prEN 10303

• Abstract:

  This document defines the grades of thin non-oriented magnetic steel strip and sheet in nominal thicknesses of 0,10 mm, 0,15 mm, 0,20 mm, 0,25 mm, 0,27 mm, 0,30 mm and 0,35 mm, and of thin grain-oriented magnetic steel strip and sheet in nominal thicknesses of 0,10 mm, 0,15 mm and 0,18 mm. In particular, it gives general requirements, magnetic properties, geometric characteristics and tolerances and technological characteristics, as well as inspection procedure.; This document applies to magnetic steel strip and sheet supplied in the finally annealed condition in coils and intended for the construction of magnetic circuits used at frequencies equal to or higher than 100 Hz.

• Status: Not Published
• Publication Date: 12-Mar-2028
• ICS: 77.140.40 - Steels with special magnetic properties
• ICS: 77.140.50 - Flat steel products and semi-products
• Technical Committee: ECISS/TC 108 - Steel sheet and strip for electrical applications
• Drafting Committee: CEN/TC 459/SC 8/WG 1 - Measurement of the coating properties of non­oriented electrical steel
• Current Stage: 4020 - Submission to enquiry - Enquiry
• Start Date: 18-Jun-2026
• Due Date: 26-Oct-2026
• Completion Date: 18-Jun-2026
• Ref Project: oSIST prEN 10303:2026 - Magnetics materials - Thin magnetic steel strip and sheet for use at medium frequencies

• Revises: EN 10303:2015 - Thin magnetic steel strip and sheet for use at medium frequencies
• Effective Date: 19-Nov-2025

SLOVENSKI STANDARD
01-september-2026
Magnetni materiali - Tanka magnetna jeklena pločevina in trakovi za uporabo pri
srednjih frekvencah
Magnetics materials - Thin magnetic steel strip and sheet for use at medium frequencies
Magnetische Werkstoffe - Dünnes Elektroband und -blech aus Stahl zur Verwendung bei
mittleren Frequenzen
Matériaux magnétiques - Bandes et tôles magnétiques minces en acier pour utilisation à
moyennes fréquences
Ta slovenski standard je istoveten z: prEN 10303
ICS:
77.140.40 Jekla s posebnimi Steels with special magnetic
magnetnimi lastnostmi properties
77.140.50 Ploščati jekleni izdelki in Flat steel products and semi-
polizdelki products
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM
June 2026
ICS 77.140.40; 77.140.50 Will supersede EN 10303:2015
English Version
Magnetics materials - Thin magnetic steel strip and sheet
for use at medium frequencies
Matériaux magnétiques - Bandes et tôles magnétiques Magnetische Werkstoffe - Dünnes Elektroband und -
minces en acier pour utilisation à moyennes blech aus Stahl zur Verwendung bei mittleren
fréquences Frequenzen
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 459/SC 8.
If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations
which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.

This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC
Management Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 10303:2026 E
worldwide for CEN national Members.

Contents Page
European foreword . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 6
4 Classification and designation . 7
4.1 Classification . 7
4.2 Designation . 7
5 Information to be supplied by purchaser . 8
5.1 Mandatory information . 8
5.2 Options . 8
5.3 Example of an order . 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 . 9
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
7.2 Mechanical properties at room temperature for non-oriented products . 12
7.3 Geometric characteristics and tolerances . 13
7.3.1 Thickness of grain-oriented steel products . 13
7.3.2 Thickness of non-oriented steel products . 13
7.3.3 Width . 14
7.3.4 Edge camber . 15
7.3.5 Edge wave (wave factor). 15
7.3.6 Residual curvature . 15
7.3.7 Burr height . 16
7.4 Technological characteristics . 16
7.4.1 Density . 16
7.4.2 Stacking factor . 16
7.4.3 Number of bends . 16
8 Inspection . 16
8.1 General . 16
8.2 Selection of samples . 17
8.3 Preparation of test specimens . 17
8.3.1 Magnetic properties . 17
8.3.2 Mechanical properties . 18
8.3.3 Geometrical characteristics and tolerances . 18
8.3.4 Technological characteristics . 19
8.4 Test methods . 19
8.4.1 General . 19
8.4.2 Magnetic properties . 19
8.4.3 Mechanical properties . 19
8.4.4 Geometrical characteristics and tolerances . 20
8.4.5 Technological characteristics . 20
8.4.6 Retests . 21
9 Marking, labelling and packaging . 21
10 Complaints . 21
Annex A (informative) Minimum stacking factor for non-oriented coated products . 22
Annex B (informative) Maximum specific total loss at 1,0 T and 700 Hz and at 1,5 T and 400 Hz for
non-oriented products . 23
Annex C (informative) Density determination . 24
Annex D (informative) Mechanical properties for non-oriented products . 25
Bibliography . 26

