JPH1046277A - Columnar ni base heat resistant alloy casting and turbine blade made of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a columnar Ni base heat resistant alloy casting usable as the turbine blade of a gas turbine. SOLUTION: This columnar Ni base heat resistant alloy casting has a compsn. contg., by weight, 10 to 14% Cr, 6 to 13% Co, 0.5 to 4% Mo, 1 to 6.2% W, 3 to 8% Ta, 2.5 to 6% Al, 0.5 to 4% Ti, 0.3 to 1.8% Hf, 0.03 to 0.20% C, 0.005 to 0.03% B, 0.001 to 0.03% Zr, and the balance Ni with inevitable impurities and has a structure in which carbides 4 are dispersed into the spaces among the dendrite structure in the matrix, on the grain boundaries 1 and in the dendrite structure 3. The content (atomic %) of Hf contained in the carbides 4 dispersed in the dendrite structure in the matrix is regulated to 3 to 20 times the content (atomic %) of Hf contained in the carbides dispersed among the spaces of the dendrite structure and on the grain boundaries.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a columnar crystal Ni-base heat-resistant alloy casting, and more particularly to a columnar crystal Ni-base heat-resistant alloy casting used as a turbine moving / stationary blade of a gas turbine and a moving blade of a high-temperature blower. It relates to a turbine blade.

[0002]

2. Description of the Related Art It is known that the turbine blades and vanes of a gas turbine and the blades of a high-temperature blower are made of a columnar crystal Ni-base heat-resistant alloy casting. For example, Japanese Patent Publication No. 61-46539. , In terms of weight% (hereinafter,% indicates weight%), Cr: 7.5 to 8.5%, Co: 9.
0 to 9.5%, Mo: 0.4 to 0.6%, W: 9.3 to
9.7%, Ta: 3.1-3.3%, Al: 5.4-
5.7%, Ti: 0.6 to 0.9%, Hf: 1.4 to
1.6%, Zr: 0.007 to 0.015%, C: 0.
A columnar crystal Ni-base heat-resistant alloy casting and a turbine blade made of a columnar crystal Ni-base heat-resistant alloy casting having a composition of 0.7 to 0.09% and B: 0.01 to 0.02%, with the balance being Ni and unavoidable impurities. Is described.

[0003] In order to produce a columnar crystal Ni-base heat-resistant alloy casting, a unidirectional solidification apparatus as shown in FIG. 2 is used. In FIG. 2, 6 is a vacuum chamber, 7 is a heat insulating material,
8 is a melting furnace, 9 is a water-cooled chill ring, 10 is a chill plate, 11
Is a water-cooled ram assembly, 12 is a columnar crystal, 13 is a mold, 14 is a susceptor, 15 is a heater, and 16 is a molten Ni-based alloy. In the vacuum chamber 6 of the unidirectional solidification device, the mold 13 is placed on the chill plate 10, and a carbon susceptor 14 is set around the mold 13.
A heater 15 is installed around the
5, a heat insulating material 7 is disposed around the chill plate 10, and a water-cooled ram assembly 11 is attached to the chill plate 10 below the mold 13.
Further, a water-cooled chill ring 9 is further attached around the chill plate 10 and the water-cooled ram assembly 11.

In such an apparatus, the inside of the vacuum chamber 6 is evacuated, and the molten Ni-base alloy 1 melted in the melting furnace 8.
6 into the mold 13, the mold heating temperature: 1480
1530 ° C, lowering speed of chill plate: 200-350m
When the mold 13 on the chill plate 10 is lowered downward through the water-cooled chill ring 9 at m / h, the columnar crystals 1 formed on the chill plate 10
2 can be grown to produce a long columnar crystal Ni-base heat-resistant alloy casting.

[0005] The structure of the cut surface of the columnar crystal Ni-base heat-resistant alloy casting obtained in this manner, which is cut at right angles to the longitudinal direction, has a grain boundary indicated by a thick solid line as shown in the sketch of FIG. It is composed of crystal grains 5 which are largely divided by 1.
The crystal grains 5 are composed of an aggregate of the columnar crystal structures 3 which are further divided into sections between the columnar crystal structures 2 indicated by thin solid lines. A relatively large carbide 4 is dispersed between the crystal grain boundary 1 and the columnar crystal structure 2.
Are dispersed in the inside of the substrate.

