HIGH STRENGTH-CORROSION RESISTANT OF AUSTENITE- MARTENSITE CLASS Russian patent published in 2001 - IPC

FIELD: metallurgy, more particularly creation of high-strength corrosion-resistant steel of austenite-martensite class intended for manufacturing highly loaded large size machine components operating at temperatures from -70 C to +300 C. SUBSTANCE: claimed steel comprises, wt %: carbon, 0.18-0.21; chromium, 13-14; nickel, 4-4.5; molybdenum, 2.3-2.8; silicon, 1.7-2.5; cobalt, 3.5-4.5; nitrogen, 0.06- 0.09; manganese, 0.1-1.0; yttrium, 0.001-0.05; cerium, 0.001-0.05; lanthanum, 0.001-0.05; and iron, the balance. In this case, sum Y+Ca+La is equal or more than 0.1%, and ratio of components which determined phase composition of steel is characterized by formulas: K_m= Cr+Mo+1,5Ni+30(C+N)+0,7(Mn+Si) = 30-35 and K_f= Cr+Mo+2Si-{1,5Ni+30(C+N)+0,7Mn} = 5-5,5 wherein K_m is martensite formation equivalent, and K_f is ferrite formation equivalent. EFFECT: increased strength, greater plasticity, impact viscosity and corrosion cracking resistance. 2 cl, 2 tbl