Corrosion of metals and alloys - Basic terms and definitions (ISO 8044:2015)

ISO 8044:2015 defines terms relating to corrosion that are widely used in modern science and technology. In addition, some definitions are supplemented with short explanations.
NOTE 1 Throughout the document IUPAC rules for electrode potential signs are applied. The term "metal" is also used to include alloys and other metallic materials.
NOTE 2 Terms and definitions related to inorganic surface treatment of metals are given in ISO 2080.
NOTE 3 See also the ISO online browsing platform (OBP): www.iso.org/obp/ui/

Korrosion von Metallen und Legierungen - Grundbegriffe (ISO 8044:2015)

Corrosion des métaux et alliages - Termes principaux et définitions (ISO 8044:2015)

ISO 8044:2015 définit les termes relatifs à la corrosion qui sont largement employés dans les sciences et techniques modernes. Certaines définitions sont complétées par de brèves explications.
NOTE 1 Dans tout le document, on applique les conventions de l'IUPAC concernant le signe des potentiels d'électrode. Le terme « métal » est utilisé aussi pour désigner les alliages et autres matériaux métalliques.
NOTE 2 Les termes et définitions relatifs au traitement de surface des métaux avec des revêtements inorganiques sont donnés dans l'ISO 2080.
NOTE 3 Voir aussi la plateforme de consultation en ligne (OBP): www.iso.org/obp/ui/

Korozija kovin in zlitin - Osnovni pojmi in definicije (ISO 8044:2015)

Ta mednarodni standard določa izraze v zvezi s korozijo, ki se najpogosteje uporabljajo v sodobnih znanstvenih in tehnoloških besedilih. Poleg tega so nekaterim definicijam dodane kratke razlage.
OPOMBA 1: V celotnem dokumentu se uporabljajo pravila IUPAC za oznake napetosti. Izraz »kovina« se uporablja tudi za zlitine in druge kovinske materiale.
OPOMBA 2: Izrazi in definicije v zvezi z obdelavo anorganskih površin so podani v standardu ISO 2080.
OPOMBA 3: Glej tudi platformo za brskanje po spletu ISO (OBP): www.iso.org/obp/ui/

General Information

Status
Withdrawn
Publication Date
15-Sep-2015
Withdrawal Date
25-Feb-2020
Current Stage
9960 - Withdrawal effective - Withdrawal
Completion Date
26-Feb-2020

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SLOVENSKI STANDARD
SIST EN ISO 8044:2015
01-december-2015
1DGRPHãþD
SIST EN ISO 8044:2000
Korozija kovin in zlitin - Osnovni pojmi in definicije (ISO 8044:2015)
Corrosion of metals and alloys - Basic terms and definitions (ISO 8044:2015)
Korrosion von Metallen und Legierungen - Grundbegriffe (ISO 8044:2015)

Corrosion des métaux et alliages - Termes principaux et définitions (ISO 8044:2015)

Ta slovenski standard je istoveten z: EN ISO 8044:2015
ICS:
01.040.77 Metalurgija (Slovarji) Metallurgy (Vocabularies)
77.060 Korozija kovin Corrosion of metals
SIST EN ISO 8044:2015 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 8044:2015
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SIST EN ISO 8044:2015
EN ISO 8044
EUROPEAN STANDARD
NORME EUROPÉENNE
September 2015
EUROPÄISCHE NORM
ICS 77.060; 01.040.77 Supersedes EN ISO 8044:1999
English Version
Corrosion of metals and alloys - Basic terms and
definitions (ISO 8044:2015)

Corrosion des métaux et alliages - Termes principaux Korrosion von Metallen und Legierungen -

et définitions (ISO 8044:2015) Grundbegriffe (ISO 8044:2015)
This European Standard was approved by CEN on 13 May 2015.

