SIST EN 61788-19:2014

Superconductivity - Part 19: Mechanical properties measurement - Room temperature tensile test of reacted Nb3Sn composite superconductors

This part of IEC61788 covers a test method detailing the tensile test procedures to be carried out on reacted Cu/Nb3Sn composite superconducting wires at room temperature. The object of this test is to measure the modulus of elasticity and to determine the proof strength of the composite due to yielding of the copper and the copper tin components from the stress versus strain curve. Furthermore, the elastic limit, the tensile strength, and the elongation after fracture can be determined by means of the present method, but they are treated as optional quantities because the measured quantities of the elastic limit and the elongation after fracture have been reported to be subject to significant uncertainties according to the international round robin test. The sample covered by this test procedure should have a bare round or rectangular crosssection with an area between 0,15 mm2 and 2,0 mm2 and a copper to non-copper volume ratio of 0,2 to 1,5 and should have no insulation.

Supraleitfähigkeit - Teil 19: Messung der mechanischen Eigenschaften –Zugversuch von reagierten Nb3Sn-Verbundsupraleitern bei Raumtemperatur

Supraconductivité - Partie 19: Mesure des propriétés mécaniques - Essai de traction à température ambiante des supraconducteurs composites de Nb3Sn mis en reaction

La IEC 61788-19:2013 spécifie une méthode d'essai détaillant les modes opératoires d'essai de traction à exécuter à température ambiante sur des fils composites supraconducteurs de Cu/Nb3Sn mis en réaction. L'objectif de cet essai est de mesurer le module d'élasticité et de déterminer la charge d'épreuve du composite due à la déformation du cuivre et des composants en cuivre et en étain sur la courbe de contrainte en fonction de la déformation. De plus, la limite élastique, la résistance à la traction et l'allongement après fracture peuvent être déterminés par le biais de la présente méthode, mais ils sont traités comme des grandeurs facultatives, car l'essai interlaboratoire international a démontré de considérables incertitudes au sujet des valeurs mesurées pour la limite élastique et pour l'allongement après fracture. Il convient que l'échantillon couvert par la présente procédure d'essai ait une section transversale circulaire ou rectangulaire avec une surface comprise entre 0,15 mm2 et 2,0 mm2 et un rapport volumique entre le cuivre et le non-cuivre de 0,2 à 1,5. Il convient également qu'il n'ait pas d'isolation. Mots clé: supraconductivité, propriétés mécaniques

Superprevodnost - 19. del: Merjenje mehanskih lastnosti - Natezni preskus reaktivnih Nb3Sn kompozitnih superprevodnikov pri sobni temperaturi (IEC 61788-19:2013)

General Information

• Status: Published
• Publication Date: 11-Mar-2014
• ICS: 29.050 - Superconductivity and conducting materials
• Technical Committee: I09 - Imaginarni 09
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 27-Feb-2014
• Due Date: 04-May-2014
• Completion Date: 12-Mar-2014
• Ref Project: EN 61788-19:2014 - Superconductivity - Part 19: Mechanical properties measurement - Room temperature tensile test of reacted Nb3Sn composite superconductors

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN 61788-19:2014
01-april-2014
Superprevodnost - 19. del: Merjenje mehanskih lastnosti - Natezni preskus
reaktivnih Nb3Sn kompozitnih superprevodnikov pri sobni temperaturi (IEC 61788-
19:2013)
Superconductivity - Part 19: Mechanical properties measurement - Room temperature
tensile test of reacted Nb3Sn composite superconductors
Supraconductivité - Partie 19: Mesure des propriétés mécaniques - Essai de traction à
température ambiante des supraconducteurs composites de Nb3Sn mis en reaction
Ta slovenski standard je istoveten z: EN 61788-19:2014
ICS:
29.050 Superprevodnost in prevodni Superconductivity and
materiali conducting materials
SIST EN 61788-19:2014 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 61788-19:2014

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SIST EN 61788-19:2014

EUROPEAN STANDARD
EN 61788-19

NORME EUROPÉENNE
February 2014
EUROPÄISCHE NORM

ICS 29.050; 77.040.10


English version


Superconductivity -
Part 19: Mechanical properties measurement -
Room temperature tensile test of reacted Nb Sn composite
3
superconductors
(IEC 61788-19:2013)


