Abstract: The present invention provides a cast steel for ring-shaped components that has a low average coefficient of thermal expansion in a temperature range of 20° C. to 500° C. and high strength and good oxidation resistance at 500° C., which are required for ring-shaped components for use as blade rings and seal ring retainers of gas turbines, and that can hence be used for blade rings and seal ring retainers of gas turbines. Specifically, the present invention provides a high-strength and low-thermal expansion cast steel comprising, on a mass percentage basis, 0.1 to 0.8% of C, 0.1 to 1.0% of Si, 0.1 to 1.0% of Mn, 0.01 to 0.1% of S, greater than 40% and up to 50% of Ni, not greater than 4% (inclusive of 0%) of Co, greater than 1.5% and up to 4% of Cr, 0.01 to 0.1% of Al, and 0.001 to 0.1% of Mg, the remainder being substantially Fe.

Abstract: The present invention provides a cast steel for ring-shaped components that has a low average coefficient of thermal expansion in a temperature range of 20° C. to 500° C. and high strength and good oxidation resistance at 500° C., which are required for ring-shaped components for use as blade rings and seal ring retainers of gas turbines, and that can hence be used for blade rings and seal ring retainers of gas turbines. Specifically, the present invention provides a high-strength and low-thermal expansion cast steel comprising, on a mass percentage basis, 0.1 to 0.8% of C, 0.1 to 1.0% of Si, 0.1 to 1.0% of Mn, 0.01 to 0.1% of S, greater than 40% and up to 50% of Ni, not greater than 4% (inclusive of 0%) of Co, greater than 1.5% and up to 4% of Cr, 0.01 to 0.1% of Al, and 0.001 to 0.1% of Mg, the remainder being substantially Fe.

Abstract: A manufacturing method, particularly a forging treatment and a heat treatment method of a Ni-based alloy having sulfidation-corrosion resistance used for component members of corrosion-resistant high-temperature equipment, that is, Waspaloy (a trademark of United Technologies) or its improved Ni-based alloy wherein the high temperature sulfidation-corrosion resistance of the alloy can be improved while maintaining hot strength properties is disclosed. A Ni-based alloy used for the method consists essentially of 0.005 to 0.1% C, 18 to 21% Cr, 12 to 15% Co, 3.5 to 5.0% Mo, not more than 3.25% Ti and 1.2 to 4.0% Al (expressed in mass percentage), with the balance substantially comprising Ni.

Abstract: A manufacturing method, particularly a heat treatment method of a Ni-based alloy having sulfidation-corrosion resistance used for component members of corrosion-resistant high-temperature equipment, that is, Waspaloy (a trademark of United Technologies) or its improved Ni-based alloy wherein the high temperature sulfidation-corrosion resistance of the alloy can be improved while maintaining hot strength properties is disclosed. A Ni-based alloy used for the method consists essentially of 0.005 to 0.1% C, 18 to 21% Cr, 12 to 15% Co, 3.5 to 5.0% Mo, not more than 3.25% Ti and 1.2 to 4.0% Al (expressed in mass percentage), with the balance substantially comprising Ni. In the manufacturing method of a Ni-based alloy having improved sulfidation-corrosion resistance, the alloy is, after solution heat treatment, subjected to stabilizing treatment at a temperature not lower than 860° C. and not higher than 920° C. for 1 to 16 hours, and aging treatment at a temperature not lower than 680° C.

Abstract: A manufacturing method, particularly a forging treatment and a heat treatment method of a Ni-based alloy having sulfidation-corrosion resistance used for component members of corrosion-resistant high-temperature equipment, that is, Waspaloy (a trademark of United Technologies) or its improved Ni-based alloy wherein the high temperature sulfidation-corrosion resistance of the alloy can be improved while maintaining hot strength properties is disclosed. A Ni-based alloy used for the method consists essentially of 0.005 to 0.1% C, 18 to 21% Cr, 12 to 15% Co, 3.5 to 5.0% Mo, not more than 3.25% Ti and 1.2 to 4.0% Al (expressed in mass percentage), with the balance substantially comprising Ni.

Abstract: A manufacturing method, particularly a heat treatment method of a Ni-based alloy having sulfidation-corrosion resistance used for component members of corrosion-resistant high-temperature equipment, that is, Waspaloy (a trademark of United Technologies) or its improved Ni-based alloy wherein the high temperature sulfidation-corrosion resistance of the alloy can be improved while maintaining hot strength properties is disclosed. A Ni-based alloy used for the method consists essentially of 0.005 to 0.1% C, 18 to 21% Cr, 12 to 15% Co, 3.5 to 5.0% Mo, not more than 3.25% Ti and 1.2 to 4.0% Al (expressed in mass percentage), with the balance substantially comprising Ni. In the manufacturing method of a Ni-based alloy having improved sulfidation-corrosion resistance, the alloy is, after solution heat treatment, subjected to stabilizing treatment at a temperature not lower than 860° C. and not higher than 920° C. for 1 to 16 hours, and aging treatment at a temperature not lower than 680° C.

Abstract: A nickel-base cast alloy for use in high-temperature forging dies operable in the atmosphere, consisting essentially of 4-10 weight % of Al, 13-23 weight % of Mo and the balance of Ni and impurities. The nickel-base cast alloy may further contain up to 0.1 weight % of at least one of rare earth metals and Y. It may also contain up to 15 weight % of W and/or Ta substituting for a part of Mo. Ni may be replaced by up to 20 weight % of Co. The cast alloy of the present invention has high resistance to compression deformation and oxidation.