Study on the evolution of material microstructure and constitutive relation during rail corrugation development

Abstract

The difference between the evolution of wear mechanism, microstructure and constitutive relation of the near-surface material at the corrugation peaks and those at the troughs were studied using a twin-disc roller type set-up. The results show that the depths of corrugation increase gradually and tend to slow down at high running cycle numbers. Significant plastic deformation can be observed near the rail surface and subsurface. When the corrugation changes from uniform stage to steady stage, the thickness of the plastic deformation layer increases gradually and slows down and the wear mechanisms changes from adhesion to fatigue. The elastic modulus and hardness of material near rail surface were obtained at different wear stages during the development of corrugation and the material constitutive relations were established with the aid of finite element method. It is found that the yield stress at the peak is higher than the trough surface at the initiation and developing stages of corrugation, however, it is higher at the trough on the steady stage. The yield stresses of surface material was found to have a good correlation with the thickness of plastic deformation.