Perm National Research Polytechnic University, Perm, Russia
O. V. Silina, Cand. Eng., Associate Prof., Dept. of Metal Science, Thermal and Laser Processing of Metals, e-mail: silina-olga@mail.ru

T. S. Byvaltseva, Master, e-mail: byvaltseava@yandex.ru

Physical-Technical Institute of the National Academy of Sciences of Belarus, Minsk, Republic of Belarus
M. N. Bosyakov, Cand. Phys.-Math., Associate Prof., e-mail: plasma.by.metal@gmail.com

JSC ELKAM-Neftemash, Perm, Russia

R. M. Polezhaev, Technical Director, e-mail: prm@elkam.ru

The research is focused on nitriding of bimetallic tubes produced by cold radial forging with a 08Kh17Т steel welded tube as an inner liner. Bimetallic cylinders are used in submersible plunger pumps for oil wells. Continuous operation, effects of mechanical particles and corrosion result inthe inner layer wear, hence a need to improve the equipment lifetime requires special attention. One way of increasing the product reliability is to apply ion-plasma nitriding on the liner. Cold radial forging has proved not to alter the welding pool area but to change the grain shape and orientation.The hardness distribution along the weld remains virtually the same, which guarantees the quality of the nitrided layer formed by the subsequent surface treatment. The study concerned the influence of the composition of the ion-plasma nitriding medium (with the same technological and energy parameters of the process) on the nitriding features at the weld zones. The structure and properties of the obtained layers were studied. It was found that during nitriding in the medium of dissociated ammonia, the hardness of the nitrided layer in the centre of the weld is significantly higher than that of the nitrided layers of other weld zones. This ‘spotty’ hardness negatively affects the product characteristics. To reduce the brittleness of nitrided layers, saturation was carried out in nitrogen–hydrogen media with different argon content and methane additives. The study allowed to determine the composition of the mediumat which a uniform hardened layer, including the weld zone, was obtained on the whole inner surface of the liner.
The study was carried out with the financial support of the Government of Perm Territory within the framework of scientific project No. C 26/513.

1. Bikbulatova G. I., Dumler E. B. Operation of rod pumping equipment. Almetyevsk : Almetyevsk State Oil Institute, 2009. 130 p.
2. Arkhipov K. I., Dumler E. B. Well rod pumping equipment for oil production: tutorial. Almetyevsk : Almetyevsk State Oil Institute, 2008. 264 p.
3. Arkhipov K. I., Popov V. I. Handbook of a mechanical engineer on repair of oil equipment. Almetyevsk : Tat ASU, 1999. 188 p.
4. GOST R 52203–2004. Tubing and coupling. Specifications. Introduced: 01.09.2004.
5. Lyubimov E. V., Shulakov N. V., Shutemov S. V. Justification of the use of a cylindrical linear valve engine in oil producing units. Uspekhi sovremennogo estestvoznaniya. 2018. No. 3. pp. 94–100.
6. Bogatov N. A., Bogatov A. A., Salikhyanov D. R. Lined pumping and compression pipes. Yekaterinburg : Izdatelstvo Uralskogo universiteta, 2017. 96 p.
7. Lakhtin Yu. M., Kogan Ya. D., Shpis G. I., Bemer Z. Theory and technology of nitriding. Moscow : Metallurgiya, 1991. 320 p.
8. Rolinski E. G. Controlling plasma nitriding of ferrous alloys. Materials Performance and Characterization. 2017. Vol. 4. pp. 698–716.
9. Silina O. V., Lobova E. S., Kovko S. P., Babkin E. O. et al. Customization of bimetallic oil-field cylinders. Journal of Machinery Manufacture and Reliability. 2023. Vol. 52, No. 7. pp. 756-762.
10. Chaus A. S., Kuracina V., Moravčík R., Hazlinger M. et al. Effect of gas and ion plasma nitriding on the structure and properties of forging die inserts. Metal science and heat treatment. 2021. Vol. 62. pp. 577–585.
11. Yao J. W., Yana F. Y., Yana M. F., Zhanga Y. X. et al. The mechanism of surface nanocrystallization during plasma nitriding. Applied Surface Science. 2019. Vol. 488. pp. 462–467.
12. Bosyakov M. N., Silina O. V., Kozlov A. A. Plasma chemical-thermal treatment. Perm : Izdatelstvo Permskogo natsionalnogo politekhnicheskogo universiteta, 2023. 135 p.
13. Gulyaev I. A. Technology of spot and projection welding. Moscow : Mashinostroenie, 1978. 245 p.
14. Mikhaylitsyn S. V., Sheksheev M. A. Fundamentals of welding production: textbook. Moscow ; Vologda : Infra-Inzheneriya, 2019. 160 p.
15. Masakov V. V., Masakova N. I., Melzitdinova A. V. Welding of stainless steels: tutorial. Tolyatti : TGU, 2011. 184 p.
16. GOST 5632–72. High-alloy steels and corrosion-proof, heat-resisting and heat treated alloys. Grades. Introduced: 01.01.1975.
17. GOST 18895–97. Steel. Method of photoelectric spectral analysis. Introduced: 01.01.1998.
18. GOST 5639–82. Steels and alloys. Methods for detection and determination of grain size. Introduced: 01.01.1983.
19. GOST 8233–56. Steel. Microstructure standards Introduced: 01.07.1957.
20. Silina O. V., Makarova K. V. Influence of plastic deformation of 40KhN steel on nitriding process. Master`s journal. 2016. No. 2. pp. 60–64.
21. Silina O. V., Babkin E. O., Kovko S. P., Bosyakov M. N. Analysis of the phase composition of hardened layers obtained by ion-plasma nitriding on corrosion-resistant steels. Proceedings of the 7^th All-Russian Scientific and Practical Conference with International Participation. ITMM-2023. pp. 251–254.
22. Lampe T., Eisenberg S., Laudien G. Verbindungsschichtbildung waehrend der Plasmanitrierung und – nitrocarburierung. Journal of Heat Treatment and Materials HTM. 1991. Vol. 46, Iss. 5. pp. 308–316.