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

© 2015 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 8044:2015 E

worldwide for CEN national Members.
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SIST EN ISO 8044:2015
EN ISO 8044:2015 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

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SIST EN ISO 8044:2015
EN ISO 8044:2015 (E)
European foreword

This document (EN ISO 8044:2015) has been prepared by Technical Committee ISO/TC 156 “Corrosion

of metals and alloys” in collaboration with Technical Committee CEN/TC 262 “Metallic and other

inorganic coatings” the secretariat of which is held by BSI.

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 March 2016, and conflicting national standards shall

be withdrawn at the latest by March 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 EN ISO 8044:1999.

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 8044:2015 has been approved by CEN as EN ISO 8044:2015 without any modification.

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SIST EN ISO 8044:2015
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SIST EN ISO 8044:2015
INTERNATIONAL ISO
STANDARD 8044
NORME
Fourth edition
Quatrième édition
INTERNATIONALE 2015-09-01
Corrosion of metals and alloys — Basic
terms and definitions
Corrosion des métaux et alliages —
Termes principaux et définitions
Korrosion von Metallen und
Legierungen — Grundbegriffe
Reference number
Numéro de référence
ISO 8044:2015(E/F)
ISO 2015
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SIST EN ISO 8044:2015
ISO 8044:2015(E/F)
COPYRIGHT PROTECTED DOCUMENT
DOCUMENT PROTÉGÉ PAR COPYRIGHT
© ISO 2015

All rights reserved. Unless otherwise specified, 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.

Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite ni utilisée

sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie, l’affichage sur

l’internet ou sur un Intranet, sans autorisation écrite préalable. Les demandes d’autorisation peuvent être adressées à l’ISO à

l’adresse ci-après ou au comité membre de l’ISO dans le pays du demandeur.
ISO copyright office
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Tel. + 41 22 749 01 11
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Published in Switzerland/Publié en Suisse

iiii © ISO 2015 – All rig© ISO 2015 – All rights rhts reserveserved/Ted/Tous drous droits roits réservéservésés

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SIST EN ISO 8044:2015
ISO 8044:2015(E/F)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

Introduction ................................................................................................................................................................................................................................vi

1 Scope ................................................................................................................................................................................................................................. 1

2 General terms .......................................................................................................................................................................................................... 1

3 Types of corrosion .............................................................................................................................................................................................. 3

4 Corrosion protection ........................................................................................................................................................................................ 9

5 Corrosion testing ...............................................................................................................................................................................................11

6 Electrochemical terms .................................................................................................................................................................................12

6.1 The electrochemical cell ..............................................................................................................................................................12

6.2 Reaction rates .......................................................................................................................................................................................16

6.3 Passivation ...............................................................................................................................................................................................18

6.4 Electrochemical protection .......................................................................................................................................................19

6.5 Electrochemical corrosion tests ............................................................................................................................................20

Bibliography .............................................................................................................................................................................................................................23

© ISO 2015 – All rights reserved/Tous droits réservés iii
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SIST EN ISO 8044:2015
ISO 8044:2015(E/F)
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 meaning of ISO specific terms and expressions related to conformity

assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers

to Trade (TBT) see the following URL: Foreword - Supplementary information

The committee responsible for this document is ISO/TC 156, Corrosion of metals and alloys.

This fourth edition cancels and replaces the third edition (ISO 8044:1999), which has been revised to

include additional terms and definitions.
iv © ISO 2015 – All rights reserved/Tous droits réservés
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SIST EN ISO 8044:2015
ISO 8044:2015(E/F)
Introduction

The definitions in this International Standard have been drawn up with the objective of achieving a

proper balance between precision and simplicity. The main objective of this International Standard is to

provide definitions that can be understood to have the same meaning by all concerned. Some corrosion

terms in present use have developed through common usage and are not always logical. It has not,

therefore, been possible to define certain terms in the form they are used in some countries. Because of

the occasional conflicts between tradition and logic some definitions inevitably represent a compromise.

