JP2002294374A - Ni BASED CAST HEAT RESISTANT SUPERALLOY AND TURBINE WHEEL MADE OF THE Ni BASED SUPERALLOY - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an Ni based cast heat resistant superalloy which has excellent durability by improving its mechanical properties at high temperatures, particularly, in elongation. SOLUTION: The Ni based cast heat resistant superalloy has a composition containing, by mass, 7.0 to 9.5% Cr, 2.5 to 5.5% Al, 8.0 to 13.0% W, 1.0 to 5.0% Mo (wherein, the content of W+2Mo lies in the range of 14 to 19), 0.5 to 3.5% Nb, <=3.0% Ti, 0.02 to 0.2% C, 0.01 to 0.35% B, <=0.02% (not inclusive of 0%) Mg (wherein, the content of Mg is 0.004 to 0.02% in the range where the content of B is 0.01 to 0.05%), <=0.1% Zr, <=1.0% Si and <=1.0% Mn, and, if required, containing <=3.0% Ti, and in which 2Mo/(W+2Mo) satisfies 0.20 to 0.55, and (W+2Mo)/Nb or (W+2Mo)/(Nb+2Ti) satisfies 1 to 10, and the balance Ni with inevitable impurities.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a high-strength Ni-base super-heat-resistant alloy and a turbine wheel made of a Ni-base super-heat-resistant alloy suitable for a turbine wheel or the like which is a component of a turbocharger for an automobile.

[0002]

2. Description of the Related Art A turbocharger is an automobile part for improving the output performance of an engine by utilizing the energy of exhaust gas. By mounting the turbocharger, it is overwhelmed from a middle speed range to a high speed range as compared with a case where it is not mounted. High acceleration can be obtained. The turbine wheel, which is a component of this turbocharger, rotates at a high speed of 100,000 rpm or more by the energy of the exhaust gas sent to the turbocharger, and serves to drive a compressor coaxially coupled with the rotation axis. Things.

[0003] Since the turbine wheel rotates at high speed while being exposed to exhaust gas of about 1000 ° C, it is essential that the material has excellent heat resistance. Alloy713C, Mar
Ni-based super heat-resistant alloys such as -M247 are known. A
lloy713C is relatively inexpensive among turbine wheel materials, is widely used for general purposes, and
-M247 is a material that is several times as expensive as Alloy713C in terms of cost, but is used for special vehicles such as rallies because of its excellent creep rupture strength.
In recent years, Ti-
Materials such as Al-based alloys have also attracted attention.

In recent years, lean burn (lean burn) engines have been promoted for the purpose of improving fuel efficiency by efficiently burning a lean air-fuel mixture. , And tend to spread further in the future. However, lean burn raises the exhaust temperature further than a normal engine, and the turbine wheel is used in a more severe environment.

As an example of the development of a Ni-base super-heat-resistant alloy casting having improved properties at high temperatures, Japanese Patent Publication No. 57-15654 discloses a conventional alloy containing one or two members selected from the group consisting of Ce, La and Nd among rare earth elements. 0.001 to 0.03 for seeds or more
It is disclosed that by containing 0% by mass, the high-temperature ductility of an aircraft jet engine or a gas turbine casting for power generation can be improved. In addition,
No. 10574 discloses a Ni-base alloy for gas turbine blades having excellent impact resistance and ductility.

[0006]

The turbine wheel made of Alloy 713C has a sufficient creep rupture strength to be mounted on an ordinary engine for ordinary vehicles. However, the exhaust temperature of the above-described lean burn engine further rises more than that of a normal engine, so that the Alloy 713C cannot withstand the severe environment. Also,
The alloys disclosed in Mar-M247, JP-B-57-15654, and JP-B-51-10574 include rare earth elements and C
It contains expensive alloy elements such as o, Ta, and Hf, and the material cost is several times that of Alloy713C. Further M
Since ar-M247 is liable to generate shrinkage cavities inside the casting due to solidification shrinkage after casting, it is necessary to perform HIP processing or the like to eliminate shrinkage cavities. Therefore, ar-M247 is much more expensive than Alloy 713C. For this reason, these alloys increase the production cost and are not suitable for lean burn engines for general vehicles.

