STEEL SHEET FOR HEAT TREATMENT Russian patent published in 2019 - IPC C21D8/04 C22C38/00 C22C38/58 

FIELD: metallurgy.

SUBSTANCE: steel sheet contains, 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, T 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 from 0 to 1.0, Nb from 0 to 1.0, REM from 0 to 0.1, Fe and impurities – the rest, at that, maximum roughness height Rz on steel sheet surface ranges from 3.0 to 10.0 mcm, and numerical density of carbide, which is present in steel sheet and having diameter of circle equivalent of 0.1 mcm or more, is 8.0 × 10³/mm² or lower.

EFFECT: high strength and toughness.

4 cl, 4 tbl