MANUFACTURING METHOD OF HIGH-STRENGTH PLATE STEEL Russian patent published in 2011 - IPC C21D8/02 C22C38/26 

FIELD: metallurgy.

SUBSTANCE: method involves manufacture of steel slabs, their steel slabs, their heating, hot plate rolling, hardening of plates with the following high-temperature tempering; at that, slabs are made from steel of the following chemical composition, wt %: 0.13-0.19 C; 0.5-1.1 Mn; 0.3-0.7 Si; 1.1-1.7 Cr; 0.03-0.08 Nb; 0.02-0.06 Al; 0.002-0.030 Ca; 0.003-0.008 N; maximum 0.010 S; maximum 0.015 P; iron is the rest. Slabs are heated at least to 1150°C; hot plate rolling is performed with total relative reduction of cross-sectional area of not less than 80% and completed in temperature range of 750-950°; hardening of plates is performed at 890-930°C, and high-temperature tempering is performed at 600-680°C.

EFFECT: improving strength properties and yield ratio.

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