SIST EN 60404-1:2017

SLOVENSKI STANDARD
01-april-2017
Magnetni materiali - 1. del: Razvrstitev (IEC 60404-1:2016)
Magnetic materials - Part 1: Classification (IEC 60404-1:2016)
Magnetische Werkstoffe - Teil 1: Einteilung
Matériaux magnétiques - Partie 1: Classification
Ta slovenski standard je istoveten z: EN 60404-1:2017
ICS:
29.030 Magnetni materiali Magnetic materials
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN 60404-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
January 2017
ICS 29.030
English Version
Magnetic materials - Part 1: Classification
(IEC 60404-1:2016)
Matériaux magnétiques - Partie 1: Classification Magnetische Werkstoffe - Teil 1: Klassifizierung
(IEC 60404-1:2016) (IEC 60404-1:2016)
This European Standard was approved by CENELEC on 2016-11-28. CENELEC 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 CENELEC 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 CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden,
Switzerland, Turkey and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2017 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN 60404-1:2017 E
European foreword
The text of document 68/533/CDV, future edition 3 of IEC 60404-1, prepared by IEC/TC 68 "Magnetic
alloys and steels" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as
The following dates are fixed:
(dop) 2017-08-28
• latest date by which the document has to be
implemented at national level by
publication of an identical national
standard or by endorsement
• latest date by which the national (dow) 2019-11-28
standards conflicting with the
document have to be withdrawn
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such
patent rights.
Endorsement notice
The text of the International Standard IEC 60404-1:2016 was approved by CENELEC as a European
Standard without any modification.
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.

NOTE 1 When an International Publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available here:
www.cenelec.eu
Publication Year Title EN/HD Year

IEC 60050-121 -  International Electrotechnical Vocabulary - -
(IEV) -
Part 121: Electromagnetism
IEC 60050-151 -  International Electrotechnical Vocabulary - -
(IEV) -
Part 151: Electrical and magnetic devices
IEC 60050-221 -  International Electrotechnical Vocabulary - -
(IEV) -
Chapter 221: Magnetic materials and
components
IEC 60401-3 -  Terms and nomenclature for cores made EN 60401-3 -
of magnetically soft ferrites -
Part 3: Guidelines on the format of data
appearing in manufacturers' catalogues of
transformer and inductor cores
IEC 60404-2 -  Magnetic materials - EN 60404-2 -
Part 2: Methods of measurement of the
magnetic properties of electrical steel
sheet and strip by means of an Epstein
frame
IEC 60404-3 -  Magnetic materials - - -
Part 3: Methods of measurement of the
magnetic properties of magnetic sheet and
strip by means of a single sheet tester
Magnetic materials -
IEC 60404-4 -  EN 60404-4 -
Part 4: Methods of measurement of d.c.
magnetic properties of iron and steel
IEC 60404-6 -  Magnetic materials - EN 60404-6 -
Part 6: Methods of measurement of the
magnetic properties of magnetically soft
metallic and powder materials at
frequencies in the range 20 Hz to 200 kHz
by the use of ring specimens
IEC 60404-7 -  Magnetic materials - - -
Part 7: Method of measurement of the
coercivity of magnetic materials in an open
magnetic circuit
Publication Year Title EN/HD Year