[0006]

The conventional columnar-crystal Ni-base heat-resistant alloy casting is apt to cause freckle defects (crystal defects that cause heterocrystals or recrystallization due to segregation of elements) during casting, and are suitable for casting large-sized castings. In addition, because of its low oxidation resistance and corrosion resistance at high temperatures, it is not preferable as a material for gas turbines that are used under high power using low-grade fuels with a large amount of oxidizing and corrosive substances generated by combustion. Use as a turbine blade made of a columnar crystal Ni-base heat-resistant alloy casting used in a severe environment is not preferable.

[0007]

The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems. As a result, the composition of the Ni-based alloy is expressed in terms of% by weight, Cr: 10 to 14%, Co: 6 to 13%, M:
o: 0.5 to 4%, W: 1 to 6.2%, Ta: 3 to 8
%, Al: 2.5 to 6%, Ti: 0.5 to 4%, Hf:
0.3 to 1.8%, C: 0.03 to 0.20%, B:
0.001 to 0.03%, Zr: 0.001 to 0.03
%, And the balance is limited to a composition consisting of Ni and unavoidable impurities. The molten metal obtained by dissolving the Ni-based alloy having such a composition is poured into a mold of a unidirectional solidifier at a higher temperature than in the past and slowly. When the chill plate is lowered, a columnar crystal Ni-base heat-resistant alloy casting having a structure in which carbides are dispersed in dendritic structures in the matrix and at grain boundaries and dendritic structures is obtained as in the past. The amount of Hf (at.%) Contained in the carbides 4 ′ dispersed in the dendrite structure 3 in the body of the columnar crystal Ni-base heat-resistant alloy casting depends on the density between the dendrite structures 2 and the crystal grain boundaries 1. Carbide dispersed in part 4
The amount of Hf (at.%) Contained in the alloy is 3 to 20 times as large, and the columnar crystal Ni-based heat-resistant alloy casting having such a structure does not cause freckle defects at the time of casting, and has higher oxidation resistance at a higher temperature than before. The inventors have found that they have excellent properties in terms of resistance and corrosion resistance, and have reached the present invention.

The present invention has been made on the basis of such findings, and (1) Cr: 10 to 14% by weight.
%, Co: 6 to 13%, Mo: 0.5 to 4%, W: 1 to 1%
6.2%, Ta: 3 to 8%, Al: 2.5 to 6%, T
i: 0.5-4%, Hf: 0.3-1.8%, C: 0.
03-0.20%, B: 0.001-0.03%, Z
r: 0.001 to 0.03%, with the balance having a composition consisting of Ni and unavoidable impurities, and further, carbides are dispersed between dendrite structures in the base material, at grain boundaries and in the dendrite structures. In a columnar crystal Ni-base heat-resistant alloy casting having a deformed structure, the amount of Hf (at.%) Contained in the carbide dispersed in the dendritic structure in the base is determined by the amount of Hf between the dendritic structures and the grain boundaries. Contained in carbides dispersed in
It is characterized by a columnar crystal Ni-base heat-resistant alloy casting having a f content (atomic%) of 3 to 20 times.

The component composition of the Ni-base alloy constituting the columnar crystal Ni-base heat-resistant alloy casting of the present invention is as follows:
１３13%, Co: 8１１11%, Mo: 1１〜３3.5%,
W: 3 to 4.5%, Ta: 3 to 5.5%, Al: 3.5
4.5%, Ti: 2-3%, Hf: 0.5-1.5
%, C: 0.05 to 0.09%, B: 0.002 to 0.
015%, Zr: 0.002 to 0.015%,
More preferably, the balance consists of Ni and unavoidable impurities. Therefore, the present invention relates to (2)
r: 12 to 13%, Co: 8 to 11%, Mo: 1 to 3.
5%, W: 3 to 4.5%, Ta: 3 to 5.5%, Al:
3.5-4.5%, Ti: 2-3%, Hf: 0.5-
1.5%, C: 0.05 to 0.09%, B: 0.002
０．０１0.015%, Zr: 0.002 to 0.015%, the balance having a composition consisting of Ni and unavoidable impurities, and between dendrite structures in the base material and at grain boundaries and dendrites In a columnar crystal Ni-base heat-resistant alloy casting having a structure in which carbides are dispersed in the structure, the amount (atomic%) of Hf contained in the carbides dispersed in the dendrite structure in the base is determined by the dendrite. It is characterized by a columnar crystal Ni-base heat-resistant alloy casting that is 3 to 20 times the Hf content (atomic%) contained in carbides dispersed between structures and crystal grain boundaries.

