Ferrous materials - Heat treatments - Vocabulary (ISO 4885:2018)

This document defines important terms used in the heat treatment of ferrous materials.
NOTE The term ferrous materials include products and workpieces of steel and cast iron.
Annex A provides an alphabetical list of terms defined in this document, as well as their equivalents in
French, German, Chinese and Japanese.
Table 1 shows the various iron-carbon (Fe-C) phases.

Eisenwerkstoffe - Wärmebehandlung - Begriffe (ISO 4885:2018)

Dieses Dokument legt die wichtigsten Begriffe für die Wärmebehandlung von Eisenwerkstoffen fest.
ANMERKUNG   Der Begriff „Eisenwerkstoffe“ umfasst Erzeugnisse und Werkstücke aus Stahl und Gusseisen.
Anhang A enthält eine alphabetische Auflistung der Begriffe, die in diesem Dokument definiert sind sowie ihre Entsprechungen in Französisch, Deutsch, Chinesisch und Japanisch.
Tabelle 1 zeigt die verschiedenen Eisen Kohlenstoff (Fe-C)-Phasen.

Matériaux ferreux - Traitements thermiques - Vocabulaire (ISO 4885:2018)

ISO 4885:2018 définit les termes importants utilisés dans le traitement thermique des matériaux ferreux.
NOTE       Le terme matériaux ferreux inclut les produits et les pièces en acier et en fonte.
L'Annexe A donne une liste alphabétique des termes définis dans ce document ainsi que leurs équivalents en anglais, allemand, chinois et japonais.
Le Tableau 1 montre les différentes phases fer-carbone (Fe-C).

Železove zlitine - Toplotna obdelava - Slovar (ISO 4885:2018)

Ta dokument določa pomembne izraze, ki se uporabljajo pri toplotni obdelavi železovih materialov.
OPOMBA: Izraz »železovi materiali« vključuje proizvode in obdelovance iz jekla in litega železa.
V dodatku A so po abecednem redu navedeni izrazi, opredeljeni v tem dokumentu, ter njihove francoske, nemške, kitajske in japonske ustreznice.
V preglednici 1 so prikazane različne faze železovega karbonata (Fe-C).

General Information

Status
Published
Public Enquiry End Date
23-Jan-2018
Publication Date
18-Apr-2018
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
12-Apr-2018
Due Date
17-Jun-2018
Completion Date
19-Apr-2018

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Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN ISO 4885:2018
01-junij-2018
1DGRPHãþD
SIST EN ISO 4885:2017
Železove zlitine - Toplotna obdelava - Slovar (ISO 4885:2018)
Ferrous materials - Heat treatments - Vocabulary (ISO 4885:2018)
Matériaux ferreux - Traitements thermiques - Vocabulaire (ISO 4885:2018)
Ta slovenski standard je istoveten z: EN ISO 4885:2018
ICS:
01.040.77 Metalurgija (Slovarji) Metallurgy (Vocabularies)
25.200 Toplotna obdelava Heat treatment
77.080.01 Železne kovine na splošno Ferrous metals in general
SIST EN ISO 4885:2018 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 4885:2018

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SIST EN ISO 4885:2018


EN ISO 4885
EUROPEAN STANDARD

NORME EUROPÉENNE

April 2018
EUROPÄISCHE NORM
ICS 01.040.25; 01.040.77; 25.200; 77.140.01 Supersedes EN ISO 4885:2017
English Version

Ferrous materials - Heat treatments - Vocabulary (ISO
4885:2018)
Matériaux ferreux - Traitements thermiques - Eisenwerkstoffe - Wärmebehandlung - Begriffe (ISO
Vocabulaire (ISO 4885:2018) 4885:2018)
This European Standard was approved by CEN on 2 April 2018.

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, Serbia, 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: Rue de la Science 23, B-1040 Brussels
© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 4885:2018 E
worldwide for CEN national Members.

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SIST EN ISO 4885:2018
EN ISO 4885:2018 (E)
Contents Page
European foreword . 3

2

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SIST EN ISO 4885:2018
EN ISO 4885:2018 (E)
European foreword
This document (EN ISO 4885:2018) has been prepared by Technical Committee ISO/TC 17 "Steel" in
collaboration with Technical Committee ECISS/TC 100 “General issues” 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 October 2018, and conflicting national standards shall
be withdrawn at the latest by October 2018.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 4885:2017.
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, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 4885:2018 has been approved by CEN as EN ISO 4885:2018 without any modification.

3

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SIST EN ISO 4885:2018

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SIST EN ISO 4885:2018
INTERNATIONAL ISO
STANDARD 4885
Third edition
2018-02
Ferrous materials — Heat treatments
— Vocabulary
Matériaux ferreux — Traitements thermiques — Vocabulaire
Reference number
ISO 4885:2018(E)
©
ISO 2018

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SIST EN ISO 4885:2018
ISO 4885:2018(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2018
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, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
Published in Switzerland
ii © ISO 2018 – All rights reserved

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SIST EN ISO 4885:2018
ISO 4885:2018(E)

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
Annex A (informative) Equivalent terms .31
Bibliography .41
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SIST EN ISO 4885:2018
ISO 4885:2018(E)

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 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 the following
URL: www .iso .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 17, Steel.
This third edition cancels and replaces the second edition (ISO 4885:2017), of which it constitutes a
minor revision with a corrected Figure 1 d).
iv © ISO 2018 – All rights reserved

