Nondestructive testing of high strength conductors for high field pulsed magnets

TL;DR

This paper presents non-destructive testing methods, including eddy current, ultrasonic, and x-ray radiography, to detect internal and surface flaws in high strength conductors used in high field pulsed magnets, ensuring their reliability.

Contribution

It introduces a comprehensive NDT approach combining multiple techniques for detecting internal cracks and surface inclusions in high strength conductors, with a new capability for long-length wire inspection.

Findings

Chevron cracks detected in some conductors by all NDT methods

Surface inclusions identified by eddy current testing

Established long-length wire inspection capability

Abstract

High field pulsed magnets at the NHMFL use high strength conductor wires up to 90% of their ultimate tensile strength. Therefore it is very important to ensure that the wires are free of flaws. It is known that in the conductors cold drawing process, internal chevron crack could occur due to unsuitable drawing die schedule or inadequate lubrication. These internal cracks occurs infrequently along the wire, so tensile tests of short samples cut from the ends of a long length conductor often miss the problem. In addition, small inclusions on the wire surface can compromise wires fatigue properties. In this paper, we present results of our non-destructive testing (NDT) inspection of Glidcop AL60 wires using eddy current testing (ECT), ultrasonic testing (UT) and x-ray radiography (2D and 3D). Chevron cracks were found in some AL60 conductors by all three NDT techniques. Surface inclusions were found by ECT. We have developed a long length ECT wire inspection capability.