ISO 4680:2022

INTERNATIONAL ISO
STANDARD 4680
First edition
2022-12
Corrosion of metals and alloys —
Uniaxial constant-load test method
for evaluating susceptibility of
metals and alloys to stress corrosion
cracking in high-purity water at high
temperatures
Corrosion des métaux et alliages — Méthode d'essai sous charge
uniaxiale pour l'évaluation de la sensibilité des métaux et des alliages
à la fissuration par corrosion sous contrainte dans l'eau de haute
pureté à hautes températures
Reference number
© ISO 2022
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Contents Page
Foreword .v
1 Scope . 1
2 Normative reference .1
3 Terms and definitions . 1
4 Principle . 2
5 Specimens. 2
5.1 General . 2
5.1.1 General requirements . 2
5.1.2 Categories and shapes of specimens. 2
5.1.3 Shapes and dimensions of grips/clevises . 2
5.1.4 Dimensions of specimen shoulder and radius . 2
5.1.5 Machined notch . 3
5.1.6 Dimensions of gauge section. 3
5.1.7 Serial loading of multiple specimens. 3
5.2 Preparation of specimens . 4
5.2.1 Orientation of specimen sampling . 4
5.2.2 Methods of specimen sampling . 4
5.2.3 Surface finishing . 5
5.2.4 Mechanical grinding and polishing. 5
5.2.5 Electrolytic or chemical polishing . 5
5.2.6 Marking . . 5
6 Test apparatus .7
6.1 Test set-up . 7
6.2 Loading mechanism . 7
6.3 Autoclave . 8
6.4 Circulating loop . . . 8
7 Experimental procedure .9
7.1 Test environment . 9
7.1.1 General . 9
7.1.2 Corrosion potential . 10
7.1.3 Measurement parameters . 10
7.2 Specimen number and applied stress . 10
7.3 Testing procedures . 10
7.3.1 General . 10
7.3.2 Test solution adjustment . 11
7.3.3 Temperature control . 11
7.3.4 Loading . 11
7.3.5 Unloading . 11
7.3.6 Completion of test. 11
7.4 Addition of crevice . 11
7.4.1 General . 11
7.4.2 Materials of crevice formation . 11
7.4.3 Procedure of crevice addition .12
7.5 Electrical resistance measurement methods . .12
7.5.1 General .12
7.5.2 Measurement requirements. 13
8 Assessment of results .13
8.1 Time to failure. 13
8.2 Validity of failure position . 13
8.3 Other evaluation indexes . .13
8.4 Observation of crack morphology . 13
8.5 Detection of crack initiation using electrical resistance measurement methods . 14
iii
9 Test report .14
Annex A (informative) A comparison of specimen orientations in standards .15
Annex B (normative) Measuring items of test solution .17
Annex C (informative) Water chemistry conditions and measurement items for simulated
BWR and PWR primary water environment tests .18
Annex D (informative) Procedures to interrupt and resume testing .20
Annex E (informative) Electrical resistance measurement methods .22
Annex F (informative) Test report items .25
Bibliography .27
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Foreword
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