MARTENSITE NITROGEN CONTAINING CORROSION RESISTANT STEEL Russian patent published in 2011 - IPC C22C38/48 

FIELD: metallurgy.

SUBSTANCE: steel contains carbon, silicon, manganese, chromium, nickel, molybdenum, vanadium, nitrogen, niobium, iron and impurities at following ratio of components, wt %: carbon 0.07 - 0.12, nitrogen 0.10 - 0.30, silicon 0.20 - 0.50, manganese 0.70 - 1.00, chromium 12 - 14, nickel 0.9 -2.5, molybdenum 0.4 - 0.8, niobium 0.04-0.08, vanadium 0.05-0.10, iron and impurities - the rest. As impurities steel contains in wt %: sulphur not over 0.010, phosphorus not over 0.010, copper not over 0.200, tin not over 0.015, lead not over 0.002 and after tempering at 950±20° C and annealing at 200 - 650° C it has fine grain structure with actual grain of 8-10 number. Ratio of total contents of niobium and vanadium to carbon (Nb+V)/C is not less, than 1.2, while ratio of chromium contents to total contents of nickel and manganese is 4.8÷7.5.

EFFECT: increased corrosion and brittle fracture resistance of item at simultaneous high hardness and ductility.

4 cl, 1 dwg, 2 tbl, 2 ex