Institute of History and Archeology, Ural branch of the Russian Academy of Sciences (Ekaterinburg, Russia):

N. N. Melnikov, Cand Hist., Associate Prof.
Vas. V. Zapariy, Cand Hist., Associate Prof.

Institute of metal Physics, Ural branch of the Russian Academy of Sciences (Ekaterinburg, Russia):
B. A. Gizhevskiy, Cand Phys.-Math.

Ural Federal University (Ekaterinburg, Russia):
Vl. V. Zapariy, Dr. Hist., Prof., Dept. of Gistory and Social relations, e-mail: vvzap@gmail.com

In the early 1930-ies, USSR’s military establishment paid special attention to tank production. Quite acceptable sort of armored steel for the tank industry was created by Soviet metallurgists. However, accumulated experience in armor engineering shown the great demands for its evolution. Broad accepted in Soviet’s construction “IZ”-mark steel was suitable only for tanks with bullet-proof armor (up to 30 mm thick). The creation of a new class of tanks in USSR, powered with canon-proof armor (up to 75 mm thick), funded the searching of a new brands of steel. For T-34 medium tanks, Mariupol metallurgical plant created special high hardness tempered 8C steel, with normal thickness 45 mm. New brand of steel was good designed according to technological and economic demands of tank industry. This steel was capable for production at the Mariupol plant with general success. New armor, tempered to high hardness, had one significant issue, as high residual pressure in the internal structures of metal. During the organization of new armored centers in the East of the USSR this flaw became the reason of serious consequences. When Eastern plants started mass production of T-34, at the first half of Great Patriotic war, too much tanks been defeated with armor cracks. Rearrangement of basic technological processes at the second half of the wartime provided sharp reduction of basic defects in armored details of T-34. The problem of tank armor cracks in the Soviet industry during whole wartime was not finality solved.
The study was carried out with the financial support of the Russian Foundation for Basic Research in the framework of the research project No. 19-09-00050.

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