SIST EN IEC 61788-25:2019

Superconductivity - Part 25: Mechanical properties measurement - Room Temperature tensile test on REBCO wires (IEC 61788-25:2018)

This part of IEC 61788 specifies the test method and procedures for testing tensile mechanical
properties of REBCO superconductive composite tapes at room temperature. This test is used
to measure the modulus of elasticity and 0,2 % proof strength. The values for elastic limit,
fracture strength and percentage elongation after fracture serve only as a reference. This
document applies to samples having a rectangular cross-section with an area of 0,12 mm2 to
6,0 mm2 (corresponding to the tapes with width of 2,0 mm to 12,0 mm and thickness of 0,06
mm to 0,5 mm).

Supraleitfähigkeit - Teil 25: Messung der mechanischen Eigenschaften - Messung der Zugfestigkeit von REBCO Supraleiterdrähten bei Raumtemperatur (IEC 61788-25:2018)

Supraconductivité - Partie 25: Mesure des propriétés mécaniques - Essai de traction à température ambiante des fils REBCO (IEC 61788-25:2018)

IEC 61788-25:2018 spécifie la méthode et les procédures d’essai relatives aux propriétés mécaniques de traction des bandes composites supraconductrices REBCO à température ambiante. Cet essai est utilisé pour mesurer le module d’élasticité et la charge d’épreuve à 0,2 %. Les valeurs de la limite élastique, de la résistance à la rupture et du pourcentage d’allongement après rupture servent uniquement de référence. Le présent document s'applique aux échantillons ayant une section rectangulaire d’une surface comprise entre 0,12 mm² et 6,0 mm² (correspondant aux bandes de largeur comprise entre 2,0 mm et 12,0 mm et d’épaisseur comprise entre 0,06 mm et 0,5 mm).

Superprevodnost - 25. del: Merjenje mehanskih lastnosti - Natezni preskus pri sobni temperaturi na žicah REBCO (IEC 61788-25:2018)

Ta del standarda IEC 61788 določa preskusno metodo in postopke za preskušanje nateznih mehanskih lastnosti superprevodnih kompozitnih trakov REBCO pri sobni temperaturi. Ta preskus se uporablja za merjenje modula elastičnosti in napetosti tečenja 0,2 %. Vrednosti za mejo elastičnosti, prelomno trdnost in odstotek raztezka po prelomu so zgolj referenčne. Ta dokument se uporablja za vzorce s pravokotnim prerezom s površino od 0,12 mm2 do 6 mm2 (kar ustreza trakom s širino od 2 mm do 12 mm in debelino od 0,06 mm do 0,5 mm).

General Information

• Status: Published
• Publication Date: 25-Nov-2018
• ICS: 29.050 - Superconductivity and conducting materials
• ICS: 29.060.10 - Wires
• ICS: 77.040.10 - Mechanical testing of metals
• Technical Committee: I09 - Imaginarni 09
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 09-Nov-2018
• Due Date: 14-Jan-2019
• Completion Date: 26-Nov-2018
• Ref Project: EN IEC 61788-25:2018 - Superconductivity - Part 25: Mechanical properties measurement - Room temperature tensile test on REBCO wires

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN IEC 61788-25:2019
01-januar-2019
Superprevodnost - 25. del: Merjenje mehanskih lastnosti - Natezni preskus pri
sobni temperaturi na žicah REBCO (IEC 61788-25:2018)
Superconductivity - Part 25: Mechanical properties measurement - Room Temperature
tensile test on REBCO wires (IEC 61788-25:2018)
Supraleitfähigkeit - Teil 25: Messung der mechanischen Eigenschaften - Messung der
Zugfestigkeit von REBCO Supraleiterdrähten bei Raumtemperatur (IEC 61788-25:2018)
Supraconductivité - Partie 25: Mesure des propriétés mécaniques - Essai de traction à
température ambiante des fils REBCO (IEC 61788-25:2018)
Ta slovenski standard je istoveten z: EN IEC 61788-25:2018
ICS:
29.050 Superprevodnost in prevodni Superconductivity and
materiali conducting materials
29.060.10 Žice Wires
77.040.10 Mehansko preskušanje kovin Mechanical testing of metals
SIST EN IEC 61788-25:2019 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN IEC 61788-25:2019

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SIST EN IEC 61788-25:2019


EUROPEAN STANDARD EN IEC 61788-25

NORME EUROPÉENNE

EUROPÄISCHE NORM
November 2018
ICS 29.050; 77.040.10

English Version
Superconductivity - Part 25: Mechanical properties measurement
- Room temperature tensile test on REBCO wires
(IEC 61788-25:2018)
Supraconductivité - Partie 25: Mesure des propriétés Supraleitfähigkeit - Teil 25: Messung der mechanischen
mécaniques - Essai de traction à température ambiante des Eigenschaften - Messung der Zugfestigkeit von REBCO
fils REBCO Supraleiterdrähten bei Raumtemperatur
(IEC 61788-25:2018) (IEC 61788-25:2018)
This European Standard was approved by CENELEC on 2018-10-03. CENELEC 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.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden,
Switzerland, Turkey and the United Kingdom.


