SIST EN ISO 17279-1:2019

SLOVENSKI STANDARD
01-marec-2019
Varjenje - Mikro spajanje visokotemperaturnih superprevodnikov druge generacije
- 1. del: Splošne zahteve za postopek (ISO 17279-1:2018)
Welding - Micro joining of 2nd generation high temperature superconductors - Part 1:
General requirements for the procedure (ISO 17279-1:2018)
Schweißen - Mikrofügen von Hochtemperatursupraleitern der zweiten Generation - Teil
1: Allgemeine Anforderungen an das Verfahren (ISO 17279-1:2018)
Soudage - Micro-assemblage des supraconducteurs à haute température de deuxième
génération - Partie 1: Exigences générales pour la procédure (ISO 17279-1:2018)
Ta slovenski standard je istoveten z: EN ISO 17279-1:2018
ICS:
25.160.10 Varilni postopki in varjenje Welding processes
29.050 Superprevodnost in prevodni Superconductivity and
materiali conducting materials
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 17279-1
EUROPEAN STANDARD
NORME EUROPÉENNE
November 2018
EUROPÄISCHE NORM
ICS 25.160.01
English Version
Welding - Micro joining of 2nd generation high
temperature superconductors - Part 1: General
requirements for the procedure (ISO 17279-1:2018)
Soudage - Micro-assemblage des supraconducteurs à Schweißen - Mikrofügen von
haute température de deuxième génération - Partie 1: Hochtemperatursupraleitern der zweiten Generation -
Exigences générales pour la procédure (ISO 17279- Teil 1: Allgemeine Anforderungen an das Verfahren
1:2018) (ISO 17279-1:2018)
This European Standard was approved by CEN on 30 September 2018.

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. 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 CEN
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 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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey 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
© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 17279-1:2018 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 17279-1:2018) has been prepared by Technical Committee ISO/TC 44 "Welding
and allied processes" in collaboration with Technical Committee CEN/TC 121 “Welding and allied
processes” the secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by May 2019, and conflicting national standards shall be
withdrawn at the latest by May 2019.
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.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 17279-1:2018 has been approved by CEN as EN ISO 17279-1:2018 without any
modification.
INTERNATIONAL ISO
STANDARD 17279-1
First edition
2018-09
Welding — Micro joining of 2nd
generation high temperature
superconductors —
Part 1:
General requirements for the
procedure
Soudage — Micro-assemblage des supraconducteurs à haute
température de 2ème génération —
Partie 1: Exigences générales pour la procédure
Reference number
ISO 17279-1:2018(E)
©
ISO 2018
ISO 17279-1:2018(E)
© ISO 2018
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2018 – All rights reserved

ISO 17279-1:2018(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms . 2
5 Requirements . 2
5.1 Joint design . 2
5.1.1 General. 2
5.1.2 Lap joint . 3
5.1.3 Bridge joint . 3
5.2 Equipment . 4
5.3 Welding procedure qualification . 5
5.4 Micro-joining and oxygenation-annealing process . 5
5.4.1 General. 5
5.4.2 Technical content of a pWPS and WPS . 8
5.5 Qualification based on standard test joint specimen . 9
5.5.1 General. 9
5.5.2 Test specimens. 9
5.5.3 Micro-joining and oxygenation-annealing procedure of test specimens . 9
5.5.4 Testing of test specimens . .13
5.5.5 Re-testing .16
5.5.6 Test record . .16
5.6 Range of qualification .16
5.6.1 General.16
5.6.2 Related to the manufacturer .16
5.6.3 Essential variables .16
5.6.4 Other variables .17
5.7 Micro-joining and oxygenation-annealing procedure specification and procedure
qualification record .17
5.8 Final treatment of production run joints .17
5.9 Acceptance criteria .18
5.10 Identification and traceability .19
6 Third-party check .19
Annex A (informative) Micro-joining and oxygenation-annealing procedure .20
Annex B (informative) Preliminary Welding Procedure Specification (pWPS) .24
Annex C (informative) Procedure qualification for micro-joining and oxygenation
annealing and Welding Procedure Qualification Record (WPQR) .27
Annex D (informative) Welding Procedure Specification (WPS) .33
Annex E (informative) Check list for micro-joining and oxygenation-annealing procedure
qualification .36
Bibliography .39
ISO 17279-1:2018(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso
.org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 44, Welding and allied processes,
Subcommittee SC 10, Quality management in the field of welding.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/members .html.
