses
Choose Annex C
No
procedures
Fatigue pre-crack
specimen
Top specimen
Measure specimen
dimensions
and crack length
Post-text
metallography
Pop-in (WP or SM)
WP SM
No metallography Metallography Metallography
Assess pop-in
signiicance
Evaluate result
Report
Figure 1 — Flow chart for testing
ISO 15653:2018(E)
X
YZ
Y
YX
XZ
XY
a) Parent metal
PQ
P
PN
N NQ
NP
b) Weld metal
Key
1 rolling direction
N normal to weld direction
P parallel to weld direction
Q weld thickness direction
NOTE 1 The first letter in the designation is the direction normal to the crack plane.
NOTE 2 The second letter in the designation is the expected direction of crack propagation.
NOTE 3 See ISO 3785 for the definitions of X, Y and Z.
Figure 2 — Crack plane orientation codes for fracture toughness
specimens of parent metal and weld metal
As shown in Figure 2, specimen orientations NP and PN shall be referred to as through-thickness
notched, while specimen orientations NQ and PQ shall be referred to as surface-notched.
6 © ISO 2018 – All rights reserved
Q
Z
ISO 15653:2018(E)
Y
X
Y
X
3 4
a) Typical butt weld
Z
b) Cruciform joint
Key
1 HAZ
2 weld
3 weld specimen orientation NP/XY
4 weld specimen orientation NP/YX
5 through-crack NP/ZX or NP/ZY
X rolling direction
Q weld thickness direction
NOTE For tests of the HAZ, where the rolling direction of the parent metal may affect resistance to crack
extension, the weld and parent metal orientations may be combined to give both the weld direction and the
parent metal rolling direction as shown in this figure and Figure 4.
Figure 3 — Crack plane orientation code for fracture toughness specimens
for testing the HAZ of a typical butt weld and cruciform joint
Q
ISO 15653:2018(E)
NP/X
a) Typical butt weld
NQ/X
NQ/Y
Y
b) Angled cruciform joint
Key
1 rolling direction
NOTE For tests of the HAZ, where the rolling direction of the parent metal may affect resistance to crack
extension, the weld and parent metal orientations may be combined to give both the weld direction and the
parent metal rolling direction as shown in this figure and Figure 3.
Figure 4 — Crack plane orientation codes for fracture toughness specimens
for testing the HAZ at an angle, α, to the parent metal rolling direction
for a typical butt weld and angled cruciform joint
7 Pre-machining metallography
7.1 Microstructural assessment of macrosections
When the notch target area is defined as SM, either separate macrosections or the ends of the welds
shall be prepared with the plane of the section perpendicular to the welding direction. These transverse
weld sections shall bound the length of weld to be tested to ensure that the target microstructure is
present at the expected crack tip position and in sufficient quantity for testing. The macrosections
shall be polished, etched and examined at a magnification suitable to identify the target area prior to
specimen manufacture. Where separate macrosections are prepared, their positions along the weld
shall be recorded.
Examination of the macrosections shall be used to establish that
a) in a through-thickness notched specimen, the intended crack tip is likely to reside in the target area
within the central 75 % of the thickness, and
8 © ISO 2018 – All rights reserved
ISO 15653:2018(E)
b) in a surface-notched specimen, the intended crack tip is no more than 0,5 mm from the target area.
If the desired microstructure is not present, there is insufficient quantity to test, or the crack tip
position tolerances cannot be achieved, the weld shall be rejected as unsuitable for testing to the SM
criteria. In this case, a new target area may be selected or a new weld prepared. If the bend specimen is
to be employed and the specific microstructure is available in sufficient quantity to test, but the crack
tip position tolerances cannot be achieved, the shallow-notched specimen testing procedures described
in Annex E may be used by agreement between the parties involved.
Owing to the lower crack tip constraint associated with a shallow notch, the fracture toughness value
determined from a shallow-notched specimen (0,10 ≤ a /W ≤ 0,45) may be higher than that obtained from
o
a standard notched specimen (0,45 ≤ a /W ≤ 0,70) for the same crack tip microstructure. The significance
o
of this potential difference shall be considered when a shallow-notched specimen is to be used.
