IEC 60404-8-7:2020

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 60404-8-7:2020 is available as IEC 60404-8-7:2020 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.
IEC 60404-8-7:2020 defines the grades of cold-rolled grain-oriented electrical steel strip and sheet in nominal thicknesses of 0,20 mm, 0,23 mm, 0,27 mm, 0,30 mm and 0,35 mm. In particular, it gives general requirements, magnetic properties, geometric characteristics, tolerances and technological characteristics, as well as inspection procedures. This document applies to Goss textured grain-oriented electrical steel strip and sheet supplied in the final annealed condition in coils or sheets, and intended for the construction of magnetic circuits. The grades are grouped into three classes:
- conventional grades;
- high permeability grades;
- magnetic domain refined high permeability grades.
They correspond to Class C22 of IEC 60404-1.
This edition includes the following significant technical changes with respect to the previous edition:
- insertion of a third class of grain-oriented electrical steels for magnetic domain refined high permeability grades;
- introduction of the single sheet tester (SST) method as reference measurement method for this third class of material together with a conversion factor for transposition of the SST measurement results to equivalent Epstein values;
- update of the electrical steel range to take account of the current offers and demands of grades.

General Information

• Status: Published
• Publication Date: 08-Sep-2020
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 29.030 - Magnetic materials
• Technical Committee: TC 68 - Magnetic alloys and steels
• Current Stage: PPUB - Publication issued
• Completion Date: 09-Sep-2020

Standards Content (sample)

IEC 60404-8-7
Edition 5.0 2020-09
INTERNATIONAL
STANDARD
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 60404-8-7:2020-09 (en)
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THIS PUBLICATION IS COPYRIGHT PROTECTED
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IEC 60404-8-7
Edition 5.0 2020-09
INTERNATIONAL
STANDARD
Magnetic materials –
Part 8-7: Specifications for individual materials – Cold-rolled grain-oriented
electrical steel strip and sheet delivered in the fully-processed state
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.030 ISBN 978-2-8322-8779-8

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

® Registered trademark of the International Electrotechnical Commission
---------------------- Page: 3 ----------------------
– 2 – IEC 60404-8-7:2020  IEC 2020
CONTENTS

FOREWORD ........................................................................................................................... 4

INTRODUCTION ..................................................................................................................... 6

1 Scope .............................................................................................................................. 7

2 Normative references ...................................................................................................... 7

3 Terms and definitions ...................................................................................................... 8

4 Classification ................................................................................................................... 8

5 Designation ..................................................................................................................... 9

6 General requirements ...................................................................................................... 9

6.1 Production process ................................................................................................. 9

6.2 Form of supply ........................................................................................................ 9

6.3 Delivery condition ................................................................................................... 9

6.4 Surface condition .................................................................................................. 10

6.5 Suitability for cutting ............................................................................................. 10

7 Technical requirements ................................................................................................. 10

7.1 Magnetic properties .............................................................................................. 10

7.1.1 General ......................................................................................................... 10

7.1.2 Magnetic polarization ..................................................................................... 10

7.1.3 Specific total loss .......................................................................................... 10

7.1.4 Magnetic properties of magnetic domain refined high permeability

grades ........................................................................................................... 10

7.2 Geometric characteristics and tolerances .............................................................. 13

7.2.1 Thickness ...................................................................................................... 13

7.2.2 Width ............................................................................................................. 14

7.2.3 Length ........................................................................................................... 14

7.2.4 Edge wave (wave factor) ............................................................................... 14

7.2.5 Residual curvature ......................................................................................... 15

7.2.6 Edge camber ................................................................................................. 15

7.2.7 Burr height ..................................................................................................... 15

7.3 Technological characteristics ................................................................................ 15

7.3.1 Density .......................................................................................................... 15

7.3.2 Stacking factor............................................................................................... 15

7.3.3 Number of bends ........................................................................................... 15

7.3.4 Deviation from the shearing line (internal stress) ........................................... 15

7.3.5 Insulation coating resistance ......................................................................... 15

8 Inspection and testing .................................................................................................... 16

8.1 General ................................................................................................................. 16

8.2 Selection of samples ............................................................................................. 16