In order to solve the above problems, Allo
Japanese Patent Application Laid-Open No. H11-131162 has been proposed as an inexpensive heat-resistant alloy material having a creep rupture strength of y713C or more, but in terms of durability, the above-mentioned Mar-M247, Japanese Patent Publication No. 57-15654, and Since it is inferior to the alloy disclosed in JP-B-51-10574, there is still a problem in application to a lean burn engine. An object of the present invention is to provide a Ni-based super-heat-resistant cast alloy and a turbine wheel made of a Ni-based super-heat-resistant cast alloy having excellent durability by improving mechanical properties at high temperatures, particularly, elongation.

[0008]

In order to solve this problem, the present inventor removes expensive elements such as Co, Ta, and Hf from an alloy particularly excellent in creep rupture strength represented by Mar-M247, and removes the material. We thought about reducing the unit price. However, since Co and Ta have a great effect of improving the creep rupture strength, the mere removal of them greatly reduces the creep rupture strength.

Therefore, the present inventor has determined that the amount of each alloy element in the γ 'phase based on Ni ₃ Al, which determines the creep rupture strength characteristics of the alloy, and the lattice of γ phase (mother phase) and γ' phase As a result of intensive studies on various alloying elements and their proper addition amounts in order to adjust the difference between the constants, it was found that W, Mo and Ti, even without adding expensive elements such as Co, Ta and Hf.
Adjusting the addition amount of elements such as Nb allows Alloy 71
It has excellent creep rupture strength exceeding 3C,
By adjusting the addition amounts of B and Mg, the method disclosed in
The inventors have found that durability higher than that of the alloy disclosed in Japanese Patent No. 131162 can be obtained, and completed the present invention. The basic idea is as follows.

First, an alloy such as Alloy713C is made of Ni.
It is strengthened by precipitation of an intermetallic compound γ ′ phase based on 3Al. In the γ ′ phase, in addition to Al, Ti, Nb, or W, Mo, or the like, forms a solid solution, thereby further improving the strength. However, when added excessively, a hetero phase is precipitated to reduce the strength. The γ 'phase becomes coarse during long-time heating at a high temperature, but its behavior depends on the parent phase (γ phase) and the precipitation strengthening phase (γ' phase).
Is affected by the difference in the lattice constant of In consideration of the above, the present inventor included expensive alloy elements such as Co, Ta, and Hf by adjusting the amount of solid solution in the γ ′ phase and the difference between the lattice constants of the γ phase and the γ ′ phase. It was possible to obtain a creep rupture strength exceeding Alloy713C with no alloy.

Specifically, the concentration (mol%) of a certain alloying element X in the γ ′ phase is γ ′ (X), and the element X alone is simply γ ′
When the solid solubility limit (mol%) in the case of solid solution in the phase (Ni3Al) is L (X), the solid solution rate S defined by the equation (1)
In I (X), SI (Cr), SI (W), SI
(Mo), SI (Nb), SI (Ti), SI (Ta)
(Hereinafter, this total is referred to as a solid solution index) is Ma
Since it was found that the high-strength material such as r-M247 was 1.2 to 1.35, the solid solution index of the Ni-based super heat-resistant alloy containing no Co, Ta, Hf or the like was set to fall within this range. It has been found that the creep rupture strength can be improved by adjusting the alloy components. SI (X) = γ ′ (X) / L (X) (1) where L (Cr) = 10, L (W) = 5, L (Mo)
= 5, L (Nb) = 8, L (Ti) = 15, L (Ta)
= 8.