A list of all parts in the ISO 17279 series can be found on the ISO website.
iv © ISO 2018 – All rights reserved

ISO 17279-1:2018(E)
Introduction
The increasing use of 2nd generation high temperature superconductors (2G HTSs) and invention of
resistance-free joining on 2G HTSs have created the need for this document in order to ensure that
joining is carried out in the most effective way and that appropriate control is exercized over all aspects
of the operation. ISO standards for micro-joining and joint evaluation procedure are accordingly
essential to get the best and uniform quality of 2G HTS joint.
The technique in this document regarding resistance-free micro-joining is patent-registered and was
reported to patent.statements@iso .org using the “Patent Statement and Licensing Declaration Form”.
A superconductor is a material that conducts electricity without resistance and has diamagnetism below
critical temperature, T, critical magnetic field, B , and critical current density, J . Once set in motion,
c c
electrical current flows forever in a closed loop of superconducting material under diamagnetism.
A 2G HTS consists of multi-layers and its total thickness is around between 60 µm and 100 µm with or
without surrounding copper stabilizer. The superconducting layer made from ReBa Cu O -x (ReBCO,
2 3 7
abbreviated term of ReBa Cu O ) is only between 1 µm and 2 µm thick depending on manufacturer’s
2 3 7-x
specifications. Re stands for Rare Earth materials, of which gadolinium, yttrium and samarium are used
for 2nd generation high temperature superconducting materials. Figure 1 shows schematic drawing of
typical multiple layers with surrounded copper stabilizer, and the constituents and thicknesses of each
layer in the 2G HTS. The two layers of No. 1 in Figure 1 does not exist in stabilizer-free 2G HTS.
Key
1 20 µm Cu stabilizer 4 5 buffing layers (total 160 nm)
2 2 µm Ag overlayer 5 50 µm hastelloy substrate
3 between 1 µm and 2 µm ReBCO super-conducting
layer
NOTE Not to scale.
Figure 1 — Typical 2G HTS multi-layers, and the constituents and thicknesses of each layer
Currently soldering, brazing or any filler is applied in superconducting industry as shown in Figure 2,
which shows high electrical resistance at the joint providing fatal flaw in the superconductor.


ISO 17279-1:2018(E)
a)  Lap joint b)  Bridge joint
Key
1 superconducting layer
2 solder
Figure 2 — Soldering to join 2G HTS
However, this document focuses on the direct autogenous joining of between 1 μm and 2 μm-
thick superconducting layers of 2G HTSs as shown in Figure 3 without filler metals and recovery of
superconducting properties by oxygenation annealing process, which shows almost no electrical
resistance at the joint.
a)  Lap joint b)  Bridge joint
Key
1 superconducting layer
Figure 3 — Direct autogenous joining of two superconducting layers of 2G HTSs for
superconducting joint
vi © ISO 2018 – All rights reserved

ISO 17279-1:2018(E)
The International Organization for Standardization (ISO) draws attention to the fact that it is claimed
that compliance with this document may involve the use of patents concerning 2G HTS resistance-
free joining. ISO takes no position concerning the evidence, validity and scope of this patent right.
