ISO 22848-2021 pdf free download – 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 ofsteels and alloys under static-load conditions in high-temperature water, such as the simulated waterenvironment of light water reactors.The crack length of the specimen is monitored by a potential dropmethod (PDM) during the test in an autoclave.
The test method is applicable to stainless steels,nickel base alloys, low alloy steels, carbon steels andother alloys.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their contentconstitutes requirements of this document.For dated references,only the edition cited applies.Forundated 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 ofprecracked 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 IS0 7539-6 and the following apply.lSO and lEC 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 methodPDM
non-destructive method for measuring a cracklength based on the change in the electric potential as acrack propagates in the presence of an applied DC or AC current
3.2
stress corrosion crack transitioningscC transitioning
use of cyclic loading at low frequency and with increasing hold time at maximum load in the testenvironment to promote a transition in the fracture surface morphology from a transgranular(TG) fatigue pre-crack to SCC, typically intergranular (lG) or interdendritic (ID) morphology foraustenitic 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 astatic loading
3.4
initial crack length
a 0
<compact tension (CT) specimen> 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 yT ) and the ultimate tensile strength (σ uT ) at the test temperature:
σ σ σ
flowT yT uT
= +
( ) /2
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 1
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 2
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.ISO 22848 pdf download.