The columnar crystal Ni-base heat-resistant alloy casting of the present invention is particularly suitable as a material for a turbine blade. Therefore, the present invention provides (3) by weight: 10 to 14% of Cr and 6: Co.
１３13%, Mo: 0.5４4%, W: 1１〜6.2%, T
a: 3 to 8%, Al: 2.5 to 6%, Ti: 0.5 to 4
%, Hf: 0.3 to 1.8%, C: 0.03 to 0.20
%, B: 0.001 to 0.03%, Zr: 0.001 to
0.03%, the balance being composed of Ni and unavoidable impurities, and further having a structure in which carbides are dispersed between dendritic structures in the base material and at grain boundaries and in the dendritic structure. In a turbine blade made of a columnar crystal Ni-base heat-resistant alloy casting, the amount of Hf (at.%) Contained in the carbide dispersed in the dendrite structure in the base material is dispersed between the dendrite structures and the crystal grain boundaries. Columnar crystal Ni-base heat-resistant alloy cast turbine blades that are 3 to 20 times the Hf amount (atomic%) contained in the carbides, and (4) wt.
１３13%, Co: 8１１11%, Mo: 1１〜３3.5%,
W: 3 to 4.5%, Ta: 3 to 5.5%, Al: 3.5
4.5%, Ti: 2-3%, Hf: 0.5-1.5
%, C: 0.05 to 0.09%, B: 0.002 to 0.
015%, Zr: 0.002 to 0.015%,
A columnar crystal Ni-base heat-resistant alloy casting having a composition in which the balance is composed of Ni and unavoidable impurities, and further has a structure in which carbides are dispersed between dendritic structures in the base material and at grain boundaries and dendritic structures. In the turbine blade, the amount of Hf (atomic%) contained in the carbide dispersed in the dendrite structure in the base is the amount of Hf contained in the carbide dispersed between the dendrite structure and the crystal grain boundaries. (Atomic%) 3 to 2
It is characterized by a turbine blade made of a columnar crystal Ni-base heat-resistant alloy casting that is 0 times.

Next, the reasons for limiting the alloy composition of the columnar crystal Ni-base heat-resistant alloy casting or the columnar crystal Ni-base heat-resistant alloy turbine blade of the present invention will be described in detail.

The Cr industrial gas turbine is required to have high-temperature oxidation resistance and corrosion resistance because it comes into contact with a combustion gas containing oxidizing and corrosive substances generated by combustion. Cr is an element that imparts oxidation resistance and corrosion resistance to the alloy, and the effect is remarkable as the Cr content in the alloy is increased. However, when the Cr content is less than 10%, the effect is small. On the other hand, in the columnar crystal Ni-base heat-resistant alloy casting of the present invention, the T
Since i, Al, Co, Mo, W, Ta, etc. are also added,
In order to balance these, it is not preferable to contain more than 14%. Therefore, the Cr content is 10 to 14
%. As described above, the Cr content of the Ni-base heat-resistant alloy for producing the columnar crystal Ni-base heat-resistant alloy cast turbine blade of the present invention is more preferably 12 to 13%.

Co Co increases the limit (solid solubility limit) of solid solution of Ti, Al, Ta, Hf and the like at a high temperature, and γ by heat treatment.
The 'phase (Ni ₃ (Ti, Al, Ta, Hf)) is finely dispersed and precipitated to improve the strength of the columnar crystal Ni-base heat-resistant alloy casting, but the amount of Co needs to be 6% or more. On the other hand, when the Co content exceeds 13%, Cr, M
Since the balance with other elements such as o, W, Ta, Al, and Ti is lost and the ductility is reduced due to the precipitation of a harmful phase, the Co content is set to 6 to 13%. Columnar crystals N of the present invention
The Co content in the Ni-based heat-resistant alloy for producing the turbine blade made of the i-based heat-resistant alloy casting is more preferably 8 to 11%.

