To date, one of the most promising areas of long products obtaining modern technologies improvement are combined technologies. These technologies allow to develop new processes improving production efficiency and significantly increase labor productivity due to reduction of low-productive operations. Also, combining technology allows to reduce production area. In recent years attention of scientists is directed to materials characterized by highly crushed structures, as they have high strength properties. But increasing strength by raising volume surface fraction of grain boundaries leads to simultaneous reduction of plastic properties. As a result, area of this type materials application is narrowed significantly. Growing requirements to modern materials make it necessary to improve their manufacturing processes in order to achieve favorable combination of mechanical properties, i.e. high strength without loss of plasticity. Therefore, development of new combined deformation technology to improve performance properties of wire is an urgent task.

Development and research of a combined technology for thermomechanical processing of austenitic chromium-nickel steel wire, which will make it possible to obtain wire with increased energy consumption.

The results of scientific research will be published at least in 3 (three) articles and (or) reviews in peer-reviewed scientific journals indexed in the Science Citation Index Expanded database Web of Science and (or) having the CiteScore percentile in the Scopus database at least 35 (thirty-five). In addition, 1 (one) article will be published in a peer-reviewed foreign or domestic publication recommended by Committee for Quality Assurance in Education and Science (CQAES) of the Ministry of Education and Science of the Republic of Kazakhstan. Research results will be presented at International European conferences in Bulgaria, Poland or other international conferences abroad, as well as at international conferences in Russia, Belarus and Kazakhstan. Based on achieved results the application for useful model patent of the Republic of Kazakhstan will be applied. The project results will be new, scientifically grounded knowledge about new developed innovative combined process of thermo-mechanical metastable austenitic stainless steels treatment, allowing to obtain long wire with ultrafine grain structure and increased level of mechanical and operational properties. Recommendations will be developed for implementation of stainless wire thermomechanical processing new method with improved performance properties. In case of further development and industry implementation of metastable austenitic stainless steel wire thermomechanical processing innovative combined technology within this project, it is possible to create innovative production and new jobs. Obtained experimental project results about γ-α transformation in metastable austenitic stainless steels during drawing at cryogenic temperatures will allow to develop and supplement existing knowledge about the mechanism of polymorphic transformation in steels and can be used in lectures for the theory of heat treatment and phase transformations in metals. In addition, obtained data will be used in relevant direction and specialization bachelors, masters and PhD students training. Obtained research results will be used by Bachelors, Masters and PhD students in educational process and in their research towards obtaining materials with unique or increased level of physical-mechanical properties.

1) An analytical review of scientific, technical and patent literature on methods and technologies for producing wire with increased operational and mechanical characteristics has been conducted. Based on this review, a new thermomechanical treatment of stainless wire has been developed. The fundamental difference between our solution and the known technological solutions for obtaining long-length products from metastable austenitic steels in a continuous manner is cryogenic cooling immediately after the drawing process for the complete transition of the austenitic structure to martensite. Additional hardening will also be achieved using the post-deformation aging stage, which will reduce the number of softening thermal treatments during wire production and thereby reduce the cost of wire. 2) A theoretical study of the factors influencing the martensitic transformation has been carried out. Such factors as: chemical composition, initial grain size, deformation temperature, type of deformation and stress-strain state, deformation rate are investigated. As well as the effect of martensitic transformation on the mechanical properties of steel. 3) To implement the combined innovative thermomechanical processing of wire at the university’s drawing mill, a design of a reservoir chamber for cryogenic cooling of wire immediately after the drawing process has been developed. The wire forming process is the same as when deformed at room temperature. The pointed end of the wire is inserted into the fiber, after which it is passed through an empty tank chamber, in which cryogenic cooling is carried out. This tank chamber is installed in the mill line immediately behind the fiber holder. Then the end of the wire is fixed to the drum of the drawing mill and wound onto the drum. When the drawing mill reaches the working deformation rate, the tank chamber is filled with liquid nitrogen. The tank chamber is equipped with a recirculating nitrogen supply system. 4) Computer models of the combined technology of thermomechanical processing of stainless wire were constructed and optimal parameters were determined to ensure the best stress-strain state and energy-strength parameters of the process. 5) An experimental setup has been created for implementing the combined technology of thermomechanical processing of stainless wire and its assembly has been carried out. Laboratory experiments were also carried out on the implementation of the combined technology of thermomechanical processing of stainless wire, and samples were obtained for further research. Based on the developed drawings, the parts and the combined installation itself were manufactured. The main tool for creating a cryogenic cooling unit is the cooling chamber, which was installed after the drawing unit in the industrial drum drawing mill B-1/550 m. Then an immersion device was made that feeds nitrogen from the Dewar vessel to the cooling chamber, and installed in the Dewar vessel itself. After that, the hoses were placed and the components of the installation were sealed. After the installation was completed, a laboratory experiment was performed on AISI 316 steel wire and samples were obtained for metallographic analysis and determination of mechanical properties. 6) The evolution of the microstructure of the initial and deformed wires is studied using optical and transmission electron microscopes. Also, for a more objective interpretation of the grain structure, EBSD and EBSD-IPF analyses of the deformed wire were performed together with TEM. 7) The use of intermediate heating makes it possible to achieve a gradient microstructure, which, in turn, contributes to improving the operational characteristics of the final product. The proportion of martensite formed in different layers of wire varies. In the surface layer, the martensite content reaches 98%, in the intermediate layer, the proportion of martensite formed is about 81%, and in the central layer, the amount of martensite decreases to about 68%. During cryogenic treatment without heating, the martensite content reaches 100% both in the center and on the surface of the wire. This is due to favorable conditions for martensitic transformation at low temperatures, the absence of thermal activation of competing processes such as recrystallization or annealing, and the relatively homogeneous state of the deformed material.