Improvement of Strain Tolerance in RE-123 Coated Conductors by Controlling the Yielding Behavior of Hastelloy C-276 Substrates

Sugano, M.; Osamura, Kōzō; Prusseit, W.; Adachi, Hiroki; Kametani, F.

doi:10.1109/tasc.2007.899393

Cited by 13 publications

(8 citation statements)

References 14 publications

(16 reference statements)

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“…The error bars attached to each data point indicate the variation of stress and strain during each measurement of interplanar spacing because of the relaxation of the stress. For all of the specimens, slight work-hardening was confirmed above the elastic limit of ε a = 0.4%, and this suggests that the Hastelloy C-276 substrate in the coated conductors exhibits continuous yielding [20].…”

Section: In Situ Strain Measurement Of Ybco Film In the Coated Conductormentioning

confidence: 75%

The direct evaluation of the internal strain of biaxially textured YBCO film in a coated conductor using synchrotron radiation

Sugano

Machiya

Osamura³

et al. 2008

Supercond. Sci. Technol.

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The internal strain state of the superconducting film in a coated conductor should be clarified to understand the strain effect on the critical current (Ic). We have developed an in situ strain measurement technique using synchrotron radiation for YBa2Cu3O7−δ (YBCO) coated conductor, and the internal strain of the YBCO film was directly evaluated. YBCO powder obtained from the film in the coated conductor was used as a reference of the zero-strain state. Shifts of the Bragg peaks of the (020) plane of the YBCO film were measured under applied tensile strain, and the internal strain was calculated from the change in the interplanar spacing. The residual strain of the YBCO film in this coated conductor at room temperature (RT) was directly determined to be −0.061%. The fracture strain of the YBCO film was also evaluated from the relationship between the applied strain and the internal strain of YBCO. Surface observation of the coated conductor suggests that fracture initiates in the MgO buffer layer. The irreversible strain (εirr) determined by Ic–strain characteristics at 77 K was compared with the result from in situ strain measurement. The validity of our technique using synchrotron radiation is discussed.

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Section: In Situ Strain Measurement Of Ybco Film In the Coated Conductormentioning

confidence: 75%

The direct evaluation of the internal strain of biaxially textured YBCO film in a coated conductor using synchrotron radiation

Sugano

Machiya

Osamura³

et al. 2008

Supercond. Sci. Technol.

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“…Figure 2 shows the stress-strain curve for the YBCO-coated conductor measured at RT and 77 K. The elastic limit of the composite coated conductor was evaluated as 927 MPa and 1300 MPa at RT and 77 K, respectively. The initial linear region and the following gradual decrease of the slope suggest that the Hastelloy substrate in the composite tape exhibits continuous yielding [6]. To continue the discussion on the fatigue mechanism, the stress states of the Ag and Hastelloy in the coated conductors during the fatigue test should be clarified.…”

Section: Static Stress-strain Curvementioning

confidence: 99%

“…As shown in figure 4, the present coated conductor exhibits continuous yielding. Discontinuous yielding occurs when Hastelloy C-276 substrates after solution treatment are annealed at 963-1073 K [6]. On the other hand, if the Hastelloy is rolled before annealing and a number of dislocations are accumulated, the Hastelloy can show continuous yielding even after annealing [6].…”

Section: C -Strain Behaviormentioning

confidence: 99%

Two different mechanisms of fatigue damage due to cyclic stress loading at 77 K for MOCVD-YBCO-coated conductors

Sugano

Yoshida

Hojo

et al. 2008

Supercond. Sci. Technol.

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Tensile fatigue tests were carried out at 77 K for YBCO-coated conductors fabricated by metal–organic chemical vapor deposition (MOCVD). The S–N relationship, variation of critical current (Ic) during cyclic loading and microscopic fatigue damage were investigated. Fatigue strength at 106 cycles was evaluated to be σmax = 1300 MPa and 890 MPa under the stress ratios of 0.5 and 0.1. Two different mechanisms of fatigue damage, depending on the number of stress cycles to failure, were observed. In one of the fracture mechanisms, fatigue behavior is characterized by overall fracture which occurs at 104–105 cycles. For these specimens, Ic after unloading does not degrade before overall fracture. Although only shallow slip bands were found at the Ag surface, fatigue cracks were found on the Hastelloy C-276 surface of the fractured specimen. These results suggest that overall fracture due to cyclic stress was caused by fatigue of the Hastelloy substrate. In the other fracture mechanism, even though overall fracture did not occur at 106 cycles, a slight decrease of Ic was detected after 105 cycles. No fatigue crack was found on the Hastelloy surface, while deep slip bands corresponding to the initial stage of fatigue crack were observed on the Ag surface. From these results, we concluded that Ic degradation at a high cycle number is attributed to the fatigue of the Ag stabilizing layer.

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“…Out of different processing conditions, MgB 2 grown on Hastelloy tape seems to have a good prospect in the industry due to the Hastelloy's flexibility and its low corrosiveness [8,[13][14]. An enhancement of J c values was observed when SiC buffer layers with varied growth temperatures were added into the MgB 2 tapes; which is actually a positive indication of the effect of SiC buffer layer in MgB 2 tape [12].…”

Section: Introductionmentioning

confidence: 98%

Superconducting properties of SiC-buffered-MgB₂tapes

Putri¹,

Kang²,

Duong³

et al. 2015

Progress in Superconductivity and Cryogenics

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Production of MgB 2 film on metallic Hastelloy with SiC as the buffer layer was achieved by means of hybrid physical-chemical vapor deposition technique, whereas SiC buffer layers with varied thickness of 170 and 250 nm were fabricated inside a pulsed laser deposition chamber. Superconducting transition temperature and critical current density were verified by transport and magnetic measurement, respectively. With SiC buffer layer, the reduced delaminated area at the interface of MgB 2 -Hastelloy and the slightly increased T c of MgB 2 tapes were clearly noticed. It was found that the upper critical field, the irreversibility field and the critical current density were reduced when MgB 2 tapes were buffered with SiC buffer layer. Clarifying the mechanism of SiC buffer layer in MgB 2 tape in affecting the superconducting properties is considerably important for practical applications.

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Improvement of Strain Tolerance in RE-123 Coated Conductors by Controlling the Yielding Behavior of Hastelloy C-276 Substrates

Cited by 13 publications

References 14 publications

The direct evaluation of the internal strain of biaxially textured YBCO film in a coated conductor using synchrotron radiation

The direct evaluation of the internal strain of biaxially textured YBCO film in a coated conductor using synchrotron radiation

Two different mechanisms of fatigue damage due to cyclic stress loading at 77 K for MOCVD-YBCO-coated conductors

Superconducting properties of SiC-buffered-MgB₂tapes

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Improvement of Strain Tolerance in RE-123 Coated Conductors by Controlling the Yielding Behavior of Hastelloy C-276 Substrates

Cited by 13 publications

References 14 publications

The direct evaluation of the internal strain of biaxially textured YBCO film in a coated conductor using synchrotron radiation

The direct evaluation of the internal strain of biaxially textured YBCO film in a coated conductor using synchrotron radiation

Two different mechanisms of fatigue damage due to cyclic stress loading at 77 K for MOCVD-YBCO-coated conductors

Superconducting properties of SiC-buffered-MgB2tapes

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Superconducting properties of SiC-buffered-MgB₂tapes