The holders of these patent rights have assured ISO that they are willing to negotiate licenses under
reasonable and non-discriminatory terms and conditions with applicants throughout the world. In this
respect, the statement of the holders of these patent rights is registered with ISO. Information may be
obtained from:
KJoins, Inc. Dae-A International IP & Law Firm
913C, H-1, KIST Venture Town 3F Hanyang B/D
Korea Institute of Science and Technology 830-71 Yeoksam dong, Gangnam gu
14-1 Hwarang ro, Seongbuk gu SEOUL 135–936
SEOUL 136–791 REP. OF KOREA
REP. OF KOREA
Tel.: +82 2 565 2500
Tel.: +82 2 921 6966
Fax: +82 2 565 2511
Contact: Dr HeeSung ANN
Contact: Patent Attorney Mr. BoHyun KIM
E-mail: andy@kjoins .com
E-mail: bohkim@ipdraju .com
Contact: Dr YoungKun OH
Email: ykoh@kjoins .com
Contact: Dr MyungWhon LEE
E-mail: mwlee@kjoins .com
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights other than those identified above. ISO shall not be held responsible for identifying any or
all such patents.
INTERNATIONAL STANDARD ISO 17279-1:2018(E)
Welding — Micro joining of 2nd generation high
temperature superconductors —
Part 1:
General requirements for the procedure
1 Scope
This document provides concepts, specification and qualification of 2G HTS joining procedure. A
welding procedure specification (WPS) is needed to provide a basis for planning joining operations
and for quality control during joining. Joining is considered as a special process in the terminology of
standards for quality systems. Standards for quality systems usually require that special processes be
carried out in accordance with written procedure specifications. This has resulted in the establishment
of a set of rules for qualification of the joining procedure prior to the release of the WPS to actual
production. This document defines these rules.
This document does not cover soldering, brazing or any fillers, which are currently available in the
industry. It can be applied for joining of all kinds of 2G HTSs.
This document does not apply to 1st Generation Bismuth Strontium Calcium Copper Oxide (1G BSCCO)
type HTS and Low Temperature Superconductor (LTS) Joining.
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 15607:2003, Specification and qualification of welding procedures for metallic materials — General rules
ISO 17279-2, Welding — Micro-joining of 2nd generation high temperature superconductors — Part 2:
Personnel qualification for micro-joining and testing
ISO/TR 25901 (all parts), Welding and related processes — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/TR 25901 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1
high temperature superconductor
HTS
superconducting material with critical temperature higher than liquid nitrogen boiling point
ISO 17279-1:2018(E)
3.2
low temperature superconductor
LTS
superconducting material with critical temperature lower than liquid nitrogen boiling point
3.3
2nd generation high temperature superconductor
2G HTS
superconducting material with critical temperature higher than liquid nitrogen boiling point, made of
rare earth and other elements like barium, copper and their oxides
Note 1 to entry: A first generation high temperature superconductor (1G HTS) is a superconducting material with
critical temperature higher than liquid nitrogen boiling point, made of bismuth strontium calcium copper oxides.
3.4
pressurized partial micro-melting diffusion
partial micro-melting of the two faying surfaces of 1 μm- to 3 μm-thick superconducting layers
and atoms diffusion in partially micro-molten pool and solid state of the superconducting layers by
pressurized force
3.5
oxygenation annealing
process to restore the oxygen stoichiometry in an oxygen-rich environment and to recover
superconducting properties
Note 1 to entry: Structure and superconducting properties of 2G HTS are strongly affected by the oxygen
stoichiometry. Joining of 2G HTS at high temperature induces oxygen out-diffusion causing a phase change from a
superconducting orthorhombic phase to a non-superconducting tetragonal phase.
3.6
pressurized solid-state diffusion
atoms diffusion in solid state of the two faying surfaces of 1 μm- to 3 μm-thick superconducting layers
with pressurized force
3.7
bridge joint
joint with a third 2G HTS piece overlapped as a bridge on top of two 2G HTS pieces
Note 1 to entry: See Figure 3 and Figure 5.
4 Symbols and abbreviated terms
The abbreviatied terms listed in ISO 15607:2003, Table 1, relevant to joining procedure for 2G HTS,
shall apply.
5 Requirements
5.1 Joint design
5.1.1 General
The joint shall be designed in accordance with defined requirements that support the end use of the
product. Documentation shall clearly define the essential information of the joint and any special
requirements, e.g. fracture critical, durability critical, mission critical, or safety critical, that are
imposed over and above the general requirements. Essential process controls shall be defined to
substantiate that all design requirements can be met by the joints that were produced in accordance
with welding procedure specification (WPS) and testing and inspection requirements.
