Rolling contact fatigue of white etching layer: Part 1

White etching layer (WEL) is a surface metallurgical feature that is commonly present on rail. An investigation of its behaviour under rolling/sliding conditions has been conducted within the laboratory using twin disc testing. This has focussed on the rolling contact fatigue behaviour of the rail, though the wear of both discs is also discussed. White etching layer has been simulated by spot welding, which creates a patch of martensite by heat treatment, and also by severe plastic deformation of the rail disc. This paper details the crack morphology observed under the microscope while the accompanying paper details the numerical results. The results show that crack morphology is dependent on the plastic deformation of the pearlite below the white etching layer.