Detection of flaws in used railroad rail by ultrasonic inspection techniques

Abstract The qualitative differences in the responses of new and used rail to ultrasonic inspection have been known for some time. The material presented in this paper quantifies the actual responses obtained from a collection of four rail samples which are typical of rail used on United States' railways. One of the samples was new, and three were used. Reflection and refraction data obtained through the rail head and probe interface indicate that the material properties in the head of used rail are anisotropic. As a result of this anisotropy, ultrasonic rail inspection systems, calibrated according to Sneil's Law in an isotropic rail, may not be fully effective in locating transverse defects (taches ovales) in rail heads.