Perm National Research Polytechnic University, Perm, Russia¹ ; JSC ELKAM-Neftemash, Perm, Russia²

I. Yu. Sokolov, Postgraduate Student, Dept. of Metal Science, Thermal and Laser Processing of Metals¹, General Director², e-mail: aspirantsokolovivan@elkam.ru

S. N. Moltsen, Postgraduate Student, Dept. of Metal Science, Thermal and Laser Processing of Metals¹, Quality Director², e-mail: stanislav@vputehod.ru

A. V. Kravchenko, Postgraduate Student, Dept. of Metal Science, Thermal and Laser Processing of Metals¹, Head of Quality Control Department², e-mail: andrew@vputehod.ru

Perm National Research Polytechnic University, Perm, Russia¹ ; Metallprom, Perm, Russia²
D. A. Nikitin, Master¹, Quality Specialist², e-mail: 89_87@bk.ru

The authors have demonstrated that Ni-Cr-B-Si coatings on sucker rod pump plungers in Bashkortostan and Udmurtia can be prone to corrosion cracking under cyclic stresses in conditions with hydrochloric acid, sulfides, and chlorides, significantly reducing plunger reliability and durability. It has been established that the nearly perpendicular arrangement of developing cracks in the coating leads to its fragmentation and flaking, forming the typical damage morphology of the Ni-Cr-B-Si layer obtained by flame spraying. The authors suggest a multi-stage mechanism for the initiation and development of cracks: the formation of corrosion cavity centers; the initiation of radial stress corrosion cracks within these cavities, which propagate deeper into the coating; the development of subsurface axial contact fatigue cracks. The coating’s failure process concludes with its delamination down to a thin, lightly etched layer that remains on the surface of the investigated plungers. The microstructure of the coating consists of a matrix solid solution based on nickel, which represents an almost closed network of mixed hard phases, including chromium carbides and borides. A transition zone has been found at the boundary of the coating and base metal with a modified structure, resistant to damage, caused by the diffusion of elements from the coating into the base material. Measures to reduce embrittling factors are recommended, including the adjustment of the content of chromium carbides and borides in the coating and modifying the length of the plungers. An evaluation of the economic efficiency of improving the resistance of the coating to hydrogen sulfide, including cost reduction, is conducted.
The study was supported by JSC ELKAM-Neftemash.
The authors express special gratitude to the head of the chair for Metal Science, Thermal and Laser Processing of Metals of PNRPU, Doctor of Engineering Sciences, Professor Yu. N. Simonov.

