SIST-TP CEN/TR 17856:2022

Measurement of the coating properties of non-oriented electrical steel

This document describes the qualification methods, relevant for the non-oriented electrical steel coatings described in EN 10342. In particular, it describes the testing methods, sample preparation, calibration methods, that are necessary to obtain reliable results that can be considered a reference for quality evaluation.
This document applies only to the coatings of non-oriented electrical steels.

Bestimmung der Beschichtungseigenschaften bei nicht kornorientiertem Elektroband und -blech

Mesures des propriétés de vernis d’aciers électriques à grains non orientés

Le présent document décrit les méthodes de qualification pertinentes pour les revêtements des aciers électriques non orientés décrits dans l’EN 10342. En particulier, il décrit les méthodes d'essai, la préparation des échantillons, les méthodes d’étalonnage, nécessaires afin d’obtenir des résultats fiables qui peuvent être considérés comme une référence lors de l’évaluation de la qualité.
Le présent document ne s’applique qu’aux revêtements des aciers électriques non orientés.

Merjenje premaznih lastnosti neorientirane elektropločevine

V tem tehničnem poročilu so opisane metode kvalifikacije, pomembne za prevleke za neorientirano elektropločevino, opisane v standardu EN 10342. Opisane so zlasti preskusne metode, priprava vzorcev in kalibracijske metode, potrebne za pridobitev zanesljivih rezultatov, ki se lahko štejejo kot referenca pri vrednotenju kakovosti.

General Information

• Status: Published
• Publication Date: 17-Aug-2022
• ICS: 77.140.40 - Steels with special magnetic properties
• ICS: 77.140.50 - Flat steel products and semi-products
• Technical Committee: IFEK - Ferrous metals
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 27-Jul-2022
• Due Date: 01-Oct-2022
• Completion Date: 18-Aug-2022
• Ref Project: CEN/TR 17856:2022 - Measurement of the coating properties of non-oriented electrical steel

Overview

SIST-TP CEN/TR 17856:2022 is a technical report developed by the European Committee for Standardization (CEN) that focuses on the measurement of coating properties of non-oriented electrical steel. This document provides standardized qualification methods, test procedures, sample preparation, and calibration techniques to ensure reliable and consistent evaluation of coatings described in EN 10342. It offers practical guidance aimed at manufacturers, quality control engineers, and researchers involved in the production and application of non-oriented electrical steel coatings.

The emphasis is on establishing reference methods for assessing coating performance, thereby overcoming inconsistencies caused by varied testing practices. The report specifically applies to coatings on non-oriented electrical steel, which is widely used in high-efficiency electrical machines such as transformers and traction motors.

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Key Topics

• Curing
  Ensures coating resistance against solvents through wipe tests (ASTM D5402-19, EN 13523-11). Properly cured coatings resist removal and do not become tacky or soft when rubbed.

• Weldability
  Evaluates coating performance under welding processes, notably TIG and laser welding. The SEP 1210 standard provides a testing framework for TIG weldability, factoring in coating type and thickness.

• Surface Insulation
  Measured according to EN 60404-11 to assess insulation resistance at room temperature and optionally at operating temperatures for electrical machine applications.

• Thermal Endurance
  Conducted per IEC 60404-12, testing coatings for continuous temperature resistance, stress relief annealing, and die casting impact. Evaluates adhesion, compressibility, and insulation after thermal exposure.

• Corrosion Resistance
  Corrosion testing adapted to application-specific conditions, including exposure to elevated temperatures, humidity, refrigerants, and transformer oil. Post-corrosion evaluations include flexibility and insulation resistance.

• Friction Coefficient
  Critical for coil stability and manufacturing handling, measured by methods like ASTM D202 and ASTM D1894. Balances between too slippery and too rough coating surfaces to optimize material processing.

• Compressibility
  Determines stack behavior under load following EN IEC 60404-13 and IEC 60404-12. Important for assessing coating deformation during lamination stacking.

