Moscow Aviation Institute (National Research University), Moscow, Russia

I. S. Belashova, Dr. Eng., Prof., Dept. 903

Moscow Automobile and Road Construction State Technical University (MADI), Moscow, Russia

L. G. Petrova, Dr. Eng., Prof., Head of the Dept. of Technology of Structural Materials

Vyatka State University, Kirov, Russia
E. A. Marinin, Cand. Eng., Associate Prof., Dept. of Information Technologies in Mechanical Engineering, e-mail: e.marrini@gmail.com

SPE NITRID, Saratov, Russia
P. S. Bibikov, Leading Engineer, Cand. Eng.

The article presents the results of study of the influence of cyclic nitriding modes of martensitic steel 13Cr11Ni2W2MoV in ammonia-air medium. One of the ways to reduce the fragility of the nitrided layer is the process of denitriding; it is usually made by holding the product at a nitriding temperature with an overlap of the ammonia supply. A significant limitation of the use of traditional gas nitriding for surface hardening of high-alloy steels (where the diffusion mobi lity of nitrogen is reduced) is the duration of the process. Cyclic nitriding processes with alternating supply of ammonia and an ammonia-air mixture showed high efficiency of intensification of layer growth in steels. There were studies of cyclic nitriding processes with alternating ammonia supply cycles with a given degree of dissociation and ammonia/air mixture supply cycles into a saturating atmosphere. It is shown that at temperatures 500-520 °C under conditions of gas cycling, there is no the formation of a nitrided layer in 13Cr11Ni2W2MoV steel. Studies of nitrided martensitic steel 13Cr11Ni2W2MoV showed the significant differences of the structure of the nitrided layer and its individual parts, depending on the regime of cyclic nitriding with alternating atmospheres of pure ammonia and ammonia with air. It was found that the stage processes with an increased temperature at the second and third stages of the process have definite advantages in comparison with isothermal processes, which consist in the growth acceleration of the diffusion layer and the possibilities of regulating the phase composition of the compound area. The suggested three-stage nitriding regime include the final stage of strongly dissociated ammonia in an atmosphere. The denitriding process leads to the decomposition of the brittle high-nitrogen ε-phase, with the formation of a surface layer based on the γ’-phase.
The material was prepared as part of scientific research under project No. FSFM-2024-0001, experimental studies were carried out using the equipment of the MADI shared Research Facility.