8.3 Preparation of test specimens ............................................................................... 16

8.3.1 Magnetic properties ....................................................................................... 16

8.3.2 Geometrical characteristics and tolerances .................................................... 17

8.3.3 Technological characteristics ......................................................................... 17

8.4 Test methods ........................................................................................................ 18

8.4.1 General ......................................................................................................... 18

8.4.2 Magnetic properties ....................................................................................... 18

8.4.3 Geometrical characteristics and tolerances .................................................... 18

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IEC 60404-8-7:2020  IEC 2020 – 3 –

8.4.4 Technological characteristics ......................................................................... 18

8.5 Retests ................................................................................................................. 19

9 Marking, labelling and packaging ................................................................................... 19

10 Complaints .................................................................................................................... 19

11 Information to be supplied by the purchaser .................................................................. 19

Bibliography .......................................................................................................................... 21

Table 1 – Technological and magnetic properties of the conventional grades of grain-

oriented electrical steel strip and sheet (magnetic properties are measured using the

Epstein method according to IEC 60404-2) ........................................................................... 11

Table 2 – Technological and magnetic properties of the high permeability grades of

grain-oriented electrical steel strip and sheet (magnetic properties are measured using

the Epstein method according to IEC 60404-2) ..................................................................... 12

Table 3 – Technological and magnetic properties of magnetic domain refined high

permeability grades of grain-oriented electrical steel strip and sheet (magnetic

properties are measured using the Single Sheet Test method* according

to IEC 60404-3). ................................................................................................................... 13

Table 4 – Tolerances on nominal thickness ........................................................................... 14

Table 5 – Tolerances on nominal width ................................................................................. 14

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– 4 – IEC 60404-8-7:2020  IEC 2020
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MAGNETIC MATERIALS –
Part 8-7: Specifications for individual materials –
Cold-rolled grain-oriented electrical steel strip and sheet
delivered in the fully-processed state
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,

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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.

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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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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 60404-8-7 has been prepared by IEC technical committee 68:

Magnetic alloys and steels.

This fifth edition cancels and replaces the fourth edition published in 2017. This edition

constitutes a technical revision.

This edition includes the following significant technical changes with respect to the previous

edition:

– insertion of a third class of grain-oriented electrical steels for magnetic domain refined high

permeability grades;

– introduction of the single sheet tester (SST) method as reference measurement method for

this third class of material together with a conversion factor for transposition of the SST

measurement results to equivalent Epstein values;

– update of the electrical steel range to take account of the current offers and demands of

grades.
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IEC 60404-8-7:2020  IEC 2020 – 5 –
The text of this International Standard is based on the following documents:
CDV Report on voting
68/641/CDV 68/657/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, 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.
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– 6 – IEC 60404-8-7:2020  IEC 2020
INTRODUCTION

This revision of International Standard IEC 60404-8-7 has been prepared by the experts of the

Working Group 1 of the IEC technical committee 68: Magnetic alloys and steels.

The insertion of a third class of electrical steels for magnetic domain refined high permeability

grades is the main reason of this revision. Most of the technologies of magnetic domain

refinement result in material that does not withstand the stress relief annealing after cutting

without changing the magnetic properties (i.e. the specific total loss). In the case of this

material, the Epstein method according to IEC 60404-2, requiring the annealing of the Epstein

test specimens, is not suitable. Therefore, the single sheet tester (SST) method specified in

IEC 60404-3 is employed for such non-heatproof magnetic material.

The introduction of the SST as the reference measurement method for these magnetic domain

refined high permeability grades was preceded by intense discussions within IEC/TC 68.

The specific total loss measured by use of the SST specified in IEC 60404-3 tends to be larger

than the value measured by the use of the Epstein frame in accordance with IEC 60404-2. The

magnetic polarization at H = 800 A/m measured by use of the SST tends to be a little lower than

the value measured by the use of the Epstein frame.

