Nosov Magnitogorsk State Technical University (Magnitogorsk, Russia)

P. P. Poletskov, Dr. Eng., Prof., Dept. of Metal Processing Technology
N. V. Koptseva, Dr. Eng., Prof., Dept. of Casting Processes and Materials Science
Yu. Yu. Efimova, Cand. Eng., Associate Prof., Dept. of Metal Processing Technology
A. S. Kuznetsova, Cand. Eng., Associate Prof., Dept. of Metal Processing Technology, e-mail: allakuznetsova.mgtu@mail.ru

The requirement in domestic high-strength cold-resistant materials increases at present time, what has positive effect on development of Russian economics. Creation of import-substituting high-strength cold-resistant steels allows to provide leading positions of national machine-building manufacturing equipment for operation in the extremal conditions of Far North and Arctic region. Regularities of phase and structural transformations in the new experimental high-strength cold-resistant steel, occurring during continuous cooling, are established and thermokinetic diagram of decomposition of overcooled austenite is built.To realize consequent mastering of the new steel in industrial conditions, laboratorial samples of rolled products were fabricated and the quenching procedure for rolled sheet metal in water from the temperature 860 WС was tested using specialized equipment of the laboratorial complex of Nosov Magnitogorsk State Technical University. It is shown that the experimental steel is characterized by high complex of mechanical properties after suggested heat treatment, owing to forming of fine-dispersed microstructure of lath martensite (up to 85 %) and bainite (up to 15 %). In this case martensite provides high strength of the researched steel (σ_в = 1,440 MPa, σ_0,2 = 1,380 MPa), while presence of dispersed structure of low-carbon bainite ensures high parameters of destruction resistance (KСV-70=59 J/cm²). Hardness more than 429 HBW (455 HV) is achieved by cooling with the speed exceeding 100 оС/s. The obtained complex of mechanical properties displays possibility of using the new experimental high-strength cold-resistant steel for manufacture of heavy-loaded constructions in machine-building, which are operated at low temperatures of Far North and Arctic region.

The research was carried out by Nosov Magnitogorsk State Technical University under financial support of the grant of Russian Scientific Fund No. 23-19-20018 dated 20.04.2023, as well as of the remedies of the Ministry of Education and Science of Chelyabinsk region (Agreement No. 164 dated 28.06.2024), https://rscf.ru/project/23-19-20018/.

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