Damage mechanism of a long-wavelength corrugated rail associated with rolling contact fatigue

Abstract

Corrugation is a common rail damage, which seriously affects the safety and reliability of wheel-rail operation. In this study, the rolling contact fatigue (RCF) damage mechanism of an ex-service small radius rail with long-wavelength corrugation was explored. The results showed that the cracks in the side abrasion area propagated parallel to the rail surface with a very small depth due to the severe wear. While the formation mechanism of cracks in the gauge corner area was the ratcheting of material. The cracks propagated to large length along the plastic deformation flow of microstructure and stopped inside the plastic deformation layer. The cracks in the rail top area propagated first along the plastic deformation flow and then turned at the bottom of the plastic deformation layer into the bulk with the direction which was almost perpendicular to the rail surface. The deflection of cracks was due to the presence of the oxides. The presence of residual austenite in the white etching layer (WEL) and slight plastic deformation area beneath the WEL indicated that the main reason for the formation of WEL was the combination of temperature rise and sustained plastic deformation. It is worth noting that a large number of cracks produced by work hardening made the spalling in the trough severer, leading to the aggravation of rail corrugation.