IEC 60404-8-1 -  Magnetic materials - EN 60404-8-1 -
Part 8-1: Specifications for individual
materials - Magnetically hard materials
IEC 60404-8-3 -  Magnetic materials - - -
Part 8-3: Specifications for individual
materials - Cold-rolled electrical non-
alloyed and alloyed steel sheet and strip
delivered in the semi-processed state
IEC 60404-8-4 -  Magnetic materials - - -
Part 8-4: Specifications for individual
materials - Cold-rolled non-oriented
electrical steel strip and sheet delivered in
the fully-processed state
IEC 60404-8-5 -  Magnetic materials - - -
Part 8: Specifications for individual
materials -
Section 5: Specification for steel sheet and
strip with specified mechanical properties
and magnetic permeability
IEC 60404-8-6 -  Magnetic materials - EN 60404-8-6 -
Part 8-6: Specifications for individual
materials - Soft magnetic metallic materials
IEC 60404-8-7 -  Magnetic materials - - -
Part 8-7: Specifications for individual
materials - Cold-rolled grain-oriented
electrical steel strip and sheet delivered in
the fully-processed state
IEC 60404-8-8 -  Magnetic materials - - -
Part 8: Specifications for individual
materials -
Section 8: Specification for thin magnetic
steel strip for use at medium frequencies
IEC 60404-8-9 -  Magnetic materials - - -
Part 8: Specification for individual materials
- Section 9: Standard specification for
sintered soft magnetic materials
IEC 60404-8-10 -  Magnetic materials - - -
Part 8-10: Specifications for individual
materials - Magnetic materials (iron and
steel) for use in relays
IEC 60404-10 -  Magnetic materials - - -
Part 10: Methods of measurement of
magnetic properties of electrical steel strip
and sheet at medium frequencies
ISO 4948-1 -  Steels; Classification - - -
Part 1: Classification of steels into
unalloyed and alloy steels based on
chemical composition
IEC 60404-1 ®
Edition 3.0 2016-10
INTERNATIONAL
STANDARD
Magnetic materials –
Part 1: Classification
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.030 ISBN 978-2-8322-3671-0

– 2 – IEC 60404-1:2016 © IEC 2016
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Magnetically soft materials (coercivity ≤1 kA/m) . 8
4.1 Class A – Irons . 8
4.1.1 Reference documents . 8
4.1.2 Chemical composition . 8
4.1.3 Basis of subclassification . 8
4.1.4 Available forms . 8
4.1.5 Physical characteristics . 8
4.1.6 Main applications . 8
4.2 Class B – Low carbon mild steels . 9
4.2.1 Class B1 – Bulk material . 9
4.2.2 Class B2 – Flat material. 9
4.3 Class C – Silicon steels . 10
4.3.1 Class C1 – Bulk material . 10
4.3.2 Class C2 – Flat material . 11
4.4 Class D – Other steels . 16
4.4.1 Class D1 – Bulk material . 16
4.4.2 Class D2 – Flat material . 18
4.4.3 Class D3 – Stainless steels . 18
4.5 Class E – Nickel-iron alloys . 19
4.5.1 Class E1 – Nickel content 70 % to 85 % . 19
4.5.2 Class E2 – Nickel content 54 % to 68 % . 20
4.5.3 Class E3 – Nickel content 40 % to 51 % . 21
4.5.4 Class E4 – Nickel content 35 % to 40 % . 22
4.5.5 Class E5 – Nickel content 29 % to 33 % . 23
4.6 Class F – Iron-cobalt alloys . 24
4.6.1 Class F1 – Cobalt content 47 % to 50 % . 24
4.6.2 Class F2 – Cobalt content 35 % . 24
4.6.3 Class F3 – Cobalt content 23 % to 30 % . 25
4.7 Class G – Other alloys . 26
4.7.1 Class G1 – Aluminium-iron alloys . 26
4.7.2 Class G2 – Aluminium-silicon-iron alloys . 27
4.8 Class H – Magnetically soft materials made by powder metallurgical
techniques . 27
4.8.1 Class H1 – Soft ferrites . 27
4.8.2 Class H2 – Magnetically soft sintered materials . 29
4.8.3 Class H3 – Powder composites . 29
4.9 Class I – Amorphous soft magnetic materials . 30
4.9.1 General . 30
4.9.2 Class I1 – Iron-based amorphous alloys . 30
4.9.3 Class I2 – Cobalt-based amorphous alloys . 31
4.9.4 Class I3 – Nickel-based amorphous alloys . 32
4.10 Class J – Nano-crystalline soft magnetic materials . 33

