COLD ROLLED HEAT PROCESSED SHEET STEEL AND ITS MANUFACTURING METHOD Russian patent published in 2022 - IPC C21D8/02 C21D9/46 C22C38/06 C22C38/54 

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, namely to cold rolled and heat processed sheet steel suitable for being used as sheet steels for cars. Cold rolled and heat processed sheet steel has a composition, in wt.%: 0.10 ≤ carbon ≤ 0.5, 1 ≤ manganese ≤ 3.4, 0.5 ≤ silicon ≤ 2.5, 0.03 ≤ aluminum ≤ 1.5, 0 ≤ sulfur ≤ 0.003, 0.002 ≤ phosphorus ≤ 0.02, 0 ≤ nitrogen ≤ 0.01, if necessary, it may contain one or several following optional elements: 0.05 ≤ chromium ≤ 1, 0.001 ≤ molybdenum ≤ 0.5, 0.001 ≤ niobium ≤ 0.1, 0.001 ≤ titanium ≤ 0.1, 0.01 ≤ copper ≤ 2, 0.01 ≤ nickel ≤3, 0.0001 ≤ calcium ≤ 0.005, 0 ≤ vanadium ≤ 0.1, 0 ≤ boron ≤ 0.003, 0 ≤ cerium ≤ 0.1, 0 ≤ magnesium ≤ 0.010, 0 ≤ zirconium ≤ 0.010, the rest is iron and unavoidable impurities. A microstructure of sheet steel contains, when expressed in surface fraction concentration, from 10 to 30% of residual austenite, from 10 to 40% of bainite, from 5 to 50% of burned martensite, from 1 to 20% of calcinated martensite, and from 0 to 30% of released martensite, while total amounts of bainite and residual austenite are more than or equal to 25%.

EFFECT: sheet steel is characterized by high strength, good weldability, as well as it is suitable for being used in molding, in particular in rolling.

19 cl, 4 tbl, 15 ex