European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2018 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
 Ref. No. EN IEC 61788-25:2018 E

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SIST EN IEC 61788-25:2019
EN IEC 61788-25:2018 (E)
European foreword
The text of document 90/404/FDIS, future edition 1 of IEC 61788-25, prepared by IEC/TC 90
"Superconductivity" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as
EN IEC 61788-25:2018.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2019-07-03
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2021-10-03
document have to be withdrawn

Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.

Endorsement notice
The text of the International Standard IEC 61788-25:2018 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards
indicated:
IEC 61788-6:2011 NOTE Harmonized as EN 61788-6:2011 (not modified)
IEC 61788-18:2013 NOTE Harmonized as EN 61788-18:2013 (not modified)
IEC 61788-19:2013 NOTE Harmonized as EN 61788-19:2014 (not modified)
IEC 61788-21:2015 NOTE Harmonized as EN 61788-21:2015 (not modified)
ISO 6892-1 NOTE Harmonized as EN ISO 6892-1


2

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SIST EN IEC 61788-25:2019
EN IEC 61788-25:2018 (E)
Annex ZA
(normative)

Normative references to international publications
with their corresponding European publications
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.
NOTE 1  Where an International Publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
NOTE 2  Up-to-date information on the latest versions of the European Standards listed in this annex is available here:
www.cenelec.eu.

Publication Year Title EN/HD Year
ISO 376 -  Metallic materials - Calibration of force-proving instruments - -
used for the verification of uniaxial testing machines
ISO 7500-1 -  Metallic materials - Calibration and verification of static EN ISO 7500-1 -
uniaxial testing machines Part 1: Tension/compression
testing machines - Calibration and verification of the force-
measuring system
ISO 9513 -  Metallic materials - Calibration of extensometer systems EN ISO 9513 -
used in uniaxial testing

3

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SIST EN IEC 61788-25:2019




IEC 61788-25

®


Edition 1.0 2018-08




INTERNATIONAL



STANDARD




NORME



INTERNATIONALE
colour

inside










Superconductivity –

Part 25: Mechanical properties measurement – Room temperature tensile test on

REBCO wires




Supraconductivité –

Partie 25: Mesure des propriétés mécaniques – Essai de traction à température


ambiante des fils REBCO













INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE


INTERNATIONALE




ICS 29.050; 77.040.10 ISBN 978-2-8322-5988-7




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

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

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SIST EN IEC 61788-25:2019
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CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 Principle . 10
5 Apparatus . 10
5.1 General . 10
5.2 Testing machine . 10
5.3 Extensometer . 10
6 Specimen preparation . 10
6.1 General . 10
6.2 Length of specimen . 10
6.3 Determination of cross-sectional area (S ) . 11
o
7 Testing conditions . 11
7.1 Specimen gripping . 11
7.2 Setting of extensometer . 11
7.3 Testing speed . 11
7.4 Test . 11
8 Calculation of results . 11
8.1 Modulus of elasticity (E) . 11
8.2 0,2 % proof strength (R and R ) . 12
p0,2-0 p0,2-U
9 Uncertainty of measurement . 12
10 Test report . 13
10.1 Specimen . 13
10.2 Results . 13
Annex A (informative) Additional information relating to Clauses 1 to 10 . 14
A.1 General . 14
A.2 Extensometer . 14
A.2.1 Double extensometer . 14
A.2.2 Single extensometer . 16
A.3 Elastic limit . 16
A.4 Gripping force . 17
A.5 Percentage elongation after fracture (A ) . 17
f
A.6 Condition of straining to fracture . 17
A.7 Relative standard uncertainty (RSU) . 17
A.8 Discretion applying this document . 19
A.9 Assessment on the reliability of the test equipment . 19
A.10 Additional information for test report . 19
A.10.1 General . 19
A.10.2 Test result . 19
A.10.3 Test conditions . 19
Annex B (informative) Evaluation of combined standard uncertainty for the modulus of
elasticity . 20
B.1 Model equation . 20
B.2 Estimation of standard uncertainty . 21