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SIST EN ISO 4885:2018
INTERNATIONAL STANDARD ISO 4885:2018(E)
Ferrous materials — Heat treatments — Vocabulary
1 Scope
This document defines important terms used in the heat treatment of ferrous materials.
NOTE The term ferrous materials include products and workpieces of steel and cast iron.
Annex A provides an alphabetical list of terms defined in this document, as well as their equivalents in
French, German, Chinese and Japanese.
Table 1 shows the various iron-carbon (Fe-C) phases.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at https:// www .iso .org/ obp
3.1
acicular structure
structure which appears in the form of needles in a micrograph
3.2
activity
effective concentration of species under non-ideal (e.g. concentrated) conditions; for heat treatment
(3.108), this means the effective concentration of carbon or nitrogen (or both) in heat treatment media
and in ferrous materials
Note 1 to entry: Ratio of the vapour pressure of a gas (usually carbon or nitrogen) in a given state (e.g. in austenite
(3.12) of specific carbon/nitrogen concentration) to the vapour pressure of the pure gas, as a reference state, at
the same temperature.
3.3
ageing
change in the properties of steels depending on time and temperature after hot working or heat
treatment (3.108) or after cold-working operation, due to the migration of interstitial elements
Note 1 to entry: The ageing phenomenon can lead to higher strength and lower ductility.
Note 2 to entry: The ageing effect can be accelerated either by cold forming and/or subsequent heating (3.109) to
moderate temperatures (e.g. 250 °C) and soaking (e.g. for 1 h).
3.4
air-hardening steel
DEPRECATED: self-hardening steel
steel, the hardenability (3.103) of which is such that cooling (3.45) in air produces a martensitic structure
in objects of considerable size
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SIST EN ISO 4885:2018
ISO 4885:2018(E)

3.5
alpha iron
stable state of pure iron at temperatures below 911 °C
Note 1 to entry: The crystalline structure of an alpha iron is body-centred cubic.
Note 2 to entry: Alpha iron is ferromagnetic at temperatures below 768 °C (the Curie point).
3.6
alpha mixed crystal
iron with body-centred cubic lattice structure with alloying elements in interstitial or substitutional
solution
Note 1 to entry: The material science for alpha mixed crystal is ferritic.
Note 2 to entry: Alpha mixed crystal is ferromagnetic.
3.7
aluminizing
DEPRECATED: calorizing
surface treatment into and on a workpiece (3.201) relating to aluminium
3.8
annealing
heat treatment (3.108) consisting of heating (3.109) and soaking (3.185) at a suitable temperature
followed by cooling (3.45) under conditions such that, after return to ambient temperature, the metal
will be in a structural state closer to that of equilibrium
Note 1 to entry: Since this definition is very general, it is advisable to use an expression specifying the aim of
the treatment. See bright annealing (3.29), full annealing (3.89), softening/soft annealing (3.186), inter-critical
annealing (3.122), isothermal annealing (3.127) and subcritical annealing.
3.9
ausferrite
fine-grained mixture of ferrite (3.85) and stabilized austenite (3.12) which should lead to high hardness
and ductility of austempered ductile cast iron (ADI)
3.10
ausforming
thermomechanical treatment (3.208) of a workpiece which consists of plastically deforming the
metastable austenite (3.12) before subjecting it to the martensitic and/or bainitic transformation
3.11
austempering
isothermal heat treatment for producing bainitic (see 3.17 and 3.18) or ausferritic (see 3.9) structure of
a workpiece
Note 1 to entry: The final cooling (3.45) to ambient temperature is not at a specific rate.
3.12
austenite
solid solution of one or more elements in gamma iron (3.91)
Note 1 to entry: See also Table 1.
3.13
austenitic steel
steel where the structure consists of austenite (3.12) at ambient temperature
Note 1 to entry: Cast austenitic steels can contain up to about 20 % of ferrite (3.85).
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SIST EN ISO 4885:2018
ISO 4885:2018(E)

3.14
austenitizing
heating (3.109) a workpiece to austenitizing temperature (3.15) and holding at this, so that the
microstructure is predominantly austenitic (3.12)
Note 1 to entry: The minimum temperature required depends on the speed of heating and the steel composition.
The length of the hold period will depend on the heating conditions used.
3.15
austenitizing temperature
temperature at which the workpiece is maintained during austenitization (3.14)
3.16
auto-tempering
self-tempering
tempering (3.203) undergone by martensite (3.137) during quenching (3.168) or subsequent cooling (3.45)
3.17
bainite
microstructure resulting from the transformation of austenite (3.12) at temperatures above martensite
(3.137) start temperature (M ) and outside the pearlite (3.155) range consisting of ferrite laths and
s
carbides which are dispersed either inside the ferrite laths (lower bainite) or between the ferrite laths
(upper bainite)
Note 1 to entry: See also Table 1.
3.18
bainitizing
austenitizing (3.14) and quenching (3.168) to a temperature above M and isothermal soaking to ensure
s
a transformation of the austenite (3.12) to bainite (3.17)
3.19
bake hardening steel
steel with the ability to gain an increase of yield strength after a plastic pre-strain and a subsequent
heat treatment (3.108) in the usual industrial paint processes (in the region of 170 °C for 20 min)
Note 1 to entry: These steels have a good suitability for cold forming and present a high resistance to plastic
straining (which is increased on finished parts during heat treatment) and a good dent resistance.
3.20
baking
heat treatment (3.108) permitting the release of hydrogen absorbed in a ferrous product without
modifying its structure
Note 1 to entry: The treatment is generally carried out following electrolytic plating or pickling, or a welding
operation.
3.21
banded structure
lines of constituents in the microstructure caused by segregation (3.179) during solidification
3.22
blacking
operation carried out in an oxidizing medium at a temperature such that the polished surface of a
workpiece becomes covered with a thin, continuous, adherent film of dark-coloured oxide (see 3.151)
3.23
black nitriding
nitriding (3.143) followed by oxidation (3.150) of the steel surface
Note 1 to entry: After nitrocarburizing (3.144), blacking (3.22) will improve the corrosion resistance and the
surface properties.
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SIST EN ISO 4885:2018
ISO 4885:2018(E)

