Patent ID: 7537727

Claim:
An alloy steel in weight percentage consisting of from about 0.16% to about 0.35% carbon, about 0.85% maximum manganese, an amount of silicon up to about 1.25% maximum, about 1.50% to about 3.25% chromium, about 5.00% maximum nickel, about 0.55% maximum molybdenum, 1.17% to about 3.25% tungsten, about 0.05% to about 0.30% vanadium, about 0.50% maximum copper, about 0.015% maximum phosphorous, about 0.012% maximum sulfur, about 0.02% maximum calcium, about 0.14% maximum nitrogen, about 0.05% maximum aluminum, and balance consisting essentially of iron, wherein said alloy steel has an ultimate tensile strength level of 233-270 ksi, Charpy V-notch impact strength of 20-43 ft-lb at -40° F. and a ductility low rate strain-to-failure of 16.6 to about 18.4%.