Mo Mo has the effect of increasing the high-temperature strength by forming a solid solution in the base material, and has the effect of contributing to the high-temperature strength by precipitation hardening. Mo is set to 0.5 to 4%, because addition of more than 4% impairs ductility due to precipitation of a harmful phase. The Mo content contained in the Ni-base heat-resistant alloy for producing the turbine blade made of the columnar crystal Ni-base heat-resistant alloy casting of the present invention is 1 to 3.
More preferably, it is 3.5%.

WW has the effect of solid solution strengthening and precipitation hardening similarly to Mo, and has the effect of contributing to the provision of high-temperature strength. However, the amount of WW is required to be 1% or more. In addition, since W itself is an element having a large specific gravity while precipitating a harmful phase, the specific gravity of the entire alloy becomes large, which is disadvantageous in a turbine rotor blade in which centrifugal force works, and a freckle defect is generated when casting a columnar crystal casting. , And the cost was further increased, so the content was set to 1 to 6.2%.
The W content contained in the Ni-base heat-resistant alloy for producing the turbine blade made of the columnar crystal Ni-base heat-resistant alloy casting of the present invention is 3 to 4.5.
% Is more preferable.

Ti Ti is an element necessary for the precipitation of a γ ′ phase for increasing the high-temperature strength of a γ ′ precipitation-hardening Ni-based alloy. If it is less than 0.5%, the precipitation strengthening of the γ ′ phase is insufficient. The required strength cannot be satisfied, and if added in excess of 4%, the amount of precipitation becomes too large, impairs ductility and, when coexisting with Hf, casts a columnar crystal casting with an irregular shape. Reaction becomes intense and the casting surface is deteriorated, which is not preferable. Therefore, the Ti content is set to 0.5 to 4%. As described above, the Ti content in the Ni-base heat-resistant alloy for producing the columnar crystal Ni-base heat-resistant alloy cast turbine blade of the present invention is 2 to 3.
More preferably, it is 3%.

Al Al is an element exhibiting the same effect as Ti. It forms a γ 'phase, increases the high-temperature strength, and contributes to the oxidation resistance and corrosion resistance at high temperatures. The quantity is 2.5
% Or more, while adding too much more than 6% impairs ductility, so the Al content was set to 2.5-6%. More preferably, the Al content in the Ni-base heat-resistant alloy for producing the turbine blade made of the columnar crystal Ni-base heat-resistant alloy casting of the present invention is 3.5 to 4.5%.

Ta Ta contributes to improvement of high-temperature strength by solid solution strengthening and γ ′ phase precipitation hardening, and is effective at 3% or more. On the other hand, too much addition lowers the ductility, so the content was made 8% or less. Therefore, although the Ta content contained in the Ni-base heat-resistant alloy for producing the columnar crystal Ni-base heat-resistant alloy cast turbine blade of the present invention is set to 3 to 8%, it is more preferably 3 to 5.5%. .

Hf Hf has a grain boundary strengthening effect when formed into columnar crystals by directional solidification, contributes to improvement in high-temperature strength by γ ′ phase precipitation hardening, and further has an effect of improving oxidation resistance and corrosion resistance. If its content is less than 0.3%, the desired effect cannot be obtained, while if its content exceeds 1.8%, it reacts with the mold to form an oxide on the casting surface, resulting in poor casting surface. , The Hf content is 0.3 to 1.8%.
It was decided. A more preferable range of the content of Hf is 0.5 to
1.5%.

C forms carbides and precipitates particularly at grain boundaries and dendrite boundaries to strengthen grain boundaries and dendrite boundaries, and contributes to improvement of high-temperature strength. There are, on the other hand, 0.
If added in excess of 2%, the ductility is impaired, so its content was made 0.03-0.2%. A more preferable range of the content of C is 0.05 to 0.09%.