3.24
blank nitriding
blank nitrocarburizing
simulation treatment which consists of reproducing the thermal cycle of nitriding (3.143)/
nitrocarburizing (3.144) without the nitriding/nitrocarburizing medium
Note 1 to entry: This treatment makes it possible to assess the metallurgical consequences of the thermal cycle of
nitriding/nitrocarburizing.
3.25
batch annealing
box annealing
process in which strip is annealed in tight coil form, within a protective atmosphere, for a predetermined
time-temperature cycle
3.26
blueing
treatment carried out in an oxidizing medium (see 3.152) at a temperature such that the bright surface
of a workpiece becomes covered with a thin, continuous, adherent film of blue-coloured oxide
Note 1 to entry: If the blueing is carried out in superheated water vapour, it is also called steam treatment.
3.27
boost-diffuse carburizing
carburizing (3.36) carried out in two or more successive stages and/or different temperatures with
different carbon potentials
3.28
boriding
thermochemical treatment (3.207) of a workpiece to enrich the surface of a workpiece with boron
Note 1 to entry: The medium in which boriding takes place should be specified, e.g. pack boriding, paste
boriding, etc.
3.29
bright annealing
annealing (3.8) in a medium preventing the oxidation (3.150) of the surface and keeps the original
surface quality
3.30
burning
irreversible change in the structure and properties brought about by the onset of melting at the grain
boundaries and surface
3.31
carbon activity
effective concentration of carbon under non-ideal (e.g. concentrated) conditions; for heat treatment
(3.108), this means the effective concentration of carbon in heat treatment media and in ferrous
materials
3.32
carbon mass transfer coefficient
coefficient of the mass of carbon transfer from the carburizing medium into steel (per unit surface area
and time)
Note 1 to entry: Also defined as the mass of carbon transferred from the carburizing medium into the steel,
per unit surface area per second, for a unit difference between the carbon potential and actual surface carbon
content.
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SIST EN ISO 4885:2018
ISO 4885:2018(E)

3.33
carbon level
carbon content in percent of mass in an austenitized probe of pure iron at a given temperature in the
equilibrium with the carburizing medium
Note 1 to entry: The “carbon level” has been defined for practical use, because the carbon potential of steels
cannot be measured directly in carburizing media; see Reference [13].
3.34
carbon profile
carbon content depending on the distance from the surface
3.35
carbonitriding
thermochemical treatment (3.207) to enrich the surface layer with carbon and nitrogen
Note 1 to entry: The elements are in solid solution in the austenite (3.12), usually the carbonitrided workpiece
undergoes quench hardening (3.167) (immediately or later).
Note 2 to entry: Carbonitriding is a carburizing (3.36) process.
Note 3 to entry: The medium in which carbonitriding takes place should be specified, e.g. gas, salt bath, etc.
3.36
carburizing
DEPRECATED: cementation
thermochemical treatment (3.207) which is applied to a workpiece in the austenitic state, to obtain a
surface enrichment in carbon, which is in solid solution in the austenite (3.12)
Note 1 to entry: The carburized workpiece undergoes quench hardening (3.167) (immediately or later).
Note 2 to entry: The medium in which carburizing takes place should be specified, e.g. gas, pack, etc.
3.37
case hardening
treatment consisting of carburizing (3.36) or carbonitriding (3.35) followed by quench hardening (3.167)
Note 1 to entry: See Figure 1.
a) Direct-hardening treatment
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SIST EN ISO 4885:2018
ISO 4885:2018(E)

b) Single-quench hardening treatment
c) Quench-hardening treatment with isothermal transformation
d) Double-quench hardening treatment
Key
1 carburizing, carbonitriding 6 cooling
2 quenching 7 quench-hardening treatment
3 tempering 8 isothermal transformation
4 Ac core 9 Ac surface after carburizing
3 3
5 Ac surface
3
Figure 1 — Schematic representation of the possible thermal cycles of various case-hardening
treatments
3.38
cast iron
alloy of iron, carbon and silicon where the carbon content is approximately more than 2 %
3.39
cementite
iron carbide with the formula Fe C
3
Note 1 to entry: See Table 1.
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SIST EN ISO 4885:2018
ISO 4885:2018(E)

Table 1 — Iron-carbon (Fe-C) phases
Phase Crystal structure Properties Typical hardness
Ferrite, α bcc soft, tough, magnetic 60 HBW to 90 HBW
Austenite, γ fcc fair strength, non-magnetic 150 HBW (1,5 % C)
Cementite, Fe C rombic hard, brittle chemical composition 820 HBW
3
Pearlite with coarse α + Fe C, lamellar combination of tough ferrite 200 HBW
3
lamellas (0,4 μm) and hard cementite
Pearlite with fine α + Fe C, lamellar harder than pearlite with 400 HBW
3
lamellas (0,1 μm) coarse lamellas
Spheroidite α + globular Fe C soft 120 HBW to 230 HBW,
3
depending on
carbon and alloy content
Upper bainite precipitations of properties such as pearlite with 400 HBW
Fe C on surface fine lamellas
3
of α
Lower bainite precipitations of strength near martensite, but 600 HBW
Fe C inside of α tougher than tempered martensite
3
Martensite, α’, bcc, slightly hard, brittle 250 HV to 950 HV,
non-tempered tetragonic depending on carbon
content
Martensite, α’, bcc, slightly softer and tougher than 250 HV to 650 HV,
tempered tetragonic non-tempered martensite depending on carbon
content and tempering
temperature
3.40
chromizing
surface treatment into and on a workpiece (3.201) relating to chromium
Note 1 to entry: The surface layer can consist of practically pure chromium (on low-carbon steels) or of chromium
carbide (on high-carbon steels).
3.41
compound layer
DEPRECATED: white layer
surface layer formed during thermochemical treatment (3.207) and made up of the chemical compounds
formed by the element(s) introduced during the treatment and certain elements from the base metal
EXAMPLE The surface layer may consist of the layer of nitrides formed during nitriding (3.143), the layer
of borides formed during boriding (3.28), the layer of chromium carbide formed during the chromizing (3.40) of
high-carbon steel.
Note 1 to entry: In English, the term “white layer” is improperly used to designate this layer on nitrided and
nitrocarburized ferrous products.
3.42
continuous annealing
process in which strip is annealed by moving continuously through an oven within a protective
atmosphere
3.43
continuous-cooling transformation diagram
CCT diagram
see 3.210.2
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SIST EN ISO 4885:2018
ISO 4885:2018(E)

