COLD-ROLLED COATED STEEL SHEET AND METHOD FOR PRODUCTION THEREOF Russian patent published in 2022 - IPC C21D8/02 C22C38/06 C21D9/46 

FIELD: metallurgy.

SUBSTANCE: invention relates to the field of metallurgy, namely, to the manufacture of a cold-rolled steel sheet used in automotive engineering. The sheet has the following chemical composition, including the following elements, in % wt.: 0.13 ≤ carbon ≤ 0.18, 1.1 ≤ manganese ≤ 1.8, 0.5 ≤ silicon ≤ 0.9, 0.6 ≤ aluminium ≤ 1.0, 0.002 ≤ phosphorus ≤ 0.02, 0 ≤ sulphur ≤ 0.003, 0 ≤ nitrogen ≤ 0.007, if necessary, one or several of the following optional elements: 0.05 ≤ chromium ≤ 1.0, 0.001 ≤ molybdenum ≤ 0.5, 0.001 ≤ niobium ≤ 0.1, 0.001 ≤ titanium ≤ 0.1, 0.01 ≤ copper ≤ 2.0, 0.01 ≤ nickel ≤ 3.0, 0.0001 ≤ calcium ≤ 0.005, vanadium ≤ 0.1, boron ≤ 0.003, cerium ≤ 0.1, magnesium ≤ 0.010, and zirconium ≤ 0.010, iron and unavoidable impurities the rest. The microstructure of said steel sheet includes, in area fractions, 60 to 75% ferrite, 20 to 30% bainite, 10 to 15% residual austenite, and 0 to 5% martensite, wherein the sum content of residual austenite and ferrite is between 70% and 80%.

EFFECT: resulting sheets have high strength characteristics and moulding capacity.

21 cl, 4 tbl