SURFACE-STRENGTHENED STEEL, METHOD FOR ITS OBTAINING AND MACHINE STRUCTURAL PART USING SURFACE-STRENGTHENED STEEL Russian patent published in 2014 - IPC C22C38/32 C21D8/06 

FIELD: metallurgy.

SUBSTANCE: invention refers to metallurgy, and namely to surface-strengthened steel. Steel contains the following, wt %: 0.05-0.20 C, 0.01-0.1 Si, 0.3-0.6 Mn, 0,03 or less P (except for 0), 0.001-0.02 S, 1.2-2.0 Cr, 0.01-0.1 Al, 0.010-0.10 Ti, 0.010 or less N (except for 0), 0.0005-0.005 B, iron and inevitable impurities are the rest. Density of released phases based on Ti, which have a diameter of equivalent circle of less than 20 nm in surface-strengthened steel, is 10-100 particles/mcm², density of released phases based on Ti, which have a diameter of equivalent circle of 20 nm or more in surface-strengthened steel, is 1.5-10 particles/mcm², and Vickers hardness number is 130 HV or less.

EFFECT: steel has high usability for cold forming and high characteristics preventing enlargement of crystalline grains after carbonisation.

7 cl, 1 dwg, 4 tbl, 1 ex