Mitsubishi Hitachi Power Systems, Ltd.

Hitachi, Ltd.

Tokyo Institute of Technology

Hironori Kamoshida

Jun Sato

Shinya Imano

Kenichi Murata

Yoshitaka Kojima

Satoshi Hirano

Takashi Shibayama

Hidetoshi Kuroki

Seunghwan Park

Hideki Tamaki

Masao Takeyama

Atsuo Ota

Takehiko Yoshida

Hiroshi Haruyama

Park Seunghwan

To provide a manufacturing process of a Ni based superalloy and a member of the Ni based superalloy which achieves both of excellent workability in a manufacturing step of the Ni based superalloy of the precipitation strengthening type which contains much amount of the gamma prime phase and excellent high temperature strength of the Ni based superalloy. The manufacturing process of a Ni based superalloy includes a step for softening the Ni based superalloy and improving the workability, in which the step for softening the Ni based superalloy and improving the workability is a step for precipitating the gamma prime phase that is incoherent with a gamma phase that is a matrix by 20 vol % or more.

Ni based superalloy, member of Ni based superalloy, and method for producing same

There are provided: an Ni-based alloy member including a &#x3b3;' phase precipitation with 36 to 60 volume % and exhibiting a high durable temperature and good cold workability; a method for producing the member; an Ni-based alloy product to be used as a precursor of the member; and a method for producing the product. The Ni-based alloy product has a two-phase structure composed of a &#x3b3; phase and a &#x3b3;&#x2032; phase being incoherent to the &#x3b3; phase, the incoherent &#x3b3;&#x2032; phase being present at a ratio of 20 volume % or higher. The Ni-based alloy member produced by cold working the Ni-based alloy product and subsequently by conducting heat treatment comprises a &#x3b3; phase and a &#x3b3;&#x2032; phase being coherent to the &#x3b3; phase, the coherent &#x3b3;&#x2032; phase being present at a ratio of 36 to 60 volume %, and has a predetermined shape.

Ni-based alloy product and method for producing same, and Ni-based alloy member and method for producing same

Provided herein are an austenite steel that satisfies desirable strength and desirable castability at the same time, and an austenite steel casting using same. The austenite steel according to an embodiment of the present invention contains Ni: 25 to 50%, Nb: 3.8 to 6.0%, Zr: 0.5% or less, B: 0.001 to 0.05%, Cr: 12 to 25%, Ti: 1.6% or less, Mo: 4.8% or less, and W: 5.2% or less in mass %, and the balance Fe and unavoidable impurities, wherein the parameter Ps represented by the following formula (1) satisfies Ps&#x2264;38,Ps=8.3[Nb]&#x2212;7.5[Ti]+2.4[Mo]+3.5[W]&#x2003;&#x2003;formula (1),where [Nb], [Ti], [Mo], and [W] represent the contents of Nb, Ti, Mo, and W, respectively, in mass %.

Austenite steel, and austenite steel casting using same

An Ni base forged alloy is easy to make hot forging and miniaturization of crystal grains while excellent high-temperature strength and segregation property are compatible. The Ni base forged alloy has solid solution temperature of a precipitation strengthening phase lower than or equal to 970&#xb0; C., difference in the solid solution temperature between a &#x3b4;-phase and the precipitation strength phase larger than or equal to 50&#xb0; C., Al of 0.5 to 1.0%, Cr of 17 to 21%, Fe of 17 to 19%, Nb of 4.5 to 5.5%, Ti of 0.8 to 1.3%, W of 3.0 to 6.0%, B of 0.001 to 0.03%, C of 0.001 to 0.1% and Mo of 1.0% or less in mass percentage [%] and remainder made of Ni and inevitable impurities.

Ni base forged alloy and gas turbine utilizing the same

To provide, in producing a large product through casting, a Ni-based alloy with a composition that minimizes variations in strength at different locations even when the solidification rate becomes slow and the amount of micro segregation increases. The Ni-based casting alloy of the present invention has a composition of, in mass %, 0.001% to 0.1% C, 15% to 23% Cr, 0% to 11.5% Mo, 3% to 18% W, 5 or less % Fe, 10 or less % Co, 0.4 or less % Ti, 0.4 or less % Al, and Nb and Ta (where 0.5%&#x2266;Nb+Ta&#x2266;4.15%), in which 7%&#x2266;Mo+1/2W&#x2266;13% is satisfied, and the composition also contains inevitable impurities and Ni.

Ni-based casting alloy and steam turbine casting part using the same

A heat resistant alloy member that maintains the creep strength and improves the fatigue characteristics is provided. The heat resistant alloy member according to the present invention includes a recrystallized structure layer including finer grains on the surface of the member than those inside of the member. The recrystallized structure layer is formed by forming a stirred layer by giving processing strain to the surface of the member using a friction stir processing, and applying recrystallization heat treatment to the stirred layer for recrystallization.

Heat resistant alloy member, method for manufacturing the same, and method for repairing the same

An operation control method for a gas turbine includes making a molten salt map of molten salt for causing high-temperature corrosion on high-temperature components of the turbine due to impurities using a thermodynamic equilibrium calculation on the basis of the impurities contained in low-quality fuel and operation data of the gas turbine, indicating a surface temperature and a pressure of the high-temperature components of the turbine on the molten salt map , predicting a lifetime of the high-temperature components of the gas turbine by estimating a corrosion rate thereof, and controlling the flow rate of the low-quality fuel supplied to a combustor so that an area of surface temperature and pressure regions of the high-temperature components superposing on the region of molten salt in the liquid phase on the molten salt map is reduced.

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Yokohama, Japan

Hironori Kamoshida