COLD-ROLLED AND HEAT-TREATED STEEL SHEET AND ITS MANUFACTURING METHOD Russian patent published in 2022 - IPC C21D8/02 C22C38/58 C22C38/38 C22C38/22 C21D1/18 C21D1/26 C21D9/46 

FIELD: metallurgy.

SUBSTANCE: invention relates to the field of metallurgy, namely cold-rolled and heat-treated steel sheet for the automotive industry. The sheet is made of steel having a composition including, wt. %: C: 0.3-0.4, Mn: 2.0-2.6, Si: 0.8 - less than 1.5, Al: 0.01-0.6, Mo: 0.15-0.5, Cr: 0.3-1.0, Nb ≤ 0.06, Ti ≤ 0.06, Ni ≤ 0.8, S ≤ 0.010, P ≤ 0.020, N ≤ 0.008, Cu ≤ 0.03, if necessary B: 0.0003-0.005 and/or V ≤ 0.2, the rest is iron and unavoidable impurities. The sheet has a microstructure consisting of, in surface fractions: 15-30% residual austenite with a carbon content of at least 0.7%, 70-85% tempered martensite, 0-5% fresh martensite and 0-5% bainite. The sheet has a yield strength of at least 1100 MPa, a tensile strength of at least 1470 MPa, a total elongation of at least 13%, a hole distribution coefficient of at least 15% and an index of resistance to liquid metal embrittlement, LME of less than 0.70.

EFFECT: expansion of the range of solutions to manufacture steel sheet.

16 cl, 5 tbl