3.44
controlled rolling
rolling process where rolling temperature and reduction are controlled to achieve enhanced mechanical
properties, e.g. normalizing rolling, thermomechanical rolling
Note 1 to entry: Controlled rolling is used for fine-grain ferritic steels (3.86) and for dual-phase steel for obtaining
fine-grain structure.
3.45
cooling
reduction of (or operation to reduce) the temperature of a hot workpiece, either continuous,
discontinuous, gradual or interrupted
Note 1 to entry: The medium in which cooling takes place should be specified, e.g. in furnace, air, oil, water. See
also quenching (3.168).
3.46
cooling condition
condition(s) (temperature and kind of cooling medium, relative movements, agitation, etc.) under which
the cooling (3.45) of the workpiece takes place
3.47
cooling function
reduction of the temperature as a function of time of a determined point of a workpiece
Note 1 to entry: This function could be shown as a graph or written in a mathematical form.
3.48
cooling rate
variation in temperature as a function of time during cooling (3.45)
Note 1 to entry: A distinction is made between
— an instantaneous rate corresponding to a specified temperature, and
— an average rate over a defined interval of temperature or time.
3.49
cooling time
interval of time separating two characteristic temperatures of the cooling function (3.47)
Note 1 to entry: It is always necessary to specify precisely what the temperatures are.
3.50
core refining
process to get a fine grain and a homogenous microstructure in the core, often done by hardening of
carburized workpieces
Note 1 to entry: See Figures 1 b), c) and d).
3.51
critical cooling course
cooling procedure necessary to avoid transformation to an undesired microstructure
Note 1 to entry: The cooling course can be characterized by the gradient of temperature or of the cooling rate
(3.48) in general or at given temperatures or times.
3.52
critical cooling rate
cooling rate (3.48) corresponding to the critical cooling course (3.51)
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SIST EN ISO 4885:2018
ISO 4885:2018(E)

3.53
critical diameter
diameter (d) of a cylinder with a length ≥3 d, having a structure of 50 % by volume of martensite (3.137)
after quench hardening (3.167) with defined conditions at its centre
3.54
decarburization
depletion of carbon from the surface layer of a workpiece
Note 1 to entry: This depletion can be either partial (partial decarburization) or nominally complete (complete
decarburization). The sum of the two types of decarburization (partial and complete) is termed total
decarburization; see ISO 3887.
3.55
decarburizing
thermochemical treatment (3.207) intended to produce decarburization (3.54) of a workpiece
3.56
decomposition of austenite
austenite transformation
decomposition into ferrite (3.85) and pearlite (3.155) or ferrite and cementite (3.39) with decreasing
temperature
3.57
delta iron
stable state of pure iron between 1 392 °C and its melting point
Note 1 to entry: The crystalline structure of a delta iron is body-centred cubic, identical to that of the alpha
iron (3.5).
Note 2 to entry: Delta iron is paramagnetic.
3.58
depth of carburizing
carburizing depth
distance between the surface of a workpiece and a specified limit characterizing the thickness of the
layer enriched in carbon, which means effective case depth
3.59
depth of decarburization
decarburization depth
distance between the surface of a workpiece and a limit characterizing the thickness of the layer
depleted in carbon
Note 1 to entry: This limit varies according to the type of decarburization (3.54) and can be defined by reference
to a structural state, a level of hardness or the carbon content of the unaltered base metal (see ISO 3887), or any
other specified carbon content.
3.60
depth of hardening
distance between the surface of a workpiece and a limit characterizing the penetration of quench
hardening (3.167)
Note 1 to entry: This limit can be defined starting from a structural state or a level of hardness.
3.61
depth of nitriding
nitriding depth
distance between the surface of a workpiece and a specified limit characterizing the thickness of the
layer enriched in nitrogen
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SIST EN ISO 4885:2018
ISO 4885:2018(E)

3.62
destabilization of retained austenite
phenomenon occurring during tempering which allows the retained austenite (3.175) to undergo
martensitic transformation within a temperature range where it would not previously have been
transformed spontaneously
3.63
diffusion
movement of atoms to new places in ferrous materials
3.64
diffusion annealing
heat treatment (3.108)/annealing (3.8) of ferrous products or workpieces to reduce segregation (3.179)
and promote homogeneity by diffusion (3.63)
Note 1 to entry: To reduce segregation of metallic elements in steel making and in bar rolling a process with
temperatures between 1 000 °C and 1 300 °C is required.
Note 2 to entry: Reducing segregations of non-metallic alloying elements (such as carbon or sulfur) in workpieces
usually would be done at a temperature below 1 000 °C.
3.65
diffusion treatment
heat treatment (3.108) to reduce a very high concentration of elements in the surface layer such as
carbon or nitrogen after carburizing (3.36) or nitriding (3.143)
Note 1 to entry: See also malleablizing (3.133), which is also a diffusion treatment.
3.66
diffusion zone
surface layer formed by a thermochemical treatment (3.207) characterized by enrichment of elements
such as carbon or nitrogen
Note 1 to entry: The enriched elements such as carbon or nitrogen are in solid solution and/or precipitates such
as carbides or nitrides.
Note 2 to entry: The concentration of the enriched elements decreases from surface to the core of a workpiece.
3.67
direct-quench hardening
quench hardening (3.167) of carburized workpieces immediately after carburizing (3.36) or
carbonitriding (3.35)
Note 1 to entry: The direct-quench hardening should be started directly after carburizing or at a lower
temperature, adjusted to the surface carbon content.
Note 2 to entry: Direct hardening from hot forging or hot rolling replaces separate austenitizing (3.14) and
quenching (3.168).
Note 3 to entry: See Figure 1 a).
3.68
direct quenching
quenching (3.168) carried out immediately following hot rolling, hot forging or after a thermochemical
treatment (3.207) or solution annealing (3.188) of stainless
...

