HOT-PRESSED STEEL SHEET PART, METHOD OF ITS MANUFACTURE AND STEEL SHEET FOR HOT PRESSING Russian patent published in 2017 - IPC C22C38/58 C22C38/06 B21D22/20 C21D1/18 

FIELD: metallurgy.

SUBSTANCE: steel features the following chemical composition, in wt %: C: 0.10 to 0.34; Si: 0.5 to 2.0; Mn: 1.0 to 3.0; soluble Al: 0.001 to 1.0; P: 0.05 or less; S: 0.01 or less; N: 0.01 or less; Ti: 0 to 0.20; Nb: 0 to 0.20; V: 0 to 0.20; Cr: 0 to 1.0; Mo: 0 to 1.0; Cu: 0 to 1.0; Ni: 0 to 1.0; Ca: 0 to 0.01; Mg: 0 to 0.01; REM: 0 to 0.01; Zr: 0 to 0.01; B: 0 to 0.01; Bi: 0 to 0.01; the rest is Fe and impurities. The share of the ferrite area in the steel structure in the zone of ​​the surface layer, extended in the range from the surface down to a depth of 15 mcm, is greater than 1.20 times the fraction of the ferrite area in the zone of the inner layer, which is the area except for the surface layer. The zone of the inner layer has the structure of steel, % of the area: ferrite from 10 to 70 and martensite from 30 to 90, and the total share of the area of ​​ferrite and martensite is from 90 to 100.

EFFECT: parts produced have a tensile strength of 980 MPa or more and a high plasticity and bendability.

12 cl, 3 tbl