IEC 60404-8-8:2017

Magnetic materials - Part 8-8: Specifications for individual materials - Thin electrical steel strip and sheet for use at medium frequencies

IEC 60404-8-8:2017(E) defines the grades of thin non-oriented electrical steel strip and sheet in nominal thicknesses of 0,05 mm, 0,10 mm, 0,15 mm, 0,20 mm, 0,25 mm, 0,30 mm and 0,35 mm and of thin grain-oriented electrical steel strip and sheet in nominal thicknesses of 0,05 mm, 0,10 mm, 0,15 mm and 0,18 mm. In particular, it gives general requirements, magnetic properties, geometric characteristics and tolerances, technological characteristics, as well as inspection procedures.
NOTE For thin non-oriented electrical steel strip and sheet, other nominal thicknesses (i.e. 0,12 mm, 0,18 mm, 0,23 mm and 0,27 mm) can be agreed between the manufacturer and the purchaser.
This document applies to electrical steel strip and sheet supplied in the finally annealed condition in coils or sheets and intended for the construction of magnetic circuits predominantly used at frequencies in the range from 100 Hz to 10 kHz.
This edition includes the following significant technical changes with respect to the previous edition:
- extension of the range of electrical steels to include the improved grades.

General Information

• Status: Published
• Publication Date: 18-Sep-2017
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 29.030 - Magnetic materials
• Technical Committee: TC 68 - Magnetic alloys and steels
• Drafting Committee: JWG 1 - TC 68/JWG 1
• Current Stage: PPUB - Publication issued
• Start Date: 06-Oct-2017
• Completion Date: 19-Sep-2017

Standards Content (Sample)

IEC 60404-8-8
®

Edition 2.0 2017-09
INTERNATIONAL
STANDARD



Magnetic materials –
Part 8-8: Specifications for individual materials – Thin electrical steel strip and
sheet for use at medium frequencies

IEC 60404-8-8:2017-09(en)

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IEC 60404-8-8

®


Edition 2.0 2017-09




INTERNATIONAL



STANDARD



















Magnetic materials –

Part 8-8: Specifications for individual materials – Thin electrical steel strip and

sheet for use at medium frequencies


























INTERNATIONAL

ELECTROTECHNICAL


COMMISSION





ICS 29.030 ISBN 978-2-8322-4805-8



  Warning! Make sure that you obtained this publication from an authorized distributor.


® Registered trademark of the International Electrotechnical Commission

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CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Classification . 7
5 Designation . 7
6 General requirements . 7
6.1 Production process . 7
6.2 Form of supply . 7
6.3 Delivery condition . 8
6.4 Surface condition . 8
6.5 Suitability for cutting . 8
7 Technical requirements . 9
7.1 Magnetic properties . 9
7.1.1 Magnetic polarization . 9
7.1.2 Specific total loss . 10
7.2 Geometric characteristics and tolerances . 10
7.2.1 Thickness . 10
7.2.2 Width . 12
7.2.3 Edge camber . 12
7.2.4 Residual curvature . 12
7.2.5 Burr height . 13
7.3 Technological characteristics . 13
7.3.1 Density . 13
7.3.2 Stacking factor. 13
7.3.3 Number of bends . 13
7.3.4 Insulation coating resistance . 13
8 Inspection and testing . 13
8.1 General . 13
8.2 Selection of samples . 14
8.3 Preparation of test specimens . 14
8.3.1 Magnetic properties . 14
8.3.2 Geometrical characteristics and tolerances . 15
8.3.3 Technological characteristics . 15
8.4 Test methods . 15
8.4.1 General . 15
8.4.2 Magnetic properties . 15
8.4.3 Geometrical characteristics and tolerances . 16
8.4.4 Technological characteristics . 16
8.5 Retests . 17
9 Marking, labelling and packaging . 17
10 Complaints . 17
11 Information to be supplied by the purchaser . 17
Annex A (informative) Optional stacking factor for non-oriented coated products . 18
Annex B (informative) Optional magnetic specifications . 19

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IEC 60404-8-8:2017  IEC 2017 – 3 –
Annex C (informative) Calculation of density values . 20
Bibliography . 21

Table 1 – Magnetic and technological characteristics of non-oriented electrical steel
strip and sheet . 9
Table 2 – Magnetic and technological characteristics of grain-oriented electrical steel
strip and sheet . 10
Table 3 – Thickness tolerances . 11
Table 4 – Width tolerance of non-oriented strip and sheet . 12
Table 5 – Width tolerance of grain oriented electrical steel products . 12
Table A.1 – Optional stacking factor for non-oriented coated products . 18
Table B.1 – Optional magnetic specifications for non-oriented electrical steel strip and
sheet . 19

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INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

MAGNETIC MATERIALS –

Part 8-8: Specifications for individual materials –
Thin electrical steel strip and sheet for use at medium frequencies

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
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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
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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6) All users should ensure that they have the latest edition of this publication.
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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 60404-8-8 has been prepared by IEC technical committee 68:
Magnetic alloys and steels.
This second edition cancels and replaces the first edition published in 1991.
This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
– extension of the range of electrical steels to include the improved grades.