IEC 60404-1:2016 © IEC 2016 – 3 –
4.10.1 Reference document . 33
4.10.2 Production process . 33
4.10.3 Chemical composition . 33
4.10.4 Basis of subclassification . 33
4.10.5 Available forms . 33
4.10.6 Physical characteristics . 33
4.10.7 Main applications . 34
5 Magnetically hard materials (coercivity > 1 kA/m) . 34
5.1 Class Q – Magnetostrictive alloys – Rare earth iron alloys (Class Q1) . 34
5.1.1 Reference document . 34
5.1.2 Chemical composition . 34
5.1.3 Basis of subclassification . 34
5.1.4 Available forms . 34
5.1.5 Physical characteristics . 34
5.1.6 Main applications . 35
5.2 Class R – Magnetically hard alloys . 35
5.2.1 Class R1 – Aluminium-nickel-cobalt-iron-titanium (AlNiCo) alloys . 35
5.2.2 Class R3 – Iron-cobalt-vanadium-chromium (FeCoVCr) alloys . 36
5.2.3 Class R5 – Rare earth cobalt (RECo) alloys . 36
5.2.4 Class R6 – Chromium-iron-cobalt (CrFeCo) alloys . 37
5.2.5 Class R7 – Rare earth-iron-boron (REFeB) alloys . 38
5.3 Class S – Magnetically hard ceramics – Hard ferrites (Class S1) . 39
5.3.1 Reference document . 39
5.3.2 Chemical composition and manufacturing method . 39
5.3.3 Basis of subclassification . 39
5.3.4 Available forms . 39
5.3.5 Physical characteristics . 40
5.3.6 Main applications . 40
5.4 Class T – Other magnetically hard materials – Martensitic steels (Class T1) . 40
5.4.1 Reference document . 40
5.4.2 Composition . 40
5.4.3 Basis of subclassification . 40
5.4.4 Available forms . 40
5.4.5 Physical characteristics . 40
5.4.6 Main applications . 41
5.5 Class U – Bonded magnetically hard materials. 41
5.5.1 General . 41
5.5.2 Class U1 – Bonded aluminium-nickel-cobalt-iron-titanium (AlNiCo)
magnets . 41
5.5.3 Class U2 – Bonded rare earth-cobalt (RECo) magnets . 42
5.5.4 Class U3 – Bonded neodymium-iron-boron (REFeB) magnets . 42
5.5.5 Class U4 – Bonded hard ferrite magnets . 43
5.5.6 Class U5 – Bonded rare earth-iron-nitrogen magnets . 44

– 4 – IEC 60404-1:2016 © IEC 2016
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MAGNETIC MATERIALS –
Part 1: Classification
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60404-1 has been prepared by IEC technical committee 68:
Magnetic alloys and steels.
This third edition cancels and replaces the second edition published in 2000 and constitutes a
technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) Removal of all tables and values describing typical properties of the material to be
consistent with the aim of the document to be a classification and not a specification.
b) Enlargement of the Ni content for the classes E1 and E3.
c) Enlargement of the Co content for the classes F3.
d) Addition of a new class: U5 bonded rare earth-iron-nitrogen magnets.

IEC 60404-1:2016 © IEC 2016 – 5 –
The text of this standard is based on the following documents:
CDV Report on voting
68/533/CDV 68/555/RVC
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 60404 series, published under the general title Magnetic
materials, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

– 6 – IEC 60404-1:2016 © IEC 2016
MAGNETIC MATERIALS –
Part 1: Classification
1 Scope
This part of IEC 60404 is intended to classify commercially available magnetic materials.
The term "magnetic materials" denotes substances where the application requires the
existence of ferromagnetic or ferrimagnetic properties.
In this document, the classification of magnetic materials is based upon the generally
recognized existence of two main groups of products:
• soft magnetic materials (coercivity ≤1 000 A/m);
• hard magnetic materials (coercivity >1 000 A/m).
Within these main groups, the classification when appropriate recognizes the following
characteristics:
• the main alloying element and the metallurgical state and physical properties of the
material;
• when possible and convenient, the relationship between these characteristics is identified.
A classification by specific areas of application cannot be applied to all materials because
different materials can very often be used for the same application depending on the
characteristics required.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements of this document. For dated references, only the edition
cited applies. For undated references, the latest edition of the referenced document (including
any amendments) applies.
IEC 60050-121, International Electrotechnical Vocabulary – Part 121: Electromagnetism
IEC 60050-151, International Electrotechnical Vocabulary – Part 151: Electrical and magnetic
devices
IEC 60050-221, International Electrotechnical Vocabulary – Chapter 221: Magnetic materials
and components
IEC 60401-3, Terms and nomenclature for cores made of magnetically soft ferrites – Part 3:
Guidelines on the format of data appearing in manufacturers catalogues of transformer and
inductor cores
IEC 60404-2, Magnetic materials – Part 2: Methods of measurement of the magnetic
properties of electrical steel sheet and strip by means of an Epstein frame
IEC 60404-3, Magnetic materials – Part 3: Methods of measurement of the magnetic
properties of magnetic sheet and strip by means of a single sheet tester

