Real time optical monitoring to understand railway rail wear and its dependence on steel metallurgy

Rail is central to the low carbon transport networks of the future, and the rail industry is constantly looking for innovations to improve overall system reliability. The whole rail system is reliant on the quality and performance of the rails themselves and on the behaviour of the rail-wheel contact. Network operators such as Network Rail are constantly seeking innovations to reduce the requirement for maintenance, and to reduce the exposure of staff to the risks associated with on-track maintenance activities.

Wear, alongside rolling contact fatigue crack growth, is one of the major factors influencing rail life and system maintenance requirements. While rapid crack growth in rails is a major safety concern wear is usually a more visible and gradual process, and can be beneficial in removing material prior to crack formation. However, wear leads to rail replacement with economic and environmental costs so there are many benefits to better understanding its rate and metallurgical origin. This research will build on the extensive body of wheel-rail contact research carried out at the University of Sheffield, including the recent collaboration with British Steel under the UK Rail Research Innovation Network (UKRRIN). This will offer the opportunity to work with a cohort of sponsored students and options to work closely with British Steel either at our Rotherham R&D facility where joint equipment is located, or at our manufacturing facility in Scunthorpe as suits student and project needs. British Steel staff are closely integrated with the University and there will be regular contact and opportunities to work collaboratively.

This project will make use of the world-class metallurgical facilities at The University of Sheffield, in addition to the suite of rail-specific characterization equipment jointly acquired under UKRRIN. The work will make use of a novel optical monitoring system to examine twin disc tribological testing of rail steels in real time, enabling a perspective of rail wear previously unavailable to researchers. Planned research includes materials characterization via wear flake capture, microscopy (optical and electron), mechanical testing such as hardness and nanoindentation, and implementation of contact and materials modelling.

British Steel will provide access to their production facilities as an R&D tool, enabling the generation of microstructures with varied prior austenite grain size and pearlite colony spacing via controlled heat treatment. The project will seek to correlate variations in wear behaviour and wear flake morphology with microstructure. It will combine this bottom-up microstructural approach with the top-down monitoring and modelling work to generate an improved understanding of wear that can guide future product development and grade selection.