Patent ID: 8361247

Claim:
A quenched and tempered high strength cobalt-free corrosion resistant steel comprising, in combination, by weight percent: about 0.30 to 0.45% carbon (C), about 3.5 to 5.5% nickel (Ni), about 0.1 to 1.0% manganese (Mn), about 0.1 to 1.0% copper (Cu), about 10.0 to 12.5% chromium (Cr), about 0.5 to 1.0% molybdenum (Mo), about 0.05 to 1.0% tungsten (W), about 0.1 to 0.8% vanadium (V), about 0.01 to 0.5% titanium and niobium (Ti+Nb), about 0.0 to 0.25% aluminum (Al), about 0.1 to 1.2% silicon (Si), the balance essentially iron (Fe) and incidental impurities, characterized in that the steel has a microstructure consisting essentially of fine packets of martensitic laths, retained austenite, and carbide particles and said steel has an ASTM grain size number of 6 to 8.