Scaling-up laser cladding of rails

With rail travel getting more popular more demands are being put on rail infrastructure. The wheel/rail contact is the one of the main parameters that is key to maintaining a high performing network. With increasing demands for higher loads and higher speeds, wear and rolling contact fatigue (RCF) are the main two problems. New maintenance techniques can overcome some problems, but new solutions that reduce the damage are needed. Laser cladding is one of the best methods for improving wear and RCF of rail steels by adding layers of more durable materials to the rail. In this article full-scale tests of clad layers have been carried out at realistic contact conditions to verify outcomes seen in twin-disc testing to see if the results can be scaled to predict field performance of clad layers. Martensitic Stainless Steel (MSS) and Stellite 6 were used for the clad layers and R260 was used as the base material. Un-clad R260 was used as reference material. Results of full-scale tests in terms of wear rates, sub-surface deformation, hardness and roughness evolution were comparable. This showed that the clad layers deposited on actual rail performed very well compared to unclad rail and that the tests run at the small-scale were appropriate for predicting full-scale behaviour.