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.

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Status
Published
Publication Date
18-Sep-2017
Current Stage
PPUB - Publication issued
Start Date
19-Sep-2017
Completion Date
19-Sep-2017
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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
IEC 60404-8-8:2017-09(en)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
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
---------------------- Page: 3 ----------------------
– 2 – IEC 60404-8-8:2017  IEC 2017
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

---------------------- Page: 4 ----------------------
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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– 4 – IEC 60404-8-8:2017  IEC 2017
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

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

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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

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Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any

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services carried out by independent certification bodies.

6) All users should ensure that they have the latest edition of this publication.

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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 60404-8-8 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.
---------------------- Page: 6 ----------------------
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.
---------------------- Page: 7 ----------------------
– 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
---------------------- Page: 8 ----------------------
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

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.
___________

In the rest of the document, the word “product” is used to mean “strip and sheet”.

---------------------- Page: 9 ----------------------
– 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

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.
___________

Not to be confused with some coloration of the insulating coating inherent to the manufacturing process.

---------------------- Page: 10 ----------------------
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
thickness density
Steel name stacking number of
at 50 Hz
W/kg
factor bends 3
for 5 000 A/m
mm kg/dm
at 400 Hz at 1 000 Hz
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

Values determined on test specimens without coating. For coated products, the values given in Annex A,

Table A.1 apply.

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.

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.

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).

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.
---------------------- Page: 11 ----------------------
– 10 – IEC 60404-8-8:2017  IEC 2017
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
H = 800 A/m
1,0 T 1,5 T Frequency T
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.

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
where
J is the magnetic polarization;
B is the magnetic flux density;
H is the magnetic field strength;
µ is the magnetic constant.
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.
---------------------- Page: 12 ----------------------
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
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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– 12 – IEC 60404-8-8
...

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