Further, as the absolute value of the lattice constant mismatch ratio LM (%) of the alloy defined by the equation (2) becomes smaller, γ ′
It is generally known that high-temperature strength tends to be improved because the consistency between the phase and the γ phase is enhanced and the γ ′ phase is prevented from becoming coarse. Further, when stress is generated in the Ni-base superalloy at a high temperature, a raft structure in which the γ ′ phase is deformed in a wavy form is formed. The more the structure is elongated, the more effective the creep rupture strength is. %) On the slightly negative side, it is also known that an elongated and good raft structure is easily obtained. The inventor does not include Co, Ta, Hf, etc.
In a Ni-based super heat-resistant alloy satisfying a solid solution index of 1.2 to 1.35, the alloy component is adjusted so that LM (%) is in a range of -0.2 to 0.12. It has been found that a creep rupture strength of Alloy713C or higher can be obtained.

LM (%) = (A (γ ′) − A (γ)) / ((A (γ ′) + A (γ)) / 2) (2) where A (γ ′) , A (γ) represent the lattice constants of the γ ′ phase and the γ phase, respectively. The concentration of a certain alloying element X in the γ ′ phase is γ ′ (X) (mol%), and the concentration in the γ phase is γ.
When (X) (mol%) is used, the values calculated from Expressions (3) and (4) are shown. A (γ ′) = 3.5208 + 0.0012γ ′ (Cr) + 0.00185γ ′ (Al) + 0.00412γ ′ (W) + 0.00435γ ′ (Mo) +0.00 645γ ′ (Nb) + 0.0034γ ′ (Ti (3) A (γ) = 3.524 + 0.0012γ (Cr) + 0.00185γ (Al) + 0.00412γ (W) + 0.00435γ (Mo) + 0.00645γ (Nb) + 0.0034γ (Ti) ... (4)

As described above, in order to calculate the solid solution index, the lattice constant mismatch ratio of the γ phase and the γ ′ phase, it is necessary to know the composition of the γ phase and the γ ′ phase. This is the calculation or gamma phase,
It can be obtained by analysis of the γ 'phase, and the inventor has used a computational method. However, since the calculation formula is complicated, it is difficult to show here, and the analysis method is inevitably accompanied by some errors. Therefore, here, the limitation of the solid solution index and the limitation of the lattice constant mismatch ratio were replaced with the limitation of the specific component composition in the present alloy.

That is, the chemical composition of a suitable Ni-base superalloy for realizing the condition that the solid solution index is 1.2 to 1.35 and the LM (%) is -0.2 to 0.12. Is Cr: 7.0 to 9.5%, Al: 2.5 to 5.5% by weight ratio,
W: 8.0 to 13.0%, Mo: 1.0 to 5.0% (W + 2Mo ranges from 14 to 19), Nb: 0.5
-3.5%, C: 0.02-0.2%, Zr: 0.1%
Hereinafter, Si: 1.0% or less, Mn: 1.0% or less, and 2Mo / (W + 2Mo) is 0.20 to 0.5.
5, and (W + 2Mo) / Nb satisfy 1 to 10, and the balance is a component consisting of Ni and unavoidable impurities, or, if necessary, can contain 3.0% or less by weight of Ti. In this case, W + 2Mo calculated by weight ratio
14 to 19 and 2Mo / (W + 2Mo) is 0.20
An alloy satisfying Ｗ0.55 and (W + 2Mo) / (Nb + 2Ti) satisfies 1１〜10 can also realize the above conditions. Further, in order to increase the durability characteristics of the alloy having such a basic composition, B and Mg were adjusted, and the optimum amount of addition for improving the high-temperature elongation was determined experimentally to be the component range.

That is, according to the present invention, the mass ratio of Cr is 7.0 to 7.0.
9.5%, Al: 2.5 to 5.5%, W: 8.0 to 1
3.0%, Mo: 1.0 to 5.0% (however, W + 2M
o ranges from 14 to 19), Nb: 0.5 to 3.5%,
C: 0.02-0.2%, B: 0.05-0.35%,
Mg: 0.02% or less, Zr: 0.1% or less, Si:
1.0% or less, Mn: 1.0% or less, and 2M
o / (W + 2Mo) is 0.20 to 0.55 and (W +
2Mo) / Nb satisfies 1 to 10, and the balance is a Ni-based super heat-resistant cast alloy comprising Ni and unavoidable impurities.