• Adhesion
  Traditional cross-cut tests lack discrimination for these coatings; instead, flexibility testing (EN ISO 1519) and falling-weight impact tests (EN ISO 6272-1) are used to evaluate coating adherence and resistance to deformation.

• Hardness
  Pencil hardness tests (EN 13523-4) and Persoz pendulum hardness methods assess cured coating hardness. Typically, hardness is stable post-curing and not checked routinely in production.

• Thickness Measurement
  Utilizes inductive (EN ISO 2178) or beta backscattering (EN ISO 3543) techniques. Calibration is critical, and method choice depends on required accuracy and thickness range. Consistency is achieved by averaging multiple measurements.

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Applications

SIST-TP CEN/TR 17856:2022 is vital for industries using non-oriented electrical steel in applications where coating quality impacts efficiency, durability, and operational safety:

• Electrical Machines
  Transformers, motors, and generators rely on coated steel laminations to minimize energy loss and withstand mechanical and thermal stresses.

• Automotive Electrification
  Electric traction motors benefit from coatings qualified according to these methods, ensuring high power density and reliability.

• Manufacturing Quality Control
  Standardized coating tests support production consistency, reduce failure rates, and enhance product certification processes.

• Research & Development
  Supports material scientists in designing advanced coatings optimized for mechanical, thermal, and electrical performance.

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Related Standards

• EN 10342 – Defines coating types for non-oriented electrical steel.
• EN 60404 Series – Provides detailed methods for magnetic materials including insulation and thermal endurance tests (EN 60404-11, IEC 60404-12, EN IEC 60404-13).
• ASTM D5402-19 – Covers solvent rub tests for coating cure assessment.
• EN ISO 1519 – Specifies coating flexibility test methods.
• EN ISO 2157 / EN ISO 6272-1 – Procedures for coating adhesion and impact resistance tests.
• EN ISO 2178 and EN ISO 3543 – Methods for non-destructive coating thickness measurement.

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By harmonizing these test methods and calibration approaches, SIST-TP CEN/TR 17856:2022 enhances coating quality evaluation, reproducibility, and comparability for non-oriented electrical steel. This contributes significantly to improved performance and longevity of electrical steel components in critical industrial applications.

Standards Content (Sample)

SLOVENSKI STANDARD
01-september-2022
Merjenje premaznih lastnosti neorientirane elektropločevine
Measurement of the coating properties of non-oriented electrical steel
Bestimmung der Beschichtungseigenschaften bei nicht kornorientiertem Elektroband und
-blech
Mesures des propriétés de vernis d’aciers électriques à grains non orientés
Ta slovenski standard je istoveten z: CEN/TR 17856:2022
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.

CEN/TR 17856
TECHNICAL REPORT
RAPPORT TECHNIQUE
July 2022
TECHNISCHER REPORT
ICS 77.140.40; 77.140.50
English Version
Measurement of the coating properties of non-oriented
electrical steel
Mesures des propriétés de vernis d'aciers électriques à Bestimmung der Beschichtungseigenschaften bei nicht
grains non orientés kornorientiertem Elektroband und -blech

This Technical Report was approved by CEN on 10 July 2022. It has been drawn up by the Technical Committee CEN/TC 459/SC
8.
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.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 17856:2022 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Curing . 5
5 Weldability . 5
6 Surface insulation . 6
7 Thermal endurance . 6
8 Corrosion resistance . 6
9 Friction coefficient . 7
10 Compressibility . 7
11 Adhesion . 7
12 Hardness . 8
13 Flexibility . 8
14 Thickness . 8
15 Break down voltage . 9
Bibliography .10

European foreword
This document (CEN/TR 17856:2022) has been prepared by Technical Committee CEN/TC 459 “ECISS -
European Committee for Iron and Steel Standardization” , the secretariat of which is held by AFNOR.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.