Supraconductivité -  Supraleitfähigkeit -
Partie 19: Mesure des propriétés Teil 19: Messung der mechanischen
mécaniques - Eigenschaften - Zugversuch von
Essai de traction à température ambiante reagierten Nb Sn-Verbundsupraleitern bei
3
des supraconducteurs composites de Raumtemperatur
Nb Sn mis en réaction (IEC 61788-19:2013)
3
(CEI 61788-19:2013)





This European Standard was approved by CENELEC on 2013-12-24. 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, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

CEN-CENELEC Management Centre: Avenue Marnix 17, B - 1000 Brussels


© 2014 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 61788-19:2014 E

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SIST EN 61788-19:2014
EN 61788-19:2014 - 2 -

Foreword
The text of document 90/328/FDIS, future edition 1 of IEC 61788-19, prepared by IEC/TC 90
"Superconductivity" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as
EN 61788-19:2014.

The following dates are fixed:
(dop) 2014-09-24
• latest date by which the document has
to be implemented at national level by
publication of an identical national
standard or by endorsement
(dow) 2016-12-24
• latest date by which the national

standards conflicting with the
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 [and/or CEN] shall not be held responsible for identifying any or all such
patent rights.

Endorsement notice
The text of the International Standard IEC 61788-19:2013 was approved by CENELEC as a European
Standard without any modification.

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SIST EN 61788-19:2014
- 3 - EN 61788-19:2014

Annex ZA
(normative)

Normative references to international publications
with their corresponding European publications

The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.

NOTE  When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD
applies.

Publication Year Title EN/HD Year

IEC 60050 series International Electrotechnical Vocabulary - -


ISO 376 - Metallic materials - Calibration of force- EN ISO 376 -
proving instruments used for the verification
of uniaxial testing machines


ISO 6892-1 - Metallic materials - Tensile testing - EN ISO 6892-1 -
Part 1: Method of test at room temperature


ISO 7500-1 - Metallic materials - Verification of static EN ISO 7500-1 -
uniaxial testing machines -
Part 1: Tension/compression testing
machines - Verification and calibration of the
force-measuring system


ISO 9513 - Metallic materials - Calibration of EN ISO 9513 -
extensometer systems used in uniaxial
testing

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SIST EN 61788-19:2014

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SIST EN 61788-19:2014




IEC 61788-19

®


Edition 1.0 2013-11




INTERNATIONAL



STANDARD




NORME



INTERNATIONALE
colour

inside










Superconductivity –

Part 19: Mechanical properties measurement – Room temperature tensile test of

reacted Nb Sn composite superconductors

3



Supraconductivité –

Partie 19: Mesure des propriétés mécaniques – Essai de traction à température


ambiante des supraconducteurs composites de Nb Sn mis en réaction
3













INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE

PRICE CODE
INTERNATIONALE

CODE PRIX X


ICS 29.050; 77.040.10 ISBN 978-2-8322-1183-0



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 61788-19:2014
– 2 – 61788-19 © IEC:2013
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 8
4 Principles . 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 Removing insulation . 11
6.4 Determination of cross-sectional area (S ). 11
0
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 . 12
8.1 Modulus of elasticity (E) . 12
8.2 0,2 % proof strength (R and R ) . 13
p0,2-0 p0,2-U
9 Uncertainty of measurand . 13
10 Test report . 13
10.1 Specimen . 13
10.2 Results . 14
10.3 Test conditions . 14
Annex A (informative) Additional information relating to Clauses 1 to 10 . 16
A.1 Scope . 16
A.2 Extensometer . 16
A.2.1 Double extensometer . 16
A.2.2 Single extensometer . 17
A.3 Optical extensometers . 18
A.4 Requirements of high resolution extensometers . 19
A.5 Tensile stress R and strain A . 20
elasticmax elasticmax
A.6 Functional fitting of stress-strain curve obtained by single extensometer
and 0,2 % proof strength (R ) . 21
p0,2-F
A.7 Removing insulation . 22
A.8 Cross-sectional area determination . 22
A.9 Fixing of the reacted Nb Sn wire to the machine by two gripping
3
techniques . 22
A.10 Tensile strength (R ) . 23
m
A.11 Percentage elongation after fracture (A) . 24
A.12 Relative standard uncertainty . 24
A.13 Determination of modulus of elasticity E . 26
0