BB is a necessary component because it increases the bonding force at the crystal grain boundaries to strengthen the crystal boundaries and raises the high-temperature strength. However, if the content is less than 0.001%, the desired effect can be obtained. On the other hand, if too much is added, the ductility may be impaired, so the content was made 0.03% or less. A more preferable range of the B content is 0.002 to 0.015%.

Zr Zr also needs to be added in an amount of 0.001% or more because it increases the bonding strength at the crystal grain boundaries to strengthen the crystal boundaries and raises the high-temperature strength. However, if too much is added, the ductility may be impaired. 0.03% or less. A more preferable range of the Zr content is 0.002 to 0.015%.

The most characteristic feature of the columnar crystal Ni-base heat-resistant alloy casting or the turbine blade made of the columnar crystal Ni-base heat-resistant alloy casting of the present invention is the columnar crystal Ni-base heat-resistant alloy casting or columnar crystal Ni-base heat-resistant casting shown in FIG. Carbide 4 'dispersed in a dendritic structure 3 in the matrix of the alloy cast turbine blade
Is that the Hf content (atomic%) contained in the carbides 4 dispersed in the dendritic crystal structures 2 and the crystal grain boundaries 1 is 3 to 20 times the Hf content (atomic%). The Hf content (atomic%) of the carbides 4 ′ dispersed in the dendritic crystal structure 3 is represented by C 1 _Hf , the Hf content contained in the carbides 4 dispersed in the dendritic crystal structures 2 and the crystal grain boundaries 1 ( Atomic%) to C2
When _Hf, is in the range of C1 _Hf / C2 _Hf = 3~20.

The amount of Hf (at.%) Contained in the carbide dispersed in the dendrite structure in the matrix of the columnar crystal Ni-base heat-resistant alloy casting of the present invention varies between the dendrite structures and the grain boundaries. 3-20 times the Hf content in the carbide are dispersed (atomic%), i.e. to the C1 _Hf / C2 _Hf = 3-20 is lowered rate of the mold heating temperature and low speed of the temperature higher than the conventional It is obtained by lowering the chill plate with.
The amount of Hf (atomic%) contained in the carbide dispersed in the dendrite structure in the matrix of the columnar crystal Ni-base heat-resistant alloy casting is determined by the amount of Hf contained in the carbide dispersed in the dendrite structure and in the crystal grain boundaries. If the amount of Hf contained (atomic%) is less than 3 times, only oxidation resistance and corrosion resistance at the same high temperature as in the prior art are exhibited, which is not preferable. On the other hand, if it exceeds 20 times, cracks are likely to occur during casting, which is not preferable. From that point, it was set to 3 to 20 times. In this case, a more preferable range is 12 to 18 times.

Conventional normal conditions (mold heating temperature: 148
0 to 1530 ° C, pull-down speed of chill plate: 200 to 35
0 mm / h) columnar crystal N produced by a unidirectional solidifier
In the i-base heat-resistant alloy casting, there is no difference in the amount of Hf (atomic%) contained in the carbide dispersed in the base material, but when the chill plate is pulled down at a higher mold heating temperature and at a slower speed than before, the columnar shape is reduced. Content (atomic%) contained in the carbide dispersed in the dendrite structure in the base material of the crystalline Ni-base heat-resistant alloy casting, and contained in the carbide dispersed between the dendrite structure and the crystal grain boundaries. When the difference in Hf amount (atomic%) increases and the chill plate is lowered under the conditions of a mold heating temperature: 1560 to 1650 ° C and a chill plate lowering speed: 100 to 150 mm / h, the base of the columnar crystal Ni-base heat-resistant alloy casting is obtained. The amount of Hf (at.%) Contained in the carbide dispersed in the dendrite structure therein is 3 times the amount of Hf (at.%) Contained in the carbide dispersed between the dendrite structures and at the grain boundaries. ~ 20
By increasing the amount of Hf contained in the carbide dispersed in the dendritic structure, the oxidation resistance and corrosion resistance at high temperatures are further improved.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Ni-base heat-resistant alloys A to P having the component compositions shown in Tables 1 and 2 were prepared. The Ni-base heat-resistant alloys A to O in Tables 1 and 2 are Ni-base heat-resistant alloys of the present invention, and the Ni-base heat-resistant alloy P is a conventional Ni-base heat-resistant alloy described in JP-B-61-46539. These Ni-base heat-resistant alloys AP are melted in vacuum, respectively,
While casting the molten O into the mold 13 of the one-way solidification apparatus shown in FIG. 2, the mold heating temperature is 1600 ° C., the chill plate is pulled down at a speed of 120 mm / h, and the diameter is 20 m.
m, length: the columnar crystal casting rods 1 to 15 of the present invention having a dimension of 200 mm were prepared, and a molten metal of a conventional Ni-base heat-resistant alloy P was cast into a mold 13 of a unidirectional solidification apparatus shown in FIG. A conventional columnar casting rod 16 having a diameter of 20 mm and a length of 200 mm was produced under the conditions of a mold heating temperature of 1500 ° C. and a pull-down speed of 300 mm / h.

