The Federal State Budgetary Educational Institution of Higher Education Moscow Aviation Institute (National Research University), Moscow, Russia:

O. N. Gvozdeva, Associate Professor, Candidate of Engineering Sciences, e-mail: gon7133@mail.ru
A. V. Shalin, Associate Professor, Candidate of Engineering Sciences, e-mail: priest87@gmail.com
A. S. Stepushin, Post-Graduate Student, e-mail: 69steel@gmail.com
G. T. Zaynetdinova, Head of a Laboratory, e-mail: gzaynetdinova@gmail.com

The paper discusses the use of titanium alloys, for example, the VT6 alloy, for local armoring, which, with their minimum specific surface area, should provide high absorption of impact energy and a slow rate of crack propagation. It is shown that the achievement of such contradictory requirements is possible due to the creation of a directional gradient structure in the semi-finished product, which varies linearly from one side of the surface to the opposite. It is shown that the creation of such structures is possible due to the combined use of thermal and chemical-thermal treatments. The regularities of the formation of a unidirectional gradient structure in plates made of titanium alloy VT6 by means of thermal hydrogen treatment are investigated. It has been established that oxide and nitride coatings formed at isothermal holdings for 4 hours and 30 minutes, respectively, work effectively as a barrier to hydrogen penetration. It has been found that the barrier oxide and nitride coatings most effectively perform the “protective” function when hydrogen is introduced up to 0.4%. It is shown that by varying the concentration of the introduced hydrogen, it is possible to change the depth of its diffusion penetration and, accordingly, the structure in the near-surface layers. It is shown that the finely dispersed structure formed on the surface of semi-finished products gives it increased strength characteristics, and the coarse-lamellar structure in the center of the samples provides good toughness and slows down the rate of crack propagation. It has been found that the barrier properties of the oxide coating during the thermal hydrogen treatment of large-sized items are slightly inferior to the same properties of the nitride coating. It is shown that the creation of a unidirectional gradient structure in plates made of VT6 alloy with a thickness of 12 mm provides them with good dynamic resistance when fired with 5.45 mm high penetration ammunition and 7.62 mm with a steel core bullet.

The research was carried out on equipment of the Aerospace Materials and Technologies Resource Center for collective use of Moscow Aviation Institute.

