The precipitation hardened martensitic stainless steel is characterized by containing, in percent by weight, 12.25 to 14.25% Cr, 7.5 to 8.5% Ni, 1.0 to 2.5% Mo, 0.05% or less C, 0.2% or less Si, 0.4% or less Mn, 0.03% or less P, 0.005% or less S, 0.008% or less N, 0.90 to 2.25% Al, the balance substantially being Fe, and the total content of Cr and Mo being 14.25 to 16.75%. A turbine moving blade and a steam turbine are manufactured by using this martensitic stainless steel.

The precipitation hardened martensitic stainless steel is characterized by containing, in percent by weight, 12.25 to 14.25% Cr, 7.5 to 8.5% Ni, 1.0 to 2.5% Mo, 0.05% or less C, 0.2% or less Si, 0.4% or less Mn, 0.03% or less P, 0.005% or less S, 0.008% or less N, 0.90 to 2.25% Al, the balance substantially being Fe, and the total content of Cr and Mo being 14.25 to 16.75%. A turbine moving blade and a steam turbine are manufactured by using this martensitic stainless steel.

The invention relates to a steel and to a flat steel product produced therefrom that have optimized mechanical properties and at the same time can be produced at low cost, without having to rely for this on expensive alloying elements that are subject to great fluctuations with regard to their procurement costs. The steel and the flat steel product have for this purpose the following composition according to the invention (in % by weight): C: 0.11-0.16%; Si: 0.1-0.3%; Mn: 1.4-1.9%; Al: 0.02-0.1%; Cr: 0.45-0.85%; Ti: 0.025-0.06%; B: 0.0008-0.002%, the remainder Fe and impurities that are unavoidable for production-related reasons, which include contents of phosphorus, sulfur, nitrogen or molybdenum as long as the following respectively apply for their contents: P: 0.02%, S: 0.003%, N: 0.008%, Mo: 0.1%. Similarly, the invention relates to a method for producing a flat steel product that consists of a steel according to the invention.

The invention relates to a steel and to a flat steel product produced therefrom that have optimized mechanical properties and at the same time can be produced at low cost, without having to rely for this on expensive alloying elements that are subject to great fluctuations with regard to their procurement costs. The steel and the flat steel product have for this purpose the following composition according to the invention (in % by weight): C: 0.11-0.16%; Si: 0.1-0.3%; Mn: 1.4-1.9%; Al: 0.02-0.1%; Cr: 0.45-0.85%; Ti: 0.025-0.06%; B: 0.0008-0.002%, the remainder Fe and impurities that are unavoidable for production-related reasons, which include contents of phosphorus, sulfur, nitrogen or molybdenum as long as the following respectively apply for their contents: P: 0.02%, S: 0.003%, N: 0.008%, Mo: 0.1%. Similarly, the invention relates to a method for producing a flat steel product that consists of a steel according to the invention.

A martensitic stainless steel alloy is strengthened by copper-nucleated nitride precipitates. The alloy includes, in combination by weight percent, about 10.0 to about 12.5 Cr, about 2.0 to about 7.5 Ni, up to about 17.0 Co, about 0.6 to about 1.5 Mo, about 0.5 to about 2.3 Cu, up to about 0.6 Mn, up to about 0.4 Si, about 0.05 to about 0.15 V, up to about 0.10 N, up to about 0.035 C, up to about 0.01 W, and the balance Fe and incidental elements and impurities. The nitride precipitates may be enriched by one or more transition metals. A case hardened, corrosion resistant variant has a reduced weight percent of Ni, enabling increased use of Cr, and decreased Co.

A martensitic stainless steel alloy is strengthened by copper-nucleated nitride precipitates. The alloy includes, in combination by weight percent, about 10.0 to about 12.5 Cr, about 2.0 to about 7.5 Ni, up to about 17.0 Co, about 0.6 to about 1.5 Mo, about 0.5 to about 2.3 Cu, up to about 0.6 Mn, up to about 0.4 Si, about 0.05 to about 0.15 V, up to about 0.10 N, up to about 0.035 C, up to about 0.01 W, and the balance Fe and incidental elements and impurities. The nitride precipitates may be enriched by one or more transition metals. A case hardened, corrosion resistant variant has a reduced weight percent of Ni, enabling increased use of Cr, and decreased Co.

A process includes: (a) providing a tantalum-coated metal alloy substrate; (b) heat annealing the tantalum-coated metal alloy substrate by heating to an annealing temperature for the tantalum-coated metal alloy substrate, holding at the annealing temperature for a period of time and then quenching to a temperature below 50 degrees Celsius; (c) heating the tantalum-coated metal substrate to the precipitation hardening temperature of the metal alloy substrate; and (d) cooling the tantalum-coated metal alloy substrate to a temperature below 50 degrees Celsius; wherein the process is further characterized by carrying out steps (b)-(d) under a tantalum-inert gas atmosphere and by quenching in step (b) and cooling in step (d) being carried out by flowing a tantalum-inert gas having a temperature of less than 50 degrees Celsius over the tantalum-coated metal alloy substrate.

A process includes: (a) providing a tantalum-coated metal alloy substrate; (b) heat annealing the tantalum-coated metal alloy substrate by heating to an annealing temperature for the tantalum-coated metal alloy substrate, holding at the annealing temperature for a period of time and then quenching to a temperature below 50 degrees Celsius; (c) heating the tantalum-coated metal substrate to the precipitation hardening temperature of the metal alloy substrate; and (d) cooling the tantalum-coated metal alloy substrate to a temperature below 50 degrees Celsius; wherein the process is further characterized by carrying out steps (b)-(d) under a tantalum-inert gas atmosphere and by quenching in step (b) and cooling in step (d) being carried out by flowing a tantalum-inert gas having a temperature of less than 50 degrees Celsius over the tantalum-coated metal alloy substrate.

A hot rolled steel sheet comprises: a predetermined chemical composition; a microstructure in which a total area ratio of a tempered bainite phase and a tempered martensite phase is 70% or more, a total area ratio of a coarse pearlite phase, a martensite phase, and a retained austenite phase is 10% or less, the tempered bainite phase and the tempered martensite phase have laths with an average width of 1.0 m or less as a substructure, a proportion of Fe-based carbides with an aspect ratio of 5 or less in Fe-based carbides precipitated inside and at boundaries of the laths is 80% or more, and MC-type carbides with an average particle size of 20 nm or less are dispersed and precipitated inside and at the boundaries of the laths; and an average dislocation density of 1.010.sup.14 m.sup.2 or more and 5.010.sup.15 m.sup.2 or less.

A material for high carburizing steel and a method for producing a gear using the material are provided. The material includes C of about 0.13 to 0.3 wt %, Si 0.7 to 1.3 wt %, Mn of about 0.3 to 1 wt %, P of about 0.02 wt % or less, S of about 0.03 wt % or less, Cr of about 2.2 to 3.0 wt %, Mo of about 0.2 to 0.7 wt %, Cu of about 0.3 wt % or less, Nb of about 0.03 to 0.06 wt %, V of about 0.1 to 0.3 wt %, Ti of about 0.001 to 0.003 wt %, a balance of Fe and other inevitable.