KhN70Yu (, also known by its experimental designation EI-652, ) 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.
+ Nominal composition per GOST 5632-72 (wt%) Ni Cr Al Fe C bal. 26 to 29 2.8 to 3.5 ≤1.0 ≤0.10
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