2 © ISO 2018 – All rights reserved

ISO 17279-1:2018(E)
The joint design shall take into account the necessary material property data. There are basically two
types of joint alignments (lap and bridge) and the suitable alignment can be selected depending on
user’s convenience. The two types of joint alignments for joining of 2G HTS are shown in Figure 3.
5.1.2 Lap joint
Figure 4 shows schematic sketch of lap joint design for welding procedure qualification as described
in 5.3. All lengths, l , and l , should be specified in the procedure qualification report (PQR). As joint
0 1
length, l , is increased, effective contact surface areas between two superconducting layers are
increased, probabilities of atoms inter-diffusion between the two layers for the joining are increased,
and accordingly joint strengths (tensile and bending) are increased. The Cu stabilizers, if included,
and Ag overlayers on top of the superconducting layers shall be perfectly removed for direct contact of
two superconducting layers and micro-joining. This process is for not contaminating superconducting
layers during micro-joining.
Key
1 superconducting layer
l 60 mm; length of two parts
l 40 mm; overlap (joint length)
Figure 4 — Lap joint
5.1.3 Bridge joint
Figure 5 illustrates the joint design for welding procedure qualification as described in 5.3. The
distance, l , between two 2G HTS parts in Figure 5 may be ranged from "0" to over 10 cm depending
on joint design. The lengths of l in Figure 5 should be the same. All lengths, l , l , l , and l , should
0 0 1 2 3
be specified in the procedure qualification report (PQR). As joint lengths, l , are increased, effective
contact surface areas between two superconducting layers are increased, probabilities of atoms inter-
diffusion between the two layers for the joining are increased, and accordingly joint strengths (tensile
and bending) and superconductivity are increased. The Cu stabilizers, if included, and Ag overlayers on
top of the superconducting layers shall be perfectly removed for direct contact of two superconducting
layers and joining. This process is to avoid contaminating the superconducting layers during joining.
ISO 17279-1:2018(E)
Key
1 superconducting layer
l 50 mm; length of two parts at bottom
l 40 mm to 50 mm; length of bridge part
l 0 mm to 10 mm; distance between parts to join
l 20 mm; overlap (joint length)
Figure 5 — Bridge joint
5.2 Equipment
The equipment shall be adequate for the application concerned. Joining equipment shall be capable
of producing joints that meet the acceptance criteria specified in 5.9. Joining equipment shall be
maintained in good condition and shall be repaired or adjusted when a joining operator, inspector or
joining coordinator is concerned about the capability of the equipment to operate satisfactorily.
After installation of new or refurbished equipment or developing the new equipment, appropriate tests
shall be performed. Such tests shall verify the equipment functions correctly.
Reproducibility tests shall be performed to demonstrate that the joining equipment can repeatedly
produce joints that meet the acceptance levels in 5.9. The reproducibility test shall be performed in
accordance with a WPS that is used in production for that machine. A minimum of three test joins shall be
made and found satisfactory. Reproducibility tests shall be carried out when any of the following occurs:
— critical component(s) of the equipment is (are) damaged, repaired, or replaced;
— equipment is dislodged or moved in a manner for which it was not designed;
— stationary equipment is moved from one location to another.
The manufacturer shall have a documented plan for equipment maintenance. The plan shall ensure that
maintenance checks are performed on the equipment that controls variables listed in the relevant WPS.
The maintenance plan may be limited to those items that are essential for producing joints that meet
the quality requirements of this document.
The joining tools, if any, that are used in production shall be permanently marked for identification
prior to use. Before joining, the joining tools, if any, shall be clean and sufficiently free of contaminants
(e.g. oil, grease or dirt) that can have a detrimental effect on joint quality. The correct tool geometry is
critical for producing a quality joint. Because the joining tool wears with use, it shall be inspected for
wear at appropriate intervals and in accordance with a written procedure. Before joining, parts and
pieces that contact the joining part shall be clean and sufficiently free of contaminants (e.g. oil, grease,
and dirt) that can have a detrimental effect on the joint.
