SURFACE-HARDENED STEEL, AND METHOD FOR ITS OBTAINING Russian patent published in 2014 - IPC C22C38/32 C21D8/06 B22D11/22 

FIELD: metallurgy.

SUBSTANCE: invention refers to metallurgy, and namely to surface-strengthened steel. Steel contains the following, wt %: C 0.05 to 0.3, Si 0.01 to 0.6, Mn 0.20 to 1.0, S 0.001 to 0.025, Cr 1 to 2.5, Al 0.01 to 0.10, Ti 0.01 to 0.10, Nb 0.01 to 0.10, B 0.0005 to 0.005, N 0.002 to 0.02, and iron and inevitable impurities are the rest. Microstructure of steel contains a ferrite component in the amount of more than 77% as to surface area; besides, among released phases containing Ti and/or Nb, phases having the size of at least 20 mcm² are present with density of particle distribution of not more than 1.0/mm², and among released phases containing Ti and/or Nb, released phases having the size of more than 5 mcm² and less than 20 mcm² and containing Mn and S are present with density of particle distribution of more than 0.7/mm² and not more than 3.0/mm².

EFFECT: steel is suitable for cold forming and has high characteristics of impact viscosity after treatment with surface strengthening.

4 cl, 4 dwg, 6 tbl, 1 ex