European foreword
This document (prEN 10303:2026) has been prepared by Technical Committee CEN/TC 459/SC 8 “Steel
sheet and strip for electrical applications”, the secretariat of which is held by DIN.
This document is currently submitted to the CEN Enquiry.
This document will supersede EN 10303:2015.
— the normative references and the definitions have been updated;
— the list of options is more detailed (see 5.2);
— “defects” has been replaced by “imperfections”;
— throughout the document technical changes have been made to improve the tolerances supplied;
— 0,05 mm thickness have been removed for both grain oriented and non-oriented grades;
— throughout the document, editorial changes have been made to improve the quality of the text.

1 Scope
This document defines the grades of thin non-oriented magnetic steel strip and sheet in nominal
thicknesses of 0,10 mm, 0,15 mm, 0,20 mm, 0,25 mm, 0,27 mm, 0,30 mm and 0,35 mm, and of thin grain-
oriented magnetic steel strip and sheet in nominal thicknesses of 0,10 mm, 0,15 mm and 0,18 mm. In
particular, it gives general requirements, magnetic properties, geometric characteristics and tolerances
and technological characteristics, as well as inspection procedure.
This document applies to magnetic steel strip and sheet supplied in the finally annealed condition in coils
and intended for the construction of magnetic circuits used at frequencies equal to or higher than 100 Hz.
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.
EN 10021, General technical delivery conditions for steel products
EN 10204, Metallic products — Types of inspection documents
EN 10251:2024, Magnetic materials — Methods of determination of the geometrical characteristics of
electrical steel sheet and strip
EN 10342, Magnetic materials — Classification of surface insulations of electrical steel sheet, strip and
laminations
EN 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 60404-2)
EN IEC 60404-11, Magnetic materials — Part 11: Methods of measurement of the surface insulation
resistance of electrical steel strip and sheet (IEC 60404-11)
EN IEC 60404-12, Magnetic materials — Part 12: Methods of test for the assessment of the thermal
endurance of surface insulation coatings on electrical steel strip and sheet (IEC 60404-12)
EN IEC 60404-13, Magnetic materials — Part 13: Methods of measurement of resistivity, density and
stacking factor of electrical steel strip and sheet (IEC 60404-13)
EN ISO 377, Steel and steel products — Location and preparation of samples and test pieces for mechanical
testing (ISO 377)
EN ISO 6892-1, Metallic materials — Tensile testing — Part 1: Method of test at room temperature
(ISO 6892-1)
EN ISO 7799, Metallic materials — Sheet and strip 3 mm thick or less — Reverse bend test (ISO 7799)
IEC 60050-121, International Electrotechnical Vocabulary — Chapter 121: Electromagnetism
IEC 60050-221, International Electrotechnical Vocabulary — Chapter 221: Magnetic materials and
components
IEC 60404-10, Magnetic materials — Part 10: Methods of measurement of magnetic properties of electrical
steel strip and sheet at medium frequencies
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 terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp/
— IEC Electropedia: available at https://www.electropedia.org/
3.1
edge wave
wave factor
variation of flatness of a length of strip or sheet taking a form of waves at the slit edge of the product after
longitudinal side trimming or slitting of the product; characterised by the wave factor, i.e. by the relation
of the height of the wave to its length
Note 1 to entry: For examples of waves, see Figure 1.
[SOURCE: EN 10251:2024, definition 3.1]