SLOVENSKI STANDARD
oSIST prEN ISO 4885:2018
01-januar-2018
Železove zlitine - Toplotna obdelava - Slovar (ISO/FDIS 4885:2017)
Ferrous materials - Heat treatments - Vocabulary (ISO/FDIS 4885:2017)
Matériaux ferreux - Traitements thermiques - Vocabulaire (ISO/FDIS 4885:2017)
Ta slovenski standard je istoveten z: prEN ISO 4885
ICS:
01.040.77 Metalurgija (Slovarji) Metallurgy (Vocabularies)
25.200 Toplotna obdelava Heat treatment
77.080.01 Železne kovine na splošno Ferrous metals in general
oSIST prEN ISO 4885:2018 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO 4885:2018
FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 4885
ISO/TC 17
Ferrous materials — Heat treatments
Secretariat: JISC
— Vocabulary
Voting begins on:
2017­11­01
Matériaux ferreux — Traitements thermiques — Vocabulaire
Voting terminates on:
2018­01­24
ISO/CEN PARALLEL PROCESSING
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.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
ISO/FDIS 4885:2017(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN­
DARDS TO WHICH REFERENCE MAY BE MADE IN
©
NATIONAL REGULATIONS. ISO 2017

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COPYRIGHT PROTECTED DOCUMENT
© ISO 2017, Published in Switzerland
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.
ISO copyright office
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Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2017 – All rights reserved

