OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 27 No. 1 2025 Further details regarding the technological process of sheet steel production using DTCT, including forging parameters, heating and cooling modes, and rolling parameters, are provided in [7]. Results and Discussion A previous study [2] indicated that employing pre-deformation thermocyclic forging prior to rolling Steel 10 plate promotes the retention of the ferrite-pearlite microstructure (Fig. 1). It is important to note that pre-deformation thermocyclic treatment (DTCT) significantly influences pearlite morphology. Specifically, DTCT results in a reduction in pearlite colony size, a decrease in their volume fraction, and a weakening of texture, manifested as a decrease in the degree of orientation of pearlite colonies along the rolling direction. These DTCT-induced microstructural changes lead to a notable improvement in mechanical properties. Moreover, the results of the study [2] showed that applying DTCT prior to rolling leads to a significant, nearly 30 % increase in the strength of hot-rolled Steel 10 sheet. This is evidenced by the increase in ultimate strength from 370 to 478 MPa and yield strength from 305 to 390 MPa (Fig. 1). It should be emphasized that such a significant increase in strength is achieved with a minimal and acceptable decrease in the material’s ductility. The application of pre-deformation thermocyclic treatment (DTCT) demonstrates significant potential for improving the mechanical properties of Steel 10, making this method highly promising for industrial applications. The strength improvement achieved is not a random outcome of the treatment but results from fundamental changes in the material’s microstructure. These changes, in turn, significantly influence the steel’s deformation and fracture mechanisms. a b Fig. 1. Microstructure of the studied samples made of Steel 10 (sheet thickness 3 mm) obtained using industrial technology (a) and using thermal cycling forging (b) Two key microstructural effects underlie the strength improvement achieved by DTCT. Firstly, DTCT promotes grain refinement in the steel. A finer grain size increases the grain boundary area, which acts as a barrier to dislocation movement, the primary mechanism of plastic deformation [2]. This impedes plastic deformation, thereby increasing the material’s strength. Finer grain size also contributes to increased yield strength and hardness of the steel. Secondly, DTCT effectively reduces texture in the material. Texture, or the preferred crystallographic orientation, often arises during metal forming and can lead to anisotropic mechanical properties. The texture reduction achieved by DTCT results in a more isotropic material, with more uniform properties in all directions. This enhances the steel’s resistance to deformation and increases its reliability under complex stress conditions. Thus, the combination of grain refinement and texture reduction achieved by DTCT provides a comprehensive improvement in mechanical properties, significantly increasing strength while maintaining high ductility of the steel. This makes DTCT an effective tool for improving the quality and expanding the application range of Steel 10.
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