ELEMENT OF HEAT-TREATED STEEL SHEET AND METHOD OF ITS PRODUCTION Russian patent published in 2019 - IPC C22C38/14 C22C38/38 C22C38/58 C21D1/18 C21D9/46 

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, namely to elements from heat-treated steel sheet. Element of heat-treated steel sheet containing the following, wt. %: C from 0.05 to 0.50; Si from 0.50 to 5.0; Mn from 1.5 to 4.0; P 0.05 or less; S 0.05 or less; N 0.01 or less; Ti from 0.01 to 0.10; B from 0.0005 to 0.010; Cr from 0 to 1.0; Ni from 0 to 2.0; Cu from 0 to 1.0; Mo from 0 to 1.0; V from 0 to 1.0; Ca from 0 to 0.01; Al ranges from 0 to 1.0; Nb from 0 to 1.0; REM from 0 to 0.1; and a residue of Fe and impurities. At that, it has microstructure of steel containing mainly martensite, as well as residual austenite 5.0 vol. % or higher. Method of producing element includes heating of steel sheet to temperature range from point Ac3 to point Ac3 + 200 °C with average speed 5 °C/s or higher, sheet cooling to point Ms with upper critical cooling rate or higher and further cooling to 100 °C with average cooling rate 5 °C/s or lower. Element of steel sheet is characterized by tensile strength of 1.4 GPa or higher and full elongation of 8.0 % or higher.

EFFECT: invention can be used in production of impact-resistant car parts.

10 cl, 4 tbl