JP2732934B2 - Constant temperature forging die made of Ni-base alloy with excellent high-temperature strength and high-temperature oxidation resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention has excellent high-temperature strength and high-temperature oxidation resistance, and is therefore used for isothermal forging of both Ti-based alloy materials and Ni-based alloy materials. The present invention relates to a thermosetting forging die made of a Ni-based alloy that can be used.

[Conventional technology]

Conventionally, it is well known that, for example, aircraft parts and the like are manufactured by using a Ti-based alloy material or a Ni-based alloy material as a material, and forged in a state where the material and a mold are heated to the same temperature and forged. By the way.

As a thermostatic forging die, for example, Japanese Patent Publication No. 61-46539
As described in Japanese Unexamined Patent Publication (Kokai) Publication No. (Kokai) Publication, the content is expressed in terms of% by weight (hereinafter% indicates% by weight), W: 9.5%, Co: 8%, Cr: 8%, Al: 5.5%, B: 0.015%, A Ti-based alloy containing 0.7%, Ta: 3.2%, Zr: 0.01%, Hf: 1.5%, with the balance being Ni and unavoidable impurities (C: 0.19% as unavoidable impurities). It is well known that a Mo-based alloy containing: 0.5% and Zr: 0.08% is used, and the remainder has a typical composition of Mo and unavoidable impurities.

[Problems to be solved by the invention]

However, the above-mentioned conventional Ni-based alloy constant temperature forging mold has relatively good high-temperature oxidation resistance, so it can be used for constant-temperature forging of Ti-based alloy materials, but the high-temperature strength is not sufficient. It is economically difficult to use Ni-based alloy materials for isothermal forging in terms of service life.Also, the above-mentioned conventional Mo-based alloy isothermal forging dies have remarkably excellent high-temperature strength, but are extremely resistant to high-temperature oxidation. Because it is bad, when using this, it is necessary to take measures such as vacuuming the forging atmosphere.On the other hand, with the recent automation and labor saving of forging machines, along with the cost reduction of products, etc. At present, there is a strong demand for forging dies to be more general-purpose and have a longer service life.

[Means for solving the problem]

Therefore, the present inventors focused on the above-described conventional Ni-based alloy constant temperature forging die from the above-described viewpoint, and improved the high-temperature strength of the die to perform high-temperature forging of the Ni-based alloy material in the atmosphere. In addition to making it possible, even if it is used for constant temperature forging of Ni-based alloys as well as Ti-based alloys by further improving high-temperature oxidation resistance, if the service life can be further extended, As a result of conducting research to reduce the temperature, constant temperature forging dies were obtained using: W: 13 to 15%, Co: 9 to 11%, Cr: 8 to 10%, Al: 4.75 to 5.75%, B: 0.01 to 0.02%, Ti: : 1.5 to 2.5%, Nb: 0.1 to 0.6%, Hf: 1.5 to 2.5%, Mo: 0.1 to 1%, Ta: 0.1 to 1%, the balance being Ni and inevitable impurities (however, C: 0.2% or less) .The resulting Ni-based alloy constant temperature forging die has a composition of the following conventional Ni-based alloy over a heating temperature range of 800 to 1200 ° C.
In addition to showing superior high-temperature strength compared to the base alloy constant temperature forging die, the above-mentioned conventional Ni-base alloy constant temperature forging die,
High-temperature oxidation resistance sharply decreases after a very limited number of uses and reaches the end of its service life, while it retains excellent high-temperature oxidation resistance even after many more uses and is excellent for a very long time. The research results show that it performs well.

The present invention has been made based on the above research results, and the reason why the component composition of the Ni-based alloy constituting the isothermal forging die is limited as described above will be described below.

(A) W The W component has a function of improving the high-temperature strength by forming a solid solution in the γ-phase base material, but if its content is less than 13%, the desired high-temperature strength improving effect cannot be obtained. If the amount exceeds 15%, the high-temperature oxidation resistance decreases, so the content was determined to be 13 to 15%.