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IEC 61788-25:2018 © IEC 2018 – 3 –
B.2.1 Precondition . 21
B.2.2 Stress measurement . 21
B.2.3 Size measurement . 22
B.2.4 Strain measurement . 23
B.2.5 Uncertainties on measurement of gauge length . 24
B.3 Significant experimental factor . 25
B.3.1 Initial strain rate [Osamura et al., 2014] . 25
B.3.2 Thickness measurement [Osamura et al., 2014] . 26
Bibliography . 27

Figure 1 – Typical stress–strain curve and definition of moduli of elasticity and 0,2 %
proof strengths. 9
Figure A.1 – Low-mass Siam twin type extensometer . 14
Figure A.2 – Low-mass double extensometer . 15
Figure A.3 – An example of the extensometer provided with balance weight and vertical
specimen axis . 16
Figure B.1 – Strain rate dependence of the relative standard uncertainty given by

Formula (B.6) . 25
Figure B.2 – Relative standard uncertainty for the thickness measurement as a function
of tape thickness . 26

Table A.1 – Relative standard uncertainty (X ) and coefficient of variance (X )
RSU
for experimental data of E and E . 17
0 U
Table A.2 – Relative standard uncertainty and coefficient of variance for experimental
data of R and R . 18
p0,2-0 p0,2-U
Table A.3 – Value of X for the data of the modulus of elasticity and the 0,2 %

proof strength tested according to this document . 19
Table B.1 – Uncertainties for experimental variables in Formula (B.6) . 24
Table B.2 – Summary of standard uncertainty evaluation, where the initial strain rate and
−4
the thickness were used as 3 × 10 /s and 0,1 mm, respectively . 25

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INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

SUPERCONDUCTIVITY –

Part 25: Mechanical properties measurement –
Room temperature tensile test on REBCO wires

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 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.
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
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence between
any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and 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 61788-25 has been prepared by IEC technical committee 90:
Superconductivity.
The text of this International Standard is based on the following documents:
FDIS Report on voting
90/404/FDIS 90/411/RVD

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 parts in the IEC 61788 series, published under the general title Superconductivity,
can be found on the IEC website.

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SIST EN IEC 61788-25:2019
IEC 61788-25:2018 © IEC 2018 – 5 –
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.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.

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INTRODUCTION
Several types of composite superconductors have now been commercialized. The
rare-earth-based oxide superconductor (SC) with chemical formula REBa Cu O is used for
2 3 7
practical SC wires, where the rare-earth element RE is typically Y, Dy, Gd, Nd, Ho or Sm, or a
combination of two or more among them. This type of practical SC wire is usually called
REBCO coated conductors. A typical architecture consists of a substrate of Ni-Cr-Mo based
alloy, Ni-W alloy or stainless steel, a buffer layer consisting of a plurality of oxides, a SC layer
and a protection layer of Ag. The substrate and buffer layer act as template to facilitate the
well-oriented SC layer. In order to resist the large electromagnetic force, the wires are often
externally reinforced by laminating thin stainless steel or Cu alloy foils. Commercial composite
superconductors have a high current density and a small cross-sectional area. The major
application of composite superconductors is to build electrical power devices and
superconducting magnets. Complex stresses and strains are applied to the composite
superconducting wires when devices are manufactured and energized. In the case of
superconducting magnets, large electromagnetic forces are experienced by the windings due to
the combination of high magnetic fields and high current density. It is therefore indispensable to
determine the mechanical properties of the practical REBCO wires.

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SUPERCONDUCTIVITY –

Part 25: Mechanical properties measurement –
Room temperature tensile test on REBCO wires



1 Scope
This part of IEC 61788 specifies the test method and procedures for testing tensile mechanical
properties of REBCO superconductive composite tapes at room temperature. This test is used
to measure the modulus of elasticity and 0,2 % proof strength. The values for elastic limit,
fracture strength and percentage elongation after fracture serve only as a reference. This
2
document applies to samples having a rectangular cross-section with an area of 0,12 mm to
2
6,0 mm (corresponding to the tapes with width of 2,0 mm to 12,0 mm and thickness of 0,06
mm to 0,5 mm).
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.
ISO 376, Metallic materials – Calibration of force-proving instruments used for the verification of
uniaxial testing machines
ISO 7500-1, Metallic materials – Calibration and verification of static uniaxial testing machines –
Part 1: Tension/compression testing machines – Calibration and verification of the
force-measuring system
ISO 9513, Metallic materials – Calibration of extensometer systems used in uniaxial testing
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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
tensile stress
R
tensile force divided by the original cross-sectional area of the test piece at any moment during
the test
3.2
tensile strain
A
displacement increment divided by initial gauge length of extensometers at any moment during
the tensile test

