Effect of material on spalling properties of railroad wheels

The objective of the present paper is to clarify the effect of material on spalling property, which is one of the typical damage that occur on the railroad wheel. Spalling tests, which consist of flat generation tests and rolling contact fatigue (RCF) tests, were conducted on 120 mm diameter disks made of four kinds of wheel steels. It was found that the maximum flat depth and the white layer thickness measured after the flat generation tests depended on a parameter of “the flat generation energy”. The maximum flat depth is not changed by material, but white layer thickness is changed by the hardenability of the material. According to the results of RCF tests by using TPs with/without flats, spalling property was determined by impact load and RCF property. The impact load which occurred due to flat depended on the shape of flat, however, it did not depend on material. Whereas, RCF property depended on the material. The lowest hardness material had the shortest life at the same Hertzian stress on the RCF test. The life of spalling seems to be determined by RCF property at the Hertzian stress magnified by the impact load.