ISO 22848:2021
(Main)Corrosion of metals and alloys — Test method for measuring the stress corrosion crack growth rate of steels and alloys under static-load conditions in high-temperature water
Corrosion of metals and alloys — Test method for measuring the stress corrosion crack growth rate of steels and alloys under static-load conditions in high-temperature water
This document specifies a test method for determining the stress corrosion crack (SCC) growth rate of steels and alloys under static-load conditions in high-temperature water, such as the simulated water environment of light water reactors. The crack length of the specimen is monitored by a potential drop method (PDM) during the test in an autoclave. The test method is applicable to stainless steels, nickel base alloys, low alloy steels, carbon steels and other alloys.
Corrosion des métaux et des alliages — Méthode d'essai pour le mesurage de la vitesse de propagation des fissures de corrosion sous contrainte des aciers et des alliages dans des conditions de charge statique dans de l'eau à haute température
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INTERNATIONAL ISO
STANDARD 22848
First edition
2021-02
Corrosion of metals and alloys —
Test method for measuring the
stress corrosion crack growth rate
of steels and alloys under static-load
conditions in high-temperature water
Corrosion des métaux et des alliages — Méthode d'essai pour le
mesurage de la vitesse de propagation des fissures de corrosion sous
contrainte des aciers et des alliages dans des conditions de charge
statique dans de l'eau à haute température
Reference number
©
ISO 2021
© ISO 2021
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
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle of test . 2
5 Specimen . 3
5.1 Specimen orientation . 3
5.2 Specimen geometry . 3
5.3 Specimen finish . 4
5.4 Specimen size requirement . 4
5.5 Specimen dimensional measurement . 5
5.6 Stress intensity factor, K .
I 5
6 Test equipment. 5
7 Crack length measurement by potential drop method . 6
8 Corrosion potential measurement . 7
8.1 General . 7
8.2 Measurement method . 7
9 Test procedure . 7
9.1 General . 7
9.2 Installation in autoclave . 8
9.3 Adjustment of test environment . 9
9.4 Loading . 9
9.4.1 General. 9
9.4.2 Fatigue pre-cracking . 9
9.4.3 SCC transitioning . 9
9.4.4 Static loading .11
10 Evaluation of test results .11
11 Test report .14
Annex A (informative) CDCB specimen geometry and stress intensity factor calculation .16
Annex B (informative) Equipment for SCC growth testing .19
Annex C (informative) Water chemistry and monitoring items in simulated BWR and PWR
environments .22
Annex D (informative) Approach to determine crack growth rate .24
Bibliography .25
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 of 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 www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 156, Corrosion of metals and alloys.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2021 – All rights reserved
INTERNATIONAL STANDARD ISO 22848:2021(E)
Corrosion of metals and alloys — Test method for
measuring the stress corrosion crack growth rate of
steels and alloys under static-load conditions in high-
temperature water
1 Scope
This document specifies a test method for determining the stress corrosion crack (SCC) growth rate of
steels and alloys under static-load conditions in high-temperature water, such as the simulated water
environment of light water reactors. The crack length of the specimen is monitored by a potential drop
method (PDM) during the test in an autoclave.
The test method is applicable to stainless steels, nickel base alloys, low alloy steels, carbon steels and
other alloys.
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 7539-6, Corrosion of metals and alloys — Stress corrosion testing — Part 6: Preparation and use of
precracked specimens for tests under constant load or constant displacement
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 7539-6 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
potential drop method
PDM
non-destructive method for measuring a crack length based on the change in the electric potential as a
crack propagates in the presence of an applied DC or AC current
3.2
stress corrosion crack transitioning
SCC transitioning
use of cyclic loading at low frequency and with increasing hold time at maximum load in the test
environment to promote a transition in the fracture surface morphology from a transgranular
(TG) fatigue pre-crack to SCC, typically intergranular (IG) or interdendritic (ID) morphology for
austenitic alloys
3.3
crack-tip re-activation loading
use of loading cycles to re-activate the tip of crack when crack retardation is observed under a
static loading
3.4
initial crack length
a
distance from the load line to the initial crack tip
Note 1 to entry: It can refer to the machined notch tip or the air fatigue pre-crack front in the specimen.
Note 2 to entry: For other fracture mechanics geometries, refer to ISO 7539-6. The crack length (a) is often
expressed as a proportion of the distance from the load-line to the end of the specimen (W): a/W.
3.5
final crack length
a
f
distance from the load line to the final crack front at the end of the stress corrosion crack growth test,
where the crack length is measured on the fracture surface of the specimen
3.6
flow stress at test temperature
σ
flowT
algebraic average of the yield stress (σ ) and the ultimate tensile strength (σ ) at the test temperature:
yT uT
σσ =+ σ /2
()
flowTyTuT
3.7
crack engagement
specimen thickness B where the stress corrosion crack has advanced
Note 1 to entry: It is expressed as a percentage.
3.8
average crack extension
A
average crack extension across the specimen thickness using a crack growth area or many equally
spaced measurements of crack length (equally divided method)
3.9
average crack extension in crack engagement area
A
average crack extension based on the fraction of the specimen thickness where the stress corrosion
crack has occurred
3.10
minimum crack extension
A
min
minimum extension of the stress corrosion crack in the specimen
3.11
maximum crack extension
A
max
maximum extension of the stress corrosion crack in the specimen
4 Principle of test
Stress corrosion cracking is a phenomenon in which a crack grows in an environment when stress is
applied to a susceptible material. Thus, stress corrosion cracking is affected by three general factors:
the material, stress and environment. The SCC growth rate is affected by the stress intensity factor,
K . The SCC growth rate, da/dt, is defined as the time derivative of the crack length. While there is
I
often no clear distinction between static loading and some very slowly increasing monotonically or
cyclic loading, the primary interest in most SCC growth testing is the behaviour under static loading. By
2 © ISO 2021 – All rights reserved
...