Through its sub-committee CEN/TC 459/SC 8 “Steel sheet and strip for electrical applications” (secretariat: DIN).
Introduction
EN 10342 describes the electrical steel coating types. The electrical steels ordered according to standards
EN 10106, EN 10265, EN 10303, EN 10341 are supplied either with or without such a coating.
The measurements necessary to qualify these coatings are based on different standards, which are not
necessarily dedicated to electrical steel coatings. The lack of a clear description of which evaluation
methods to use, with which calibration methods, sample preparation, etc. brings inconsistency in
obtained measurement results. The purpose of this technical report is to overcome the problem of
differences in coating qualification results, by combining the aspects of Non-Oriented Electrical Steel
coating testing in a clear guideline.
In particular, the non-oriented fully processed electrical steels in high efficiency applications, such as
electric traction, benefit from the clarifications that this technical report brings to the specific coating
challenges, of such high power density machines.
1 Scope
This document describes the qualification methods, relevant for the non-oriented electrical steel coatings
described in EN 10342. In particular, it describes the testing methods, sample preparation, calibration
methods, that are necessary to obtain reliable results that can be considered a reference for quality
evaluation.
This document applies only to the coatings of non-oriented electrical steels.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at https://www.electropedia.org/
— ISO Online browsing platform: available at https://www.iso.org/obp
4 Curing
A properly cured coating cannot be wiped off and its testing is therefore a resistance against solvents
such as ethanol or methyl ethyl ketone, in a wipe test. Other methods use spectrometry. The wipe test,
also called solvent rub test, as described in ASTM D5402-19:2019 Method A (Standard Method) or
EN 13523-11 represents common practice. The ASTM reference uses a manual rubbing, whereas the EN
reference uses a mechanical rubbing system. The outcome of the test can be interpreted as following:
— some discolouration and polishing effect is allowed, localized at the rubbed area;
— the coating is considered properly cured when it is not removed down to the substrate, when it does
not smear out, when it does not become soft, when it does not become tacky.
5 Weldability
The welding performance of a coating depends on its coating type, coating thickness, the substrate and
welding process. TIG weldability is a well-established process. The use of laser welding has become
further established for electrical steels, due to its advantages such as limited Heat Affected Zone.
The SEP 1210 was established for welding testing of the TIG process. It eliminates the steel substrate
effect by testing the coatings using a low Si grade in 0,50 mm gauge. The use of a standardized sample
geometry, a standardized welding test process, allows considering the welding speed and current as a
measure for the coating’s TIG weldability.
For laser welding such standardized test has not been identified yet.
6 Surface insulation
The surface insulation measurement occurs according to EN 60404-11. This document is written within
the series of EN 60404 and reflects well all aspects to be taken into account for electrical steel coatings.
It refers to measurements at room temperature, which are generally communicated.
It can be relevant to verify the insulation level of the coating at the operating temperature of the electrical
machine, in which the insulated steel lamination will be used. ASTM A717-12 allows for heating the
sample using a hot plate, during the Franklin measurement described in EN 60404-11. Clearly such
specific measurement remains within the purpose of an approval procedure and is not performed for
certification purposes.
7 Thermal endurance
The thermal endurance measurement occurs according to IEC 60404-12. This document is written within
the series of EN 60404 and reflects well all aspects to be taken into account for electrical steel coatings.
The application cases to be considered are:
— continuous temperature resistance;
— stress relief annealing;
— refurbishing;
— Al- or Cu- die casting.
The aspects of the coating relevant as thermal endurance measurement are:
— adhesion;
— surface insulation resistance;
— compressibility.
8 Corrosion resistance
Corrosion testing needs to be identified for the relevant application conditions of the non-oriented
electrical steel application. The medium / temperature / time profile of the test is set accordingly. The
application cases to be considered are:
air, at elevated temperatures, according to IEC 60404-12;
— humidity;
— refrigerants;
— transformer oil.
IEC 60404-12 uses the flexibility test and the surface insulation resistance measurement, after the
corrosion treatment, to evaluate the coating.
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