Abstract: High strength precipitation hardening stainless steel alloy is disclosed. The steel alloy has a composition by weight %, about: 30.0% max nickel (Ni), 0.0 to 15.0% cobalt (Co), 25.0% max chromium (Cr), 5.0% max molybdenum (Mo), 5.0% max titanium (Ti), 5.0% max vanadium (V), about 0.5% max lanthanum (La) and/or cerium (Ce), and in balance iron (Fe) and inevitable impurities. The steel alloy provides a unique combination of corrosion resistance, strength and toughness and is a material for aircraft landing gears and structures.

Abstract: High strength precipitation hardening stainless steel alloy is disclosed. The steel alloy has a composition by weight %, about: 30.0% max nickel (Ni), 0.0 to 15.0% cobalt (Co), 25.0% max chromium (Cr), 5.0% max molybdenum (Mo), 5.0% max titanium (Ti), 5.0% max vanadium (V), and iron (Fe) and inevitable impurities are in balance. The steel alloy is predominantly hardened (strengthened) by precipitates: two or more binary intermetallic phases Ni3Ti and Ni3V and complex intermetallic phases (Ni, Me1)3(Ti, Me2) and (Ni, Me1)3(V, Me2), wherein M1 is one or more elements of Ni-site substitution and M2 is one or more elements of Ti and V-site substitutions. The disclosed steel alloy provides a unique combination of corrosion resistance, strength and toughness.

Abstract: The present invention relates to a wrought, quenched and tempered, fine-grained, with deep hardenability, high strength and low alloy steel having a sum of the alloying elements: nickel, molybdenum, tungsten, vanadium, titanium, and niobium in weight percent 1.0% to 1.60%. The air melted and hot forged steel of the present invention has hardness of HRC 55, an ultimate tensile strength of 300 ksi, a yield strength of 257 ksi, a total elongation of 9%, a reduction of area of 32%, and Charpy v-notch impact toughness energy of 15 ft-lb after normalizing, gas quenching, and tempering at 450° F.

Abstract: The present invention relates to a wrought, quenched and tempered, fine-grained, with deep hardenability, high strength and low alloy steel having a sum of the alloying elements: nickel, molybdenum, tungsten, vanadium, titanium, and niobium in weight percentage of 1.60% maximum in the first embodiment; vanadium, titanium, and niobium in weight percentage of 0.40% maximum in the second embodiment; titanium and niobium in weight percentage of 0.10% in the third embodiment. The air melted and hot forged steel of the first embodiment has hardness of HRC 55, an ultimate tensile strength of 300 ksi, a yield strength of 257 ksi, a total elongation of 9%, a reduction of area of 32%, and Charpy v-notch impact toughness energy of 15 ft-lb after normalizing, gas quenching, and tempering at 450° F.

Abstract: A high hardness, high strength, and high impact toughness steel for military articles such as armor plates, bodies of deep penetrating bombs, and missiles. The steel has a HRC of 54 to 56, UTS of 290 to 305 ksi, YS of 225 to 235 ksi, an elongation of 13-14%, a reduction of area of 47-50% and a Charpy V-notch impact toughness energy of 26 to 28 ft-lbs at room temperature. The microstructure of the steel consists essentially of fine packets of martensitic lathes, fine titanium carbides as centers of growth of the martensitic lathes, and retained austenite.

Abstract: A quenched and tempered high strength, corrosion resistant steel suitable for aircraft landing gears and structures, having a unique combination of mechanical and corrosion resistant properties: ultimate tensile strength of 295 to 305 ksi, yield strength of 225 to 235 ksi; elongation of 12 to 13.5%, reduction of area of 34 to 36%, Charpy v-notch impact toughness energy of about 14 to 16 ft-lb, fracture toughness of 55 to 60 ksiVin, and corrosion resistance in salt spray test.