The present invention also relates to the present invention, wherein the mass ratio of Cr is 7.0 to 7.0.
9.5%, Al: 2.5 to 5.5%, W: 8.0 to 1
3.0%, Mo: 1.0 to 5.0% (however, W + 2M
o ranges from 14 to 19), Nb: 0.5 to 3.5%,
C: 0.02-0.2%, B: 0.05-0.35%,
Mg: 0.02% or less, Ti: 3.0% or less, Zr:
0.1% or less, Si: 1.0% or less, Mn: 1.0% or less, and 2Mo / (W + 2Mo) is 0.20 to 0.20.
0.55 and (W + 2Mo) / (Nb + 2Ti) is 1
-10 are satisfied, and the balance is a Ni-based super heat-resistant cast alloy composed of Ni and unavoidable impurities.

The present invention also relates to the present invention, wherein the mass ratio of Cr is 7.0 to 7.0.
9.5%, Al: 2.5 to 5.5%, W: 8.0 to 1
3.0%, Mo: 1.0 to 5.0% (however, W + 2M
o ranges from 14 to 19), Nb: 0.5 to 3.5%,
C: 0.02-0.2%, B: 0.01-0.05%,
Mg: 0.004 to 0.02%, Zr: 0.1% or less,
Si: 1.0% or less, Mn: 1.0% or less, 2Mo / (W + 2Mo) satisfies 0.20 to 0.55, and (W + 2Mo) / Nb satisfies 1 to 10, the balance being Ni
And a Ni-based super heat-resistant cast alloy comprising unavoidable impurities.

The present invention also relates to the present invention, wherein the mass ratio of Cr is 7.0 to 7.0.
9.5%, Al: 2.5 to 5.5%, W: 8.0 to 1
3.0%, Mo: 1.0 to 5.0% (however, W + 2M
o ranges from 14 to 19), Nb: 0.5 to 3.5%,
C: 0.02-0.2%, B: 0.01-0.05%,
Mg: 0.004 to 0.02%, Ti: 3.0% or less,
Zr: 0.1% or less, Si: 1.0% or less, Mn: 1.
0% or less, and 2Mo / (W + 2Mo) is 0.1%.
20 to 0.55, and (W + 2Mo) / (Nb + 2T)
i) satisfies 1 to 10, and the balance is a Ni-based super heat resistant cast alloy comprising Ni and unavoidable impurities.

Further, the present invention is a turbine wheel made of a Ni-base super-heat-resistant alloy comprising the above-mentioned Ni-base super-heat-resistant cast alloy.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The reasons for limiting each element of the Ni-base superalloy of the present invention for realizing the above conditions will be described below. Cr forms an oxide film having high adhesion on the surface of the alloy during high-temperature heating, and enhances oxidation resistance. At least 7.0% by mass is necessary to guarantee oxidation resistance for turbine wheels, but if it exceeds 9.5%, the structure becomes unstable and hard and brittle harmful phases such as σ phase are eliminated. The Cr content is in the range of 7.0 to 9.5% by mass ratio because it is formed and causes a decrease in creep rupture strength and room temperature ductility.

The γ ′ phase is an intermetallic compound mainly composed of Ni ₃ Al, and has a high high-temperature strength of itself and a high ductility among the intermetallic compounds. Therefore, the γ ′ phase is used for strengthening many super heat-resistant alloys. However, Al is an indispensable element for precipitating a stable γ 'phase and obtaining a desired creep rupture strength, and requires at least 2.5% by mass. However, 5.5
%, An excessively large amount is added, so that a coarse eutectic γ 'phase is formed and conversely, the creep rupture strength is lowered.
The amount of l is in the range of 2.5 to 5.5% by mass ratio.

