Physical metallurgy aspects of rolling contact fatigue of rail steels

The relation between rolling contact fatigue (RCF) strength and contamination of a rail steel (with oxides, size, and shape of carbides etc.), the laminated nature of the initial structure, content of carbon, austenitic grain size, structural heterogeneity, thermomechanical damages (TMD) and the scale factor has been studied. It has been shown, how the alumina fraction, alumina inclusion size, grain size, degree of structural heterogeneity, intensity of thermomechanical damages and the carbide volume fraction exert the most influence on RCF strength. On the basis of these studies a new RCF strength index – shelling index (SI) is presented.