Abstract: A method of designing low cost, high strength, high toughness martensitic steel uses mathematical modeling to define optimum low cost chemical compositions, the content of retained austenite, and critical temperatures; melting an ingot, processing same, making steel articles, and heat treating the articles using the critical temperatures and the content of retained austenite. The new steel comprises, by weight, about 0.3-0.45% of C; at most 2.5% of Cr; at most 1.0% of Mo; at most 3.50% of Ni; about 0.3 to 1.5% of Mn; about 0.1-1.3% of Si; about 0.1-1.0% of Cu; Cu being less than Si; about 0.1 to 1.0% of V+Ti+Nb; at most 0.25% of Al; the sum of alloying elements being less than about 11.5%; the balance being essentially Fe and incidental impurities. Procedures of melting, processing and heat treatment using the mathematical model are disclosed.

Abstract: A cobalt-free low cost high strength martensitic stainless steel, with concentration of Ni up to 3.0% and Mo up to 1.0% of weight, has HRC of 53, UTS of 297 ksi, YS of 220 ksi, Charpy V-notch impact energy of 17.8 ft-lb, corrosion resistance in salt spray test ASTM 117. The steel was melted in an open induction furnace and vacuum arc remelting (VAR) and/or electroslag remelting (ESR) were not used to refine the steel. Further processing included homogenized annealing, hot rolling, and recrystallization annealing. The steel was heat treated by oil quenching, refrigeration, and low tempering. The steel has a microstructure consisting essentially of small packets of fine martensite laths, retained austenite, and carbides as centers of growth of the martensite laths. The cost and energy in making the steel are substantially reduced.

Abstract: A quenched and tempered high strength, corrosion resistant steel suitable for aircraft landing gears and structures, having a unique combination of mechanical and corrosion resistant properties: ultimate tensile strength of 295 to 305 ksi, yield strength of 225 to 235 ksi; elongation of 12 to 13.5%, reduction of area of 34 to 36%, Charpy v-notch impact toughness energy of about 14 to 16 ft-lb, fracture toughness of 55 to 60 ksiVin, and corrosion resistance in salt spray test.

Abstract: A method for designing a low cost, high strength, high toughness martensitic steel in which a mathematical model is used to establish an optimum low cost alloying concentration that provides specified levels of strength toughness. The model also predicts critical temperatures and the amount of retained austenite. Laboratory scale ingots of the optimum alloying composition were produced comprising by % wt. of about: 0.37 of C; 1.22 of Ni; 0.68 of Mn; 0.86 of Si; 0.51 of Cu; 1.77 of Cr; and 0.24 of V; and the balance Fe and incidental impurities were melted in an open induction furnace. After homogenized annealing, hot rolling, recrystallization annealing, and further oil quenching, refrigerating, and low tempering, a tempered martensite microstructure was produced consisting of small packets of martensitic laths, fine vanadium carbide, as centers of growth of the martensitic lathes, and retained austenite.

Abstract: A low cost high hardness, high strength, and high impact toughness steel for military articles such as armor plates, bodies of deep penetrating bombs, and missiles. After oil quenching, refrigerating, and low tempering, the new steel consisting of (% wt.): C=0.35, Cr=1.32, Mo=0.35, W=0.52, Ni=2.66, Mn=0.85, Cu=0.51, Si=0.83, V=0.26, Ti=0.12, and a balance of Fe and incidental impurities has a HRC of 55, UTS of 301 ksi, YS of 233 ksi; and Charpy V-notch impact toughness energy of 26 ft-lbs.

Abstract: A cobalt-free low cost high strength martensitic stainless steel, with concentration of Ni up to 3.0% and Mo up to 1.0% of weight, has HRC of 53, UTS of 297 ksi, YS of 220 ksi, Charpy V-notch impact energy of 17.8 ft-lb, corrosion resistance in salt spray test ASTM 117. The steel was melted in an open induction furnace and vacuum arc remelting (VAR) and/or electroslag remelting (ESR) were not used to refine the steel. Further processing included homogenized annealing, hot rolling, and recrystallization annealing. The steel was heat treated by oil quenching, refrigeration, and low tempering. The steel has a microstructure consisting essentially of small packets of fine martensite laths, retained austenite, and carbides as centers of growth of the martensite laths. The cost and energy in making the steel are substantially reduced.