An example of this kind of conflict is the term “corrosion”. This has been used to mean the process,

results of the process and damage caused by the process. In this International Standard corrosion is

understood to mean the process. Any detectable result of corrosion in any part of a corrosion system is

termed “corrosion effect”. The term “corrosion damage” covers any impairment of the function of the

technical system of which the metal and the environment form a part. Consequently the term “corrosion

protection” implies that the important thing is to avoid corrosion damage rather than to prevent

corrosion, which in many cases is impossible and sometimes not necessary.
© ISO 2015 – All rights reserved/Tous droits réservés v
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SIST EN ISO 8044:2015
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SIST EN ISO 8044:2015
INTERNATIONAL STANDARD ISO 8044:2015(E/F)
Corrosion of metals and alloys — Basic terms and
definitions
1 Scope

This International Standard defines terms relating to corrosion that are widely used in modern science

and technology. In addition, some definitions are supplemented with short explanations.

NOTE 1 Throughout the document IUPAC rules for electrode potential signs are applied. The term “metal” is

also used to include alloys and other metallic materials.

NOTE 2 Terms and definitions related to inorganic surface treatment of metals are given in ISO 2080.

NOTE 3 See also the ISO online browsing platform (OBP): www.iso.org/obp/ui/
2 General terms
2.1
corrosion

physicochemical interaction between a metal and its environment that results in changes in the

properties of the metal, and which may lead to significant impairment of the function of the metal, the

environment, or the technical system, of which these form a part
Note 1 to entry: This interaction is often of an electrochemical nature.
2.2
corrosive agent
corrodent
substance which when in contact with a given metal will cause corrosion (2.1)
2.3
corrosive environment
environment that contains one or more corrosive agents (2.2)
2.4
corrosion system

system consisting of one or more metals and those parts of the environment that influence corrosion

(2.1)

Note 1 to entry: Parts of the environment may be, for example, coatings, surface layers or additional electrodes

(6.1.2).
2.5
corrosion effect
change in any part of the corrosion system (2.4) caused by corrosion (2.1)
2.6
corrosion damage

corrosion effect (2.5) that causes impairment of the function of the metal, the environment or the

technical system, of which these form a part
2.7
corrosion failure

corrosion damage (2.6) characterized by the total loss of function of the technical system

© ISO 2015 – All rights reserved/Tous droits réservés 1
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SIST EN ISO 8044:2015
ISO 8044:2015(E/F)
2.8
corrosion product
substance formed as a result of corrosion (2.1)
2.9
scale
solid layer of corrosion products (2.8)formed on a metal at high temperature

Note 1 to entry: The term “scale” is also used in some countries for deposits from supersaturated water.

2.10
rust
visible corrosion products (2.8) consisting mainly of hydrated iron oxides
2.11
corrosion depth

distance between a point on the surface of a metal affected by corrosion (2.1) and the original surface

of the metal
2.12
corrosion rate
corrosion effect (2.5) on a metal per time

Note 1 to entry: The unit used to express the corrosion rate depends on the technical system and on the type of

corrosion effect. Thus corrosion rate may be expressed as an increase in corrosion depth (2.11) per time, or the

mass of metal turned into corrosion products (2.8) per area of surface and per time, etc. The corrosion effect may

vary with time and may not be the same at all points of the corroding surface. Therefore, reports of corrosion

rates should be accompanied by information on the type, time dependency and location of the corrosion effect.

2.13
corrosion resistance

ability of a metal to maintain serviceability (2.16) in a given corrosion system (2.4)

2.14
corrosivity

ability of an environment to cause corrosion (2.1) of a metal in a given corrosion system (2.4)

2.15
corrosion likelihood

qualitative and/or quantitative expression of the expected corrosion effects (2.5) in a defined corrosion

system (2.4)
2.16
serviceability (with respect to corrosion)

ability of a corrosion system (2.4) to perform its specified functions without impairment due to corrosion

(2.1)
2.17
durability (with respect to corrosion)

ability of a corrosion system (2.4) to maintain serviceability (2.16) over a specified time when the specified

requirements for use and maintenance have been fulfilled
2.18
service life (with respect to corrosion)

time during which a corrosion system (2.4) meets the requirements for serviceability (2.16)

