KhN70Yu (Russian: ХН70Ю, also known by its experimental designation EI-652, Russian: ЭИ652) is a GOST-grade heat-resistant nickel-based alloy, containing about 27 wt% chromium and 3 wt% aluminium. The grade designation follows the standard Russian system: Х for chromium, Н70 for ≈70% nickel, and Ю for aluminium (Russian alyuminiy). It was first reported in 1957 by A. P. Boyarinova as an alloy designed for resistance-heating, rated for service up to ~1200 °C. The addition of chromium and aluminium makes it resist scaling at high temperatures.
Documented uses include electrical heating elements, components of gas-handling and furnace equipment operating at 1100–1200 °C, and welded structural assemblies. Despite the alloy's high scaling resistance, it did not enter widespread industrial use, in part because its ductility drops sharply during 700–800 °C.
References
Further reading Maslenkov, S. B. (1983). Жаропрочные стали и сплавы: справочник [Heat-Resistant Steels and Alloys: Handbook] (in Russian). Moscow: Metallurgiya. p. 96. Liberman, L. Ya.; Peysikhis, M. I. (1967). Свойства сталей и сплавов, применяемых в котлотурбостроении [Properties of Steels and Alloys Used in Boiler-Turbine Construction] (in Russian). Vol. I–III. Leningrad: ONTI TsKTI. p. 600. Abramov, O. V.; Zhuk, N. P. (1961). Коррозия и защита конструкционных материалов [Corrosion and Protection of Structural Materials] (in Russian). Mashgiz. p. 19. Boyarinova, A. P.; Melkumov, I. N.; et al. (1962). [без названия]. Metallovedenie I Termicheskaya Obrabotka Metallov (in Russian) (4): 14. Сплав ХН70Ю (ЭИ652) [Alloy KhN70Yu (EI652)] (in Russian). Evek GmbH. Retrieved 2026-06-06. Сталь ХН70Ю (ЭИ 652): Расшифровка марки [Steel KhN70Yu (EI 652): Grade designation decoded] (in Russian). Stal-Maximum. Retrieved 2026-06-06. "CrN70Yu alloy pipe". Evek GmbH. Retrieved 2026-06-06.