Institute of History and Archeology, Ural Branch of the Russian Academy of Sciences, Ekaterinburg, Russia:

N. N. Melnikov, Cand. Hist., Researcher, e-mail: meln2011kit@gmail.com
Vas. V. Zapariy, Cand. Hist., Associate Professor, Researcher, e-mail: pantera.zap@gmail.com

Ural Federal University, Ekaterinburg, Russia:
V. V. Zapariy, Dr. Hist., Professor, Dept. of History and Social Technologies, e-mail: vvzap@mail.ru

M. N. Mikheev Institute of Metal Physics, Ural Branch of the Russian Academy of Sciences, Ekaterinburg, Russia:
B. A. Gizhevsky, Cand. Eng., Senior Researcher, e-mail: gizhevskii@imp.uran.ru

Since the mid 1930-s soviet metallurgists made lot efforts for creation the optimal tanks hull armor system. Due to irresistible technological difficulties, all plans about mass production of heterogeneous armor were rejected. Therefore, the new soviet tanks, designed in the pre-war period, received homogeneous armor of high (T-40 and T-34) or medium (KV) hardness. The armor system of the new heavy tank of the KV series was based on the 42S steel grade. It was distinguished by high manufacturability, acceptable mechanical properties. The relatively low content of scarce alloying elements made this steel inexpensive in fabrication, which made it possible to deploy mass production of armor for Soviet heavy tanks even under the most difficult conditions of evacuation to the Urals.
The metallurgical part of the work was carried out within the framework of the Spin program.

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