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IEC 60404-8-8:2017  IEC 2017 – 5 –
The text of this International Standard is based on the following documents:
CDV Report on voting
68/546/CDV 68/562/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 the parts in the IEC 60404 series, 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.

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– 6 – IEC 60404-8-8:2017  IEC 2017
MAGNETIC MATERIALS –

Part 8-8: Specifications for individual materials –
Thin electrical steel strip and sheet for use at medium frequencies



1 Scope
This part of IEC 60404 defines the grades of thin non-oriented electrical steel strip and sheet
in nominal thicknesses of 0,05 mm, 0,10 mm, 0,15 mm, 0,20 mm, 0,25 mm, 0,30 mm and
0,35 mm and of thin grain-oriented electrical steel strip and sheet in nominal thicknesses of
0,05 mm, 0,10 mm, 0,15 mm and 0,18 mm. In particular, it gives general requirements,
magnetic properties, geometric characteristics and tolerances, technological characteristics,
as well as inspection procedures.
NOTE For thin non-oriented electrical steel strip and sheet, other nominal thicknesses (i.e. 0,12 mm, 0,18 mm,
0,23 mm and 0,27 mm) can be agreed between the manufacturer and the purchaser.
This document applies to electrical steel strip and sheet supplied in the finally annealed
condition in coils or sheets and intended for the construction of magnetic circuits
predominantly used at frequencies in the range from 100 Hz to 10 kHz.
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
(available at http://www.electropedia.org/)
IEC 60050-221, International Electrotechnical Vocabulary – Chapter 221: Magnetic materials
and components (available at http://www.electropedia.org/)
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 60404-9, Magnetic materials – Part 9: Methods of determination of the geometrical
characteristics of magnetic steel sheet and strip
IEC 60404-10, Magnetic materials – Part 10: Methods of measurement of magnetic properties
of magnetic steel sheet and strip at medium frequencies
IEC 60404-13, Magnetic materials – Part 13: Methods of measurement of resistivity, density
and stacking factor of electrical steel strip and sheet
ISO 404, Steel and steel products – General technical delivery requirements
ISO 7799, Metallic materials – Sheet and strip 3 mm thick or less – Reverse bend test
ISO 10474, Steel and steel products – Inspection documents

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IEC 60404-8-8:2017  IEC 2017 – 7 –
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-121 and
IEC 60050-221 and the following apply.
3.1
number of bends
number of alternate bends possible before the appearance of the first crack in the base metal
visible to the naked eye
Note 1 to entry The number of bends constitutes an indication of the ductility of the product.
3.2
edge camber
greatest distance between a longitudinal edge of a length of strip or a sheet and the line
joining the two extremities of the measured length of this edge
Note 1 to entry: See IEC 60404-9.
4 Classification
The grades covered by this document are classified according to the maximum value of the
1
specific total loss in watts per kilogram and according to the nominal thickness of the product
(0,05 mm, 0,10 mm, 0,15 mm, 0,20 mm, 0,25 mm, 0,30 mm and 0,35 mm for non-oriented
electrical steel; 0,05 mm, 0,10 mm, 0,15 mm and 0,18 mm for grain-oriented electrical steel).
5 Designation
The steel name comprises the following in the order given:
a) the characteristic letters:
• NO for non-oriented electrical steel;
• GO for grain-oriented electrical steel;
b) one hundred times the nominal thickness of the product, in millimetres;
c) the specified value of the maximum specific total loss at 1,0 T and the given frequency for
non-oriented electrical steel grades.
EXAMPLE: NO 20-13: non-oriented strip or sheet in nominal thickness of 0,20 mm with a maximum specific total
loss of 13 W/kg at 1,0 T and 400 Hz.
6 General requirements
6.1 Production process
The production process of the steel and its chemical composition are left to the discretion of
the manufacturer.
6.2 Form of supply
The product is supplied in coils in the case of strip and in bundles in the case of sheets.
The mass of the coils or the bundles of sheets shall be agreed between the manufacturer and
the purchaser at the time of enquiry and order.
___________
1
 In the rest of the document, the word “product” is used to mean “strip and sheet”.

