ISO/FDIS 8044

FINAL DRAFT
International
Standard
ISO/TC 156
Corrosion of metals and alloys —
Secretariat: SAC
Vocabulary
Voting begins on:
Corrosion des métaux et alliages — Vocabulaire 2024-09-26
Voting terminates on:
2024-11-21
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Reference number
FINAL DRAFT
International
Standard
ISO/TC 156
Corrosion of metals and alloys —
Secretariat: SAC
Vocabulary
Voting begins on:
Corrosion des métaux et alliages — Vocabulaire
Voting terminates on:
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
© ISO 2024
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms related to corrosion in general . 1
4 Terms related to types of corrosion . 3
5 Terms related to corrosion protection . 9
6 Terms related to corrosion testing . 10
7 Terms related to electrochemical matters .11
7.1 Electrochemical cell .11
7.2 Reaction rates . 15
7.3 Passivation .17
7.4 Electrochemical protection . .18
7.5 Electrochemical corrosion tests .19
Annex A (informative) Graphical representations of certain terms .21
Bibliography .23
Index .24

iii
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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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, in
collaboration with the European Committee for Standardization (CEN) Technical Committee CEN/TC 262,
Metallic and other inorganic coatings, including for corrosion protection and corrosion testing of metals and
alloys, in accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
This sixth edition cancels and replaces the fifth edition (ISO 8044:2020) which has been technically revised.
The main changes are as follows:
— several definitions have been changed, including the definition of corrosion;
— several editorial changes were made, including the addition of cross-references to other terms within the
definitions.
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
Introduction
The definitions in this document have been drawn up with the objective of achieving a proper balance
between precision and simplicity. The main objective of this document 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, the
results of the process and the damage caused by the process. In this document, 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.

v
FINAL DRAFT International Standard ISO/FDIS 8044:2024(en)
Corrosion of metals and alloys — Vocabulary
1 Scope
This document defines terms relating to corrosion that are widely used in modern science and technology.
In addition, some definitions are supplemented with short explanations.
Throughout the document, International Union of Pure and Applied Chemistry rules for electrode potential
signs are applied. The term “metal” is also used to include alloys and other metallic materials.
Terms and definitions related to the inorganic surface treatment of metals are given in ISO 2080.
2 Normative references
There are no normative references in this document.
3 Terms related to corrosion in general
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
corrosion
chemical or electrochemical interaction between a material, usually a metal, and its environment
Note 1 to entry: This can lead to deterioration of material properties, the environment or the function of the system
containing that material.
3.2
corrosive agent
substance that initiates or promotes corrosion (3.1) when in contact with a given metal
3.3
corrosive environment
environment that contains one or more corrosive agents (3.2)
3.4
corrosion system
system consisting of one or more metals and those parts of the environment that influence corrosion (3.1)
Note 1 to entry: Parts of the environment can be, for example, coatings, surface layers or additional electrodes (7.1.2).
3.5
corrosion effect
change in any part of the corrosion system (3.4) caused by corrosion (3.1)
3.6
corrosion damage
corrosion effect (3.5) that causes impairment of the function of the metal, the environment or the technical
system of which these form a part

3.7
corrosion failure
corrosion damage (3.6) characterized by the total loss of function of the technical system
3.8
corrosion product
substance formed as a result of corrosion (3.1)
3.9
scale
solid layer of corrosion products (3.8) 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.
3.10
rust
visible corrosion products (3.8) consisting mainly of hydrated iron oxides
3.11
corrosion depth
distance between a point on the surface of a metal affected by corrosion (3.1) and the original surface of the metal
3.12
corrosion rate
corrosion effect (3.5) on a metal per unit 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 is typically expressed as an increase in corrosion depth (3.11) per unit time, or
the mass of metal turned into corrosion products (3.8) per area of surface and per unit time, etc. The corrosion effect
can vary with time and will not be the same at all points of the corroding surface. Therefore, reports of corrosion rates
are typically accompanied by information on the type, time dependency and location of the corrosion effect.
3.13
corrosion resistance
ability of a metal to maintain serviceability (3.16) in a given corrosion system (3.4)
3.14
corrosivity
ability of an environment to cause corrosion (3.1) of a metal in a given corrosion system (3.4)
3.15
corrosion likelihood
qualitative and/or quantitative expression of the expected corrosion effects (3.5) in a defined corrosion
system (3.4)
3.16
serviceability
ability of a corrosion system (3.4) to perform its specified functions without impairment due to corrosion (3.1)
3.17
durability
ability of a corrosion system (3.4) to maintain serviceability (3.16) over a specified time when the specified
requirements for use and maintenance have been fulfilled
3.18
service life
time during which a corrosion system (3.4) meets the requirements for serviceability (3.16)
3.19
critical humidity
value of the relative humidity of an atmosphere above which there is a sharp increase in the corrosion rate
(3.12) of a given metal
...