FORMATION OF STRUCTURE-PHASE STATES IN RAILS OF HIGH QUALITY CLASS

Abstract

The quantitative parameters of structure phase states and dislocation substructure in volumetric quenched rails of high quality class were established by methods of transmission electron diffraction microscopy. In accordance with the morphological indication the following structure constituents of rail steel were selected: plate perlite, grains of ferrite-carbide mixture and grains of structure-free ferrite. The grains of perlite are main type of steel structure, their relative content is 0.68; relative content of ferrite-carbide grains is 0.28; the grains of structure free ferrite is rest. The analysis of curvature extinction contours was carried out and it was shown that interfaces of cementite plates of perlite grains; interfaces of perlite and ferrite grains; interfaces of globular particles of carbides – ferrite matrix are the sources of stress concentrators. It was established that interfaces of globular particles of carbides – ferrite matrix are the places with the highest value of stress concentrates. They were regarded as the places of possible crack formation.