[0027]

[Table 1]Ni-base heat-resistant alloy (% by weight)  Element ABCD FGH Cr 12.6 12.0 13.0 12.5 12.5 12.3 12.1 10.5 Co 9.0 8.3 10.1 10.5 9.7 8.8 9.3 9.3 Mo 2.1 1.0 3.5 1.5 2.4 2.7 3.0 1.5 W 4.0 3.5 4.3 3.7 4.5 4.1 3.9 5.5 Ta 3.3 5.4 4.9 3.0 3.8 3.5 3.8 4.2 Al 4.0 3.5 4.3 3.7 4.5 4.1 3.9 3.8 Ti 2.7 2.3 3.2 2.5 2.9 3.0 2.8 2.7 Hf 0.6 1.0 1.3 1.5 0.8 0.5 1.1 1.5 C 0.08 0.06 0.07 0.05 0.09 0.09 0.06 0.08 B 0.003 0.009 0.007 0.015 0.013 0.012 0.010 0.015 Zr 0.010 0.011 0.012 0.004 0.007 0.008 0.055 0.011Ni remaining remaining remaining remaining remaining remaining remaining remaining

[0028]

[Table 2]Ni-base heat-resistant alloy (% by weight)  Element IJKLMNOP Cr 12.6 12.0 13.0 12.5 12.5 12.3 12.1 8.0 Co 9.0 8.3 10.1 10.5 9.7 8.8 9.3 9.3 Mo 2.1 1.0 3.5 1.5 2.4 2.7 3.0 0.5 W 6.1 3.5 4.9 3.7 5.3 4.1 1.9 9.5 Ta 3.3 5.4 4.9 3.0 3.8 3.5 3.8 3.2 Al 4.0 3.5 4.3 3.7 4.5 4.1 3.9 5.6 Ti 2.7 2.3 3.2 2.5 2.9 3.0 2.8 0.7 Hf 0.6 1.0 1.3 1.5 0.8 0.5 1.1 1.5 C 0.08 0.16 0.07 0.12 0.09 0.19 0.06 0.08 B 0.003 0.009 0.007 0.015 0.013 0.012 0.010 0.015 Zr 0.010 0.011 0.012 0.004 0.007 0.008 0.055 0.011Ni remaining remaining remaining remaining remaining remaining remaining remaining

Analysis of the amount of Hf contained in the carbide in the body The centers of the columnar casting rods 1 to 15 of the present invention and the conventional columnar casting rod 16 obtained were cut at right angles to the longitudinal direction, and the branches on the cut surface were cut. Amount (atomic%) of Hf contained in carbides dispersed in dendritic structure: C1 _Hf and H contained in carbides dispersed between dendritic structures and at grain boundaries.
f amount (atomic%): The C2 _Hf measured by EPMA analysis,
Further, the value of _C1Hf / _C2Hf was determined, and the results are shown in Tables 3 and 4.

