DISTRIBUTION OF STRUCTURE-PHASE STATES ALONG THE RAIL HEAD CROSS-SECTION DURING THEIR LONG-TERM PERFORMANCE

Abstract

Methods of transmission electron microscopy detected the formation of structural-phase states in the head of the 100-meter differentially hardened rails after long-term performance. It is shown that long-term operation is accompanied by the creation of gradients in the structure, phase composition, defective substructure in the rail head, consisting in a regular change in the content of plate pearlite, fractured pearlite, ferrite-carbide mixture, scalar and excess dislocation density. As we approach the surface of the rail fillet, the relative content of the metal volume with the structure of plate pearlite decreases, and with the structure of the destroyed pearlite and ferrite-carbide mixture increases. In a ferrite-carbide mixture, the size of grains and subgrains forming this type of structure varies from 40 to 70 nm; the particle size of the carbide phase located at the grain boundaries and subgrains varies from 8 to 20 nm.