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 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 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 relatively high strength high toughness medium Carbon Copper-Nickel-Chromium alloy steel and method that eliminates and/or reduces the use of scarce, expensive alloying elements and is lower in cost than existing high strength high toughness alloy steels with comparable strength and toughness properties. In a first embodiment, the alloy steel is comprised of by weight about 0.40–1.00% Copper, about 2.50–8.00% Nickel, and about 0.80–3.50% Chromium. In a second embodiment the alloy steel is comprised of by weight about 0.55–0.70% Copper, about 1.0–6.0% Nickel, and about 1.0–2.2% Chromium.

Abstract: A composition and method for reducing cost and improving the mechanical properties of alloy steels. The invention resides in the ability of certain combinations of carbon-subgroup surfactants and d-transition metals to modify and control diffusion mechanisms of interstitial elements; to reduce or prevent the formation of non-equilibrium segregations of harmful admixtures and brittle phases on free metal surfaces and grain and phase boundaries; and to alter and control phase transformation kinetics in steel during heating and cooling.

Abstract: A composition and method for reducing cost and improving the mechanical properties of alloy steels. The invention resides in the ability of certain combinations of carbon-subgroup surfactants and d-transition metals to modify and control diffusion mechanisms of interstitial elements; to reduce or prevent the formation of non-equilibrium segregations of harmful admixtures and brittle phases on free metal surfaces and grain and phase boundaries; and to alter and control phase transformation kinetics in steel during heating and cooling.

Abstract: A composition and method for reducing cost and improving the mechanical properties of alloy steels. The invention resides in the ability of certain combinations of carbon-subgroup surfactants and d-transition metals to modify and control diffusion mechanisms of interstitial elements; to reduce or prevent the formation of non-equilibrium segregations of harmful admixtures and brittle phases on free metal surfaces and grain and phase boundaries; and to alter and control phase transformation kinetics in steel during heating and cooling.