STEEL SHEET FOR DIE FORGING Russian patent published in 2022 - IPC C22C38/32 C21D8/02 

FIELD: metallurgy.

SUBSTANCE: invention relates to the field of metallurgy, namely to a steel steel sheet used for manufacturing vehicle parts by dry forging. The sheet comprises, % wt.: C 0.25 or more and 0.4 or less, Si 1.05 or more and 1.4 or less, Mn 0 or more and 1.4 or less, Cr 0.6 or more and 3.0 or less, P 0 or more and 0.03 or less, S 0 or more and 0.02 or less, Al 0.01 or more and 1 or less, N 0 or more and 0.01 or less, B 0.0005 or more and 0.005 or less, Ti 0.005 or more and 0.1 or less, if necessary, at least one element from: Mo 0 or more and 1.0 or less, Nb 0 or more and 0.1 or less, V 0 or more and 0.1 or less, Cu 0 or more and 0.5 or less, and Ni 0 or more and 0.5 or less, the rest iron and unavoidable impurities. The sheet compies with the following conditions: [C] + 2/9[Si] + 7/9[Mn] + 8/9[Cr] - 7/4 > 0, B (HV) > -4.0A + 627, B (HV) ≥ 516, |C-B| ≤ 35 (HV), wherein [C] represents the content of C, [Si] represents the content of Si, [Mn] represents the content of Mn, [Cr] represents the content of Cr, A (J/cm²) represents the absorbed energy in a Charpy impact test at -40°C when the sheet is hardened using a die, B (HV) represents the hardness when the steel sheet is heated to the austenite region and then cooled to room temperature with a cooling rate of 10°C /s and hardened, C (HV) represents the hardness when the steel sheet is heated to the austenite region and then cooled to room temperature with a cooling rate of 30°C /s and hardened.

EFFECT: sheet exhibits excellent hardness stability in addition to the balance between strength and impact toughness.

1 cl, 4 dwg, 2 tbl