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

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, namely to steel sheets used as structural elements in automotive vehicles for performance of function of protection against damage or shock energy absorption. Sheet is made from steel having a composition comprising, 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, and optionally Ni≤0.5, the rest is iron and unavoidable impurities. Sheet has a microstructure including, in surface fractions, 60–95% of ferrite, the rest being martensite-austenite islands, pearlite or bainite. Said steel sheet includes a base, on top of which there is a surface layer occupying the most distant from centre of 10% of thickness on each of their two sides of the base. Said surface layer is characterized by its filling with inclusions, in which surface fraction of oxides is equal to or less than 60⋅10^-6.

EFFECT: press-hardened steel parts made from sheet have high mechanical properties and bending angle.

5 cl, 1 dwg, 4 tbl