1. Alekseev M. O., Chistyakov E. N., Kupryunin D. G. Modern State of Armor Materials. Eksport Vooruzhenii. 2017. No. 130. pp. 50–56.
2. Petrov A. P., Shlenskiy A. G. Application of Aluminum Alloys in Armored Protection of Aircraft. Technology of Light Alloys. 2019. No. 3. pp. 76–85.
3. Mylnikov V. V., Abrosimov A. A., Romanov I. D., Romanov A. D. The Analysis of Materials and Their Properties Applied to Means Individual Armored Protection. Advances in Current Natural Sciences. 2014. No. 9-2. pp. 143–147.
4. Grigoryan V. A., Kobylkin I. F., Marinin V. M., Chistyakov E. N. Materials and Protective Structures for Local and Individual Armoring. Moscow : Izdatelstvo RadioSoft, 2008. 406 p.
5. Anastasiadi G. P., Silnikov M. V. Operability of Armor Materials. St. Petersburg : Asterion, 2004. 624 p.
6. Konovalov S., Komissarova I., Ivanov Y., Gromov V., Kosinov D. Structural and Phase Changes under Electropulse Treatment of Fatigue-Loaded Titanium Alloy VT1-0. Journal of Materials Research and Technology. 2019. Vol. 8, Iss. 1. pp. 1300–1307. DOI: 10.1016/j.jmrt.2018.09.008
7. Xie L., Liu C., Song Y., Guo H., Wang Z., Hua L., Wang L., Zhang L.-C. Evaluation of Microstructure Variation of TC11 Alloy After Electroshocking Treatment. Journal of Materials Research and Technology. 2020. Vol. 9, Iss. 2. pp. 2455–2466. DOI: 10.1016/j.jmrt.2019.12.076.
8. Kolachev B. A., Ilyin A. A., Nosov V. K., Mamonov A. M. Achievements of Hydrogen Technology of Titanium Alloys. Technology of Light Alloys. 2007. No. 3. pp. 10–26.
9. Ilyin A. A., Skvortsova S. V., Mamonov A. M., Kolerov M. Yu. Influence of Hydrogen on Phase and Structural Transformations in Titanium Alloys of Different Classes. Physicochemical Mechanics of Materials. 2006. No. 3. pp. 33–39.
10. Senkevich K. S., Skvortsova S. V., Kudelina I. M., Knyazev M. I., Zasypkin V. V. Effect of a Microstructure and
Surface Hydrogen Alloying of a VT6 Alloy on Diffusion Welding. Russian Metallugry (Metally). 2014. Iss. 1. pp. 66–70.
11. Mamonov A. M., Safaryan A. I., Agarkova E. O., Zhilyakova M. A. Analysis of the Possibilities of Transformation of Lamellar Structures of Titanium and Zirconium Alloys by Methods of Thermohydrogen Treatment. Metal Science and Heat Treatment. 2018. Vol. 60, Iss. 1-2. pp. 80–88.
12. Ovchinnikov A., Skvortsova S., Mamonov A.,Yermakov E. Influence of Hydrogen on Plastic Flow of the Titanium and Its Alloys. Acta Metallurgica Slovaca. 2017. Vol. 23, Iss. 2. pp. 122–134.
13. Ilyin A. A., Skvortsova S. V., Spector V. S., Kudelina I. M., Mamontova N. A. Formation of a Gradient Structure in Titanium Alloy by Thermal Hydrogen Treatment. Technology of Light Alloys. 2011. No. 2. pp. 37–41.
14. Skvortsova S. V., Spektor V. S., Kudelina I. M., Neiman A. P., Mamontova N. A. Formation of a Gradient Structure in VT6 alloy Under Thermal Hydrogen Treatment. Titan-2011 in CIS : Proceedings of the International Conference. Lvov. 2011. pp. 375–377.
15. Gvozdeva O. N., Shalin A. V., Stepushin A. S. The Correlation Among Chemical Composition, Structure and Mechanical Properties in Ttanium Alloys for the Elements with Increased Dynamic Ability. IOP Conference Series: Materials Science and Engineering. Vol. 709, Iss. 1. 022082. DOI: 10.1088/1757-899x/709/2/022082
16. Skvortsova S. V., Gvozdeva O. N., Shalin A. V., Stepushin A. S. Linear Gradient Structure Creation in VT6 Titanium Alloy. Titan. 2019. No. 3. pp. 25–31.
17. Ilyin A. N., Kolachev B. A., Polkin I. S. Titanium Alloys. Composition, Structure, Proreties. Reference Book. Moscow: VILS – MATI, 2009. 520 p.
18. GOST R 50744–95. Armor Сlothes. Classification and General Technical Requirements. Moscow: Izdatelstvo standartov, 2003. 32 p.
19. GOST R 50963–96. Armor Protection Cars. General Technical Requirements. Moscow: Izdatelstvo standartov, 2003. 30 p.
20. Lukina E., Kollerov M., Meswania J., Panin P., Khon A., Blunn G. The Influence of TiN and DLC Deposition on the Wear Resistance of Nitinol – Ti6Al4V Combination for the Medical Application. Materials Today: Proceedings. 2017. Vol. 4, Iss. 3. pp. 4675–4679.
21. Skvortsova S. V., Spector V. S., Sarychev S. M., Orlov A. A. Influence of Surface Structures on Torque of VT6 Alloy Cortical Screws. IOP Conference Series: Materials Science and Engineering. 2020. Vol. 971. 032030. DOI: 10.1088/1757-899x/971/3/032030
22. Mamonov A. M., Sarychev S. M., Slezov S. S., Chernyshova Yu. V. Effect of Vacuum Ion-Plasma Treatment on Surface Layer Structure, Corrosion and Erosion Resistance of Titanium Alloy with Intermetallic a2-Phase. Metal Science and Heat Treatment. 2018. Vol. 60, Iss. 5–6. pp. 290–296.
23. Illarionov A. G., Zloba A. V., Leder M. O., Stepanov S. I., Berestov А. V., Popov A. A. Structure, Mechanical and Ballistic Properties Formation in Heat-Treated Sheets of VST2 Alloy with Various Compositions. Titan. 2018. No. 2. pp. 13–18.