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– 8 – IEC 60404-8-8:2017  IEC 2017
The recommended value for the internal diameter of coils is 508 mm; however, another value
(e.g. 400 mm) may be agreed for the internal diameter of coils between the manufacturer and
the purchaser.
The strip shall be of constant width and wound in such a manner that the edges are
superimposed in a regular manner and that the side faces of the coil are substantially flat.
The coils shall be sufficiently tightly wound in order that they do not collapse under their own
weight.
The strip may exhibit welds or interleaves resulting from the removal of defective zones,
subject to prior agreement between the manufacturer and the purchaser at the time of enquiry
and order. The value of the additional thickness due to the weld shall be the subject of an
agreement. If necessary, the marking of welds or interleaves may form the subject of a
special agreement.
For coils containing repair welds or interleaves, each part of the strip shall be of the same
grade.
The edges of parts welded together shall not be so much out of alignment as to affect the
further processing of the product.
Sheets which make up each bundle shall be stacked so that the side faces are substantially
flat and approximately perpendicular to the top face.
6.3 Delivery condition
Products according to this document are delivered without coating or with a coating on one or
both sides. Different types of coating can be provided (see IEC 60404-1-1).
6.4 Surface condition
2
The surfaces shall be smooth and clean, free from grease and rust . Dispersed defects such
as scratches, blisters, cracks, etc. are permitted if they are within the limits of the tolerances
on thickness and if they are not detrimental to the correct use of the supplied products.
The insulation coating present on the surface of the product shall be sufficiently adherent so
that it does not become detached during cutting operations or heat treatment under conditions
specified by the supplier.
If the product is to be immersed in a fluid, an agreement between the manufacturer and the
purchaser, initiated by the purchaser, should be reached to ensure compatibility between the
fluid and the coating.
6.5 Suitability for cutting
The product shall be suitable for cutting accurately into the usual shapes at any point when
appropriate cutting tools are used.
___________
2
Not to be confused with some coloration of the insulating coating inherent to the manufacturing process.

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IEC 60404-8-8:2017  IEC 2017 – 9 –
7 Technical requirements
7.1 Magnetic properties
7.1.1 Magnetic polarization
The specified minimum values of magnetic polarization for a magnetic field strength of
5 000 A/m (peak value) and at 50 Hz for non-oriented electrical steel shall be as given in
Table 1.
Table 1 – Magnetic and technological characteristics
of non-oriented electrical steel strip and sheet
Maximum specific Minimum
total loss at 1,0 T magnetic
Nominal Conventional
b,c
Minimum
Minimum
and polarization
e
thickness density
Steel name stacking number of
at 50 Hz
a
W/kg
d
factor bends 3
for 5 000 A/m
mm kg/dm
at 400 Hz at 1 000 Hz
T
NO 5-45 0,05 – 45 1,50 0,88
2 7,60
NO 10-13 0,10 13 – 1,55 0,91
NO 15-11 11 – 1,55
0,15 0,92 2 7,60
NO 15-14 14 – 1,55
NO 20-13 13 – 1,58
0,20 0,93 2 7,60
NO 20-15 15 – 1,59
NO 25-14 14 – 1,59
0,25 0,94 2 7,60
NO 25-17 17 – 1,60
NO 30-16 16 – 1,59
0,30 0,94 2 7,60
NO 30-19 19 – 1,60
NO 35-19 19 – 1,60 7,60
0,35 0,95 2
NO 35-22 22 – 1,60 7,65
a
Values determined on test specimens without coating. For coated products, the values given in Annex A,
Table A.1 apply.
b
For some steel grades in nominal thicknesses of 0,20 mm; 0,30 mm and 0,35 mm values for the optional
maximum specific total loss at 1,0 T and 700 Hz are given in Annex B and may be agreed between the
manufacturer and the purchaser at the time of enquiry and order.
c
For some steel grades in nominal thicknesses of 0,25 mm and 0,30 mm, values for the optional maximum
specific total loss at 1,0 T and 1 000 Hz are given in Annex B and may be agreed between the manufacturer
and the purchaser at the time of enquiry and order.
d
The values of minimum magnetic polarization at 50 Hz for 2 500 A/m and 10 000 A/m may be agreed
between the manufacturer and the purchaser at the time of enquiry and order (see Annex B).
e
Other values may be agreed between the manufacturer and the purchaser, see Annex C.

The specified minimum values of magnetic polarization for a magnetic field strength of
800 A/m (peak value) and at 50 Hz for grain-oriented electrical steel shall be as given in
Table 2.

