HEAT-TREATED COLD-ROLLED STEEL SHEET AND METHOD OF ITS MANUFACTURING Russian patent published in 2024 - IPC C21D8/02 C22C38/58 C22C38/60 C22C38/54 C22C38/50 C22C38/48 C22C38/46 C22C38/44 C22C38/42 C22C38/40 C22C38/38 C22C38/32 C22C38/28 C22C38/26 C22C38/24 C22C38/22 C22C38/20 

FIELD: metallurgy.

SUBSTANCE: invention relates to production of heat-treated cold-rolled steel sheet used for production of automotive parts. Sheet has a chemical composition consisting of the following elements, wt.%: 0.1≤C≤0.2, 1.2≤Mn≤2.2, 0.05≤Si≤0.6, 0.001≤Al≤0.1, 0.01≤Cr≤0.5, 0≤S≤0.09, 0≤P≤0.09, 0≤N≤0.09, optionally, at least one element selected from 0≤Mo≤0.5, 0≤Ti≤0.1, 0≤Nb≤0.1, 0≤V≤0.1, 0≤Ni≤1, 0≤Cu≤1, 0≤Ca≤0.005, 0≤B≤0.05, 0≤Ce≤0.1, 0≤Mg≤0.05 and 0≤Zr≤0.05, the rest is iron and unavoidable impurities. Microstructure of steel consists of, in percentage of area, 60–85% of tempering martensite, total amount of ferrite and bainite, which is 15–38%, optional amount residual austenite of 0–5%, and an optional amount of fresh martensite of 0–5%. Sheet has tensile strength of 980–1,150 MPa in direction transverse to rolling direction, and ultimate tensile strength 980–1,150 MPa in rolling direction.

EFFECT: sheet has the required level of mechanical properties and formability both in the rolling direction and in the direction transverse to the rolling direction.

17 cl, 4 tbl