(B) Co The Co component has a function of improving the high-temperature strength by forming a solid solution in the same manner as W, but if its content is less than 9%, the desired effect cannot be obtained, whereas 11% Even if the content exceeds the above range, no further improvement effect can be obtained due to the high temperature strength, and the content is set to 9 to 11% in consideration of economy.

(C) Cr The Cr component has a function of improving the high-temperature oxidation resistance by dissolving in the base material, but if its content is less than 8%, the desired high-temperature oxidation resistance cannot be secured. Its content is 10
%, The high-temperature strength decreases.
Its content was determined to be 8-10%.

(D) Al The Al component combines with Ni to form γ-prime (Ni ₃ Al) which is finely and uniformly dispersed and precipitated on the substrate, thereby strengthening the alloy by precipitation and improving the high-temperature strength. If the content is less than 4.75%, the desired high-temperature strength cannot be ensured. On the other hand, if the content exceeds 5.75%, the amount of γ-prime dispersed and precipitated on the base material is too large, causing casting cracks and the like. The content was determined to be 4.75 to 5.75% because the content became easy.

(E) BB The B component has an effect of preferentially precipitating at the grain boundaries, preventing grain boundary cracking of the alloy, and improving the high-temperature strength. When the content exceeds 0.02%, the alloy becomes brittle and casting cracks easily occur. Therefore, the content is set to 0.01 to 0.02%.

(F) Ti The Ti component has a function of increasing the high-temperature strength by dissolving in γ-prime, but if its content is less than 1.5%, it is not possible to secure a desired excellent high-temperature strength. If the content exceeds 2.5%, the content becomes brittle and casting cracks easily occur. Therefore, the content is set to 1.5 to 2.5%.

(G) Nb The Nb component also has a function of improving the high-temperature strength by forming a solid solution in γ-prime. However, if the content is less than 0.1%, the desired high-temperature strength cannot be secured. Is 0.
If it exceeds 6%, the high-temperature oxidation resistance rapidly deteriorates, so its content is set to 0.1 to 0.6%.

(H) Hf The Hf component has an effect of improving the high-temperature oxidation resistance of the grain boundary. However, if the content is less than 1.5%, the desired effect cannot be obtained, whereas the content is 2.5%. If the content exceeds 1.5%, casting defects are likely to occur.
It was determined to be 2.5%.

(I) Mo The Mo component has a function of improving the high-temperature strength by forming a solid solution with the γ phase of the base material, but if its content is less than 0.1%, the desired high-temperature strength cannot be secured. If the content exceeds 1%, the high-temperature oxidation resistance is remarkably deteriorated. Therefore, the content is set to 0.1 to 1%.

(J) Ta The Ta component has a function of improving the high-temperature strength by forming a solid solution with the Mo component in a state coexisting with the Mo component.
When the content is less than 1%, the desired high-temperature strength cannot be obtained. On the other hand, when the content exceeds 1%, the high-temperature oxidation resistance deteriorates. Therefore, the content is set to 0.1 to 1%.

(H) If the CC component as an unavoidable impurity exceeds 0.2%, metal carbides are formed, which not only embrittles the alloy but also easily causes intergranular corrosion. It is desirable to keep the amount below 0.2%.

〔Example〕

Next, the thermostatic forging die of the present invention will be specifically described with reference to examples.

By a normal melting method, a Ni-base alloy having the component composition shown in Table 1 is smelted and cast to obtain a high-temperature tensile test having a size of 20 mm x 150 mm in length, and a diameter of: The constant temperature forging die materials 1 to 9 of the present invention, the comparative constant temperature forging die materials 1 to 16, and the conventional constant temperature forging die materials of the present invention having a size of 20 mm × thickness: 10 mm for a high temperature oxidation test were produced.