4 © ISO 2018 – All rights reserved

ISO 17279-1:2018(E)
Defective equipment shall not be used.
NOTE Joining machine and oxygenation annealing machine are rarely commercially available. It is
the responsibility of each company or organization performing joining to develop the machines, if suitable
commercial machines are not available.
5.3 Welding procedure qualification
The manufacturer shall be fully responsible for the specification and performance of micro-joining and
oxygenation-annealing for recovery of superconductivity which is determined by the manufacturer.
A record of the micro-joining and oxygenation-annealing shall be made before, during and after the
process.
The following information shall be specified for each joint in WPS:
a) supplier’s product specification of 2G HTS;
b) superconducting layer material specification;
c) pre-joint surface preparation, including complete removal of Cu stabilizer if included and Ag
overlayer;
d) joint type (lap, bridge or other joint type if other than lap or bridge);
e) specimen dimensions including joint length (l , l , l , l of Figure 4 or Figure 5);
0 1 2 3
f) final joint finishing and configuration (any reinforcement for increasing joint strength);
g) joint dimensions; the dimensions of the joint on the welding procedure specification (WPS) shall be
the final dimensions.
A form of WPS is shown in Annex D.
5.4 Micro-joining and oxygenation-annealing process
5.4.1 General
The requirements for the specification of micro-joining and oxygenation-annealing process for 2G HTS
are specified. Qualification of micro-joining and oxygenation-annealing procedures shall be performed
prior to production joining. The manufacturer shall prepare a welding procedure qualification
report (WPQR) and a welding procedure specification (WPS) and shall ensure that it is applicable
for production using experience from previous production jobs and the general knowledge of joining
technology.
The superconducting layer is made from ReBCO (ReBa Cu O ) in which the molar ratio of Re: Ba: Cu
2 3 7-x
is 1:2:3 and the mole fraction (7-x) of oxygen (O), is typically in the range of 6,4 to 7. In oxygen partial
pressure of around 21,5 kPa in ambient air, a superconducting joint is rarely obtained without melting
the Ag overlayer that protects the superconducting layer because the melting point of ReBCO is higher
than that of Ag. However, a successful superconducting joint can be obtained without deformation
of the ReBCO layer by reducing the oxygen partial pressure, which helps reduce the melting point of
ReBCO. Thus, joining in vacuum condition is required. On the other hand, joining under a vacuum,
which is controlled by the out-diffusion of oxygen, can degrade the superconducting properties. The
structure and superconducting properties of ReBCO are strongly affected by the oxygen stoichiometry,
hence oxygen deficiencies cause a phase change from a superconducting orthorhombic phase to a non-
superconducting tetragonal phase. This phase transition is dependent on the temperature and oxygen
partial pressure. Moreover, the phase transition in an atmosphere containing oxygen is reversible
with changes in temperature. However, it is irreversible in the vacuum state resulting in a tetragonal
phase that remains stable after heat-treatment at high temperatures. Therefore, it is important to
develop oxygenation annealing at elevated temperatures around just under transition temperature
ISO 17279-1:2018(E)
of superconducting orthorhombic phase to a non-superconducting tetragonal phase in an oxygen rich
environment, to restore the oxygen stoichiometry and hence superconducting properties at the joint.
Figures 6 and 7 illustrate micro-joining process and oxygenation-annealing process cycles, respectively.
Micro-joining takes place in direct contact of two superconducting layers with extremely short period
of time. However, oxygenation-annealing takes place for hours or days depending on the furnace
(chamber) capacity, oxygen environment, purity and concentration, joint types and quality. Micro-
joining and oxygenation-annealing may be performed in separate equipment. Separate operation of
oxygenation-annealing has advantages to anneal many specimens in one time depending on chamber
size. Figure 8 shows micro-joining and oxygenation-annealing processes in the same chamber and with
continuous operation.
Key
1 application of heat and pressure on lapped pieces 4 fast heating
2 oxygen out-diffusion from superconducting layer 5 fast-moderate cooling
3 peel-off stabilizers and/or overlayers on top of the
superconducting layer and lapped
NOTE Heat and pressure under vacuum during joining.
