Thesis objective - the process of formation of hot-rolled low- and ultra-low-alloy steels, which were subjected to further cold deformation. Subject of inquiry - improvement of the complex of mechanical properties by revealing patterns of micro, fine structure, texture formation of low- and ultra-low carbon steels 08пс, 01ЮТ, 01ЮТ(Са), 01ЮТА at the combined plastic deformation. Research methods: metallographic, electron-microscopic, X-ray diffraction, EBSD analysis, nanoindentation. Theoretical and practical results: the rational regimes of the IPD have been developed to improve the properties of low and ultra low carbon steel steels. For the first time, by the method of nanoindentation, the data of the dependence of the durability and ductility characteristics of hot-rolled steels 08пс, 01ЮТ, 01ЮТ(Са), 01ЮТА on the parameters of IPD were obtained; it was established that the best indexes of strength and plasticity of the investigated steels provide IPD by the HPT method at 5 turns and a pressure of 310 kgf/cm2. This allows to predict the expansion of the use of low and ultra low carbon steel steels in aircraft, car and rocket construction in order to reduce the weight of structures; the results obtained in the dissertation are used at the Department of Materials Science of the National Metallurgical Academy of Ukraine in the educational process during, as well as when students complete diploma and master's papers on the basis of the obtained data of the dissertation work the research of industrial testing of a special thin sheet of low carbon steel for the manufacture of machine parts and mechanisms in the conditions of LLC "INTER AIRA INVEST" was conducted. Novelty of the research: for the first time, the possibility of forming an ultra fine-grained structure with elements of the nano-structure in hot-rolled steels 08пс, 01ЮТ, 01ЮТ(Са), 01ЮТА followed by cold deformation by precipitation methods and HPT was established; for the first time, the influence of the deformation degree on the parameter of the crystalline lattice a-ferrite, phase composition, dislocation density and microscopic pressure of the investigated steels were established; for the first time, by the method of nanoindentation, mechanical properties of hot-rolled steels with further cold deformation by the method of HPT were obtained; for the first time, using the EBSD-analysis method, the effect of deformation on the formation of texture components in hot-rolled steel 08пс and 01ЮТ with the subsequent cold plastic deformation by the method of HPT is shown. Implementation extent: On the basis of the obtained data of the dissertation work the research of industrial testing of a special thin sheet of low carbon steel for the manufacture of machine parts and mechanisms in the conditions of LLC "INTER AIRA INVEST".
