HOT-FORMED MEMBER AND PROCESS FOR ITS MANUFACTURING Russian patent published in 2018 - IPC C22C38/58 C21D8/00 B21D22/20 

FIELD: machine building.

SUBSTANCE: invention relates to machine building. To increase the ductility of the element, the base steel sheet containing, by mass%: C 0.05–0.40, Si 0.5–3.0, Mn 2.4–8.0, P 0.05 or less, S 0.01 or less, solute Al 0.001–2.0, N 0,01 or less, Ti 0–1.,0, Nb 0–1.0, V 0–1.0, Cr 0–1.0, Mo 0–1.0, Cu 0–1.0, Ni 0-1.0, Ca 0–0.01, Mg 0–0.01, REM 0–0.01, Zr 0–0.01, B 0–0.01, Bi 0–0.01, Fe and impurities – the rest having a microstructure with a total relative area of bainite and/or martensite of more than or equal to 70 % of the area, and cementite particles with a density greater than or equal to 1.0 particles per micron², is heated to a temperature greater than or equal to 670 °C and less than 780 °C, which is less than the temperature Ac₃, maintained in the said area for 2–20 minutes, form in a hot state and cool with an average cooling rate of 5 to 500 °C/s in the temperature range 600–150 °C to obtain a hot-formed element having a microstructure with an austenite content with a relative area of 10 to 40 % of the area at which the total numerical density of the austenite particles and the martensite particles is greater than or equal to 1.0 particles per micron², and a tensile strength of 900 to 1300 MPa.

EFFECT: increase in the ductility of the hot-formed member.

7 cl, 4 tbl, 1 dwg