Acoustic Assessment of the Internal Stress and Mechanical Properties of Differentially Hardened Rail

Abstract

An acoustic method of determining the longitudinal residual stress in DT-350 differentially hardened rail is described. The measurements are made by means of an electromagnetic–acoustic converter on the basis of the measured difference in the time for two orthogonally polarized shear waves to pass from the head to the base of the rail and back. Rail samples from different melts are tested. The relation of the residual stress to the mechanical characteristics of rail steel (strength, yield point, hardness, and relative elongation) is investigated. The speed of the bow waves and surface waves correlates well with the stress measured by tensometric converters (correlation coefficient 0.96).