COLD-ROLLED AND HEAT-TREATED SHEET STEEL, METHOD OF ITS PRODUCTION AND USE OF SUCH STEEL FOR PRODUCTION OF VEHICLE PARTS Russian patent published in 2021 - IPC C21D6/00 C21D8/02 C22C38/02 C22C38/04 C22C38/06 

FIELD: metallurgy.

SUBSTANCE: invention relates to the field of metallurgy, namely to low density steels, and can be used for the manufacture of structural parts of a vehicle or vehicle parts responsible for safety. Cold-rolled and heat-treated sheet steel contains, in wt%: 0.10 ≤ carbon ≤ 0,6, 4 ≤ manganese ≤ 20, 5 ≤ aluminum ≤ 15, 0 ≤ silicon ≤ 2, aluminum + silicon + nickel ≥ 6,5 and optionally containing at least one of the following elements: 0,01 ≤ niobium ≤ 0,3, 0,01 ≤ titanium ≤ 0,2, 0,01 ≤ vanadium ≤ 0,6, 0,01 ≤ copper ≤ 2,0, 0,01 ≤ nickel ≤ 2,0, cerium ≤ 0,01, boron ≤ 0,01, magnesium ≤ 0,05, zirconium ≤ 0,05, molybdenum ≤ 2,0, tantalum ≤ 2,0, tungsten ≤ 2, 0, iron and inevitable impurities - the rest. The microstructure of sheet steel includes surface fractional concentrations from 10 to 50% austenite and the rest is ferrite, including ordered ferrite with the D0₃ structure in an amount of more than 0.1%, and the said austenite phase optionally includes up to 2% of intragranular kappa carbides (Fe, Mn)₃AlC_x, where x is less than 1.

EFFECT: steel has density equal to or less than 7.4, tensile strength of 900 MPa or more, and an elongation of 9% or more.

8 cl, 4 tbl, 8 ex, 1 dwg