METHOD FOR PRODUCTION OF HIGH-STRENGTH STEEL SHEET Russian patent published in 2016 - IPC C21D8/02 C22C38/54 C21D9/46 C21D9/42 

FIELD: metallurgy.

SUBSTANCE: invention relates to ferrous metallurgy, particularly to production of new highly efficient type of metal products-rolled plates from high-strength low-alloy steel for bullet-proof protection of vehicles. To provide high strength properties while maintaining sufficient ductility and impact strength, method involves obtaining a continuously cast slab, heating, hot rolling, hardening and tempering sheets, continuously cast slab is made from steel of following chemical composition, wt%: 0.23-0.32 C, 0.17-0.40 Si, 0.70-1.20 Mn, 0.40-0.80 Cr, 0.80-1.40 Ni, 0.30-0.50 Mo, 0.02-0.05 V, 0.01-0.08 Al, 0.001-0.010 N, 0.10-0.20 Cu, 0.002-0.015 Nb, 0.002-0.010 Ti, 0.001-0.005 B, not more than 0.010 S, not more than 0.015 P, Fe, hardening is performed at temperature of 930-980 °C, tempering at temperature of 170-200 °C.

EFFECT: after heat treatment sheet steel has following mechanical properties: conditional yield point σ_{0 2/10} not less than 1,250 N/mm², tensile strength σ_v 1,450-1,750 N/mm², hardness of 480-540 HBW, percentage elongation δ₅ not less than 8 % and impact strength KCV^-40 not less than 30 J/cm².

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