1. Gromov V. I., Voznesenskaya N. M., Pokrovskaya N. G., Tonysheva O. A. High-strength structural and corrosion-resistant steels of FSUE “VIAM” for aviation equipment articles. Aviatsionnye materialy i tekhnologii. 2017. No. 5. pp. 159–174.
2. Voznesenskaya N. M., Tonysheva O. A., Eliseev E. A. Modern structural steels for cryogenic purposes and the influence of some alloying elements on their properties (review). Trudy VIAM. 2020. No. 1 (85). pp. 3–14.
3. Alekseeva G. P., Banas I. P., Belyakova V. I. et al. Steels for gears and fuel equipment parts, strengthened by chemical-thermal treatment. Aviatsionnaya promyshlennost. 1982. No. 8. pp. 31–32.
4. Bibikov P. S., Belashova I. S., Prokofyev M. V. Features of nitriding technology for high-alloy corrosion-resistant steels for aviation purposes. Vestnik Moscovskogo aviatsionnogo instituta. 2021. Vol. 28. No. 2. pp. 206–215.
5. Aizawa T., Yoshino T., Morikawa K., Yoshihara S.-I. Microstructure of plasma nitrided AISI 420 martensitic stainless steel at 673 K. Crystals. 2019. Vol. 9, Iss. 2. 60. DOI: 10.3390/cryst9020060
6. Alphonsa I., Chainani A., Raole P. M., Ganguli B. et al. A study of martensitic stainless steel AISI 420 modified using plasma nitriding. Surf. Coat. Technol. 2002. Vol. 150, Iss. 2. pp. 263–268. DOI: 10.1016/S0257-8972(01)01536-5
7. Petrova L. G., Belashova I. S., Lisovskaya O. B., Marinin E. A. Formation of nitrided layers in iron under thermal cycling conditions. Chernye Metally. 2023. No. 7. pp. 42–46.
8. Hongyu Shen, Liang Wang. Influence of temperature and duration on the nitriding behavior of 40Cr low alloy steel in mixture of NH₃ and N₂. Surface and Coatings Technology. 2019. Vol. 378. 124953. DOI: 10.1016/j.surfcoat.2019.124953
9. Faltejsek P., Joska Z., Pokorný Z., Dobrocký D. et al. Effect of nitriding on the microstructure and mechanical properties of stainless steels. Manufacturing technology. 2019. Vol. 19, Iss. 5. pp. 745–748. DOI: 10.21062/ujep/365.2019/a/1213-2489/MT/19/5/745
10. Arun Prasad M., Dharmalingam G., Salunkhe S. Microstructural evaluation of gas nitrided AISI 316 LN austenitic stainless steel. Materials Today: Proceedings. 2022. Vol. 68, Iss. 6. pp. 1887–1890. DOI: 10.1016/j.matpr.2022.08.060
11. Lakhtin Yu. M., Kogan Ya. D., Shpis G. I., Bemer Z. Theory and technology of nitriding. Moscow : Metallurgiya, 1991. 320 p.
12. Niu J. B., Zhang X. H., Ma X. X., Liu Y. et al. Characterization of vein-like structures formed in nitrided layers during plasma nitriding of 8Cr4Mo4V steel. Materialia. 2022. Vol. 22. 101378. DOI: 10.1016/j.mtla.2022.101378
13. Han Z., Lu J., Yin C., Lai P. et al. Composition, microstructure, and phase evolution of 17-4 PH stainless steel with a work-hardened layer in the low-temperature plasma nitriding process. Surf. Coat. Technol. 2022. Vol. 451. 128950. DOI: 10.1016/j.surfcoat.2022.128950
14. Borisyuk Yu. V., Oreshnikova N. M., Pisarev A. A. Low-temperature plasma nitriding of high-chromium and low-chromium steels. Izvestiya RAN. Seriya: Fizicheskaya. 2020. Vol. 84. No. 6. pp. 892–898.
15. Khusainov Yu. G., Ramazanov K. N., Esipov R. S. Low-temperature ion nitriding of structural steels 13Kh11N2B2МF-Sh and 12Kh18N10Т with ultrafine-grained structure. Uprochnyayushchie tekhnologii i pokrytiya. 2017. No. 10. pp. 459–463.
16. Petrova L. G., Belashova I. S., Bibikov P. S. Improvement of chemical-thermal treatment technologies for surface hardening of high-alloy steels for aviation purposes. Naukoemkie tekhnologii v mashinostroenii. 2022. No. 8 (134). pp. 3–11. DOI: 10.30987/2223-4608-2022-8-3-11
17. Shestopalova L. P., Aleksandrov V. A. The influence of cyclic oxynitriding on technical characteristics of structural alloy steels. Uprochnyayushchie tekhnologii i pokrytiya. 2018. Vol. 14. No. 5. pp. 220–224.
18. Bin Liu, Bo Wang, Xudong Yang, Xingfeng Zhao et al. Thermal fatigue evaluation of AISI H13 steels surface modified by gas nitriding with pre- and post-shot peening. Applied Surface Science. 2019. Vol. 483. pp. 45–51. DOI: 10.1016/j.apsusc.2019.03.291
19. Belashova I. S., Petrova L. G. Control of the nitrided layer phase composition in iron during chemical-thermal treatment under thermal cycling conditions. Vestnik Moscovskogo aviatsionnogo instituta. 2022. Vol. 29. No. 2. pp. 237–245.
20. Tadepalli L. D., Gosala A. M., Kondamuru L., Bairi S. Ch. et al. A review on effects of nitriding of AISI409 ferritic stainless steel. Materials Today: Proceedings. 2020. Vol. 26, Iss. 2. pp. 1014–1020. DOI: 10.1016/j.matpr.2020.01.299
21. GOST 5632–2014. Stainless steels and corrosion resisting, heat-resisting and creep resisting alloys. Grades. Introduced: 01.01.2015.