Ni-based superalloy having high oxidation resistance and gas turbine part

Abstract

A Ni-based alloy hardened with the γ phase, which is able to exhibit not only superior strength at high temperatures, but also excellent hot corrosion resistance and oxidation resistance at high temperatures in spite of containing no Re or reducing the amount of Re. The Ni-based superalloy contains, by weight, C: 0.01 to 0.5%, B: 0.01 to 0.04%, Hf: 0.1 to 2.5%, Co: 0.8 to 15%, Ta: more than 0% but less than 8.5%, Cr: 1.5 to 16%, Mo: more than 0% but less than 1.0%, W: 5 to 14%, Ti: 0.1 to 4.75%, Al: 2.5 to 7%, Nb: more than 0 % but less than 4%, V: 0 to less than 1.0%, Zr: 0 to less than 0.1%, Re: 0 to less than 9%, at least one of platinum group elements: 0 to less than 0.5% in total, at least one of rare earth elements: 0 to less than 0.1% in total, and the rest being Ni except for unavoidable impurities.

Description

CROSS-REFERENCES [0001] This is a continuation application of U.S. Ser. No. 10 / 804,065, filed Mar. 19, 2004.BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to a Ni-based superalloy having excellent oxidation resistance at high temperatures, and a gas turbine part made of the Ni-based superalloy. The Ni-based superalloy of the present invention is suitable for use in rotor blades and stator vanes of gas turbines. [0004] 2. Description of the Related Art [0005] The combustion gas temperature in gas turbines tends to increase year by year for the purpose of increasing thermal efficiency. Correspondingly, gas turbine parts have been required to have more superior strength, hot corrosion resistance, and oxidation resistance at high temperatures. [0006] Hitherto, Ni-based superalloys hardened with γ′-precipitation have been used in rotor blades and stator vanes of gas turbines. Also, improvements of material properties of alloys have been ...

AI Technical Summary

Benefits of technology

The present invention provides a Ni-based superalloy that exhibits two different natures of characteristics, i.e., superior creep strength at high temperatures and excellent hot corrosion resistance and oxidation resistance at high temperatures. This is achieved by optimizing the balance among elements such as Cr, Mo, W, and Ti in the superalloy, and by adding specific elements like rare earth elements and platinum group elements. The superalloy contains specific amounts of elements such as C, B, Hf, Co, Ta, Cr, Mo, W, Ti, Al, Nb, V, and Zr. The rest is Ni and unavoidable impurities. The technical effect of the invention is to provide a superalloy that exhibits both superior strength at high temperatures and excellent resistance to hot corrosion and oxidation at high temperatures.

Problems solved by technology

On the other hand, Ni-based superalloys developed for use in industrial gas turbines contain large amounts of Cr and Ti with importance put on hot corrosion resistance, and contain a small amount of expensive Re.

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