W is an element that forms a solid solution in the γ phase and the γ ′ phase, strengthens both phases, and has an effect of significantly increasing the creep rupture strength. To obtain this effect, at least 8.0% by mass is required. is necessary. However, when the content exceeds 13.0%, a harmful phase such as a σ phase is precipitated, which causes a decrease in ductility at room temperature, and also causes a decrease in oxidation resistance and adhesion of an oxide film. The mass ratio is in the range of 8.0 to 13.0%.

Mo partially forms a solid solution in the γ ′ phase, but mainly forms a solid solution in the γ phase to increase the high-temperature strength. For this reason, Mo needs to be at least 1.0% by mass, but excessive addition causes precipitation of a harmful phase such as a σ phase, resulting in a decrease in room-temperature ductility. Therefore, the upper limit is set to 5.0%. Where W and M
Since o is a homologous element and has a similar effect, in order to enhance the strength and structure stability of the alloy, W + 2 calculated by the total amount of both elements taking into account the atomic weight, that is, the mass ratio
It is necessary to limit the value of Mo. When W + 2Mo is less than 14, sufficient creep rupture strength cannot be obtained, and when W + 2Mo is more than 19, harmful phases such as σ phase are precipitated. Therefore, W + 2
The value of Mo must be limited to 14-19, preferably 15-18.

Nb forms a solid solution in the γ ′ phase and strengthens the γ ′ phase by solid solution to help improve the high-temperature strength. For this purpose, Nb needs to be added in a mass ratio of 0.5% or more. However, if it exceeds 3.5%, the structure becomes unstable, and the ductility and toughness of the alloy decrease. Therefore, the Nb content is set to 0.5 to 3.5% by mass.

Ti forms a solid solution in the γ ′ phase similarly to Nb, and strengthens the γ ′ phase to improve the creep rupture strength, so that Ti is added as necessary. However, excessive addition exceeding 3.0% destabilizes the γ 'phase, causing a decrease in strength after long-time use at high temperatures and also impairs ductility. 0.0% or less.

Since the lattice constant mismatch rate (LM%) of the alloy is mainly affected by elements such as W, Mo, Ti, and Nb, it is necessary to adjust the balance of these elements.
First, W and Mo, which are elements that mainly dissolve in the γ phase,
The ratio of the elements Ti and Nb, which are mainly dissolved in the γ 'phase, is defined as a value in consideration of the atomic weight, and is expressed as (W + 2Mo) / (Nb +
If this value is 1 or less, the LM% is too large, and if it is 10 or more, the LM% is too small. When Ti is added, the value of (W + 2Mo) / (Nb + 2Ti) is limited to 1 to 10. , Ti-free (W + 2Mo)
It is necessary to limit the value of / Nb to 1 to 10.

Next, W and Mo mainly dissolve in the γ phase and have a similar effect, but differ in the proportion of solid solution in the γ phase and the γ ′ phase. Therefore, in order to more strictly limit the lattice constant mismatch rate, it is necessary to limit the value of 2Mo / (W + 2Mo). If this value is smaller than 0.20, the lattice constant mismatch ratio becomes too large, and if it is larger than 0.55, the lattice constant mismatch ratio becomes too small. Therefore 2M
It is necessary to limit the value of o / (W + 2Mo) to 0.20 to 0.55.

C forms carbides, and precipitates particularly at grain boundaries and dendrite boundaries to strengthen grain boundaries and dendrite boundaries, and contributes to improvement in high-temperature strength. Although it is necessary, if added in excess of 0.2%, ductility may be impaired, so the C content is set in the range of 0.02 to 0.2% by mass. Zr contributes to the improvement of high-temperature strength by the action of strengthening the crystal grain boundary, but if added in excess of 0.1%, ductility may be impaired. Therefore, the Zr content is set to a range of 0.1% or less by mass ratio. .