Figure 6 — Cycle of micro-joining process in joining chamber
6 © ISO 2018 – All rights reserved

ISO 17279-1:2018(E)
Key
1 oxygen in-diffusion into the superconducting layer 3 oxygenation annealing
during oxygenation annealing 4 slow cooling
2 moderate heating
Figure 7 — Cycle of oxygenation-annealing process under pressurized oxygen environment in
oxygenation-annealing chamber
Key
1 application of heat and pressure on lapped pieces 5 fast heating
2 oxygen out-diffusion from superconducting layer 6 fast-moderate cooling
3 peel-off stabilizers and/or overlayers on top of the 7 oxygenation annealing
superconducting layer and lapped 8 slow cooling
4 oxygen in-diffusion into the superconducting layer
during oxygenation annealing
Figure 8 — Cycle of micro-joining and oxygenation-annealing processes in the same chamber
and with continuous operation
A preliminary welding procedure specification (pWPS) shall be used as the basis for the
establishment of a welding procedure qualification test (WPQT) and a welding procedure
ISO 17279-1:2018(E)
qualification record (WPQR). For testing the pWPS, see the test methods given in ISO 17279-3,
Under preparation.
Examples of a micro-joining and oxygenation-annealing procedure, pWPS form, WPQR and WPS are
shown in Annex A, B, C and D, respectively.
5.4.2 Technical content of a pWPS and WPS
The following information, as a minimum, shall be included in a pWPS and WPS:
a) manufacturer’s information: identification of the manufacturer, the pWPS and WPS;
b) 2G HTS superconducting material type (YBCO, GdBCO, SmBCO, etc);
c) 2G HTS parent material dimensions:
1) total thickness of the 2G HTS members;
2) thickness of the superconducting layer comprising the joint;
3) width of 2G HTS members;
d) equipment identification: model, serial number, manufacturer;
e) joint design: sketch of the joint design and dimensions and configuration of the joint;
f) joint preparation and cleaning methods:
1) Cu stabilizer and/or Ag overlayer removal;
2) materials (chemical etchants, etc) to remove Cu stabilizer and/or Ag overlayer;
3) any specific;
g) joining details:
1) chamber vacuum level, heat treatment cycle sketch and heating rate to peak temperature;
2) pressure applied to the specimen, peak temperature, and dwell time at peak temperature;
3) cooling rate from peak temperature to room temperature;
4) details of any changes and/or any specifics.
h) oxygenation annealing details:
1) heat treatment cycle sketch, oxygen flow rate, chamber internal pressure;
2) heating rate, peak temperature, and dwell time at oxygenation-annealing temperature;
3) cooling rate from oxygenation-annealing temperature to room temperature;
4) designation (if any), manufacturer, name and purity of oxygen gas;
5) details of any changes and or any specifics;
i) joint reinforcement details: methods, materials and thickness, if measured.
8 © ISO 2018 – All rights reserved

ISO 17279-1:2018(E)
5.5 Qualification based on standard test joint specimen
5.5.1 General
The preparation and micro-joining of test specimens should be in accordance with 5.4.2. Fulfilment
of the requirements of ISO 17279-2 can serve to qualify the personnel performing micro-joining and
oxygenation annealing, and testing the standard test joint specimens.
5.5.2 Test specimens
The length and number of test specimens shall be sufficient to allow all required tests to be performed.
Specimens shall have dimensions illustrated in Figure 4 or Figure 5, and at least 3 test specimens shall
be required for the test, respectively.
Perfect removal of Cu stabilizer and or Ag overlayer is critically important not to contaminate the
superconducting layers during micro-joining. Elimination procedure of these materials shall be
established and Cu stabilizer and or Ag overlayer shall be completely removed by the established
procedure before micro-joining. The 2G ReBCO HTS virgin material and faying surfaces shall be
sufficiently free of surface oxides, protective finishes, adhesives, oils, grease, dirt, and any other
contaminants that can have a detrimental effect on joint quality.
The specimen identifications shall be marked on the test specimen before the test.
