Competition between wear and rolling contact fatigue at the wheel-rail interfaces some experimental evidence on rail steel

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Competition between wear and rolling contact fatigue at the wheel-rail interfaces some experimental evidence on rail steel

Donzella, G. / Mazzu, A. / Petrogalli, C.

Recent studies of the rail-wheel interface have shown that wear and RCF (rolling contact fatigue) are competitive phenomena. Wear, by removing the material from the contact surface, tends to limit the propagation of cracks formed by cyclic contact stresses. Several parameters influence these phenomena. This article studies the effects of various working conditions on the surface damage of railway steels. The competition between wear and RCF is particularly strong in dry rolling-sliding contacts, in which the damage severity of our test cases can be adequately predicted using the shakedown map. In wet contacts, RCF is prevalent. Cracks rapidly propagate into the subsurface layer in response to hydraulic pressure penetration and then branch towards the surface causing severe damage in the way of macroscopic pitting. The severity of this phenomenon depends strongly on the applied load and cannot be inhibited by wear due to the low friction. On the basis of these results, a general procedure is proposed to the structural integrity of rails.