Regularities and Mechanisms of Thermomechanical Hardening of Rolled Low-Carbon Steel

Abstract

The results of investigations of physical nature of the 09G2S steel (0.1% C, 1% Mn, 2% Si) H-beam thermomechanical strengthening are presented. The quantitative regularities of formation of the structure, phase composition, defect substructure, and mechanical properties in different H-beam cross sections under accelerated cooling in different regimes are revealed. The gradient structure—phase states formation is characterized by the regular change of dislocation substructure types and parameters, average cementiteparticles sizes and nanosize-range α-phase fragments on cross section are revealed by methods of transmission electron-diffraction microscopy. As revealed, the substructure and deformation mechanisms depending on the martensite and bainite formation are the main causes responsible for the hardened layer strength increase. These mechanisms contribution is a regulated value, and it depends on the steel treatment regime essentially.

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