Cryogenic Temperature Dependence of Mechanical Properties and Strain Dependence of Critical Current of Commercial REBCO Coated Conductors

The effects of variable cryogenic temperature on the mechanical and electromechanical properties are implemented for REBCO coated conductor (CC) tapes. A versatile facility was used to provide the successive cooling environment from room temperature (about 293 K) to 5 K with a cryogenic-type extensometer for the strain measurement of the tested samples. At different cryogenic temperatures, the mechanical parameters were measured during the REBCO CC tapes being stretched. The cryogenic temperature dependence of mechanical behavior, including elastic limit, offset yield strength and equivalent elastic modulus of the REBCO CC tapes with two different substrates were captured at different cryogenic levels. In addition, the tensile strain dependence of the critical current ( I c ) of REBCO CC tapes with two different substrates at variable cryogenic temperatures was investigated, and the relations between I c degradation and mechanical properties were revealed. The experimental results show that all the investigated mechanical parameters exhibit a temperature dependence. A uniaxial strain dependence of I c is found under all the test temperatures, and the irreversible strains are between elastic limit and offset yield strains regardless of temperature for both two kinds of test specimens.