Each of the comparative isothermal forging mold materials 1 to 16 was composed of a Ni-based alloy having a component content (marked with * in Table 1) out of this range. is there.

Next, for the various constant temperature forging die materials obtained as a result, for the purpose of evaluating the high temperature strength, the tensile strength at a normal constant temperature forging temperature of 1100 ° C. is measured, and the high temperature oxidation resistance is also evaluated. For the purpose, the sample was heated from 200 ° C. to 1100 ° C. in the air, kept at 1100 ° C. for 30 minutes, rapidly cooled to 200 ° C. in one cycle, and the amount of oxidation increase after 100 and 1000 cycles was measured. The measurement results are shown in Table 1.

Furthermore, from a molten metal having the composition of the constant temperature forging die material 2 of the present invention and the conventional constant temperature forging die material shown in Table 1, by precision casting, an outer diameter: 300 mm, a center boss diameter: 100 mm, and a center boss thickness: A constant temperature forging die having an outer diameter of 800 mm and having a cavity for manufacturing a disk for a gas turbine engine having a dimension of 75 mm and a rim thickness of 25 mm was manufactured.

Next, using the above two kinds of constant temperature forging dies, Ni-0.038% C-3.9% formed by ordinary powder metallurgy
Al-0.015% B-15.5% Co-11.0% Cr-0.46% Hf-1.73
% Nb-3.9% Ti-6.1% W-0.05% Zr-3% Mo, and a preform made of a disc-shaped Ni-based sintered alloy having dimensions of 200 mm in diameter x 65 mm in thickness, While the preform and the mold were heated to 1050 ° C., constant temperature forging was performed in the air to produce a gas turbine engine disk having the above dimensions. This disk for gas turbine engines was manufactured until cracks due to stress concentration occurred on the cavity surface of the mold.In the conventional constant temperature forging mold, cracks occurred on the cavity surface after 500 disks were manufactured. On the other hand, in the constant temperature forging die of the present invention, no crack was observed on the cavity surface even after manufacturing 1000 disks, and the disk could be used continuously.

〔The invention's effect〕

From the results shown in Table 1, the thermostatic forging die material 1 of the present invention was obtained.
To 9 show higher temperature strength and higher temperature oxidation resistance than conventional constant temperature forging mold materials, and particularly with respect to high temperature oxidation resistance. High temperature oxidation resistance, which is not much different from that after 100 cycles, whereas oxidation of the conventional constant temperature forging die material starts to progress rapidly after 100 cycles, and it is clear that oxidation after 1000 cycles becomes remarkable. It is.

Also, as seen in the comparative thermostatic forging mold materials 1 to 16,
It is clear that if the content of any one of the constituents is out of the range of the present invention, at least one of the properties of high-temperature strength and high-temperature oxidation resistance will be deteriorated.

As described above, the Ni-based alloy constant temperature forging die of the present invention has excellent high-temperature strength and high-temperature oxidation resistance.
In addition to the constant-temperature forging of the base alloy material, not only the constant-temperature forging of the Ni-base alloy material in the air, which was practically difficult with the constant temperature forging die made of the conventional Ni-based alloy, but also the In practical use, it has industrially useful characteristics such as exhibiting excellent performance over an extremely long period.

Claims (1)

(57) [Claims] [Claim 1] W: 13 to 15%, Co: 9 to 11%, Cr: 8 to 10%, Al: 4.75 to 5.75%, B: 0.01 to 0.02%, Ti: 1.5 to 2.5%, Nb: 0.1 ~ 0.6%, Hf: 1.5 ~ 2.5%, Mo: 0.1 ~ 1%, Ta: 0.1 ~ 1%, the balance consists of Ni and unavoidable impurities, and the C content as unavoidable impurities is 0.2% or less A constant temperature forging die made of a Ni-base alloy having excellent high-temperature strength and high-temperature oxidation resistance, comprising a Ni-base alloy having the following composition (at least% by weight).