The significant difference between Epstein and SST loss results made it necessary to introduce

a conversion factor, F , applied to the SST results. This conversion factor is to create continuity

in the quality characteristics ratio of conventional grain-oriented electrical steel grades and of

high permeability grades (Epstein related loss values) to the magnetic domain refined high

permeability grades (SST related loss values), particularly over the transition zone between

these grades. Otherwise, it could be confusing to the users of this document that the higher

quality materials assessed by the SST method would be listed with seemingly higher values of

the specific total loss, compared with the lower values obtained by the Epstein method on the

lower quality materials.

Considerations of the widely spread grades of domain refined high permeability grain-oriented

electrical steel led to the consented value of F = 0,925 to be applied to the specific total loss

values at 1,7 T measured by the SST method.

The magnetic polarization of magnetic domain refined high permeability grades at H = 800 A/m

is the value taken from the SST measurement without conversion to an equivalent Epstein

value.

Consequently, the magnetic domain refined high permeability grades will be listed in a new

Table 3 as a new class of grain-oriented electrical steel strip and sheet.
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IEC 60404-8-7:2020  IEC 2020 – 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
1 Scope

This part of IEC 60404 defines the grades of cold-rolled grain-oriented electrical steel strip and

sheet in nominal thicknesses of 0,20 mm, 0,23 mm, 0,27 mm, 0,30 mm and 0,35 mm. In

particular, it gives general requirements, magnetic properties, geometric characteristics,

tolerances and technological characteristics, as well as inspection procedures.

This document applies to Goss textured grain-oriented electrical steel strip and sheet supplied

in the final annealed condition in coils or sheets, and intended for the construction of magnetic

circuits.
The grades are grouped into three classes:
– conventional grades;
– high permeability grades;
– magnetic domain refined high permeability grades.
They correspond to Class C22 of IEC 60404-1.
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 60050-221, International Electrotechnical Vocabulary – Chapter 221: Magnetic materials

and components
IEC 60404-1, Magnetic materials – Part 1: Classification

IEC 60404-1-1, Magnetic materials – Part 1-1: Classification – Surface insulations of electrical

steel sheet, strip and laminations

IEC 60404-2, Magnetic materials – Part 2: Methods of measurement of the magnetic properties

of electrical steel strip and sheet by means of an Epstein frame

IEC 60404-3, Magnetic materials – Part 3: Methods of measurement of the magnetic properties

of electrical steel strip and sheet by means of a single sheet tester

IEC 60404-9, Magnetic materials – Part 9: Methods of determination of the geometrical

characteristics of electrical steel strip and sheet

IEC 60404-11, Magnetic materials – Part 11: Method of test for the determination of surface

insulation resistance of magnetic sheet and strip

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
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– 8 – IEC 60404-8-7:2020  IEC 2020

ISO 7799, Metallic materials – Sheet and strip 3 mm thick or less – Reverse bend test

ISO 10474, Steel and steel products – Inspection documents
3 Terms and definitions

For the purposes of this document, the terms and definitions given in IEC 60050-121,

IEC 60050-221 and the following 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
3.1
edge wave
wave factor

variations of flatness of a length of strip or a sheet taking a form of waves at the slit edge of the

product

Note 1 to entry: The edge wave is characterized by the wave factor which is the relation of the height of the wave

to its length, expressed as a percentage.
[SOURCE: IEC 60404-9:2018, 3.1]
3.2
residual curvature

variations of flatness of a length of strip or a sheet taking a permanent curvature in the rolling

direction of the product
[SOURCE: IEC 60404-9:2018, 3.2]
3.3
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
[SOURCE: IEC 60404-9:2018, 3.3]
3.4
deviation from the shearing line
internal stress

greatest distance between corresponding points on the two sheared edges of a length of strip

or a sheet sheared in the middle of the width, in parallel to the rolling direction of the product,

which characterizes the internal stress of the materials
[SOURCE: IEC 60404-9:2018, 3.4]
3.5
number of bends

counts of alternate bending in the reverse bend test prior to the appearance of the first crack in

the base metal of the specimen visible to the naked eye or prior to when sudden failure occurs

by fracture
[SOURCE: IEC TR 63114:2018, 3.2]
4 Classification

The grades covered by this document are classified according to the specified value of

maximum specific total loss at a magnetic polarization of 1,7 T and 50 Hz, in watts per kilogram,

