Zavdoveev A. Formation of the structure and physical-mechanical properties of low carbon steels 20G2S and 08G2S during severe plastic deformation

Object: low carbon steels 20G2S and 08G2S treated by severe plastic deformation methods: warm screw extrusion and hot rolling with a shift, accordingly. The purpose: the determination of the mechanisms of the structure and properties formation of low carbon steels after severe plastic deformation by methods of warm screw extrusion and hot rolling with shift and also after deformation in subsequent treatments. Methods: metallographic analysis; X-ray analysis, the measurement of hardness, microhardness, density and indicators of mechanical properties; the analysis of the fine structure by methods of transmission electron microscopy, scanning electron microscopy, electron back scattering diffraction, fractography. Results: the mechanism of the structure formation of the low-carbon steels 20 G2S and 08G2S treated by severe plastic deformation by methods of hot screw extrusion and hot rolling with shift is determined. This mechanism is to form mainly high-angle grain boundaries in the specimens of steel because of use of that thermomechanical treatment. It leads to the decrease of dislocation density in body of ferrite grains. The manifestation and the mechanisms of the development of fragmentation, grain boundary sliding and dynamic recrystallization are shown. Field of application: solid state physics, physics of strength and plasticity, metallophysics