IEC 60404-1:2016 © IEC 2016 – 7 –
IEC 60404-4, Magnetic materials – Part 4: Methods of measurement of d.c. magnetic
properties of iron and steel
IEC 60404-6, Magnetic materials – Part 6: Methods of measurement of the magnetic
properties of magnetically soft metallic and powder materials at frequencies in the range
20 Hz to 200 kHz by the use of ring specimens
IEC 60404-7, Magnetic materials – Part 7: Method of measurement of the coercivity of
magnetic materials in an open magnetic circuit
IEC 60404-8-1, Magnetic materials – Part 8-1: Specifications for individual materials –
Magnetically hard materials
IEC 60404-8-3, Magnetic materials – Part 8-3: Specifications for individual materials – Cold-
rolled electrical non-alloyed and alloyed steel sheet and strip delivered in the semi-processed
state
IEC 60404-8-4, Magnetic materials – Part 8-4: Specifications for individual materials – Cold-
rolled non-oriented electrical steel strip and sheet delivered in the fully-processed state
IEC 60404-8-5, Magnetic materials – Part 8: Specifications for individual materials –
Section Five: Specification for steel sheet and strip with specified mechanical properties and
magnetic permeability
IEC 60404-8-6, Magnetic materials – Part 8-6: Specifications for individual materials – Soft
magnetic metallic materials
IEC 60404-8-7, Magnetic materials – Part 8-7: Specifications for individual materials –Cold-
rolled grain-oriented electrical steel strip and sheet delivered in the fully processed state
IEC 60404-8-8, Magnetic materials – Part 8: Specifications for individual materials –
Section 8: Specification for thin magnetic steel strip for use at medium frequencies
IEC 60404-8-9, Magnetic materials – Part 8: Specifications for individual materials –
Section 9: Standard specification for sintered soft magnetic materials
IEC 60404-8-10, Magnetic materials – Part 8-10: Specifications for individual materials –
Magnetic materials (iron and steel) for use in relays
IEC 60404-10, Magnetic materials. Part 10: Methods of measurement of magnetic properties
of magnetic sheet and strip at medium frequencies
ISO 4948-1, Steels – Classification – Part 1: Classification of steels into unalloyed and alloy
steels based on chemical composition
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-121,
IEC 60050-151, IEC 60050-221 and in the product standards of the IEC 60404-8 series apply.
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 http://www.iso.org/obp

