CORROSION-RESISTANT AGE HARDENED STEEL Russian patent published in 2007 - IPC C22C38/52 

FIELD: production of corrosion-resistant age hardened steel strengthened by chemical and heat treatment such as carburizing or nitrocarburizing.

SUBSTANCE: steel according to invention contains, mass %: carbon, 0.12 - 0.19; silicon, 0.1 - 0.6; manganese, 0.1 -0.6; chrome, 14 -15; nickel, 2.3 -3.3; cobalt, 1.0 - 4.0; molybdenum, 1.5 - 2.3; vanadium, 0.1 - 0.2; tungsten, 0.5 -0.8; niobium, 0.06 - 0.12; cerium, 0.005 - 0.05; lanthanum, 0.005 - 0.05; calcium, 0.005 - 0.05; nitrogen, 0,05 - 0.1; iron, the balance. Such steel may operate in temperature range from -70°C till 500°C. After heating at 400°C for 500 h hardness of carburized layer (≥ 59 HRC) and hardness of nitrocarburized layer (≥60 HRC) remains the same and it decreases by 1 HRC at 500°C. Fatigue strength ( σ_-1 = 840 MPa) of such steel in nitrocarburized state exceeds that of any corrosion resistant steel with carburized, nitrocarburized and nitrided layer.

EFFECT: increased fatigue strength of steel.

3 cl, 4 tbl, 4 ex