STEEL SHEET AND HIGH-STRENGTH PRESS-HARDENED STEEL PART AND METHOD OF ITS MANUFACTURING Russian patent published in 2024 - IPC C21D8/02 C21D1/673 C22C38/22 C22C38/26 C22C38/28 C22C38/32 C22C38/44 C22C38/48 C22C38/50 C22C38/54 

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, namely to steel sheet used for production of high-strength press-hardened steel parts for automotive industry. Sheet is made from steel having the following composition, wt.%: C 0.3–0.4, Mn 0.5–1.0, Si 0.4–0.8, Cr 0.1–1.0, Mo 0.1–0.5, Nb 0.01–0.1, Al 0.01–0.1, Ti 0.008–0.03, B 0.0005–0.003, P≤0.020, Ca≤0.0010, S≤0.004, N≤0.005, optionally Ni<0.5, the rest is iron and unavoidable impurities formed as a result of melting. Sheet has microstructure including 60–95% ferrite in the surface fraction, the rest being martensite-austenite islands, pearlite or bainite. Sheet includes a base and a surface layer located on top of the base, which occupies the most remote from centre of 10% of the thickness on each of their two sides of the base. Said surface layer is characterized by its filling with inclusions, in which the total surface fraction of oxides, MnS and TiNbCN is equal to or less than 75⋅10^-6.

EFFECT: steel parts made from sheets have a combination of high mechanical properties and bending angle.

5 cl, 1 dwg, 4 tbl