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IEC 60404-8-7:2020  IEC 2020 – 9 –

and according to the nominal thickness of the product (0,20 mm, 0,23 mm, 0,27 mm, 0,30 mm

and 0,35 mm).
5 Designation
The steel name comprises the following in the order given:
1) a letter “M” for electrical steel;

2) one hundred times the specified value of maximum specific total loss at 1,7 T and 50 Hz, in

watts per kilogram;
3) one hundred times the nominal thickness of the product, in millimeters;
4) the characteristic letter
– “S” for conventional grades;
– “P” for high permeability grades;
– “R” for magnetic domain refined high permeability grades;
5) one tenth of the frequency 50 Hz, i.e. 5.

EXAMPLE M120-30S5 for cold-rolled grain-oriented electrical steel strip or sheet of conventional grade with a

maximum specific total loss of 1,20 W/kg at 1,7 T and 50 Hz, and a nominal thickness of 0,30 mm, supplied in the

fully-processed state.
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 or in bundles in the case of sheets.

The mass of the coils or bundles of sheets shall be agreed between the manufacturer and the

purchaser at the time of enquiry and order.

The recommended value for the internal diameter of coils is approximately 508 mm.

Strip shall be of constant width and wound in such a manner that the edges are superimposed

in a regular manner and the side faces of the coil are substantially flat.

Coils shall be sufficiently tightly wound in order that they do not collapse under their own weight.

Strip may exhibit welds or interleaves resulting from the removal of defective zones if agreed

between the manufacturer and the purchaser at the time of enquiry and order. If necessary, the

marking of welds or interleaves may be agreed between the manufacturer and the purchaser at

the time of enquiry and order.

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

Cold-rolled grain-oriented electrical steel products are usually supplied with an insulating

coating on both sides. This coating generally consists of an EC-5-G coating on an EC-2 coating

___________

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

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– 10 – IEC 60404-8-7:2020  IEC 2020

in accordance with IEC 60404-1-1. Other types of coating exist which are used only when

particularly specified.
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 only 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 product.

The insulation coating present on the surface of the product shall be sufficiently adherent so

that it does not become detached during core manufacturing operations or heat treatment under

conditions specified by the manufacturer.

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.
7 Technical requirements
7.1 Magnetic properties
7.1.1 General

The properties defined in 7.1.2 and 7.1.3 shall apply to products in the delivery condition defined

in 6.3 and to the aged condition defined in 8.3.1.1 and 8.3.1.2.

The Epstein strips shall receive a stress relief heat treatment after cutting under conditions

specified by the manufacturer.

The test specimen for the single sheet tester (SST) method shall not be heat treated.

7.1.2 Magnetic polarization

The specified minimum values of peak magnetic polarization at the peak magnetic field strength

of 800 A/m at 50 Hz or 60 Hz shall be as given in Tables 1 to 3.
7.1.3 Specific total loss

The specified values of maximum specific total loss at 50 Hz or 60 Hz shall be as given in Table

1, Table 2 and Table 3.
7.1.4 Magnetic properties of magnetic domain refined high permeability grades

The magnetic properties are measured in accordance with the single sheet tester method

specified in IEC 60404-3.

In Table 3, the specific total loss at 1,7 T and 50 Hz or 60 Hz is treated on the basis of an

equivalent Epstein value obtained by multiplying the SST measurement result at 1,7 T and

50 Hz or at 60 Hz by a conversion factor, F , equal to 0,925.

The conversion factor, F , for non-specific values, e.g. at 1,5 T, may be subject to agreement

between the manufacturer and the purchaser at the time of enquiry and order.

In Table 3, the magnetic polarization at H = 800 A/m is measured in accordance with the SST

method without conversion to an equivalent Epstein value.
___________

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

The specific total loss measured by an SST specified in IEC 60404-3 tends to be higher than the value measured

by an Epstein frame specified in IEC 60404-2. The magnetic polarization at H = 800 A/m measured by an SST

tends to be a little lower than the value measured by an Epstein frame.
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IEC 60404-8-7:2020  IEC 2020 – 11 –
There are technologies of heatproof magnetic domain refinement which res
...