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3.3
extensometer gauge length
L
G
length of the parallel portion of the test piece used for the measurement of elongation by means
of an extensometer
3.4
distance between grips
L
0
inward distance between grips that hold a test specimen in position before the test is started
3.5
modulus of elasticity
E
slope of the straight portion of the stress–strain curve in the elastic deformation region
SEE: Figure 1
Note 1 to entry: The straight portion of the initial stress–strain curve is very narrow as indicated in Figure 1. To
measure this quantity with a small standard uncertainty, the use of double extensometer systems will be an
appropriate technique. In this sense, the quantity of E should be a representative data for the present text, while E
U 0
should be reported only when the measure is performed by means of double extensometer system.
Note 2 to entry: In the case of composite superconductor, however, it can be determined differently depending upon
the adopted procedures; one from the initial loading curve by the zero offset line expressed as E , the other one
0
given by the slope of line during unloading, expressed as E . The dotted straight lines drawn along the initial loading
U
curve and the unloading one in Figure 1 b) are only a guide to the eye for determining the slope.
IEC

a)

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IEC 61788-25:2018 © IEC 2018 – 9 –

IEC
b)
The red curves are the observed data and the black continuous and black dotted straight lines are additional lines to
indicate how to determine the moduli of elasticity and 0,2 % proof strengths.
Figure 1 – Typical stress–strain curve and definition of moduli of elasticity
and 0,2 % proof strengths
3.6
0,2 % proof strength
R
p0,2
stress value where the superconductive composite wire yields by 0,2 %
SEE: Figure 1
3.7
fracture strength
R
f
tensile stress at the fracture
3.8
tensile stress at elastic limit
R
el
tensile force divided by the original cross-sectional area at the elastic limit corresponding to the
transition from elastic to plastic deformation indicated by point P in Figure 1 b)
3.9
tensile strain at elastic limit
A
el
strain at the elastic limit corresponding to the transition from elastic to plastic deformation
indicated by point P in Figure 1 b)

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4 Principle
The test consists of straining a test piece by a tensile force, generally to fracture, for the
purpose of determining the modulus of elasticity and 0,2 % proof strength described in
Clause 1.
Depending on the employed strain measuring method, however, the quantities determined by
the present test should be limited. When using the conventional single extensometer system,
the determination of E and R is recommended. On the other hand, all E , E , R and
U p0,2-U 0 U p0,2-0
R can be determined by using double extensometer system, because of its capability to
p0,2-U
compensate the bending effects of the specimen and to guarantee a proper determination of
the modulus of elasticity.
Additional information relating to Clauses 1 to 10 is given in Annex A.
5 Apparatus
5.1 General
The test machine and the extensometer shall conform to ISO 7500-1 and ISO 9513,
respectively. The calibration shall obey ISO 376. The special requirement for this document is
presented in 5.2 and 5.3.
5.2 Testing machine
A tensile machine control system that provides a constant cross head speed shall be used.
Grips shall have a structure and strength appropriate for the test specimen and shall be
constructed to provide a firm connection with the tensile machine. The faces of the grips shall
be filed or knurled, or otherwise roughened, so that the test specimen will not slip during testing.
Gripping may be a screw type, or pneumatically or hydraulically actuated.
5.3 Extensometer
The mass of the extensometer shall be 30 g or less, so as not to affect the mechanical
properties of superconductive composite wires. The mass of the extensometers shall be balanced
around the wire to avoid any non-alignment force. The generation of bending moments due to the
non-alignment force shall be prevented (see Clause A.2).
6 Specimen preparation
6.1 General
Bending and/or pre-loading shall be prevented when the specimen is handled manually.
6.2 Length of specimen
The length of the test specimen shall be the sum of the inward distance between grips and the
grip lengths. The minimum specimen length (L ) shall be calculated as,
sm
L = 2× L + L + 2× L (1)
sm g G x
where L is the grip length, L is the gauge length of extensometer. L is the free gap distance
g G x
between grip and extensometer and shall meet the condition,
L ≥ 0,7× L (2)
x G

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