High-Temperature Corrosion Resistance Test The obtained columnar cast rods 1 to 15 of the present invention and the conventional columnar cast rod 16 were subjected to HIP at 1180 ° C., 1500 atm for 2 hours and then Ar at 1240 ° C. for 2 hours. Gas-cooled solution heat treatment, first aging treatment at 1050 ° C. for 5 hours, followed by second heating at 870 ° C. for 18 hours
Step aging treatment and diameter: 12m by machining
m, length: The product finished to a size of 150 mm was held for 100 hours while rotating in a natural gas flame containing hydrogen sulfide gas at a temperature of about 950 ° C., and the scale formed on the surface of the casting rod subjected to such treatment was removed. After the removal, the weight loss of the casting rod was measured, and the results are shown in Tables 3 and 4, and the high-temperature corrosion resistance was evaluated.

High temperature creep rupture strength test After the same treatment as that performed in the high temperature corrosion resistance test was applied to the columnar casting bars 1 to 15 of the present invention and the conventional columnar casting bar 16, the diameter of the parallel portion was 6.0 mm. A test piece was prepared by machining to obtain a test piece, and the obtained test piece was held at a temperature of 960 ° C. with a load of 26 kg / mm ² applied thereto, and a life (hour) until breakage was measured. The results are shown in Tables 3 and 4, and the high-temperature creep rupture strength was evaluated.

[0032]

[Table 3]

[0033]

[Table 4]

From the results shown in Tables 3 and 4, C1 _Hf /
The columnar casting rods 1 to 15 of the present invention having a C2 _Hf within the range of 3 to 20 times have a higher high-temperature creep rupture strength than the conventional columnar casting rod 16 having a _C1Hf / _C2Hf of 1.3. Although not changed, it can be seen that the high-temperature corrosion resistance is remarkably excellent because the weight loss of the casting bar is extremely small.

Castability Test A mold having a cavity having a diameter of 31 mm and a length of 165 mm in which a silica core (diameter: 29 mm, length: 180 mm) was set in the center was attached to the unidirectional solidification apparatus shown in FIG. Mold heating temperature: 1600 ° C., chill plate pulling speed: Melt of Ni-base heat-resistant alloys A to P in Tables 1 to 2
Casting was performed under the condition of 120 mm / h to prepare the columnar crystal hollow casting pieces 1 to 15 of the present invention and the conventional columnar hollow casting pieces 16.

The obtained columnar crystal hollow casting pieces 1 to 15 of the present invention are obtained.
The surface of the conventional columnar crystal hollow casting 16 was macro-etched with a mixed solution of hydrochloric acid and hydrogen peroxide, and the presence or absence of the occurrence of fleckle defects was observed. The results are shown in Table 5.

[0037]

[Table 5]

As shown in Table 5, the Ni-base heat-resistant alloys A to O of the present invention had no castle defects, and therefore had better castability than the conventional Ni-base heat-resistant alloy P. I understand.

[0039]

According to the results shown in Tables 1 to 5, the Ni-base heat-resistant alloys A to O of the present invention are the same as those of the conventional Ni-base heat-resistant alloy P
And the columnar castings made of the Ni-base heat-resistant alloys A to O of the present invention have higher corrosion resistance at high temperatures than the columnar casts made of the conventional Ni-base heat-resistant alloy P. The turbine blade made of the columnar crystal Ni-base heat-resistant alloy casting of the present invention has excellent combustion characteristics including oxidizing substances generated when low-grade fuel is burned. Even when brought into contact with a gas, it is excellent in high-temperature oxidation resistance and high-temperature corrosion resistance, so that it can be used for a long period of time, and has excellent industrial effects.

[Brief description of the drawings]

FIG. 1 is a sketch showing the structure of a columnar crystal Ni-base heat-resistant alloy casting.

FIG. 2 is a schematic cross-sectional view of an apparatus for producing a columnar crystal Ni-base heat-resistant alloy casting.

