High Temperature superconductors (HTS) are the only way to achieve elds with superconducting magnets higher than the 25 T of Low
Temperature Superconductors (LTS). No-Insulation (NI) REBCO magnets using REBa2Cu3Ox as the superconductor require less copper stabilizer than
insulated magnets and thin (30 m) substrates have now become available. In our recent small coil attack on elds greater than 40 T, we have seen
that overstrain damage can easily occur even at frequently used design strain of 0.4%. Here we present an experimental study of the uniaxial
stress () characteristics of SuperPower and SuNAM coated conductors and also do strain-critical current (Ic()) measurements to nd the onset of
permanent damage to Ic. We found considerable variability in their 77 K mechanical properties. The cold-rolled Hastelloy C-276 substrate of the
SuperPower is much stronger than the cold-rolled 310 stainless steel substrate used by SuNAM, but of more concern is the variability of the
strength of dierent batches of SuNAM tape. Mechanical variability in the dierent SuNAM batches creates a challenge when designing for magnets.
We also examined the eects of strain on critical current performance, nding that the critical current of the SuNAM conductor becomes
irreversible over a wide range of strains from 0.3-0.6%. Suspecting that some annealing of the substrates occurs during REBCO deposition in the
vicinity of 750 C, we performed short heat treatments at 700, 750, and 800 C of samples of the as-delivered substrates used by manufacturers. We
found that there was little change to strength of the Hastelloy used by SuperPower but substantial change to the 310 stainless steel used by
SuNAM. Our results show that any high eld operation at strains of 0.4% or more requires detailed knowledge of the mechanical properties of the
tapes being used, especially for magnets using SuNAM tapes with cold-rolled 310 stainless steel substrates. / A Thesis submitted to the Department of Mechanical Engineering in partial fulfillment of the requirements for
the degree of Master of Science. / Fall Semester 2018. / November 15, 2018. / Includes bibliographical references. / Seungyong Hahn, Professor Directing Thesis; David C. Larbalestier, Committee Member; Lance D. Cooley,
Committee Member.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_661170 |
| Contributors | Radcliff, Kyle (author), Hahn, Seung Yong (professor directing thesis), Larbalestier, D. (committee member), Cooley, L. (committee member), Florida State University (degree granting institution), FAMU-FSU College of Engineering (degree granting college), Department of Mechanical Engineering (degree granting departmentdgg) |
| Publisher | Florida State University |
| Source Sets | Florida State University |
| Language | English, English |
| Detected Language | English |
| Type | Text, text, master thesis |
| Format | 1 online resource (58 pages), computer, application/pdf |
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