Structure-phase states evolution in rails during a long operation

By methods of scanning and transmission electron microscopy the transformation regularities of structure-phase states, defect substructure, fracture surface of rail surface layer up to 10 mm deep in process of long-term operation (passed tonnage of gross weight 1000 mln tons) were revealed. It has been shown that the surface layer ∼20 μm in thickness has a multiphase, submicro- and nanocrystalline structure and it contains micropores and microcracks. The increased density of bend extinction contours at 2 mm depth from the tread contact surface was noted. The analysis of structure morphological constituents and internal stress fields, created by intra- and interphase boundaries after long operation was carried out. It was shown that the maximum amplitude of stress fields was formed on the interphase boundary the globular cementite particle–matrix. The evaluation of stress fields was done.