METHOD OF MAKING STEEL FLAT PRODUCTS Russian patent published in 2013 - IPC C21D9/42 C22C38/52 C21C7/00 F41H5/02 

FIELD: metallurgy.

SUBSTANCE: steel smelting is performed, steel is refined to obtain that containing the following substances in wt % 0.25-0.35 of C, 0.6-0.7 of Si, 0.6-0.9 of Mn, 0.10-0.15 of Al, 0.70-0.95 of Ni, 3.1-3.3 of Co, 0.4-0.6 of Cu, 2.9-3.3 of Cr, 0.4-0.5 of Mo, 0.1-0.2 of V, not over 0.005 of S, not over 0.005 of P, Fe making the rest, ingots are cast and casting is terminated at temperature, at least 8°C higher than liquidus temperature. Obtained ingots are heated and subjected to multipass blooming in lengthwise direction with total relative reduction of, at least, 85% for production of slab. Said slab is subjected to rolling in several steps. Note here that, in first step, slab is reduced to sheet depth 2-10 times larger than final depth and cooled by water at the rate of 400°C/min. Then, sheet is heated to, at least, 900°C and rolled to final depth at rolling end temperature of, at least, 650°C and subjected to water tempering immediately. Low-temperature tempering is performed in, at least, 8 h at 100-200°C.

EFFECT: higher durability of armor sheets.

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