– 8 – IEC 60404-1:2016 © IEC 2016
4 Magnetically soft materials (coercivity ≤1 kA/m)
4.1 Class A – Irons
4.1.1 Reference documents
These materials are covered by IEC 60404-8-6 and IEC 60404-8-10.
4.1.2 Chemical composition
The basic constituent of these materials is pure iron, and they are often referred to as
"commercially pure" or "magnetically soft" irons. The material also contains unavoidable
impurities that may affect magnetic properties. The amount of impurities that adversely affect
the remanence, coercivity, saturation, magnetic polarization and stability of the magnetic
properties are limited to produce the required magnetic properties for the proposed
application. For information the most significant impurities when they are present in these
materials are carbon (up to 0,03 %), silicon (up to 0,1 %), manganese (up to 0,2 %),
phosphorus (up to 0,015 %), sulphur (up to 0,03 %), aluminium (up to 0,08 %), titanium (up to
0,1 %) and vanadium (up to 0,1 %).
NOTE For improved free machining capability, the amount of phosphorus and sulphur can be higher than
indicated above.
4.1.3 Basis of subclassification
The recommended subclassification is based on coercivity values.
4.1.4 Available forms
These materials are available in a wide variety of forms. They may be supplied as slabs,
billets, ingots or forgings; as hot-rolled bar in rectangular and square cross-sections; as hot-
rolled wire rod in round, hexagonal and octagonal cross-sections; in cold-rolled and drawn
forms as bar and wire; as hot- or cold-rolled sheet and strip.
4.1.5 Physical characteristics
In addition to the values of coercivity, a more complete definition of these materials can be
based on the following characteristics:
saturation magnetic polarization, magnetic polarization at various
• magnetic:
values of magnetic field strength (from which permeability can be
derived), stability of characteristics with time;
• mechanical: hardness, suitability for punching operations, free machining
capability, deep drawing properties, tensile strength;
• metallurgical state: hot- or cold-worked, forged, deep drawn, fully processed state, i.e.
final annealed.
NOTE For material not delivered in the fully processed state, subclassification is based on the coercivity
measured after heat treatment according to the requirements of the product standard or the recommendations of
the manufacturer.
Ranges of specified values for the above-mentioned magnetic characteristics in the fully
processed state are given in the corresponding product specifications.
4.1.6 Main applications
The main applications are in DC relays, loudspeakers, electromagnets, magnetic clutches,
brakes, parts for magnetic circuits in instruments and control apparatus, as well as for pole
pieces and other DC parts for generators and motors.

IEC 60404-1:2016 © IEC 2016 – 9 –
4.2 Class B – Low carbon mild steels
4.2.1 Class B1 – Bulk material
4.2.1.1 Reference document
Some of these materials are covered by IEC 60404-8-10.
4.2.1.2 Chemical composition
The basic constituent of these materials is iron containing unavoidable impurities, together
with a low level of other elements which may arise from additions necessitated during the
manufacturing process. The amount of alloying elements is limited to that of a non-alloy steel
as defined in ISO 4948-1, in particular silicon is less than 0,5 %.
4.2.1.3 Basis of subclassification
The recommended subclassification is based on the coercivity.
4.2.1.4 Available forms
These materials are normally supplied in the form of castings or forgings in a final heat-
treated condition or partially machined to drawings supplied by the user or as bar, wire rod or
wire in the hot-rolled, cold-rolled or cold-drawn condition.
4.2.1.5 Physical characteristics
In addition to the coercivity a more complete definition of these materials can be based on the
following properties:
magnetic polarization at various values of magnetic field strength;
• magnetic:
yield strength (or 0,2 % proof stress) elongation (L = 5 d ),
• mechanical:
o o
freedom from defects;
hot- or cold-worked, annealed to produce required magnetic
• metallurgical state:
characteristics.
Mechanical and non-destructive tests are made in accordance with the appropriate
ISO standards. Coercivity shall be measured in accordance with IEC 60404-7, other magnetic
properties in accordance with IEC 60404-4.
Ranges of typical values of magnetic and mechanical properties are given in the
corresponding product specification.
4.2.1.6 Main applications
The materials are used for large DC magnets where no mechanical strength is required, for
example, in deflection magnets in elementary particle physics and for relay applications.
4.2.2 Class B2 – Flat material
4.2.2.1 Reference documents
These materials are covered by IEC 60404-8-3, IEC 60404-8-4 and IEC 60404-8-10.
4.2.2.2 Chemical composition
The basic constituent of these materials is iron containing unavoidable impurities, together
with a low level of other elements which may arise from additions necessitated during the
manufacturing process. The amount of alloying elements is limited to that of non-alloy steel as

