Deformation-Induced Transformation of the Lamellar Pearlite Structure in Rail Steel during Tension

Abstract—The methods of modern physical materials science are used to study the defective substructure of lamellar pearlite and the properties of rail steel subjected to fracture under uniaxial tension. The ultimate tensile strength is found to be 1247–1335 MPa, and the relative strain to failure is 0.22–0.26. Three zones of fracture surface, i.e., fibrous, radial, and shear zones, are revealed. The deformation of rail steel is accompanied by the destruction of cementite plates in pearlite colonies and the repeated precipitation of tertiary cementite particles ≈8.3 nm in size in the volume of ferrite plates. The scalar dislocation density in ferrite increases from 3.2 × 1010 cm–2 in the initial state to 7.9 × 1010 cm–2 after fracture. Ferrite and cementite plates are fragmented. The average cementite fragment size is ≈9.3 nm.