Speaker
Description
High field pulsed magnets at the NHMFL use high strength conductors up to 90% of its ultimate tensile strength. Therefore it is critical to ensure that the conductor is free of defects for its entire piece length which could be as long as a few hundred meters. It is known that in the wire drawing process, internal crack or so-called ‘chevron crack’ can occur due to unsuitable drawing die schedule, poor lubrication and so on. These cracks occurs infrequently along the wire, so tensile tests of samples cut from ends of a long length conductor often miss the problem. In addition, small inclusions on the wire surface might have impact on its fatigue properties. So it is critically important to inspect these defects using non-destructive testing (NDT) methods.
In this paper, we present results of our NDT inspection of Glidcop AL-60 and Cu-Nb wires using Eddy current testing, ultrasonic testing and x-ray tomography (2D and 3D). The minimum detectable flaw sizes for our conductors are established for each NDT technique. Some chevron cracks are found in some Glidcop conductors by all three NDT techniques. We have developed a long length Eddy current wire inspection capability, the technical details of which will be presented.
Acknowledgement
We would like to thank Mr. Daniel Bone of Delphi Precision Imaging for x-ray tomography, Mr. Chuck Edie of Olympus NDT for eddy current and ultrasonic testing of short samples, and Mr. Justin Deterding and Donald Richardson of the NHMFL for eddy current inspection of long length wire. The NHMFL is supported by NSF through NSF-DMR-1157490 and 1644779, and the State of Florida.