Key
1 flat surface
2 sheet
3 rolling direction
h height of wave (mm)
l length of wave (mm)
Figure 1 — Example of wave
3.2
residual curvature
variations of flatness of a length of unwound strip or a sheet taking a permanent curvature in the direction
of rolling of the product
[SOURCE: EN 10251:2024, definition 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
Note 1 to entry: See Figure 2.
[SOURCE: EN 10251:2024, definition 3.3]

Figure 2 — Verification of the edge camber
3.4
number of bends
number of alternate bends possible before the appearance of the first crack in the base metal visible to
the naked eye indicating the ductility of the material
4 Classification and designation
4.1 Classification
The grades covered by this document are classified according to the value of the maximum specific total
loss, in watts per kilogram, and according to the nominal thickness of the material (0,10 mm, 0,15 mm,
0,20 mm, 0,25 mm, 0,27 mm, 0,30 mm and 0,35 mm for non-oriented steel, respectively 0,10 mm,
0,15 mm and 0,18 mm for grain-oriented steel).
4.2 Designation
For the steel grades covered by this document, the conventional designation of the different grades
comprises the following in the order:
a) the characteristic letters:
1) NO for non-oriented strip and sheet;
2) GO for grain-oriented strip and sheet;
b) one hundred times the nominal thickness of the material, in millimetres;
EXAMPLE NO 20: non-oriented strip in thickness of 0,20 mm.
c) number of the specified value of maximum specific total loss by given frequency, in watts per
kilogram and corresponding to the nominal product thickness, in cases where steel grades with
different values for maximum specific total loss per nominal thickness are stated (see Table 2).
5 Information to be supplied by purchaser
5.1 Mandatory information
For material to adequately comply with the requirements of this document, the purchaser shall include
the following information in his enquiry or order:
a) the quantity required (see 6.2);
b) the type of product (strip or sheet);
c) the number of this document, i.e. EN 10303;
d) the grade designation of the material (see 4.2);
e) the direction of coils, axis horizontal (h) or vertical (v) (see 6.2);
f) the internal diameter of coil (see 6.2);
g) any limitation on the mass of a bundle of sheets or of a coil or limitation of external diameter (see
6.2);
h) any limitation of the mass of the packing unit (6.2);
i) the presence and type of insulation coating (see 6.3);
j) the dimensions of strips or sheets required, including any limitations of the internal and external
diameter of a coil-(see 6.2 and 7.3.3);
k) the inspection procedure required including the nature of the related documents (see 8.1).
5.2 Options
The following options may be agreed at the time of enquiry and order. lf the purchaser does not indicate
his wish to implement one of these options, the products shall be supplied in accordance with the basis
specification of this document (see 6.1).
1) smaller value of the internal diameter (see 6.2);
2) permissibility of welds or interleaves and their optional marking (see 6.2);
3) insulation coating properties (see 6.3);
d
4) density determination (see Table 2, Footnote and Annex C);
5) minus or plus tolerances for nominal width (see Table 4 or Table 5);
6) stacking factor values of non-oriented products supplied with insulation coating (see 7.4.2);
7) specific inspection (see 8.1);
8) type of acceptance unit (see 8.1);
9) higher number of strips for Epstein test (see Table 6);
10) marking of the products (see Clause 9);
11) mechanical properties for non-oriented products (see Table D.1).
5.3 Example of an order
18 t strip with 0,30 mm thickness in accordance with EN 10303, made of steel grade NO 27-15, delivered
in coils with a width of 1 000 mm and a maximum mass of 3 500 kg, vertical coil axis (v), with specific
inspection, inspection report 3.1 in accordance with EN 10204:
18 t – strip – EN 10303 — NO 27-15 – 1000 mm – max. 3500 kg – v – 3.1
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 material is supplied in coils.
The mass of coils and/or the external diameter shall be agreed at the time of enquiry and order.
The mass of the package unit shall be agreed at the time of enquiry and order.
The recommended value for the internal diameter of coils is approximately 508 mm or 610 mm. Smaller
internal diameters can be agreed between the manufacturer and the purchaser at the time of enquiry and
order (see 5.2, option 1).
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 so that they do not collapse under their own weight.
The 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 (see 5.2, option 2). If
necessary, the marking of welds or interleaves may be agreed between the manufacturer and the
purchaser at the time of enquiry and order 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 material.
The edges of parts welded together shall not be so much out of alignment as to affect further processing
of the product.
6.3 Delivery condition
The products are usually supplied either without insulation or with insulation in accordance with
EN 10342. When the product is supplied with insulation, the nature of the insulation, its thickness and
properties, the stacking factor and their verification shall be agreed at the time of enquiry and order
(see 5.2, Option 3) and in accordance with the values stated in Table A.1.
6.4 Surface condition
1)
The surfaces shall be smooth and clean and free from grease and rust. Dispersed imperfections such as
scratches, blisters, cracks, etc. are only permitted if the products are within the tolerances on thickness
and if these imperfections are not detrimental to the correct use of the supplied material.

