DOUBLE-ANNEALED STEEL SHEET HAVING HIGH MECHANICAL STRENGTH AND DUCTILITY, METHOD OF MANUFACTURE AND USE OF SUCH SHEETS Russian patent published in 2018 - IPC C21D8/04 C21D9/46 C22C38/02 

FIELD: metallurgy.

SUBSTANCE: to enhance the mechanical properties of a steel sheet, said steel sheet is made from steel containing, wt. %: 0.20≤C≤0.40, 0.8≤Mn≤1.4, 1.60≤Si≤3.00, 0.015≤Nb≤0.150, Al≤0.1, Cr≤1.0, S≤0.006, P≤0.030, Ti≤0.05, V≤0.05, Mo≤0.03, B≤0.003, N≤0.01, iron and unavoidable impurities - the balance, by hot rolling, cold rolling, first and second annealing and cooling, wherein the microstructure comprises, in surface area proportions, 10 to 30 % residual austenite, 30 to 60 % annealed martensite, 5 to 30 % bainite, 10 to 30 % fresh martensite, and less than 10 % ferrite.

EFFECT: improved mechanical properties of steel sheet.

16 cl, 3 tbl