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Abstract

A precipitation-hardenable martensitic low alloy steel for use in producing forgings having an improved combination of strength and toughness. The steel may be quenched directly from forging temperature. The composition of the steel consists essentially of, in weight percent, less than 0.20 carbon, 1.0 to 2.5 manganese, 0.10 to 1.5 silicon, 0.01 to less than 1.0 of at least one carbide, nitride or carbonitride forming element which may be niobium, titanium, vandium aluminum, zirconium or tantalum, less than 0.05 nitrogen, 0.01 to less than 2.0 of at least one of molybdenum, nickel and chromium and the balance iron. The steel upon quenching directly from forging temperature has a yield strength of 90,000 to 165,000 psi, a tensile strength of 120,000 to 210,000 psi, impact energy greater than 15 foot pounds at -22.degree. F. and a ductile-to-brittle transition temperature between minus 40.degree. F. and -25.degree. F.

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