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Lookup NU author(s): Dr Francis Franklin,
Professor Ajay Kapoor
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Rolling contact fatigue (RCF) is currently one of the principal limitations of railway infrastructure productivity. Head checks in particular are prevalent in curves and switches where flange contact at the gauge corner results in increased slip and decreased wheel-rail contact area. These surface-initiated cracks can lead to complete failure of the rail and potentially derailment. The focus of the EU Fifth Framework project InfraStar is on improving the durability and lifetime of the rail along stretches of track with narrow and moderate radius curve, high-traffic volumes and high axle loads by applying a surface coating to the railhead. The main goal of the project is to develop a railhead with an additional surface layer (the InfraStar two-material rail) which prevents RCF and reduces noise emissions in narrow-radius curved rail. Results are presented here from twin-disc laboratory testing and metallurgical analysis of specimens with the two selected new surface materials. The effects of lubrication, applied load and coating thickness were studied. An eddy current probe was used for crack detection. Both materials survived 200,000 cycles of water-lubricated twin-disc testing without crack formation, in contrast to UIC (260 grade) 900A base material which showed severe cracking after only 4000 cycles. Metallurgical investigations show excellent RCF resistance, although one coating developed cracks quickly during water-lubricated testing after 15,000 dry cycles, and bonding of the tested coatings (delamination occurred at the bonding interface of one coating during high-pressure tests).
Author(s): Franklin FJ, Weeda G-J, Kapoor A, Hiensch EJM
Publication type: Article
Publication status: Published
ISSN (print): 0043-1648
ISSN (electronic): 1873-2577
Publisher: Elsevier BV
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