Surface Damage and Fracture of Subway Rails

摘要

During periodic track inspection of the Vienna subway a new type of surfacerndamage failure was discovered which in some cases led to total failure of the rail. Arnthorough macroscopic investigation revealed that many tiny surface cracks developrnwithin the running area of the rail together with and in competition with contactrollingrninduced sub-surface shear damage. Failures of this kind seem to have comerninto existence with the exchange of softer rails by head-hardened rails fabricated ofrnperlitic steel. It was found that, under certain conditions, the lifetime of these newrnrails was drastically reduced. This paper describes the damage and fracture of thernrails, shows how to calculate the lifetime of the rail and discusses possible measuresrnfor avoiding this kind of unwanted failure