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Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
Annex A (informative) Equivalent terms .31
Bibliography .41
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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 non­governmental, 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 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 the following
URL: www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 17, Steel.
This third edition cancels and replaces the second edition (ISO 4885:2017), of which it constitutes a
minor revision with a corrected Figure 1 d).
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FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 4885:2017(E)
Ferrous materials — Heat treatments — Vocabulary
1 Scope
This document defines important terms used in the heat treatment of ferrous materials.
NOTE The term ferrous materials include products and workpieces of steel and cast iron.
Annex A provides an alphabetical list of terms defined in this document, as well as their equivalents in
French, German, Chinese and Japanese.
Table 1 shows the various iron­carbon (Fe­C) phases.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http://www.electropedia.org/
—  ISO Online browsing platform: available at https://www.iso.org/obp
3.1
acicular structure
structure which appears in the form of needles in a micrograph
3.2
activity
effective concentration of species under non­ideal (e.g. concentrated) conditions; for heat treatment
(3.108), this means the effective concentration of carbon or nitrogen (or both) in heat treatment media
and in ferrous materials
Note 1 to entry: Ratio of the vapour pressure of a gas (usually carbon or nitrogen) in a given state (e.g. in austenite
(3.12) of specific carbon/nitrogen concentration) to the vapour pressure of the pure gas, as a reference state, at
the same temperature.
3.3
ageing
change in the properties of steels depending on time and temperature after hot working or heat
treatment (3.108) or after cold­working operation due to the migration of interstitial elements
Note 1 to entry: The ageing phenomenon can lead to higher strength and lower ductility.
Note 2 to entry: The ageing can be accelerated either by cold forming and/or subsequent heating (3.109) to
moderate temperatures (e.g. 250 °C) and soaking (e.g. for 1 h) to create the ageing effects.
3.4
air-hardening steel
DEPRECATED: self­hardening steel
steel, the hardenability (3.103) of which is such that cooling (3.45) in air produces a martensitic structure
in objects of considerable size
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3.5
alpha iron
stable state of pure iron at temperatures below 911 °C
Note 1 to entry: The crystalline structure of an alpha iron is body-centred cubic.
Note 2 to entry: Alpha iron is ferromagnetic at temperatures below 768 °C (the Curie point).
3.6
alpha mixed crystal
iron with body-centred cubic lattice structure with alloying elements in interstitially or substitutively
solution
Note 1 to entry: The material science for alpha mixed crystal is ferritic.
Note 2 to entry: Alpha mixed crystal is ferromagnetic.
3.7
aluminizing
DEPRECATED: calorizing
surface treatment into and on a workpiece (3.201) relating to aluminium
3.8
annealing
heat treatment (3.108) consisting of heating (3.109) and soaking at a suitable temperature followed by
cooling (3.45) under conditions such that, after return to ambient temperature, the metal will be in a
structural state closer to that of equilibrium
Note 1 to entry: Since this definition is very general, it is advisable to use an expression specifying the aim of
the treatment. See bright annealing (3.29), full annealing (3.89), softening/soft annealing (3.186), inter-critical
annealing (3.122), isothermal annealing (3.127) and subcritical annealing.
3.9
ausferrite
fine-grained mixture of ferrite (3.85) and stabilized austenite (3.12) which should lead to high hardness
and ductility of austempered ductile cast iron (ADI)
3.10
ausforming
thermomechanical treatment (3.207) of a workpiece which consists of plastically deforming the
metastable austenite (3.12) before subjecting it to the martensitic and/or bainitic transformation
3.11
austempering
isothermal heat treatment for producing bainitic (see 3.17 and 3.18) or ausferritic (see 3.9) structure of
a workpiece
Note 1 to entry: The final cooling (3.45) to ambient temperature is not at a specific rate.
3.12
austenite
solid solution of one or more elements in gamma iron (3.91)
Note 1 to entry: See also Table 1.
3.13
austenitic steel
steel structure which is austenitic at ambient temperature
Note 1 to entry: Cast austenitic steels can contain up to about 20 % of ferrite (3.85).
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3.14
austenitizing
heating (3.109) a workpiece to austenitizing temperature (3.15) and holding at this, so that the
microstructure is predominantly austenitic
Note 1 to entry: The amount of the minimum required temperature results from the heat speed and the steel
composition. The holding period depends on the heating conditions used.
3.15
austenitizing temperature
temperature at which the workpiece is maintained during austenitization
3.16
auto-tempering
self-tempering
tempering undergone by martensite (3.137) during quenching (3.168) or subsequent cooling (3.45)
3.17
bainite
microstructure resulting from the transformation of austenite (3.12) at temperatures above martensite
(3.137) start temperature (M ) and outside the pearlite (3.155) range consisting of ferrite laths and
s
carbides which are dispersed either inside the ferrite laths (lower bainite) or between the ferrite laths
(upper bainite)
Note 1 to entry: See also Table 1.
3.18
bainitizing
austenitizing (3.14) and quenching (3.168) to a temperature above M and isothermal soaking to ensure
s
a transformation of the austenite (3.12) to bainite (3.17)
3.19
bake hardening steel
steel with the ability to gain an increase of yield strength after a plastic pre-strain and a subsequent
heat treatment (3.108) in the usual industrial paint processes (in the region of 170 °C for 20 min)
Note 1 to entry: These steels have a good suitability for cold forming and present a high resistance to plastic
straining (which is increased on finished parts during heat treatment) and a good dent resistance.
3.20
baking
heat treatment (3.108) permitting the release of hydrogen absorbed in a ferrous product without
modifying its structure
Note 1 to entry: The treatment is generally carried out following an electrolytic plating or pickling, or a welding
operation.
3.21
banded structure
lines of constituents of the microstructure caused by segregation (3.179) during solidification
3.22
blacking
operation carried out in an oxidizing medium at a temperature such that the polished surface of a
workpiece becomes covered with a thin, continuous, adherent film of dark-coloured oxide (see 3.151)
3.23
black nitriding
nitriding (3.143) followed by oxidation (3.150) of the steel surface
Note 1 to entry: After nitrocarburizing (3.144), blacking (3.22) will improve the corrosion resistance and the
surface properties.
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3.24
blank nitriding
blank nitrocarburizing
simulation treatment which consists of reproducing the thermal cycle of nitriding (3.143)/
nitrocarburizing (3.144) without the nitriding/nitrocarburizing medium
Note 1 to entry: This treatment makes it possible to assess the metallurgical consequences of the thermal cycle of
nitriding/nitrocarburizing.
3.25
batch annealing
box annealing
process in which strip is annealed in tight coil form, within a protective atmosphere, for a predetermined
time-temperature cycle
3.26
blueing