5.5.3 Micro-joining and oxygenation-annealing procedure of test specimens
5.5.3.1 General
The procedures described in this document are examples and recommended procedures.
Manufacturer(s) or service operator(s) shall establish the procedures depending on design and
operation manual of equipment.
The test specimens shall be micro-joined and oxygenation-annealed by welding personnel qualified
according to ISO 17279-2 and the WPS. Micro-joining and oxygenation-annealing of the test specimens
shall be witnessed by an examiner or other designated personnel. The recommended procedures for
micro-joining and oxygenation-annealing of the test specimens are specified in 5.4, 5.5.3.2 and 5.5.3.3,
respectively. Annex A shows the procedure check lists.
5.5.3.2 Micro-joining procedure
a) Exposed two superconducting layers are faced each other as shown in Figure 4 and Figure 5.
b) Align the a) specimen on the holder of joining chamber.
c) Set the chamber vacuum level, time to reach the peak temperature (heating rate), peak temperature
(maximum joining temperature), pressure to pressurize the b) holder, and dwell time at the peak
temperature (joining time).
d) Micro-joining is started by pressurizing the holder (the area to be joined) with pre-set pressure
when pre-set peak temperature is reached within pre-set time under pre-set vacuum level.
— Heating rate should be as high as possible to protect oxygen out-diffusion from the
superconducting layers of 2G HTSs.
— Peak temperature (maximum joining temperature) should be as low as possible to protect
oxygen out-diffusion from the superconducting layers of 2G HTSs and to avoid formation of
Re BaCuO , BaCuO , and CuO which provide negative effect on superconductivity through the
2 5 2
chemical reaction of ReBa Cu O →1/2 [Re BaCuO + (3BaCuO + 2CuO) + O ].
2 3 7-x 2 5 2 2
e) Micro-joining is finished when pre-set dwell time at the peak temperature is reached. Holder
pressure is back to "0".
ISO 17279-1:2018(E)
f) Supply oxygen so that the vacuum chamber reaches to the atmospheric pressure, and continue
to supply oxygen to cool down the chamber and joined superconductor to room temperature.
Moderate-fast cooling rate is necessary to stop the oxygen out-diffusion.
g) Pick-up the joined specimen and move it to the oxygenation-annealing chamber.
NOTE 1 Heating rate and cooling rate are automatically determined once temperature and time are set, if the
equipment is designed as automatic control.
NOTE 2 Controllers and gauges in the joining chamber can be as follows for example, depending on joining
chamber design:
— vcuum controller and gauge, time controller and gauge, temperature controller and gauge;
— current meter, voltage meter and pressure controller and gauge;
1) 2)
— PID controller or any other controller and TPR or any other regulator.
5.5.3.3 Oxygenation-annealing procedure
a) Align the joined 2G HTS obtained through 5.5.3.2 to the oxygenation-annealing chamber as
much as possible depending on chamber design. Set the time to reach the oxygenation-annealing
temperature from room temperature (heating rate), oxygenation-annealing temperature,
oxygen flow rate in the oxygen tank, and dwell time at the oxygenation-annealing temperature
(oxygenation-annealing time), time to cool down to room temperature.
b) Heat the superconductor from room temperature to oxygenation-annealing temperature with a
pre-determined moderate heating rate.
c) Anneal at predetermined temperature with oxygen supply. Hours or days of oxygenation-annealing
are necessary depending on the furnace capacity, oxygen environment, purity and concentration,
joint types, etc.
d) Supply uniform oxygen flow into the chamber and release the oxygen uniformly to the atmosphere
during entire oxygenation-annealing. Micro oxygen gas release knob is installed in the chamber
to control the oxygen release. Control the micro oxygen gas release knob by regulating the oxygen
supplying pressure and chamber internal pressure.
e) Check the chamber internal pressure all the time during entire oxygenation-annealing. The
chamber internal pressure is the difference between oxygen supplying pressure and oxygen release
pressure.
f) Oxygenation annealing is finished at the pre-determined time set.
g) Cool down to room temperature at predetermined cooling ra
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