STEEL WITH IMPROVED HARDENABILITY FOR COLD DIE FORGING Russian patent published in 2004 - IPC

FIELD: metallurgy, namely constructional steels designed for making complex-profile heat-treatable parts by cold die forging process. SUBSTANCE: high-strength steel includes next relation of components, mass %: carbon, 0.28 - 0.35; manganese, 0.90 - 1,40; silicon, 0.01 - 0.17; sulfur, 0.005 - 0.020; chrome, 0.01 - 0.25; vanadium, 0.01 -0.07; molybdenum, 0.01 - 0,10; nickel, 0.01 - 0,10; niobium, 0.005 - 0.02; titanium, 0.01 - 0.04; boron, 0.0005 - 0.0050; aluminum, 0.02 - 0.06; nitrogen, 0.005 -0.015; iron, the balance. Next conditions are satisfied: (12/C - Mn/0.55) less or equal to 20; 500 x (Ti/24 - N/7) + 2.2 more or equal to 0; 40 less or equal to (C/0.01 + B/0.001) more or equal to 33. Rolled bars of such steel with diameter up to 35 mm may be hardened in their whole volume. EFFECT: possibility for making complex-profile hardened parts by cold die forging. 2 tbl