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SIST EN 61788-19:2014
61788-19 © IEC:2013 – 3 –
A.14 Assessment on the reliability of the test equipment . 27
A.15 Reference documents . 27
Annex B (informative) Uncertainty considerations . 28
B.1 Overview . 28
B.2 Definitions . 28
B.3 Consideration of the uncertainty concept . 28
B.4 Uncertainty evaluation example for TC 90 standards . 30
B.5 Reference documents of Annex B . 31
Annex C (informative) Specific examples related to mechanical tests . 33
C.1 Overview . 33
C.2 Uncertainty of the modulus of elasticity . 33
C.3 Evaluation of sensitivity coefficients . 34
C.4 Combined standard uncertainties of each variable . 35
C.5 Uncertainty of 0,2 % proof strength R . 38
p0,2
Bibliography . 43

Figure 1 – Stress-strain curve and definition of modulus of elasticity and 0,2 % proof
strengths for Cu/Nb Sn wire . 15
3
Figure A.1 – Light weight ultra small twin type extensometer . 16
Figure A.2 – Low mass averaging double extensometer . 17
Figure A.3 – An example of the extensometer provided with balance weight and
vertical specimen axis . 18
Figure A.4 – Double beam laser extensometer . 19
Figure A.5 – Load versus displacement record of a reacted Nb Sn wire . 20
3
Figure A.6 – Stress-strain curve of a reacted Nb Sn wire . 21
3
Figure A.7 – Two alternatives for the gripping technique. . 23
Figure A.8 – Details of the two alternatives of the wire fixing to the machine . 23
Figure C.1 – Measured stress-strain curve . 33
Figure C.2 – Stress-strain curve . 39

Table A.1 – Standard uncertainty value results achieved on different Nb Sn wires
3
during the international round robin tests . 25
Table A.2 – Results of ANOVA (F-test) for the variations of E . 26
0
Table B.1 – Output signals from two nominally identical extensometers . 29
Table B.2 – Mean values of two output signals . 29
Table B.3 – Experimental standard deviations of two output signals . 29
Table B.4 – Standard uncertainties of two output signals . 30
Table B.5 – Coefficient of Variations of two output signals . 30
Table C.1 – Load cell specifications according to manufacturer’s data sheet. 35
Table C.2 – Uncertainties of displacement measurement . 36
Table C.3 – Uncertainties of wire diameter measurement . 37
Table C.4 – Uncertainties of gauge length measurement . 37
Table C.5 – Calculation of stress at 0 % and at 0,1 % strain using the zero offset
regression line as determined in Figure C.1 (b) . 38
Table C.6 – Linear regression equations computed for the three shifted lines and for
the stress – strain curve in the region where the lines intersect . 40

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SIST EN 61788-19:2014
– 4 – 61788-19 © IEC:2013
Table C.7 – Calculation of strain and stress at the intersections of the three shifted
lines with the stress – strain curve . 40
Table C.8 – Measured stress versus strain data and the computed stress based on a
linear fit to the data in the region of interest . 41

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SIST EN 61788-19:2014
61788-19 © IEC:2013 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

SUPERCONDUCTIVITY –

Part 19: Mechanical properties measurement –
Room temperature tensile test of reacted Nb Sn
3
composite superconductors

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 61788-19 has been prepared by IEC technical committee 90:
Superconductivity.
The text of this standard is based on the following documents:
FDIS Report on voting
90/328/FDIS 90/330/RVD

Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of the IEC 61788 series, published under the general title Superconductivity,
can be found on the IEC website.

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SIST EN 61788-19:2014
– 6 – 61788-19 © IEC:2013
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication 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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SIST EN 61788-19:2014
61788-19 © IEC:2013 – 7 –
INTRODUCTION
The Cu/Nb Sn superconductive composite wires are multifilamentary composite materials.
3
They are manufactured in different ways. The first method is the bronze route, where fine Nb /
Nb alloy filaments are embedded in a bronze matrix, a barrier and a copper stabilizer. The
second is the internal-tin method, where fine multifilaments are composed with copper matrix
including Sn reservoirs, a barrier, and a copper stabilizer. The third is the powder-in-tube
method, where Nb / Nb alloy tubes are filled with Sn rich powders and are embedded in a Cu
stabilizing matrix.
Common to all types of Nb Sn composite wires is that the superconducting A15 phase Nb Sn
3 3
has been formed at final wire dimension by applying one or more heat treatments for several
days with a temperature at the last heat treatment step of around 640 °C or above. This
superconducting phase is very brittle and failure of filaments occurs – accompanied by the
degradation of the superconducting properties.
Commercial composite superconductors have a high current density and a small cross-
sectional area. The major application of the composite superconductors is to build
superconducting magnets. This can be done either by winding the superconductor on a spool
and applying the heat treatment together with the spool afterwards (wind and react) or by heat
treatment of the conductor before winding the magnet (react and wind). While the magnet is
being manufactured, complicated stresses are applied to its windings. Therefore the react and
wind method is the minority compared to the wind and react manufacturing process.
In the case that the mechanical properties should be determined in the unreacted, non-
superconducting stage of the composite, one should also apply this standard or alternatively
IEC 61788-6 (Superconductivity– Part 6: Mechanical properties measurement – Room
temperature tensile test of Cu/Nb-Ti composite superconductors).
While the magnet is being energized, a large electromagnetic force is applied to the
superconducting wires because of their high current density. In the case of the react and wind
manufacturing technique, the winding strain and stress levels are very restricted.
It is therefore a prerequisite to determine the mechanical properties of the superconductive
reacted Nb Sn composite wires of which the windings are manufactured.
3

