HIGH-STRENGTH COLD-ROLLED SHEET STEEL AND METHOD OF ITS PRODUCTION Russian patent published in 2014 - IPC C22C38/24 C21D8/02 

FIELD: metallurgy.

SUBSTANCE: sheet is made of steel containing in wt %: 0.06-0.12 C, 0.4-0.8 Si, 1.6-2.0 Mn, 0.01-1.0 Cr, 0.001-0.1 V, 0.05 or less P, 0.01 or less S, 0.01-0.5 sol. Al, and 0.005 or less N, iron and unavoidable impurities making the rest. Said sheet features structure including the following components in volume fractions: polygonal ferrite - 50% or more, martensite - 5-15, residual austenite - 1-5, bainite or perlite or both making the rest.

EFFECT: mean grain size of residual austenite makes 10 mcm or less while aspect ratio of residual austenite phase makes 5 or less.

5 cl, 4 tbl, 2 ex