STEEL SHEET HAVING VERY HIGH MECHANICAL PROPERTIES OF STRENGTH AND DUCTILITY, MANUFACTURING METHOD AND USE OF SUCH SHEETS Russian patent published in 2019 - IPC C21D8/02 C22C38/38 C22C38/34 

FIELD: metallurgy.

SUBSTANCE: invention relates to the field of metallurgy, in particular to the manufacture of annealed cold-rolled steel sheet with a strength of more than 900 MPa, elastic limit of more than 700 MPa and distributed elongation of more than 12 %, used for the manufacture of vehicle parts. In the method, the composition of the steel sheet includes, wt.%: 0.26≤C≤0.45; 1.0≤Mn≤3.0; 1.0≤Si≤3.0; Al≤0.10; Cr≤1.5; S≤0.005; P≤0.020; Nb≤0.1; Ti≤0.020; V≤0.015; N≤0.01, the rest is iron and inevitable impurities resulting from the production process. Further, the microstructure of the sheet comprises, in units of surface area, 13–25 % residual austenite, 13–30 % of islands of martensite and residual austenite, the rest is bainite and ferrite.

EFFECT: inventions ensure sheets with the desired set of properties.

17 cl, 3 tbl