1. American Petroleum Institute. API 11AX: Specification for subsurface sucker rod pumps and fittings. 13^th ed., Washington, D.C. : API Publishing Services, 2022. 218 p.
2. NACE Standard MR-0176-2020. Material Requirements. Metallic Materials for Sucker-Rod Pumps for Corrosive Oilfield Environments. p. 7.
3. GOST 31825–2012. Sucker rods, mouth stocks and couplings for them. Specifications. Introduced: 01.01.2014.
4. Corrosion resistance of chemical production equipment: Methods for protecting equipment from corrosion. L. : Chemistry, 1987. 280 p.
5. Simunovic K., Saric T., Simunovic G. Different approaches to the investigation and testing of the Ni-based self-fluxing alloy coatings. A review. Part 1: General facts, wear and corrosion investigations. Tribol. Trans. 2014. Vol. 57. pp. 955–979.
6. Sokolov I. Yu., Simonov Yu. N., Moltsen S. N., Kravchenko A. V. Influence of application technology and structure of NiCrBSi coating on crack formation. Vestnik Permskogo natsionalnogo issledovatelskogo politekhnicheskogo universiteta. Mashinostroenie, materialovedenie. 2023. Vol. 25. No. 3. pp. 23–36.
7. Heidersbach R. Metallurgy and corrosion control in oil and gas production. John Wiley & Sons, Inc., 2011. 293 p.
8. Pumpyansky D. A., Pyshmintsev I. Yu., Vydrin A. V., Kuznetsov V. I. et al. Fundamentals of metal science and production technology of pipes from corrosion-resistant steels. Moscow : Metallurgizdat, 2023. 682 p.
9. Brown B. F. Stress corrosion cracking control measures. National Bureau of Standards. Monograph, Vol. 156. Washington. 1977. pp. 65–66.
10. Shtremel M. A. Destruction. In 2 books. Book 1. Destruction. Monograph. Moscow : Izdatelskiy dom MISiS, 2015. 976 p.
11. GOST 1050–2013. Metal products from nonalloyed structural quality and special steels. General specification. Introduced: 01.01.2015.
12. GOST 19281–2014. High strength rolled steel. General specification. Introduced: 01.01.2015.
13. Fauchais P., Heberlein J., Boulos M. Thermal spray fundamentals, from powder to part. New York, NY, USA : Springer, 2014. 1566 p.
14. GOST 18895–97. Steel. Method of photoelectric spectral analysis. Introduced: 01.01.1998.
15. Kuroda S., Clyne T. W. The quenching stress in thermally sprayed coatings. Thin Solid Films. 1991. Vol. 200, Iss. 1. pp. 49–66. DOI: 10.1016/0040-6090(91)90029-W
16. Popov A. A., Popova L. E. Isothermal and thermokinetic diagrams of decomposition of undercooled austenite: Handbook of thermist. 2^nd ed., revised and supplemented. Moscow : Metallurgiya, 1965. 495 p.
17. Makarov A. V., Soboleva N. N., Malygina I. Yu., Osintseva A. L. Formation of wear-resistant chromium-nickel coating with a particularly high level of heat resistance by combined laser-thermal treatment. Metallovedenie i termicheskaya obrabotka metallov. 2015. No. 3 (717). pp. 39–46.
18. Makarov A. V. et al. Improving the properties of a rapidly crystallized NiCrBSi laser clad coating by high-temperature processing. J. Crystal Growth. 2019. Vol. 525, Iss. 6. 125200.
19. Simonov Yu. N., Georgiev M. N. Crack resistance of iron-carbon alloys: monograph. Perm : Izdatelstvo PNIPU, 2013. pp. 79–80.
20. Šimunović K., Franz M., Marić G. Investigation and estimation of residual stress in flame sprayed and fused NiCrBSi coatings. Metalurgija. 2008. Vol. 47, Iss. 2. pp. 93–97.
21. Skulev H., Malinov S., Sha W., Basheer P. A. M. Microstructural and mechanical properties of nickel-base plasma sprayed coatings on steel and cast iron substrates. Surface and Coatings Technology. 2005. Vol. 197, Iss. 2-3. pp. 177–184. DOI: 10.1016/j.surfcoat.2005.01.039
22. Habib K. A., Cano D. L., Serrano-Mira J. et al. Impact of microstructure on remelting parameters and mechanical behavior of thermally sprayed NiCrBSi coating. J. Therm Spray Tech. 2024. Vol. 33. pp. 290–307. DOI: 10.1007/s11666-023-01684-1
23. Yoshida S. et al. Direct observation of indentation deformation and cracking of silicate glas ses. J. Mater. Res. 2015. Vol. 30, Iss. 15. pp. 2291–2299.
24. Valean P.-C., Kazamer N., Pascal D.-T., Muntean R. et al. Characteristics of thermally sprayed NiCrBSi coatings before and after electromagnetic induction remelting process. Acta Polytechnica Hungarica. 2019. Vol. 16. pp. 7–18.
25. Lebaili S., Durand-Charee M., Hamar-Thibault S. The metallurgical structure of as-solidified Ni - Cr - B - Si - C hardfacing alloys. J. of Material Science. 1988. Vol. 23, Iss. 10. pp. 3603–3611.
26. Houdková Š., Smazalová E., Vostˇrák M., Schubert J. Properties of NiCrBSi coating, as sprayed and remelted by different technologies. Surf. Coat. Technol. 2014. Vol. 253. pp. 14–26.
27. Kazamer N., Muntean R., Vălean P. C., Pascal D. T. et al. Comparison of Ni-based self-fluxing remelted coatings for wear and corrosion applications. Materials. 2021. Vol. 14. 3293. DOI: 10.3390/ma14123293
28. Simonov Yu. N. Physics of strength and mechanical testing of metals. Perm : Izdatelstvo PNIPU, 2017. p. 4.
29. Davis J. R. Handbook of thermal spray technology. ASM International: Materials Park, OH, USA; Novelty, OH, USA, 2004. 338 p.
30. Harsha S., Dwivedi D. K., Agarwal A. Influence of CrC addition in Ni-Cr-Si-B flame sprayed coatings on microstructure, microhardness and wear behavior. Int. J. Adv. Manuf. Technol. 2008. Vol. 38. pp. 93–101. DOI: 10.1007/s00170-007-1072-2
31. Cameron D. C. Films and coatings: technology and recent development. Elsevier, 2014. pp. 239–240.
32. Ganina N. I., Zakharov A. M., Olenicheva V. G., Petrova L. A. State diagrams of metal systems, published in 1984. Issue XXIX. Moscow : VINITI, 1986. 524 p.
33. Surface engineering. Handbook Vol. 5, ASM International, 1994. 1449 p.
34. Tucker R. C. Thermal Spray Technology. ASM Handbook, Vol. 5A. 2013. pp. 60–64.
35. Alloy phase diagrams. ASM Handbook, ASM International. 2003.
36. ISO 14920:2015 Thermal spraying. Spraying and fusing of self-fluxing alloys.
37. Callister W. D., JR. Materials science and engineering. An introduction. John Wiley and Sons, Inc., Wiley 2014. 990 p.