Wear and chattering characteristics of rail materials by ultrasonic nanocrystal surface modification

Abstract

Stick-slip wear, sliding wear, rolling contact wear, fatigue failure and chattering are persistent problems of a wheel-rail interface, especially at corner track. Generally, high strength alloy and heat-treated rail were used at corner track in order to improve the service life and chattering level, but these targets still remain as unceasing challenge subject. Ultrasonic nanocrystal surface modification (UNSM) was applied to rail materials with the aim of replacing with heat treatment and/or improving the service life of rails. In this study, the mechanical and wear properties of the untreated and UNSM-treated specimens which were prepared from normal and heat treated rails. Friction and wear tests were performed to measure the friction coefficient and the amount of wear. Results revealed that the wear performance of the UNSM-treated specimens was improved due to the increased hardness and induced compressive residual stress after UNSM treatment. The wear mechanism of the UNSM-treated specimens was explained with the changes in surface properties of rail materials.