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SIST EN 61788-19:2014
– 8 – 61788-19 © IEC:2013
SUPERCONDUCTIVITY –

Part 19: Mechanical properties measurement –
Room temperature tensile test of reacted Nb Sn
3
composite superconductors



1 Scope
This part of IEC61788 covers a test method detailing the tensile test procedures to be carried
Sn composite superconducting wires at room temperature.
out on reacted Cu/Nb
3
The object of this test is to measure the modulus of elasticity and to determine the proof
strength of the composite due to yielding of the copper and the copper tin components from
the stress versus strain curve.
Furthermore, the elastic limit, the tensile strength, and the elongation after fracture can be
determined by means of the present method, but they are treated as optional quantities
because the measured quantities of the elastic limit and the elongation after fracture have
been reported to be subject to significant uncertainties according to the international round
robin test.
The sample covered by this test procedure should have a bare round or rectangular cross-
2 2
section with an area between 0,15 mm and 2,0 mm and a copper to non-copper volume
ratio of 0,2 to 1,5 and should have no insulation.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60050 (all parts), International Electrotechnical Vocabulary (available at
)
ISO 376, Metallic materials – Calibration of force-proving instruments used for the verification
of uniaxial testing machines
ISO 6892-1, Metallic materials – Tensile testing – Part 1: Method of test at room temperature
ISO 7500-1, Metallic materials – Verification of static uniaxial testing machines – Part 1:
Tension/compression testing machines – Verification and calibration 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 definitions given in IEC 60050-815 and ISO 6892-1, as
well as the following, apply.

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SIST EN 61788-19:2014
61788-19 © IEC:2013 – 9 –
3.1
tensile stress
R
tensile force divided by the original cross-sectional area at any moment during the test
3.2
strain
A
displacement increment divided by initial gauge length of extensometers at any moment
during the test
3.3
modulus of elasticity
E
gradient of the straight portion of the stress-strain curve in the elastic deformation region
3.4
extensometer gauge length
length of the parallel portion of the test piece used for the measurement of displacement by
means of an extensometer
3.5
distance between grips
L
g
length between grips that hold a test specimen in position before the test is started
3.6
0,2 % proof strength
R
p0,2
stress value where the ductile components yield by 0,2 %.
Note 1 to entry: The designated proof strengths, R and R correspond to point A or point C obtained
p0,2-0 p0,2-U
from unloading slope U between 0,3 % and 0,4 % in Figure 1(a), respectively. This strength is regarded as a
representative 0,2 % proof strength of the composite.
3.7
tensile strength
R
m
tensile stress corresponding to the maximum testing force
3.8
tensile stress at elastic limit

R
elasticmax
tensile force divided by the original cross-sectional area at the transition of elastic to plastic
deformation
3.9
strain at elastic limit
A
elasticmax
strain at the transition of elastic to plastic deformation
Note 1 to entry: The stress R and the corresponding strain A refer to point G in Figure A.6 o0f
elasticmax elasticmax
Annex A.5 and are regarded as the transition point of elastic to plastic deformation.

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SIST EN 61788-19:2014
– 10 – 61788-19 © IEC:2013
4 Principles
The test consists of straining a test piece by tensile force beyond the elastic deformation
regime, in principle for the purpose of determining the modulus of elasticity (E) and the proof
strengths of R
p0,2.
5 Apparatus
5.1 General
The test machine and the extensometers shall conform to ISO 7500-1 and ISO 9513,
respectively. The calibration shall obey ISO 376. The special requirements of this standard
are presented here.
5.2 Testing machine
A tensile machine control system that provides
...