Volgograd State Technical University, Volgograd, Russia

V. F. Petrova, Сand. Eng., Associate Prof., Dept. of Materials Technology, e-mail: tecmat@vstu.ru
A. A. Kuznetsova, Student, Dept. of Materials Technology, e-mail: An-kuz@bk.ru

At present time, products made of steel type 18-10 have high requirements for strength characteristics. In domestic standards, the requirements for the temporary resistance of hotdeformed products are high, which is why it is necessary to look for ways to improve these parameters. The current technology for the production of hot-pressed pipes does not allow for ultra-fine grain processing, which includes significant deformation at room temperature, leading to the formation of martensite. During subsequent heat treatment, α’-ferrite undergoes a transformation with the decomposition of small austenite grains. The requirements of the current regulatory documentation limit the maximum content of carbide-forming elements in 08Kh18N10T steel, which is why carbodispersed hardening cannot be widely used in industry. Thus, the most accessible way to improve strength characteristics is associated with changing the pressing parameters - speed or temperature. The results of the study of the metal of pipes pressed in two modes, differing in speed at a comparable temperature, made it possible to determine that a decrease in the pressing speed leads to an increase in the proportion of “small” grains (not larger than 45 μm), at a maximum value, by 30 %. According to the results of scanning on an electron microscope, significant liquation of low-melting components in the cross-section of the samples was not detected. Thus, it was confirmed that a decrease in the deformation rate leads to an increase in the level of microhardness of the austenitic matrix, due to an increase in the level of microstresses, and not liquation of the main chemical elements (chromium and nickel).

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