National Research Center “Kurchatov Institute” – VIAM, Moscow, Russia

N. M. Voznesenskaya, Cand. Eng., Leading Researcher at Laboratory No. 605 “Structural and Special Steels”
O. A. Tonysheva, Cand. Eng., Senior Researcher at Laboratory No. 605 “Structural and Special Steels”

E. A. Eliseev, Cand. Eng., Head of the Laboratory No. 605 “Structural and Special Steels”

National Research Center “Kurchatov Institute” – VIAM, Moscow, Russia¹ ; Gubkin branch of the National University of Science and Technology “MISIS”, Gubkin, Russia²

D. N. Romanenko, Cand. Eng., Senior Researcher at Laboratory No. 605 “Structural and Special Steels”¹, Associate Prof. at the Dept. of Mining Engineering², e-mail: romanenko-kstu46@yandex.ru

The work is devoted to the study of technological plasticity in the cast state of austenitic corrosion-resistant steel grade VNS53-Sh (08Kh21G11AN6-Sh), containing up to 0.6 % nitrogen, at deformation temperatures (precipitation) from 800 to 1200 °С. Steel VNS53-Sh was smelted in an open induction furnace of the IST-0.05 type, followed by electroslag remelting in a semi-industrial plant DESHP-0.1. Corrosion-resistant steel of the austenitic class VNS53-Sh is designed for the manufacture of thin-walled pipes operating under high pressure. Tests for technological plasticity were carried out in accordance with STO 1-595-23-514-2016 by upsetting cylindrical samples with a diameter of 15 ± 0.1 mm and a height of 20 ± 0.05 mm. The analysis of steel microstructure after upsetting at different temperatures was carried out. Microstructure studies were carried out in accordance with instructions no. 804-76 on an OLYMPUS GX-51 optical microscope. Metallographic sections were subjected to electrolytic etching in a 10% oxalic acid solution. It has been established that deformation at 800–900 °С causes the appearance of grain-boundary precipitates in the structure, formed as a result of discontinuous decomposition of the solid solution with the formation of pearlite-like colonies (a mixture of chromium nitride and austenite plates). When samples are compressed at temperatures above 900 °С, recrystallization processes are observed. New austenite grains are formed mainly along the grain boundaries, as along the most defective zones containing additional centers of recrystallization – carbonitrides, while pearlite-like colonies are not detected. The appearance of a nitride-austenitic mixture in the structure does not allow deformation of VNS53-Sh steel with a reduction ratio of more than 20% without cracking. The manufacturability of steel increases with an increase in the upsetting temperature, however, the permissible degree of deformation does not exceed 35%.
The work was carried out within the framework of the government contract No. 21411.1770290019.18.006 dated 03/01/2021, code “Height” on the topic Vs-09 “Development of technology for smelting, deformation, heat treatment of pipe billets for the manufacture of thin-walled pipes operating under high pressure conditions from VNS-53Sh class corrosion-resistant austenitic steel ".

1. Misra R. D. K., Injeti V. S. Y., Somani M. C. The significance of deformation mechanisms on the fracture behavior of phase reversion-induced nanostructured austenitic stainless steel. Sci. Rep. 2018. Vol. 8, Iss. 1. 7908. DOI: 10.1038/s41598-018-26352-1
2. Liu G., Liu Y., Cheng Y., Li J. et al. The intergranular corrosion susceptibility of metastable austenitic Cr – Mn – Ni – N – Cu high-strength stainless steel under various heat treatments. Materials. 2019. Vol. 12, Iss. 9. 1385. DOI: 10.3390/ma12091385
3. Cui P., Xing G., Nong Z. et al. Recent advances on composition-microstructure-Properties Relationships of Precipitation hardening stainless steel. Materials. 2022. Vol. 15, Iss. 23. 8443. DOI: 10.3390/ma15238443
4. Kablov E. N., Bakradze M. M., Gromov V. I., Voznesenskaya N. M. et al. New high-strength structural and corrosion-resistant steels for aerospace technology developed by FSUE “VIAM” (review). Aviatsionnye materialy i tekhnologii. 2020. No. 1. pp. 3–11. DOI: 10.18577/2071-9140-2020-0-1-3-11
5. Shcherenkova I. S., Shkatov V. V., Gadalov V. N. Study of electrolytic chromium coatings with ultradisperse superhard fillers. Chemical and Petroleum Engineering. 2015. Vol. 51, Iss. 3. pp. 277–282.
6. Gubanov O. M., Shkatov V. V., Kozhukhov A. А. Formation of non-uniform grain structure of steel in the process of heat treatment and method of evaluation of microstructure with significantly non-uniform grain. Journal of Chemical Technology and Metallurgy. 2017. Vol. 52, Iss. 5. pp. 996–1001.
7. Sevalnev G. S., Antsyferova M. V., Dulnev K. V., Sevalneva T. G. et al. Effect of nitrogen concentration on the structure and properties of economically alloyed structural steel. Aviatsionnye materialy i tekhnologii. 2020. No. 2. pp. 10–16. DOI: 10.18577/2071-9140-2020-0-2-10-16
8. Tonysheva O. A., Voznesenskaya N. M., Gromov V. I., Leonov A. V. High-strength corrosionresistant VNS-74 steel as applied to aircraft fasteners. Trudy VIAM. 2022. No. 7. 01. DOI: 10.18577/2307-6046-2022-0-7-3-12
9. Pridantsev M. V., Talov N. P., Levin F. L. High-strength austenitic steels. Moscow : Metallurgiya, 1969. 250 p.
10. Shanina B. D., Tyshchenko A. I., Glavatskyy I. N. et al. Chemical nano-scale homogeneity of austenitic CrMnCN steels in relation to electronic and magnetic properties. Journal of materials science. 2011. Vol. 46. pp. 7725–7736.
11. Dzugutov M. Ya. Plastic deformation of high-alloy steels and alloys. Moscow : Metallurgiya, 1977. 142 p.
12. Krylov S. A., Evgenov A. G., Shcherbakov A. I., Makarov A. A. New electroslag furnace under pressure DESHP-0.1: mastering and development prospects. Trudy VIAM. 2016. No. 5. 04. DOI: 10.18577/2307-6046-2016-0-5-4-4
13. GOST 9450–76. Measurement of microhardness by diamond instruments indentation. Introduced: 01.01.1977.
14. GOST R ISO 22309–2015. Microbeam analysis. Introduced: 01.06.2016.
15. Bannykh I. O., Bannykh O. A. Current state of research and application of high-nitrogen austenitic steels. Moscow : Nauka i tekhnologii, 2017. 15 p.
16. Efros B. M., Korshunov L. G., Efros N. B., Dmitrienko V. Yu. Structure and properties of hybrid materials of the “sandwich” type based on a nitrogen-containing alloy. 1 Phase and structural transformations. Fizika i tekhnika vysokikh davleniy. 2016. Vol. 26. No. 3-4. pp. 89–94.
17. Houdremont E. Handbuch der Sonderstahlkunde. Translated from Germany. Vol. 2. Moscow : Metallurgiya, 1966. 583 p.