[Explanation of symbols]

 Reference Signs List 1 crystal grain boundary 2 between columnar crystal structures 3 columnar crystal structure 4 carbide 4 ′ carbide 5 crystal grain 6 vacuum chamber 7 heat insulator 8 melting furnace 9 water-cooled chill ring 10 chill plate 11 water-cooled ram assembly 12 columnar crystal 13 mold 14 susceptor 15 heater 16 Ni-base alloy melt

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hisataka Kawai 2-1-1, Shinaihama, Arai-machi, Takasago City, Hyogo Prefecture Mitsubishi Heavy Industries, Ltd. (72) Koji Takahashi 2-1-1, Shinama, Araimachi, Takasago-shi, Hyogo Prefecture Inside Mitsubishi Heavy Industries, Ltd. Takasago Works (72) Inventor Ikuo Okada 2-1-1, Niihama, Arai-machi, Takasago City, Hyogo

Claims (4)

[Claims] Claims: 1. A weight percentage of Cr: 10-14%, Co:
6 to 13%, Mo: 0.5 to 4%, W: 1 to 6.2%,
Ta: 3 to 8%, Al: 2.5 to 6%, Ti: 0.5 to
4%, Hf: 0.3 to 1.8%, C: 0.03 to 0.2
0%, B: 0.001 to 0.03%, Zr: 0.001
-0.03%, the balance being composed of Ni and unavoidable impurities, and a structure in which carbides are dispersed between dendrite structures in the base material and at grain boundaries and in the dendrite structure. In the columnar crystal Ni-base heat-resistant alloy casting, the amount of Hf (atomic%) contained in the carbide dispersed in the dendritic crystal structure in the base material is dispersed between the dendritic crystal structures and the crystal grain boundaries. Hf content (atomic%) in carbide
A columnar crystal Ni-based heat-resistant alloy casting characterized by being 3 to 20 times as large as the above. 2. Cr: 12 to 13% by weight, Co:
8 to 11%, Mo: 1 to 3.5%, W: 3 to 4.5%,
Ta: 3 to 5.5%, Al: 3.5 to 4.5%, Ti:
2-3%, Hf: 0.5-1.5%, C: 0.05-
0.09%, B: 0.002 to 0.015%, Zr:
0.002 to 0.015%, the balance being composed of Ni and unavoidable impurities, and further, carbides are dispersed between dendritic structures in the base material and at grain boundaries and dendritic structures. In a columnar crystal Ni-base heat-resistant alloy casting having a microstructure, the amount of Hf (at.%) Contained in the carbide dispersed in the dendritic crystal structure in the base material is dispersed between the dendritic crystal structures and the crystal grain boundaries. Hf content (atomic%) contained in carbides
A columnar crystal Ni-based heat-resistant alloy casting characterized by being 3 to 20 times as large as the above. 3. Cr: 10 to 14% by weight, Co:
6 to 13%, Mo: 0.5 to 4%, W: 1 to 6.2%,
Ta: 3 to 8%, Al: 2.5 to 6%, Ti: 0.5 to
4%, Hf: 0.3 to 1.8%, C: 0.03 to 0.2
0%, B: 0.001 to 0.03%, Zr: 0.001
-0.03%, the balance being composed of Ni and unavoidable impurities, and a structure in which carbides are dispersed between dendrite structures in the base material and at grain boundaries and in the dendrite structure. In a turbine blade made of a columnar crystal Ni-base heat-resistant alloy casting, the amount of Hf (at.%) Contained in carbides dispersed in the dendritic structure in the base material is dispersed between the dendritic structures and in the crystal grain boundaries. Hf content (atomic%) contained in carbides
A turbine blade made of a columnar crystal Ni-based heat-resistant alloy casting, which is 3 to 20 times as large as the above. 4. Cr: 12 to 13% by weight, Co:
8 to 11%, Mo: 1 to 3.5%, W: 3 to 4.5%,
Ta: 3 to 5.5%, Al: 3.5 to 4.5%, Ti:
2-3%, Hf: 0.5-1.5%, C: 0.05-
0.09%, B: 0.002 to 0.015%, Zr:
0.002 to 0.015%, the balance being composed of Ni and unavoidable impurities, and further, carbides are dispersed between dendritic structures in the base material and at grain boundaries and dendritic structures. In a turbine blade made of a columnar crystal Ni-base heat-resistant alloy casting having a microstructure, the amount of Hf (atomic%) contained in carbides dispersed in the dendritic crystal structure in the base material is determined by the difference between the dendritic crystal structures and the crystal grains. Of Hf (atomic%) contained in carbides dispersed in the boundary
A turbine blade made of a columnar crystal Ni-based heat-resistant alloy casting, which is 3 to 20 times as large as the above.