– 10 – IEC 60404-1:2016 © IEC 2016
defined in ISO 4948-1, in particular silicon is less than 0,5 %. These materials can have an
annealing treatment after punching to enhance their magnetic properties.
4.2.2.3 Basis of subclassification
The recommended subclassification is based either on the specific total loss which is a
function of thickness and is normally measured at a magnetic polarization value of 1,5 T and
at normal industrial power frequencies or (for relay application) on the coercivity.
4.2.2.4 Available forms
These materials are supplied in the form of cold-rolled coils or sheets or (for relay application)
in the form of hot-rolled strip, sheet or plate.
4.2.2.5 Physical characteristics
In addition to specific total loss, a more complete definition of these materials can be based
on the following properties:
magnetic polarization at various values of magnetic field strength;
• magnetic:
suitability for punching operations, surface condition, stacking
• mechanical:
factor;
hot-rolled; hard state – i.e. cold-rolled; semi-processed state – i.e.
• metallurgical state:
annealed and finally cold-rolled;
fully processed state – i.e. final annealed.
NOTE For material delivered in the hard or semi-processed state, subclassification is based on the total specific
loss or coercivity measured after heat treatment according to the requirements of the product standard or
recommendations of the manufacturer.
thickness, width and (as required) length.
• dimensions:
Recommended nominal thicknesses for the cold-rolled materials are given in the
corresponding product specifications.
Magnetic measurements are made in accordance with IEC 60404-2, IEC 60404-3 or
IEC 60404-7.
Ranges of specified values of maximum specific total loss, after annealing, for the commonly
used thicknesses are also shown in the corresponding product specifications.
The specified maximum value of coercivity for relay material ranges from 40 A/m to 240 A/m.
4.2.2.6 Main applications
The materials are used in the manufacture of laminated cores for electrical apparatus and
especially small machines and for relay applications.
4.3 Class C – Silicon steels
4.3.1 Class C1 – Bulk material
4.3.1.1 Reference documents
Some of these materials are covered by IEC 60404-8-6 and IEC 60404-8-10.
4.3.1.2 Chemical composition
The basic constituent of these materials is iron in which the main alloying element is silicon
with a content of up to approximately 5 %.

IEC 60404-1:2016 © IEC 2016 – 11 –
4.3.1.3 Basis of subclassification
The recommended subclassification is based on coercivity values or on electrical resistivity
which is a function of silicon content.
4.3.1.4 Available forms
These materials are available as hot-rolled and cold-drawn bar, wire, ground bar and forging
billets and require heat treatment after mechanical working to achieve the required magnetic
properties.
4.3.1.5 Physical characteristics
In addition to the coercivity and the electrical resistivity, a more complete definition of these
materials can be based on the following characteristics:
saturation magnetic polarization, magnetic polarization at various
• magnetic:
values of magnetic field strength, remanent magnetic polarization;
machinability, ductility, hardness;
• mechanical:
hot- or cold-worked, annealed to produce required magnetic
• metallurgical state:
characteristics.
4.3.1.6 Main applications
The main applications are for the magnetic circuits of relays, magnetic clutches, magnetic
pole pieces, stepping motors and gyro housings.
4.3.2 Class C2 – Flat material
4.3.2.1 Class C21 – Isotropic (non-oriented) steels for use at power frequencies
4.3.2.1.1 Reference documents
These materials are covered by IEC 60404-8-3, IEC 60404-8-4, IEC 60404-8-6 and
IEC 60404-8-10.
4.3.2.1.2 Chemical composition
The basic constituent of these materials is iron. The main alloying element is silicon, whose
content may be up to approximately 5 %. Other alloying elements, for example aluminium,
may also be present. The material also contains unavoidable impurities, together with a low
level of other elements which may arise from additions necessitated during the manufacturing
process.
4.3.2.1.3 Basis of subclassification
The recommended subclassification is based on the specific total loss which is a function of
thickness and normally measured at a magnetic polarization value of 1,5 T and at power
frequencies.
When the application demands it (for example relays), it may be more appropriate for the
subclassification to be based on coercivity or permeability.
____________
This describes a material which is substantially isotropic and deliberately processed to be so.

