Mitsubishi Steel Mfg. Co., Ltd.

Mitsubishi Heavy Industries Limited

Mitsubishi Jukogyo Kabushiki Kaisha

Itaru Tamura

Ikuo Okada

Taiji Torigoe

Hisataka Kawai

Tsuyoki Kokubun

Koji Takahashi

Kouji Takahashi

Ichiro Tsuji

Koji Sassa

Masakatsu Nishida

Shyuichi Sakashita

Shuichi Sakashita

Toshio Mochizuki

Takashi Kawabata

Akio Ishida

Kazunori Tokoro

Provided is a process for improving alloy properties which can improve the high-temperature ductility of a Ni-base heat-resisting alloy while maintaining its excellent high-temperature strength and weldability. Specifically, it relates to a process for the heat treatment of a Ni-base heat-resisting alloy having a specific composition which comprises the steps of subjecting the alloy to a first-stage solution treatment by keeping it at a specific temperature for a specific period of time; cooling the alloy to a second-stage solution treatment temperature at a specific cooling rate; subjecting the alloy to a second-stage solution treatment by keeping it at a specific temperature for a specific period of time; cooling the alloy rapidly to room temperature at a specific cooling rate; subjecting the alloy to a stabilizing treatment by keeping it at a specific temperature for a specific period of time; cooling the alloy rapidly to room temperature at a specific cooling rate; and subjecting the alloy to an aging treatment by keeping it at a specific temperature for a specific period of time.

Process for the heat treatment of a Ni-base heat-resisting alloy

A production process of a wax pattern having a core, which is used for casting a product having a complicated hollow portion, comprising the steps of: producing two or more wax shells each having a contour of an external surface of a desired casting; and combining the wax shells with a core to obtain a wax pattern having a hollow portion between the wax shells and the core. Using the method, the occurrence of breakage of the core during dewaxing or production of the pwax pattern is extremely reduced, and a lowering in yield rate due to the breakage of the core is remarkably ameliorated.

Production process of wax pattern

A heat-resistant nickel-based alloy having excellent welding properties, said nickel-based alloy consisting essentially of, in terms of wt. %, 0.05 to 0.25% of C, 18 to 25% of Cr, 15 to 25% of Co, at least one selected from the group consisting of up to 3.5% of Mo and 5 to 10% of W, with W+1/2Mo being 5 to 10%, 1.0 to 5.0% of Ti, 1.0 to 4.0% of Al, 0.5 to 4.5% of Ta, 0.2 to 3.0% of Nb, 0.005 to 0.10% of Zr, 0.001 to 0.01% of B and the balance being Ni and unavoidable impurities, wherein the (Al+Ti) content and the (W+1/2Mo) content are within the range surrounded by the lines connecting points A (Al+Ti: 5%, W+1/2Mo: 10%), B (Al+Ti: 5%, W+1/2Mo: 5%), C (Al+Ti: 7%, W+1/2Mo: 5%), and D (Al+Ti: 7%, W+1/2Mo: 10%) excluding the line A-B in FIG. 1. Another alloy has substantially the same composition as described above except that the Cr content is 10 to 20% and the (Al+Ti) content and the (W+1/2Mo) content are within the range surrounded by the lines connecting points A, B, E (Al+Ti: 4%, W+1/2Mo: 5%), F (Al+Ti: 4%, W+1/2Mo: 0.5%), G (Al+Ti: 7%, W+1/2Mo: 0.5%) and D, excluding the line A-B-E, in FIG. 1.

Heat-resistant nickel-based alloy excellent in weldability

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Yokohama, Japan

Itaru Tamura