INTERNATIONAL ISO
STANDARD 22848
First edition
2021-02
Corrosion of metals and alloys —
Test method for measuring the
stress corrosion crack growth rate
of steels and alloys under static-load
conditions in high-temperature water
Corrosion des métaux et des alliages — Méthode d'essai pour le
mesurage de la vitesse de propagation des fissures de corrosion sous
contrainte des aciers et des alliages dans des conditions de charge
statique dans de l'eau à haute température
Reference number
©
ISO 2021
© ISO 2021
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
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle of test . 2
5 Specimen . 3
5.1 Specimen orientation . 3
5.2 Specimen geometry . 3
5.3 Specimen finish . 4
5.4 Specimen size requirement . 4
5.5 Specimen dimensional measurement . 5
5.6 Stress intensity factor, K .
I 5
6 Test equipment. 5
7 Crack length measurement by potential drop method . 6
8 Corrosion potential measurement . 7
8.1 General . 7
8.2 Measurement method . 7
9 Test procedure . 7
9.1 General . 7
9.2 Installation in autoclave . 8
9.3 Adjustment of test environment . 9
9.4 Loading . 9
9.4.1 General. 9
9.4.2 Fatigue pre-cracking . 9
9.4.3 SCC transitioning . 9
9.4.4 Static loading .11
10 Evaluation of test results .11
11 Test report .14
Annex A (informative) CDCB specimen geometry and stress intensity factor calculation .16
Annex B (informative) Equipment for SCC growth testing .19
Annex C (informative) Water chemistry and monitoring items in simulated BWR and PWR
environments .22
Annex D (informative) Approach to determine crack growth rate .24
Bibliography .25
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 of 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 www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 156, Corrosion of metals and alloys.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2021 – All rights reserved
INTERNATIONAL STANDARD ISO 22848:2021(E)
Corrosion of metals and alloys — Test method for
measuring the stress corrosion crack growth rate of
steels and alloys under static-load conditions in high-
temperature water
1 Scope
This document specifies a test method for determining the stress corrosion crack (SCC) growth rate of
steels and alloys under static-load conditions in high-temperature water, such as the simulated water
environment of light water reactors. The crack length of the specimen is monitored by a potential drop
method (PDM) during the test in an autoclave.
The test method is applicable to stainless steels, nickel base alloys, low alloy steels, carbon steels and
other alloys.
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 7539-6, Corrosion of metals and alloys — Stress corrosion testing — Part 6: Preparation and use of
precracked specimens for tests under constant load or constant displacement
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 7539-6 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
potential drop method
PDM
non-destructive method for measuring a crack length based on the change in the electric potential as a
crack propagates in the presence of an applied DC or AC current
3.2
stress corrosion crack transitioning
SCC transitioning
use of cyclic loading at low frequency and with increasing hold time at maximum load in the test
environment to promote a transition in the fracture surface morphology from a transgranular
(TG) fatigue pre-crack to SCC, typically intergranular (IG) or interdendritic (ID) morphology for
austenitic alloys
3.3
crack-tip re-activation loading
use of loading cycles to re-activate the tip of crack when crack retardation is observed under a
static loading
3.4
initial crack length
a
distance from the load line to the initial crack tip
Note 1 to entry: It can refer to the machined notch tip or the air fatigue pre-crack front in the specimen.
Note 2 to entry: For other fracture mechanics geometries, refer to ISO 7539-6. The crack length (a) is often
expressed as a proportion of the distance from the load-line to the end of the specimen (W): a/W.
3.5
final crack length
a
f
distance from the load line to the final crack front at the end of the stress corrosion crack growth test,
where the crack length is measured on the fracture surface of the specimen
3.6
flow stress at test temperature
σ
flowT
algebraic average of the yield stress (σ ) and the ultimate tensile strength (σ ) at the test temperature:
yT uT
σσ =+ σ /2
()
flowTyTuT
3.7
crack engagement
specimen thickness B where the stress corrosion crack has advanced
Note 1 to entry: It is expressed as a percentage.
3.8
average crack extension
A
average crack extension across the specimen thickness using a crack growth area or many equally
spaced measurements of crack length (equally divided method)
3.9
average crack extension in crack engagement area
A
average crack extension based on the fraction of the specimen thickness where the stress corrosion
crack has occurred
3.10
minimum crack extension
A
min
minimum extension of the stress corrosion crack in the specimen
3.11
maximum crack extension
A
max
maximum extension of the stress corrosion crack in the specimen
4 Principle of test
Stress corrosion cracking is a phenomenon in which a crack grows in an environment when stress is
applied to a susceptible material. Thus, stress corrosion cracking is affected by three general factors:
the material, stress and environment. The SCC growth rate is affected by the stress intensity factor,
K . The SCC growth rate, da/dt, is defined as the time derivative of the crack length. While there is
I
often no clear distinction between static loading and some very slowly increasing monotonically or
cyclic loading, the primary interest in most SCC growth testing is the behaviour under static loading. By
2 © ISO 2021 – All rights reserved
...
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