COLD-ROLLED AND HEAT-TREATED STEEL SHEET AND METHOD OF MANUFACTURING THEREOF Russian patent published in 2025 - IPC C22C38/38 C22C38/34 C22C38/26 C22C38/32 C22C38/28 C22C38/24 C22C38/22 C22C38/20 C22C38/40 C22C38/58 C22C38/54 C22C38/50 C22C38/48 C22C38/46 C22C38/44 C22C38/42 C21D8/02 

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, namely to cold-rolled and heat-treated steel sheet used as material for fabrication of structural or safety parts of a vehicle. Sheet has a composition containing the following elements, wt.%: 0.1 ≤ carbon ≤ 0.5, 1 ≤ manganese ≤ 3.4, 0.5 ≤ silicon ≤ 2.5, 0.01 ≤ aluminium ≤ 1.5, 0.05 ≤ chrome ≤ 1, 0.001 ≤ niobium ≤ 0.1, sulphur ≤ 0.003, 0.002 ≤ phosphorus ≤ 0.02, nitrogen ≤ 0.01, optionally at least one element selected from: molybdenum ≤ 0.5, 0.001 ≤ titanium ≤ 0.1, 0.01 ≤ copper ≤ 2, 0.01 ≤ nickel ≤ 3.0.0001 ≤ calcium ≤ 0.005, vanadium ≤ 0.1, boron ≤ 0.003, cerium ≤ 0.1, magnesium ≤ 0.010, zirconium ≤ 0.010, rest is iron and unavoidable impurities. Microstructure of steel sheet includes, in area fractions, from 10% to 60% of bainite, from 5% to 50% of ferrite, from 5% to 25% of residual austenite, from 2% to 20% of martensite, from 0% to 25% of tempered martensite, wherein the rest is annealed martensite, the content of which ranges from 1% to 45%.

EFFECT: obtaining sheets with ultimate tensile strength of at least 960 MPa and total elongation of at least 20%.

15 cl, 4 tbl