treatment carried out in an oxidizing medium (see 3.152) at a temperature such that the bright surface
of a workpiece becomes covered with a thin, continuous, adherent film of blue-coloured oxide
Note 1 to entry: If the blueing is carried out in superheated water vapour, it is also called steam treatment.
3.27
boost-diffuse carburizing
carburizing carried out in two or more successive stages and/or different temperatures with different
carbon potentials
3.28
boriding
thermochemical treatment (3.207) of a workpiece to enrich the surface of a workpiece with boron
Note 1 to entry: The medium in which boriding takes place should be specified, e.g. pack boriding, paste
boriding, etc.
3.29
bright annealing
annealing (3.8) in a medium preventing the oxidation (3.150) of the surface and keeps the original
surface quality
3.30
burning
irreversible change in the structure and properties brought about by the onset of melting at the grain
boundaries and surface
3.31
carbon activity
effective concentration of carbon under non­ideal (e.g. concentrated) conditions; for heat treatment
(3.108), this means the effective concentration of carbon in heat treatment media and in ferrous
materials
3.32
carbon mass transfer coefficient
coefficient of the mass of carbon transfer from the carburizing medium into steel (per unit surface area
and time)
Note 1 to entry: Also defined as the mass of carbon transferred from the carburizing medium into the steel,
per unit surface area per second, for a unit difference between the carbon potential and actual surface carbon
content.
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3.33
carbon level
carbon content in percent of mass in an austenitized probe of pure iron at a given temperature in the
equilibrium with the carburizing medium
Note 1 to entry: The “carbon level” has been defined for practical use, because the carbon potential of steels
cannot be measured directly in carburizing media; see Reference [13].
3.34
carbon profile
carbon content depending on the distance from the surface
3.35
carbonitriding
thermochemical treatment (3.207) to enrich the surface layer with carbon and nitrogen
Note 1 to entry: The elements are in solid solution in the austenite (3.12), usually the carbonitrided workpiece
undergoes quench hardening (3.167) (immediately or later).
Note 2 to entry: Carbonitriding is a carburizing (3.36) process.
Note 3 to entry: The medium in which carbonitriding takes place should be specified, e.g. gas, salt bath, etc.
3.36
carburizing
DEPRECATED: cementation
thermochemical treatment (3.207) which is applied to a workpiece in the austenitic state, to obtain a
surface enrichment in carbon, which is in solid solution in the austenite (3.12)
Note 1 to entry: The carburized workpiece undergoes quench hardening (3.167) (immediately or later).
Note 2 to entry: The medium in which carburizing takes place should be specified, e.g. gas, pack, etc.
3.37
case hardening
treatment consisting of carburizing (3.36) or carbonitriding (3.35) followed by quench hardening (3.167)
Note 1 to entry: See Figure 1.
a) Direct-hardening treatment
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b) Single-quench hardening treatment
c) Quench-hardening treatment with isothermal transformation
d) Double-quench hardening treatment
Key
1 carburizing, carbonitriding 6 cooling
2 quenching 7 quench­hardening treatment
3 tempering 8 isothermal transformation
4 Ac core 9 Ac surface after carburizing
3 3
5 Ac surface
3
Figure 1 — Schematic representation of the possible thermal cycles of various case-hardening
treatments
3.38
cast iron
alloy of iron, carbon and silicon where the carbon content is approximately more than 2 %
3.39
cementite
iron carbide with the formula Fe C
3
Note 1 to entry: See Table 1.
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Table 1 — Iron-carbon (Fe-C) phases
Phase Crystal structure Properties Typical hardness
Ferrite, α bcc soft, tough, magnetic 60 HBW to 90 HBW
Austenite, γ fcc fair strength, non­magnetic 150 HBW (1,5 % C)
Cementite, Fe C rombic hard, brittle chemical composition 820 HBW
3
Pearlite with coarse α + Fe C, lamellar combination of tough ferrite 200 HBW
3
lamellas (0,4 μm) and hard cementite
Pearlite with fine α + Fe C, lamellar harder than pearlite with 400 HBW
3
lamellas (0,1 μm) coarse lamellas
Spheroidite α + globular Fe C soft 120 HBW to 230 HBW,
3
depending on
carbon and alloy content
Upper bainite precipitations of properties such as pearlite with 400 HBW
Fe C on surface fine lamellas
3
of α
Lower bainite precipitations of strength near martensite, but 600 HBW
Fe C inside of α tougher than tempered martensite
3
Martensite, α’, bcc, slightly hard, brittle 250 HV to 950 HV,
non­tempered tetragonic depending on carbon
content
Martensite, α’, bcc, slightly softer and tougher than 250 HV to 650 HV,
tempered tetragonic non­tempered martensite depending on carbon
content and tempering
temperature
3.40
chromizing
surface treatment into and on a workpiece (3.201) relating to chromium
Note 1 to entry: The surface layer can consist of practically pure chromium (on low-carbon steels) or of chromium
carbide (on high­carbon steels).
3.41
compound layer
DEPRECATED: white layer
surface layer formed during thermochemical treatment (3.207) and made up of the chemical compounds
formed by the element(s) introduced during the treatment and certain elements from the base metal
EXAMPLE The surface layer may consist of the layer of nitrides formed during nitriding (3.143), the layer
of borides formed during boriding (3.28), the layer of chromium carbide formed during the chromizing (3.40) of
high­carbon steel.
Note 1 to entry: In English, the term “white layer” is improperly used to designate this layer on nitrided and
nitrocarburized ferrous products.
3.42
continuous annealing
process in which strip is annealed by moving continuously through an oven within a protective
atmosphere
3.43
continuous-cooling transformation diagram
CCT diagram
see 3.210.2
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3.44
controlled rolling
rolling process where rolling temperature and reduction are controlled to achieve enhanced mechanical
properties, e.g. normalizing rolling, thermomechanical rolling
Note 1 to entry: Controlled rolling is used for fine-grain ferritic steels (3.86) and for dual­phase steel for obtaining
fine-grain structure.
3.45
cooling
reduction (or operation to reduce) of the temperature of a hot workpiece continuous, discontinuous,
gradually or interrupted
Note 1 to entry: The medium in which cooling takes place should be specified, e.g. in furnace, air, oil, water. See
also quenching (3.168).
3.46
cooling condition
condition(s) (temperature and kind of cooling medium, relative movements, agitation, etc.) under which
the cooling (3.45) of the workpiece takes place
3.47
cooling function
reduction of the temperature as a function of time of a determined point of a workpiece
Note 1 to entry: This function could be shown as a graph or written in a mathematical form.
3.48
cooling rate
variation in temperature as a function of time during cooling (3.45)
Note 1 to entry: A distinction is made between
— an instantaneous rate corresponding to a specified temperature, and
— an average rate over a defined interval of temperature or time.
3.49
cooling time
interval of time separating two characteristic temperatures of the cooling function (3.47)
Note 1 to entry: It is always necessary to specify precisely what the temperatures are.
3.50
core refining
process to get a fine grain and a homogenous microstructure in the core, often done by hardening of
carburized workpieces
Note 1 to entry: See Figures 1 b), c) and d).
3.51
critical cooling course
cooling course to avoid transformation in undesired microstructure
