Fine structure of rails after ultra long-term operation

Using the methods of transmission electron diffraction microscopy the structure phase state and defect substructure in head of differentially quenched 100-meter rails at different depth after ultra long-term operation (passed gross tonnage 1770 mln. tons) are studied. The investigations are carried out along the rail head central axis of symmetry and working fillet rounding radius at the distances 0, 2, 10 mm from the tread surface. Dislocation ferrite substructure is presented by chaotically distributed dislocations and nets. The scalar and excess dislocation density increase as they approach the head rail surface. The values of these parameters on the surface are more than twice the corresponding value at a depth of 10 mm. The value of excess dislocation density is lower than scalar dislocation density which indicates elastic character of crystal lattice curvature-torsion. The quantitative evaluation of mechanisms dislocation strengthening is carried out.