JP2569712B2 - Ti-A ▲ -based metal compound cast alloy with excellent high temperature oxidation resistance - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a Ti-Al-based intermetallic compound type casting alloy which is particularly excellent in high-temperature oxidation resistance, is lightweight, and has room temperature strength and room temperature ductility. Things.

[Conventional technology]

In recent years, as a light-weight, high-strength Ti alloy, for example, as described in US Pat. No. 4,294,615, Al: 30 to 36%, and if necessary, V: 4% The following has been proposed a Ti-Al-based intermetallic compound type casting alloy having the following composition and the balance consisting of Ti and unavoidable impurities (more than% by weight, below% indicates% by weight).

[Problems to be solved by the invention]

On the other hand, the above-mentioned conventional Ti-Al-based intermetallic compound type cast alloy is used, for example, in the manufacture of a turbine wheel for a supercharger of an automobile or a special wheel, a turbine wheel of a gas turbine, or the like for the purpose of utilizing the characteristics of the alloy. Attempts have been made, but these have not been able to be put to practical use due to insufficient high-temperature oxidation resistance.

[Means for solving the problem]

Therefore, the present inventors focused on the above-mentioned conventional Ti-Al-based intermetallic compound type cast alloy from the above-described viewpoints, and conducted a study to impart high-temperature oxidation resistance thereto. When Cr is included as an alloy component, high-temperature oxidation resistance is remarkably improved, and in addition, Y, Re, and C,
It has been found that when Si and B are contained, the crystal grain boundaries are strengthened, and the ordinary strength and the ordinary temperature ductility are further improved.

The present invention has been made based on the above findings, and contains: Al: 22 to 35%, Cr: 5 to 20%, Y: 0.01 to 3%, Re: 0.01 to 3%, C: One or more of 0.01 to 0.2%, Si: 0.01 to 1%, B: 0.01 to 0.2%, with the balance being Ti and unavoidable impurities. The present invention is characterized by a Ti-Al-based intermetallic compound type cast alloy having excellent room temperature strength and room temperature ductility.

Next, the reason why the composition of the cast alloy of the present invention is limited as described above will be described.

(A) Al If the content is less than 22%, the precipitation of Ti ₃ Al relatively increases, and the alloy rapidly becomes brittle. On the other hand, even if the content exceeds 35%, -Since the Al concentration in the Al phase becomes high and the alloy becomes brittle also in this case,
Its content was determined to be 2-35%.

(B) Cr The Cr component has the effect of improving the high-temperature oxidation resistance of the alloy as described above. However, if its content is less than 5%, the desired effect of improving the high-temperature oxidation resistance cannot be obtained. 20%
Since the alloy becomes embrittled when it exceeds, the content is set to 5 to 20%.

(C) Y, Re, C, Si, and B These components have the effect of strengthening the grain boundaries as described above, thereby increasing the room-temperature strength and room-temperature ductility of the alloy. : Less than 0.01%, Re: less than 0.01%, C:
If the content is less than 0.01%, Si: less than 0.01%, and B: less than 0.01%, the desired effect cannot be obtained in the above-described action, while the content is
Y: 3%, Re: 3%, C: 0.2%, Si: 1%, and B: 0.
If it exceeds 2%, the embrittlement of the alloy becomes remarkable, so its contents are Y: 0.01 to 3%, Re: 0.01 to 3%, and C: 0.01 to 0.2.
%, Si: 0.01-1%, and B: 0.01-0.2%.

〔Example〕

Next, the cast alloy of the present invention will be specifically described with reference to examples.

Using a normal arc melting furnace, the present cast alloys 1 to 4 having the compositions shown in Tables 1 to 4 in an Ar atmosphere, respectively.
4, and the conventional cast alloys 1 to 5 are melted and centrifugally cast into a ceramic mold to form a round bar having a diameter of 12 mmφ × length: 70 mm. ×
Length: Tensile test specimen having a gauge length of 10 mm, and diameter: 10
mmφ × thickness: cut out high-temperature oxidation specimens with dimensions of 6 mm, measure tensile properties at room temperature, evaluate room temperature strength and room temperature rollability, and maintain temperature: 900 ° C for 500 hours. A high-temperature oxidation test was performed under the conditions, the weight loss after oxidation after descaling with a brush was measured, and the high-temperature oxidation resistance was evaluated. The results of these measurements are shown in Tables 1-4.

〔The invention's effect〕

From the results shown in Tables 1 to 4, the casting alloys 1 to 5 of the present invention were obtained.
No. 44 has remarkably excellent high-temperature oxidation resistance as compared with the conventional cast alloys 1 to 5, and has excellent room-temperature strength and room temperature due to Y, Re, C, Si, and B contained as alloy components. It is clear that it has ductility.

As described above, the Ti-Al-based intermetallic compound cast alloy of the present invention has a much higher temperature oxidation resistance than the conventional Ti-Al-based intermetallic compound cast alloy, It also has excellent room-temperature strength and room-temperature ductility, enabling it to be used in various types of turbine wheels and turbine blades.

Claims (1)

(57) [Claims] (1) Al: 22 to 35%, Cr: 5 to 20%, Y: 0.01 to 3%, Re: 0.01 to 3%, C: 0.01 to 0.2%, Si: 0.01 to 1 %, B: 0.01 to 0.2%, and one or more of the following, and the balance has a composition (more than weight%) consisting of Ti and unavoidable impurities. Ti-Al intermetallic compound casting alloy.