The influence of a repeated bending strain at room temperature on the critical current densitiy of bronze route Nb 3 Sn wires was investigated. We found that the critical current I c is significantly increased by applying a repeated bending load (pre-bending treatment) at room temperature. The maximum enhancement of I c was approximately twice at 16 T for CuNb-reinforced Nb 3 Sn wires by a 0.5% prebending strain and the critical current density J c became about 528 A/mm 2 at 4.2 K and 16 T. A comparison of the stress dependent I c values obtained before and after applying prebending treatments for CuNb/Nb 3 Sn wires indicates that not only the stress dependence of I c but also the maximum I c at the axial strain-free state are improved. The improvement of the stress dependent I c is in agreement with the prediction made based on the calculation using the uniaxial stress/strain distribution model. Moreover, the increase in the maximum I c may be related to the release of stress/strain states along the radial direction through prebending treatments.
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Awaji et al. (2003) studied this question.