7.2 Additional requirements for heat-affected zone tests
When the target area is SM in the HAZ, microstructural examinations additional to those in 7.1 shall
be conducted on the polished and etched macrosection to determine whether or not the target
microstructure is within the central 75 % of the thickness and in sufficient quantity for a successful test.
The measured positions and lengths of the target microstructure may optionally be presented in map
form (an example is shown in Annex B). If such a map is drawn, it shall include the full macrosection
thickness, showing the positions of the target microstructure. The percentage of target microstructure
shall be calculated over the central 75 % of the specimen thickness.
Where surface-notched specimens are selected, the macrosection shall be used to confirm that the
target microstructure is present within the range 0,45 ≤ a /W ≤ 0,70.
o
If it is considered unlikely that the fatigue crack tip is placed in accordance with the SM acceptance
criteria, then consideration shall be given to revising the target area, preparing a new weld or using a
shallow-notched specimen as described in 7.1.
8 Machining
8.1 Tolerances on specimen dimensions
Specimen blanks shall be machined from the product so that the target area identified for testing can
be successfully notched. Blanks shall be machined to the dimensional tolerances defined here prior to
notching.
Compact specimens shall meet the dimensional requirements of ISO 12135. Standard bend specimens
shall conform to Figure 5. Shallow-notched bend specimens (see 7.1, 7.2 and Annex E) shall likewise
conform to Figure 5, except that the relative crack length shall be in the range 0,10 ≤ a /W ≤ 0,45.
o
NOTE 1 The dimensional tolerances in Figure 5 for the standard single-edge-notched bend specimen are
intentionally less stringent than those of ISO 12135 in order to minimize alteration of the original weld product.
Weld misalignment, weld distortion and specimen blank curvature (for blanks removed from pipe
sections) shall conform to the requirements of Figure 6. The straightness requirement of 2,5 % of
W on specimen blank sides applies to pipe curvatures (expressed as the ratio of pipe radius to weld
thickness) ≥10. Welded joints not meeting the specified straightness/misalignment requirements shall
be straightened by local bending prior to notching. The points of straightening-force application shall
be located at a minimum distance B from the region to be notched. It is essential that the region to be
notched is not deformed by straightening operations. A method for straightening specimen blanks from
distorted or curved sections is illustrated in Figure 7.
When it is not possible to straighten a specimen blank taken from pipe, a rectangular block of test
material may be cut from the pipe and joined by welding to suitable extension pieces. The total length
of the test block and extension pieces shall give a specimen of sufficient length to satisfy the curvature
ISO 15653:2018(E)
requirements of Figure 6. The weld joints shall be sufficiently distant so as not to affect the target
microstructure.
NOTE 2 Laser and electron beam welding processes have proved useful in producing narrow joints with low
distortion between the test block and the extension pieces.
When a full section thickness specimen is intended, machining shall be kept to a minimum in order to
meet the tolerance requirements and the requirements for local compression (see C.2).
Weld overfill shall be machined level with the original product surface.
When the metal thicknesses on each side of the weld differ by 10 % or more, the blank shall be
machined down to the thickness of the thinner side. In such cases, the original and final specimen blank
dimensions shall be reported.
8.2 Notch placement for through-thickness notched specimens
The procedure for through-thickness notch placement for the NP crack plane orientation is illustrated
in Figure 8. Both the surface to be notched (side A) and the opposite surface (side B) are ground and
etched to reveal the weld and HAZ. A reference line is scribed on each prepared surface A and B normal
to the specimen axis ±5° and along the targeted microstructure. These scribed lines are carried over
onto the surfaces normal to the prepared surfaces. A new line is then constructed equidistant between
the carried-over lines. This line is used to delineate the intended plane of the notch to be machined into
surface A.
NOTE This procedure is designed to ensure that the final crack tip is in the targeted microstructure
(especially if it is the HAZ) when the specimen axis in not perpendicular to the weld direction and a /W = 0,5.
o
If a /W ≠ 0,5, the line constructed to delineate the intended plane of the machined notch is adjusted laterally to
o
ensure that the final crack tip is in the targeted microstructure.
8.3 Notch placement for surface-notched specimens
The procedure for surface-notch placement for the NP crack plane orientation is illustrated in Figure 9.