2.19
critical humidity

value of the relative humidity of an atmosphere above which there is a sharp increase in the corrosion

rate (2.12) of a given metal
2 © ISO 2015 – All rights reserved/Tous droits réservés
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SIST EN ISO 8044:2015
ISO 8044:2015(E/F)
2.20
corrosion attack

corrosion effect (2.5) that is detrimental but has not progressed to the point of impairment of the function

of the metal, the environment, or the technical system of which they form a part
2.21
pickling

removal of oxides or other compounds from a metal surface by chemical or electrochemical action

2.22
pitting resistance equivalent number
PREN

indication of the resistance of stainless steels and nickel-based alloys to pitting in the presence of

chloride-containing water
Note 1 to entry: A widely accepted formula for PREN is given by
 
PREN =+%,Cr 33 %,Mo +05 %%WN+16 .
() () ()
 

Note 2 to entry: The higher the PREN, the higher is the resistance to pitting corrosion.

2.23
trap

micro structural site at which the residence time for a hydrogen atom is long compared to the residence

time in an interstitial lattice site
2.24
time of wetness

period when a metallic surface is covered by adsorptive and/or liquid films of electrolyte to be capable

of causing atmospheric corrosion
2.25
threshold stress (for stress corrosion cracking)

tensile stress above which stress corrosion cracks initiate and grow, for the specified test conditions

2.26
threshold stress intensity factor for stress corrosion cracking
ISCC

stress intensity factor above which stress corrosion crack propagation is sustained

Note 1 to entry: The threshold stress intensity factor is a concept of linear elastic fracture mechanics (LEFM) and

is applicable when the plastic zone size is large compared with the microstructure, the crack is sufficiently long,

and a high constraint to plastic deformation prevails, i.e. under plane strain predominant conditions. For growing

stress corrosion cracks, LEFM is not necessarily applicable in all detail but is adopted as a pragmatic tool that is

commonly used.

Note 2 to entry: Stress corrosion cracks may initiate at a surface or a surface defect and grow in the “short crack”

regime at stress intensity factor levels below the apparent threshold stress intensity factor. Therefore, LEFM is

not applicable in the “short crack” regime.
3 Types of corrosion
3.1
electrochemical corrosion

corrosion (2.1) involving at least one anodic reaction (6.1.9) and one cathodic reaction (6.1.6)

3.2
chemical corrosion
corrosion (2.1) not involving electrochemical reaction
© ISO 2015 – All rights reserved/Tous droits réservés 3
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SIST EN ISO 8044:2015
ISO 8044:2015(E/F)
3.3
gaseous corrosion

corrosion (2.1) with dry gas as the only corrosive environment (2.3) and without any liquid phase on the

surface of the metal
3.4
atmospheric corrosion

corrosion (2.1) with the earth’s atmosphere at ambient temperature as the corrosive environment (2.3)

3.5
marine corrosion

corrosion (2.1) with sea water as the main agent of the corrosive environment (2.3)

Note 1 to entry: This definition includes both immersed and splash zone conditions.

3.6
underground corrosion
corrosion (2.1) of buried metals, soil being the corrosive environment (2.3)

Note 1 to entry: The term soil includes not only the naturally occurring material but also any other material, such

as ballast and backfill, used to cover a structure.
3.7
microbial corrosion

corrosion (2.1) associated with the action of micro-organisms present in the corrosion system (2.4)

3.8
bacterial corrosion
microbial corrosion (3.7) due to the action of bacteria
3.9
general corrosion

corrosion (2.1) proceeding over the whole surface of the metal exposed to the corrosive environment

(2.3)
3.10
localized corrosion

corrosion (2.1) preferentially concentrated on discrete sites of the metal surface exposed to the corrosive

environment (2.3)

Note 1 to entry: Localized corrosion can result in, for example, pits, cracks, or grooves.

