New insights on the influence of hard transformed regions created on R260 rails using lasers on damage behaviour during rolling-sliding contact tests

This research examines the influence of laser-induced hard transformed regions (consisting of white and likely brown etching layers) on the damage behaviour of R260 rail steel under rolling–sliding contact conditions. The laser-based approach was found to produce very consistent transformed regions across different specimens. The research explores how the transformed regions contribute to crack initiation and propagation, particularly at the interface with the substrate material and within the transformed region itself. Crack formation was consistent in terms of location, angle, and length for regions of the same geometry, while systematic variations in crack position and length were observed when comparing regions of different lengths. Localised material deformation, including unique material flow patterns at the trailing edge, was found to play a key role in crack development. The findings provide deeper insight into rail surface degradation mechanisms and have implications for the design, treatment, and maintenance of railway components. The consistency of the layer-based approach and the possibility to efficiently test many hard transformed regions for the first time has allowed generation of repeatable and consistent data sets that can be used with confidence as inputs for rail damage modelling and for providing a benchmark for comparing against other rail grades.