Investigation into the wear evolution and fatigue crack propagation behaviour of rails subjected to laminar plasma discrete quenching and tempering treatment

Abstract

Tempering treatment can improve the fatigue resistance while maintaining the wear resistance of laminar plasma discrete quenching (LPDQ) rails, but the fatigue crack initiation and propagation forms of LPDQ rails and tempered rails (TLPDQ) are not clear. In this study, twin-disc tests are performed on LPDQ and TLPDQ rails to obtain the wear and fatigue damage evolution of wheels and rails, and discuss the crack propagation mechanism. The results show that fatigue cracks in LPDQ rails initiate at the quenching zone edge and tend to propagate along the boundary after expanding to the quenching zone/substrate boundary in the depth direction. Whereas TLPDQ rail cracks tend to penetrate the boundary and propagate towards the substrate interior after expanding to the boundary.