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Table 2 – Magnetic and technological characteristics
of grain-oriented electrical steel strip and sheet
Steel name Nominal Maximum specific total loss Minimum magnetic Minimum Minimum
thickness polarization stacking number of
W/kg at
at 50 Hz for factor bends
mm
a
H = 800 A/m
1,0 T 1,5 T Frequency T
Hz
GO 5 0,05 24 – 1 000 1,60 0,88 1
GO 10 0,10 – 15 400 1,70 0,91 1
GO 15 0,15 – 16 400 1,70 0,92 1
GO 18 0,18 – 17 400 1,80 0,93 1

NOTE The difference between B and J at 800 A/m amounts up to 0,001 T.
a
It has been common practice for many years to give values of magnetic flux density in tables such as the one
above. In fact the Epstein frame is used to determine magnetic polarization (intrinsic flux density) which is
defined as:
J = B – µ H

0
where
J is the magnetic polarization;
B is the magnetic flux density;
H is the magnetic field strength;
µ is the magnetic constant.
0

7.1.2 Specific total loss
The specified values of the maximum specific loss shall be as given in Table 1 and Table 2
and reflect the aged conditions (see 8.3.1).
For grain-oriented electrical steel, they also apply to test specimens that have received, after
cutting, a stress relief heat treatment under conditions specified by the manufacturer.
Depending on the nominal thicknesses, the values are specified at 1,0 T for non-oriented
electrical steel grades and at 1,0 T or 1,5 T for grain-oriented electrical steel grades and at
the frequency specified in Table 1 and Table 2.
7.2 Geometric characteristics and tolerances
7.2.1 Thickness
7.2.1.1 Non-oriented electrical steel products
The nominal thicknesses are 0,05 mm, 0,10 mm, 0,15 mm, 0,20 mm, 0,25 mm, 0,30 mm and
0,35 mm.
For thickness tolerance, a distinction is made between:
• allowable tolerance on the nominal thickness within the same acceptance unit;
• difference in thickness in a sheet or in a length of strip in a direction parallel to the
direction of rolling;
• difference in thickness in a direction perpendicular to the direction of rolling. This
tolerance applies only to materials with a width greater than 25 mm.

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IEC 60404-8-8:2017  IEC 2017 – 11 –
At any point the allowable tolerance on the nominal thickness within the same acceptance unit
shall not exceed the values given in Table 3. The additional thickness due to welds, with
respect to the measured thickness of the steel strip shall not exceed 0,050 mm.
The difference in thickness in a length of strip (see 8.3.2) in a direction parallel to the
direction of rolling shall not exceed 10 % for nominal thicknesses of 0,05 mm, 0,10 mm,
0,15 mm, 0,20 mm, 0,25 mm and 8 % for nominal thicknesses of 0,30 mm and 0,35 mm.
The difference in thickness in a direction perpendicular to the direction of rolling shall not
exceed the values given in Table 3.
7.2.1.2 Grain-oriented electrical steel products
The nominal thicknesses are 0,05 mm, 0,10 mm, 0,15 mm and 0,18 mm.
For thickness tolerance, a distinction is made between:
• the allowable tolerance on nominal thickness within the same acceptance unit;
• the difference in thickness in a direction parallel to the direction of rolling;
• the difference in thickness in a direction perpendicular to the direction of rolling. This
tolerance applies only to material with a width greater than 150 mm, the measurement
being made at least 40 mm from the edges.
At any point, the allowable tolerance on the nominal thickness within the same acceptance
unit shall not exceed the values given in Table 3.
The difference in thickness in a length of strip (see 8.3.2) in a direction parallel to the
direction of rolling shall not exceed 0,020 mm.
The difference in thickness in a direction perpendicular to the direction of rolling shall not
exceed the values given in Table 3.
Table 3 – Thickness tolerances
Permitted variation on the nominal Maximum difference in thickness
thickness within the same acceptance unit in a direction perpendicular
to the direction of rolling

Nominal
thickness
mm mm
mm
Non-oriented Grain-oriented Non-oriented Grain-oriented
electrical steel electrical steel electrical steel electrical steel
products products products products
+ 0,010 + 0,010
0,05 0,008 0,008
– 0,005 – 0,005
0,10 ± 0,010 ± 0,010 0,010 0,010
0,15 ± 0,015 ± 0,015 0,020 0,020
0,18 – ± 0,025 – 0,020
0,20 ± 0,020 – 0,020 –
0,25 ± 0,025 – 0,020 –
0,30 ± 0,030 – 0,020 –
0,35 ± 0,030 – 0,020 –

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