IEC TR 63114:2018

IEC TR 63114 ®
Edition 1.0 2018-04
TECHNICAL
REPORT
Electrical steel – Reverse bend test method for electrical steel strip and sheet

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IEC TR 63114 ®
Edition 1.0 2018-04
TECHNICAL
REPORT
Electrical steel – Reverse bend test method for electrical steel strip and sheet

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.030 ISBN 978-2-8322-5616-9

– 2 – IEC TR 63114:2018 © IEC 2018
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Symbols and designations . 7
5 Principles . 7
6 Apparatus . 7
7 Test specimen . 8
8 Procedure . 8
9 Expression of results . 10
Annex A (informative) An example of the apparatus used for the reverse bend test . 11
Annex B (informative) Dependence of the number of bends on tensile force applied to
the test specimen. 13
B.1 General . 13
B.2 Test results . 13
B.3 Deformation situation of the specimen after failure . 14
B.4 Conclusions . 15
Bibliography . 16

Figure 1 – Apparatus for the reverse bend test of Mode A and Mode B . 7
Figure 2 – Schematic view of the mandrels for Mode A and Mode B . 8
Figure 3 – Method of counting reverse bends. 9
Figure A.1 – Schematic view of a specially designed apparatus for the reverse bend test . 11
Figure B.1 – Number of bends for different tensile forces with Mode A . 13
Figure B.2 – Number of bends for different tensile forces with Mode B . 14
Figure B.3 – Side views of the specimens after failure with Mode A and Mode B for
different tensile forces . 14

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRICAL STEEL –
REVERSE BEND TEST METHOD FOR
ELECTRICAL STEEL STRIP AND SHEET

FOREWORD
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The main task of IEC technical committees is to prepare International Standards. However, a
technical committee may propose the publication of a technical report when it has collected
data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
IEC TR 63114, which is a technical report, has been prepared by IEC Technical Committee 68:
Magnetic alloys and steels.
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
68/565/DTR 68/579A/RVDTR
Full information on the voting for the approval of this technical report can be found in the
report on voting indicated in the above table.

– 4 – IEC TR 63114:2018 © IEC 2018
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
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.

INTRODUCTION
Before the preparation of this document, the working group discussed the actual situation of
industry concerning the application of reverse bend tests for the evaluation of the ductility of
electrical steel strip and sheet, including non-oriented and grain-oriented materials. The
following points were noted:
– The reverse bend test is widely used in industry for the evaluation of ductility of electrical
steel, and is referenced by the products standards;
– In actual industry practice, the reverse bend test mainly uses as test specimens Epstein
strips of 30 mm in width;
– The product standards of IEC 60404-8-4 [1] , IEC 60404-8-7 [2] and IEC 60404-8-8 [3]
refer to ISO 7799 for the reverse bend test. However, ISO 7799 specified the width of test
specimen to be less than the width of the Epstein strip (30 mm). Therefore, the Epstein
strip does not meet with the requirement of ISO 7799;
– There are two modes for the reverse bend test, Europe generally adopts the method of
reverse bend test according to ISO 7799 (defined as Mode A), alternatively America and
Asia generally adopt that according to ASTM A720 [4] (for non-oriented materials) and
JIS C2550 [5] (defined as Mode B), see also the references [6-7];
NOTE ASTM A721 [8] defined a bend method, which is different from the reverse bend test, to determine the
ductility of grain-oriented materials.
– The apparatus and the requirements for the reverse bend test are slightly different
between Mode A and Mode B, especially on the gap between the specimen and the round
edges of the clamp and the requirement that a tensile force is applied to the test specimen;
This may cause different deformation mechanisms during bending;
– A comparison test between the two modes has been carried out. It was revealed that
number of bends obtained with Mode A and Mode B are different.
The above points indicate the need for a standardization of the reverse bend test method
particular to electrical steel to explain how to use the two modes in industry.
This document describes the general principle and technical details of the reverse bend test
especially for the evaluation of the ductility of electrical steel with respect to the two modes,
Mode A according to ISO 7799 and Mode B according to ASTM A720 and JIS C2550.
Annex A provides information on a specially designed apparatus for the reverse bend test,
which can be used for both modes.
Annex B gives test results on the dependence of the number of bends on the tensile force
applied to the specimen. The results were obtained using the apparatus described in Annex A
in different conditions for Mode A and for Mode B.

___________
Numbers in square brackets refer to the Bibliography.

– 6 – IEC TR 63114:2018 © IEC 2018
ELECTRICAL STEEL –
REVERSE BEND TEST METHOD FOR
ELECTRICAL STEEL STRIP AND SHEET

1 Scope
This Technical Report describes the general principle and technical details of the reverse
bend test method used for evaluating the ductility of electrical steel strip and sheet.
This test method is applicable to Epstein test strip specimens obtained from non-oriented and
grain-oriente
...