Rail Strengthening Nature in the Course of Long-Term Operation

Using the methods of transmission electron diffraction microscopy and measurement of microhardness, the regularities of the change in the structural-phase states and defective substructure of the surface layers of rails up to 10 mm by fillet after long-term operation (the passed tonnage of 1000 million tons gross) are established. The possible causes of the observed regularities are discussed. A quantitative analysis of the mechanisms of strengthening of rails at different distance from the rolling surface by fillet after long-term operation is carried out. It is shown that strengthening is multifactorial in nature and is due to substructural strengthening caused by the formation of nanoscale fragments; dispersion strengthening by carbide phase particles; strengthening caused by the formation of Cottrell and Suzuki atmospheres on dislocations; internal stress fields, formed inside; and interphase boundaries.