3.11
uniform corrosion

general corrosion (3.9) proceeding at almost the same rate over the whole surface

3.12
galvanic corrosion
corrosion (2.1) due to the action of a corrosion cell (6.1.13)

Note 1 to entry: The term has often been restricted to the action of bimetallic corrosion cells, i.e. to bimetallic

corrosion (3.13).
3.13
bimetallic corrosion
DEPRECATED: contact corrosion

galvanic corrosion (3.12), where the electrodes (6.1.2) are formed by dissimilar metals

3.14
impressed current corrosion

electrochemical corrosion (3.1) due to the action of an external source of electric current

4 © ISO 2015 – All rights reserved/Tous droits réservés
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SIST EN ISO 8044:2015
ISO 8044:2015(E/F)
3.15
stray-current corrosion

impressed current corrosion (3.14) caused by current flowing through paths other than the intended

circuits
3.16
pitting corrosion

localized corrosion (3.10) resulting in pits, i.e. cavities extending from the surface into the metal

3.17
crevice corrosion

localized corrosion (3.10) associated with, and taking place in, or immediately around, a narrow aperture

or clearance formed between the metal surface and another surface (metallic or non-metallic)

3.18
deposit corrosion

localized corrosion (3.10) associated with, and taking place under, or immediately around, a deposit of

corrosion products (2.8) or other substance
3.19
water-line corrosion

corrosion (2.1) along, and as a consequence of the presence of, a gas/liquid boundary

3.20
selective corrosion

corrosion (2.1) of an alloy whereby the components react in proportions that differ from their proportions

in the alloy
3.21
dezincification of brass
selective corrosion (3.20) of brass resulting in preferential removal of zinc
3.22
graphitic corrosion

selective corrosion (3.20) of grey cast iron, resulting in partial removal of metallic constituents, leaving

graphite
3.23
intergranular corrosion
corrosion (2.1) in or adjacent to the grain boundaries of a metal
3.24
weld corrosion

corrosion (2.1) associated with the presence of a welded joint and taking place in the weld or its vicinity

3.25
knife-line corrosion

corrosion (2.1) resulting in a narrow slit in or adjacent to the filler/parent boundary of a welded or

brazed joint
3.26
layer corrosion

corrosion (2.1) of internal layers of wrought metal, occasionally resulting in exfoliation, i.e. detachment

of unattacked layers

Note 1 to entry: Exfoliation is generally oriented in the direction of rolling, extrusion or principal deformation.

© ISO 2015 – All rights reserved/Tous droits réservés 5
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SIST EN ISO 8044:2015
ISO 8044:2015(E/F)
3.27
erosion corrosion
process involving conjoint corrosion (2.1) and erosion

Note 1 to entry: Erosion corrosion can occur in, for example, pipes with high fluid flow velocity and pumps and

pipe lines carrying fluid containing abrasive particles in suspension or entrained in a gas flow.

3.28
cavitation corrosion
process involving conjoint corrosion (2.1) and cavitation

Note 1 to entry: Cavitation corrosion can occur, for example, in rotary pumps and on ships’ propellers.

3.29
fretting corrosion

process involving conjoint corrosion (2.1) and oscillatory slip between two vibrating surfaces in contact

Note 1 to entry: Fretting corrosion can occur, for example, at mechanical joints in vibrating structures.

3.30
wear corrosion

process involving conjoint corrosion (2.1) and friction between two sliding surfaces in contact

3.31
corrosion fatigue

process involving conjoint corrosion (2.1) and alternating straining of the metal, often leading to cracking

Note 1 to entry: Corrosion fatigue can occur when a metal is subjected to cyclic straining in a corrosive environment

(2.3).
3.32
stress corrosion

process involving conjoint corrosion (2.1) and straining of the metal due to applied or residual stress

3.33
stress corrosion cracking
cracking due to stress corrosion (3.32)
3.34
hydrogen embrittlement

process resulting in a decrease of the toughness or ductility of a metal due to absorption of hydrogen