– 12 – IEC 60404-1:2016 © IEC 2016
4.3.2.1.4 Available forms
These materials are normally supplied in the form of cold-rolled coils or sheets.
4.3.2.1.5 Physical characteristics
In addition to the values of specific total loss, a more complete definition of these materials
can be based on the following characteristics:
magnetic polarization at various values of magnetic field strength,
• magnetic:
specific apparent power for different values of magnetic polarization
anisotropy of loss;
type of surface insulation and its resistance, resistivity;
• electrical:
suitability for punching operations, ductility, tensile strength,
• mechanical:
hardness, surface condition and finish, stacking factor, flatness,
edge camber;
hard state, i.e. as cold rolled semi-processed state, i.e. annealed or
• metallurgical state:
annealed and temper rolled; fully-processed state, i.e. final
annealed;
NOTE For material delivered in the hard or semi-processed state, the subclassification is based on the specific
total losses measured after heat treatment according to the requirements of the product standard or the
recommendations of the manufacturer.
• dimensions: thickness, width and (as required) length.
The values of nominal thickness are given in the corresponding product specifications.
Magnetic measurements are made in accordance with IEC 60404-2 or IEC 60404-3. The
density values to be used for magnetic measurements should be as defined in the relevant
product standard. In other cases, the density values should be the subject of agreement.
Ranges of specified values of specific total loss, after final annealing, for four commonly used
thicknesses are shown in the corresponding product specifications.
4.3.2.1.6 Main application
These materials are used mainly in the magnetic circuits of electrical apparatus, particularly in
the parts of rotating machines in which the flux is not unidirectional. They may also be used
in electromagnetic relays, small transformers, chokes for fluorescent tubes, electrical meters,
shielding and magnetic poles of electron and proton synchrotrons.
4.3.2.2 Class C22 – Anisotropic (oriented) steels for use at power frequencies
4.3.2.2.1 Reference documents
These materials are covered by IEC 60404-8-6, IEC 60404-8-7 and IEC 60404-8-8.
4.3.2.2.2 Chemical composition
The basic constituent of these materials is iron and the main alloying element is silicon
(approximately 3 %), together with unavoidable impurities and low levels of other elements
which may arise from additions necessitated during the manufacturing process. This type of
magnetic material possesses anisotropic properties (orientation) such that the direction
parallel to the axis of rolling shows the lowest values of specific total losses and the highest
permeability. These properties are sensitive to mechanical treatment, and stress relief
annealing may be used to optimize the inherent properties.
____________
This describes a material which is substantially anisotropic and deliberately processed to be so.

IEC 60404-1:2016 © IEC 2016 – 13 –
4.3.2.2.3 Basis of subclassification
The recommended subclassification is based on the perfection of crystal orientation
expressed by the magnetic polarization for a magnetic field strength of 800 A/m and on the
specific total loss, which is a function of thickness and of the orientation, and is normally
measured at magnetic polarization values of 1,5 T or 1,7 T and at power frequencies.
4.3.2.2.4 Available forms
These materials are normally supplied in the form of cold-rolled coils or sheets having an
inorganic insulating coating.
4.3.2.2.5 Physical characteristics
In addition to the perfection of crystal orientation and to the values of specific total loss, a
more complete definition of these materials can be based on the following characteristics:
magnetic polarization at various values of magnetic field strength;
• magnetic:
type of surface insulation and its resistance, resistivity;
• electrical:
• mechanical: ductility, surface condition and finish, stacking factor, flatness, edge
camber;
• metallurgical state: annealed and fully recrystallized;
thickness, width and (if required) length.
• dimensions:
The values of nominal thickness normally used are given in the corresponding product
specifications.
Magnetic measurements are made in accordance with IEC 60404-2 or IEC 60404-3. The
density used for calculations is normally 7,65 kg/dm³ and test pieces are taken parallel to the
axis of rolling and, before measurement, undergo stress relief annealing in accordance with
the recommendations of the manufacturer.
Ranges of specified values of maximum specific total loss, after stress relief annealing, for the
normally used thicknesses are also shown in the corresponding product specifications.
In addition, materials which are not yet specified in IEC 60404-8-7 are available.
4.3.2.2.6 Main applications
These materials are used mainly for the manufacture of magnetic cores in which the magnetic
flux paths are substantially parallel to the direction of cold-rolling, as for example in
transformer cores.
4.3.2.3 Class C23 – Thin silicon steels
4.3.2.3.1 Reference document
These materials are covered by IEC 60404-8-8.
4.3.2.3.2 Chemical composition
The basic constituent of these materials is iron. The main alloying element is silicon, whose
content may be between 2 % and 4 %. Other alloying elements, namely aluminium,
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