The side surfaces (those at right angles to the surface to be notched) are ground and etched to reveal
the weld metal and HAZ. Reference lines are scribed upwards from the selected target-microstructure
area to the surface to be notched. Perpendiculars emanating from the scribe lines (normal to the
specimen axis ±5°) are marked (again by scribing) on the surface to be notched. A new line is constructed
equidistant between the two lines. This line is used to delineate the intended plane of the machined notch.
NOTE This procedure is designed to ensure that the final crack tip, at the specimen mid-thickness, is in the
targeted microstructure when the specimen axis is not perpendicular to the weld direction.
10 © ISO 2018 – All rights reserved
ISO 15653:2018(E)
8.4 Notch machining
Notch machining shall follow the guidelines provided in ISO 12135.
X
B 5%
X
A
0,8
2,3 W 2,3 W
0,2% W A
0,8
2,5% W A
a) Rectangular-section specimen
a
W 2,5%
ISO 15653:2018(E)
X
B 5%
X
A
0,8
2,3 W 2,3 W
0,2% W A
0,8
2,5% W A
b) Square-section specimen
a) Rectangular-section specimen b) Square-section specimen
Width = W Width = W
Thickness = B = 0,5W Thickness = B = W
Crack length = a = 0,45W to 0,7W Crack length = a = 0,45W to 0,7W
Loading span = 4W Loading span = 4W
Notch width = 0,062 5W Notch width = 0,062 5W
max max
Specimen straightness; see Figure 6 Specimen straightness; see Figure 6
Figure 5 — Proportional dimensions and tolerances for bend specimens
12 © ISO 2018 – All rights reserved
a
W 2,5%
B
B
ISO 15653:2018(E)
10%W
10%W
10%W
B
a) Misalignment b) Misalignment and/or c) Curvature
angular distortion
2,5%W
B
d) Curvature
Key
1 loading points
2 curved surface due to tube radius 4W = span
Figure 6 — Tolerances for misalignment, distortion and curvature
in single-edge-notched bend specimens
4 W
W
4 W
ISO 15653:2018(E)
B
a) To reduce angular distortion
B
B
b) To reduce curvature of specimen blank from pipe
(each specimen arm straightened separately)
c) Resultant “gull wing” specimen blank shape
Key
1 applied straightening force
2 weld
Figure 7 — Method for straightening bend specimens
14 © ISO 2018 – All rights reserved
ISO 15653:2018(E)
Key
1 reference scribe line A 4 reference scribe line B
2 fusion line 5 side A (notched side)
3 side B (unnotched side) 6 notch
NOTE NP crack plane orientation.
Figure 8 — Notch placement procedure using reference scribe lines
in a through-thickness notched specimen
41 3
Key
1 notch 5 reference scribe line A
2 fusion line 6 side A
3 notched side 7 side B
4 reference scribe line B
NOTE NP crack plane orientation.
Figure 9 — Notch placement procedure in a surface-notched specimen
W
B
90 5
a
W
B
ISO 15653:2018(E)
9 Specimen preparation
9.1 Fatigue precracking
Fatigue precracking shall be carried out in accordance with ISO 12135. For specimens where the
intended fatigue crack tip is located in weld metal, the calculation of the maximum fatigue precracking
force, F , and the maximum fatigue stress intensity factor, K , shall be based on the tensile properties of
f f
the weld metal, i.e. the region in which the fatigue crack is to be located. In all other cases, the properties
of the adjacent material with the lowest tensile properties shall be used.
Any post-weld or stress relief heat treatment shall be completed before fatigue precracking.
When possible, use of the shortest fatigue crack length permitted in ISO 12135 is recommended in
order to minimize fatigue crack front bowing and crack deviation from the specified target area.
Problems may occur in meeting the fatigue crack front straightness requirements specified in 12.3.3,
particularly with specimens prepared from as-welded or partially stress-relieved welds. In such
instances, the procedures given in Annex C shall be considered.
NOTE 1 The magnitude and distribution of residual stresses in as-welded and partially post weld heat treated
specimens depend on the material, the welding procedure, the degree of restraint and the post-weld specimen
preparation.
NOTE 2 Residual stresses may (or may not) contribute to uneven fatigue crack extension, and may have an
effect on the resulting fracture toughness determination.
If the specimen is prepared from a post-weld heat-treated weld, then the procedures in Annex C may
not be necessary.
NOTE 3 A straight fatigue crack front
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.