STRENGTHENING MECHANISMS OF RAIL STEEL UNDER COMPRESSION

Strain hardening of steels is an effective approach to changing the structural-phase state and properties. Understanding the mechanisms of formation of structural-phase states and properties of pearlitic steel during plastic deformation is crucial for controlling the process of de-formation behavior. The importance of knowledge in this area is due to serious problems in the field of physical materials science, as well as the practical consequences of the use of pearlitic steel, which is widely used in the railway industry. Currently, there is great interest in understanding the general relationships characterizing strain hardening. This interest is associated with the possibility of developing a complex theory of this phenomenon and studying the dislocation mechanisms that determine the observed stress-strain curves σ(ε). It is noteworthy that advances have been made in the field of strength physics, in particular in understanding the dislocation structure of bainitic and martensitic steels. These advances have contributed to expanding our understanding of strain hardening phenomena. Present work the evolution of structural-phase states and dislocation substructure of rail steel under uniaxial com-pression to the degree of 50 % was studied by transmission electron microscopy. The obtained data formed the basis for a quantitative analysis of the mechanisms of rail steel strengthening at degrees of deformation by compression 15, 30, 50 %. Contributions to the strengthening caused by the friction of matrix lattice, dislocation substructure, presence of carbide particles, internal stress fields, solid solution and substructural strengthening, pearlite component of the steel structure are estimated. Using the adaptivity principle, which as-sumes the independent action of each of the strengthening mechanisms, the dependence of rail steel strength on the degree of plastic deformation by compression is estimated. A com-parative analysis of the stress-strain curves σ(ε) obtained experimentally and calculated theo-retically is performed.

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