Note 1 to entry: The cooling course can be characterized by the gradient of temperature or of the cooling rate
(3.48) in general or at given temperatures or times.
3.52
critical cooling rate
cooling rate (3.48) corresponding to the critical cooling course (3.51)
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3.53
critical diameter
diameter (d) of a cylinder with a length ≥3 d, having a structure of 50 % by volume of martensite (3.137)
after quench hardening (3.167) with defined conditions at its centre
3.54
decarburization
depletion of carbon from the surface layer of a workpiece
Note 1 to entry: This depletion can be either partial (partial decarburization) or nominally complete (complete
decarburization). The sum of the two types of decarburization (partial and complete) is termed total
decarburization; see ISO 3887.
3.55
decarburizing
thermochemical treatment (3.207) intended to produce decarburization (3.54) of a workpiece
3.56
decomposition of austenite
austenite transformation
decomposition into ferrite (3.85) and pearlite (3.155) or ferrite and cementite (3.39) with decreasing
temperature
3.57
delta iron
stable state of pure iron between 1 392 °C and its melting point
Note 1 to entry: The crystalline structure of a delta iron is body-centred cubic, identical to that of the alpha
iron (3.5).
Note 2 to entry: Delta iron is paramagnetic.
3.58
depth of carburizing
carburizing depth
distance between the surface of a workpiece and a specified limit characterizing the thickness of the
layer enriched in carbon, which means effective case depth
3.59
depth of decarburization
decarburization depth
distance between the surface of a workpiece and a limit characterizing the thickness of the layer
depleted in carbon
Note 1 to entry: This limit varies according to the type of decarburization (3.54) and can be defined by reference
to a structural state, a level of hardness or the carbon content of the unaltered base metal (see ISO 3887), or any
other specified carbon content.
3.60
depth of hardening
distance between the surface of a workpiece and a limit characterizing the penetration of quench
hardening (3.167)
Note 1 to entry: This limit can be defined starting from a structural state or a level of hardness.
3.61
depth of nitriding
nitriding depth
distance between the surface of a workpiece and a specified limit characterizing the thickness of the
layer enriched in nitrogen
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3.62
destabilization of retained austenite
phenomenon occurring during tempering which allows the retained austenite (3.175) to undergo
martensitic transformation within a temperature range where it would not previously have been
transformed spontaneously
3.63
diffusion
movement of atoms to new places in ferrous materials
3.64
diffusion annealing
heat treatment (3.108)/annealing (3.8) of ferrous products or workpieces to reduce segregation (3.179)
and promote homogeneity by diffusion (3.63)
Note 1 to entry: To reduce segregation of metallic elements in steel making and in bar rolling a process with
temperatures between 1 000 °C and 1 300 °C is required.
Note 2 to entry: Reducing segregations of non-metallic alloying elements (such as carbon or sulfur) in workpieces
usually would be done at a temperature below 1 000 °C.
3.65
diffusion treatment
heat treatment (3.108) to reduce a very high concentration of elements in the surface layer such as
carbon or nitrogen after carburizing (3.36) or nitriding (3.143)
Note 1 to entry: See also malleablizing (3.133), which is also a diffusion treatment.
3.66
diffusion zone
surface layer formed by a thermochemical treatment (3.207) characterized by enrichment of elements
such as carbon or nitrogen
Note 1 to entry: The enriched elements such as carbon or nitrogen are in solid solution and/or precipitated such
as carbides or nitrides.
Note 2 to entry: The concentration of the enriched elements decreases from surface to the core of a workpiece.
3.67
direct-quench hardening
quench hardening (3.167) of carburized workpieces immediately after carburizing (3.36) or
carbonitriding (3.35)
Note 1 to entry: The direct-quench hardening should be started directly from the carburizing or a lower
temperature, adjusted to the surface carbon content.
Note 2 to entry: Direct hardening from hot forging or hot rolling replaces separate austenitizing (3.14) and
quenching (3.168).
Note 3 to entry: See Figure 1 a).
3.68
direct quenching
quenching (3.168) carried out immediately following hot rolling or hot forging or solution annealing
(3.188) of stainless steels or after a thermochemical treatment (3.207)
3.69
dislocation
crystallographic defect or irregularity, within a crystal structure
EXAMPLE There are two primary types, “edge dislocations” and “screw dislocations”.
Note 1 to entry: Cold forming increases the amount of dislocations and results in higher hardness.
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3.70
distortion
any change in the shape and original dimensions of a ferrous workpiece, occurring during heat
treatment (3.108)
Note 1 to entry: The causes are manifold including not only the heat treatment process but also the workpiece
geometry, steel inhomogeneity and the production conditions.
3.71
double-quench hardening treatment
heat treatment (3.108) consisting of two successive quench-hardening treatments, generally carried
out at different temperatures
Note 1 to entry: In the case of carburized products, the first quench hardening (3.167) could be done immediately
after carburizing (3.36) from carburizing temperature. The second quench hardening could be carried out from a
lower temperature adjusted to the carbon content of core.
Note 2 to entry: Double-quench hardening is also used for grain refining.
Note 3 to entry: See Figure 1 d).
3.72
effective case depth after carburizing
case-hardening hardness depth
carburizing depth
perpendicular distance between the surface of a case­hardened workpiece and the point where the
hardness has the limit hardness value
Note 1 to entry: This limit should be specified, e.g. for the total case depth, this limit will correspond to the
carbon content of the unaltered base metal.
Note 2 to entry: The term case depth is used in relation to any case-hardening or surface-hardening process.
[SOURCE: ISO 18203:2016, 3.1, modified.]
3.73
effective case depth after nitriding
nitriding hardness depth
perpendicular distance from the surface of a nitrided or nitrocarburized workpiece to the point where
the hardness has the limit hardness value
[SOURCE: ISO 18203:2016, 3.4, modified.]
3.74
effective case depth after surface hardening
surface hardening hardness depth
distance between the surface and the point at which the Vickers hardness (HV) is equal to 80 % of the
minimum surface hardness required for the workpiece considered
[SOURCE: ISO 18203:2016, 3.5, modified.]
3.75
electron beam hardening
austenitizing (3.14) the surface layer of a workpiece by heating (3.109) with an electron beam
Note 1 to entry: Quenching (3.168) for hardening could be done by external quenching media (3.170) or it takes
place by self-cooling.
© ISO 2017 – All rights reserved 11

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oSIST prEN ISO 4885:2018
ISO/FDIS 4885:2017(E)

3.76
embrittlement
severe loss of toughness of a material
Note 1 to entry: Steels can be affected by different forms of embrittlement such as blue embrittlement, temper
embrittlement (3.202), quench­age embrittlement, sigma­phase embrittlement, strain­age embrittlement,
thermal embrittlement and low­temperature or cold embrittlement.
3.77
endogas
gas mixture produced by incomplete combustion of hydrocarbons
Note 1 to entry: Endogas has a conventional composition of 20 % by volume to 2
...

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