1) This should not be confused with some coloration of the insulating coating inherent in the manufacturing
process.
For products supplied with insulation coating, the coating shall be sufficiently adherent so that it does
not to become detached during manufacturing operations. During the reverse bend test (see 8.4.4.2), the
coating shall not become detached after a bend of 90°. If the coating becomes detached during the test,
the piece from which the sample of the product from which the test specimen was taken shall be subjected
to a shearing test. By shearing the sample with well sharpened tools, a detachment of large pieces of the
coating shall not be admissible. However, some slight chipping of the coating at the sheared edges shall
be tolerated.
If the product is to be immersed in a fluid or is to be given an additional coating or impregnation, an
agreement initiated by the purchaser should be reached with the supplier to ensure compatibility
between the fluid and the surface insulation coating.
For non-oriented products, CEN/TR 17856 and CEN/TR 18048 describe all the relevant measurement
procedures for coating properties.
6.5 Suitability for cutting
The product shall be suitable for cutting or punching without causing premature wear of the tools. The
product shall be suitable for cutting or punching accurately into the usual shapes when appropriate
cutting or punching tools and technologies are used.
7 Technical requirements
7.1 Magnetic properties
7.1.1 General
The properties defined in 8.1.2 to 8.1.4 are applicable to products in the delivery conditions defined in
7.3. The magnetic properties shall be measured in accordance with EN 60404-2 for power frequencies or
IEC 60404-10 for medium frequencies.
For products supplied with insulation coating, the mass of the coating should be taken into account to
determine the magnetic properties.
7.1.2 Magnetic polarization
The specified minimum values of magnetic polarization at the peak magnetic field strength H of 800 A/m
and at the frequency specified in Table 1 for grain-oriented material shall be as given in Table 1.
The specified minimum values of magnetic polarization at a peak magnetic field strength of H 2 500 A/m,
5 000 A/m and 10 000 A/m and at the frequency specified in Table 2 for non-oriented material shall be
as given in Table 2.
7.1.3 Specific total loss
The specified values of maximum specific total loss shall be as given in Tables 1 and 2. The values in
Tables 1 and 2 reflect the aged conditions (see 9.3.1). 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 thicknesses, the values are specified at 1,0 T for the non-oriented steel and at 1,0 T or
1,5 T for the grain-oriented material and at the frequency specified in Tables 1 and 2.
Annex B gives, fo
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