OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 27 No. 1 2025 In this regard, a study was carried out to investigate the effect of the DTCT mode, including thermocyclic deformation (forging) at a temperature above the Ac3 point, and subsequent normalizing on the mechanical properties of Steel 10 plate. The aimof thework was to determine the optimal parameters of DTCT to achievemaximumimprovement of the mechanical properties of this steel, which will allow us to expand its field of application and create more reliable and durable engineering products. To achieve this aim, several tasks were undertaken, such as manufacturing samples, conducting mechanical tests, and analyzing changes in the mechanical properties of steel under the influence of DTCT. The results obtained will allow us to justify the application of DTCT to improve the properties of Steel 10 plate and other low-carbon steels. Methods and materials Steel 10, produced at Novokuznetsk Metallurgical Complex (OJSC NKMC,), was selected as the starting material for this study. This steel was chosen due to its widespread use in mechanical engineering and relatively low cost, making it an attractive subject for studying the effect of various processing methods on its mechanical and microstructural properties. To accurately determine the chemical composition of the steel under study, a modern spectral analysis method was used. Specifically, an ARL 4460 emission spectrometer was used to determine the quantitative content of various elements in the steel. The obtained chemical composition data were used for comparison with literature data and to assess the steel’s compliance with the declared standards (Table 1). Ta b l e 1 Chemical composition of Steel 10 being treated Steel Element content, % (weight) C Mn Si P Cr S Cu Ni 10 0.134 0.422 0.226 0.0139 0.048 0.0181 0.198 0.041 During an experiment conducted at JSC West Siberian Metallurgical Complex (Novokuznetsk), a steel slab measuring 900 mm × 700 mm × 500 mm underwent cyclic forging using a single-pass drawing method on a 20 MN hydraulic press. The deformation process was performed at a heating temperature of 1,250 °C, with the slab held in the furnace for 2 hours prior to forging (excluding heating time). The holding time was carefully selected to ensure uniform heating of the slab throughout its volume. During the experiment, 10 deformation cycles were performed, resulting in a significant change in the structure and properties of the starting material. As a result of repeated deformation, the thickness of the billet after deformation thermocyclic treatment (DTCT) was reduced to 300–310 mm, demonstrating a substantial degree of plastic deformation. Following DTCT, the resulting billets were further processed by rolling at JSC Novosibirsk Metallurgical Plant named after A.N. Kuzmin (Novosibirsk). The rolling was performed according to an industrial technological mode to obtain sheet material of a specified thickness. The rolling process resulted in sheets with a thickness of 3 mm, exhibiting altered properties compared to the initial slab. This change in properties is a consequence of the combined effect of deformation and heat treatment, which constitute the essence of DTCT. To comprehensively evaluate the effect of deformation thermocycling treatment (DTCT) on the properties of sheet steel, comprehensive mechanical testing was performed on the resulting material. Flat specimens with a thickness of 3 mm, fabricated from sheet steel that had undergone DTCT and subsequent rolling, were used. The tests were conducted on an Instron 3369 universal testing machine. During testing, key mechanical properties of the resulting sheet steel were determined. These included: ultimate strength (σu), yield strength (σy), percentage elongation (δ), and percentage reduction in area (ψ).
RkJQdWJsaXNoZXIy MTk0ODM1