Note 1 to entry: Hydrogen embrittlement often accompanies hydrogen formation, for example by corrosion (2.1)

or electrolysis, and can lead to cracking.
3.35
blistering

process resulting in dome-shaped defect visible on the surface of an object and arising from localized

loss of cohesion below the surface

Note 1 to entry: For example, blistering can occur on coated metal due to loss of adhesion between coating and

substrate, caused by accumulation of products from localized corrosion (3.10). On uncoated metal, blistering can

occur due to excessive internal hydrogen pressure.
3.36
spalling
fragmentation and detachment of portions of the surface layer or scale
3.37
tarnishing

dulling, staining or discoloration of a metal surface, due to the formation of a thin layer of corrosionproducts

(2.8)
6 © ISO 2015 – All rights reserved/Tous droits réservés
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SIST EN ISO 8044:2015
ISO 8044:2015(E/F)
3.38
aqueous corrosion
corrosion with water or a water-based solution as the corrosive environment
3.39
microbiologically influenced corrosion
MIC
corrosion influenced by the action of microorganisms
Note 1 to entry: Compare with microbial corrosion (3.7).
3.40
dealloying
see selective corrosion (3.20)
3.41
environmentally assisted cracking

cracking of a susceptible metal or alloy due to the conjoint action of an environment and mechanical

stress
3.42
hydrogen induced cracking
HIC

planar cracking that occurs in metals due to induced stresses when atomic hydrogen diffuses into the

metal and then combines to form molecular hydrogen at trap sites
3.43
hydrogen stress cracking
HSC

cracking that results from the presence of hydrogen in a metal and tensile stress (residual or applied or

both)

Note 1 to entry: HSC describes cracking in metals that are not sensitive to sulphide stress corrosion cracking (SSCC)

(3.46) but which may be embrittled by hydrogen when galvanically coupled, as the cathode, to another metal

that is corroding actively as an anode. The term “galvanically induced HSC” has been used for this mechanism of

cracking.
3.44
irradiation assisted stress corrosion cracking

intergranular cracking of austenitic stainless steels resulting from a reduction in the chromium

concentration in a very narrow band at the grain boundaries following exposure to high neutron

irradiation doses exceeding one displacement per atom (which causes the migration of point defects to

the grain boundaries)
3.45
stepwise cracking
SWC

cracking that connects hydrogen induced cracks (HICs) on adjacent planes in a metal

Note 1 to entry: This term describes the crack appearance. The linking of hydrogen induced cracks to produce

stepwise cracking is dependent upon local strain between the cracks and embrittlement of the surrounding steel

by dissolved hydrogen. HIC/SWC is usually associated with low-strength plate steels used in the production of

pipes and vessels.
© ISO 2015 – All rights reserved/Tous droits réservés 7
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SIST EN ISO 8044:2015
ISO 8044:2015(E/F)
3.46
sulfide stress corrosion cracking
SSCC

cracking of metal involving corrosion and tensile stress (residual and/or applied) in the presence of

water and hydrogen sulfide

Note 1 to entry: SSCC is a form of hydrogen stress cracking (HSC) and involves embrittlement of the metal by

atomic hydrogen that is produced by acid corrosion on the metal surface. Hydrogen uptake is promoted in the

presence of sulfides. The atomic hydrogen can diffuse into the metal, reduce ductility and increase susceptibility

to cracking. High strength metallic materials and hard weld zones are prone to SSCC.

3.47
stress oriented hydrogen induced cracking
SOHIC

staggered small cracks formed approximately perpendicular to the principal stress (residual or applied)

resulting in a “ladder-like” crack array linking (sometimes small) pre-existing HIC cracks

Note 1 to entry: The mode of cracking can be categorised as SSCC caused by a combination of external stress and

the local strain around hydrogen induced cracks. SOHIC is related to SSCC and HIC/SWC. It has been observed in

parent material of longitudinally welded pipe and in the heat affected zone of welds in pressure vessels. SOHIC is

a relatively uncommon phenome
...

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