When B is added in an amount of 0.01% or more by mass, it contributes to the enhancement of high-temperature strength due to the action of strengthening the crystal grain boundaries. In the component system of the alloy of the present invention, B is particularly added when added in a mass ratio of 0.05 or more. Experiments have shown that the ductility in the high-temperature range of 800 ° C. or higher is improved. However, the addition of 0.35% or more lowers the high-temperature strength. Mg contributes to refinement of carbides and improvement of ductility, but the effect becomes remarkable by adding 0.004% or more by mass ratio. However, if it is added in excess of 0.02%, a low melting point compound is formed at the grain boundary to lower the grain boundary strength. Therefore, in order to have both high temperature ductility and strength, when the amount of B is 0.01 to 0.05% by mass, which has a relatively small effect of improving ductility, the amount of Mg is 0.004 to 0.02% by mass. But B
When the amount is 0.05 to 0.35% by mass, B contributes to the improvement of the high-temperature ductility. Therefore, even if the addition of Mg is less than 0.004% by mass, the effect of improving the ductility can be obtained. Is an element to be added.

Both Si and Mn are added as deoxidizers. However, if Si exceeds 1.0%, ductility decreases, and if Mn exceeds 1.0%, high-temperature strength decreases. Therefore, both are set to 1.0% or less by mass ratio. In addition,
The following elements may be contained as impurities in the alloy of the present invention within the following range (mass ratio). P ≦ 0.04%, S ≦ 0.
03%, Cu ≦ 0.30%, V ≦ 0.3%, Ta ≦ 0.
5%, Ca ≦ 0.02%, Co ≦ 2%, Fe ≦ 3%, H
f ≦ 0.2%

In order to obtain the creep rupture strength required for the turbine wheel, the solid solution index is preferably in the range of 1.2 to 1.35, and the component range of the alloy of the present invention can satisfy this value. The turbine wheel made of the alloy of the present invention described above has excellent creep rupture strength and high-temperature ductility, and can have durability that can be used in a lean burn engine.

[0033]

EXAMPLE No. 1 shown in Table 1 was used. 1 is a comparative alloy, a typical alloy described in JP-A-11-131162,
No. 2 to No. 2 No. 10 is the alloy of the present invention. 11 is Alloy713C of a conventional comparative alloy. In addition, as shown in Table 2, 12 to No. 12 No. 17 fixes the amount of B to 0.2% in a mass ratio within the range of the present invention, and for other elements, Cr, Al, Ti, Mo, W, Nb, M
This is an alloy of the present invention in which alloy elements such as g are changed. Furthermore, creep rupture tests were performed on these alloys, and their properties were compared. In addition,-mark shown in Table 1 is no addition (0%).

[0034]

[Table 1]

[0035]

[Table 2]

First, No. 1 to No. Each alloy of No. 11 was melted in a vacuum furnace and cast into a lost wax ceramic mold set in the furnace to produce a rod of φ12 mm × 82 mm. Next, the as-cast bar is parallel part with φ5.0mm.
After machining into a creep rupture test specimen of φ6.4 mm and φ6.4 mm, a specimen of φ5.0 mm was subjected to a load stress of 700 MPa in a 720 ° C. atmosphere, and a specimen of a load stress of 500 MPa in an atmosphere of 820 ° C. and a specimen of φ6.4 mm were subjected to 1000. A creep rupture test was performed in an atmosphere at a load stress of 180 MPa in an atmosphere at a temperature of ° C., and the rupture life and elongation were measured.

[0037]

[Table 3]

As a goal of the present invention, in order to provide a turbine wheel that can support a lean burn engine,
720 ° C-700M of the material constituting the turbine wheel
Break life at Pa is 100 hr or more, 820 ° C-5
The breaking life at 00 MPa is 50 hours or more and 1000
The breaking life at -180 MPa is 10 hr or more, and the breaking elongation at 720 ° C is 3.0% or more, 820
The elongation at break in ° C. needs to be 4.0% or more. As shown in Table 3, the alloys of the present invention and the comparative alloys greatly exceeded the conventional alloys in the rupture life, and the elongation of the alloys of the present invention was significantly higher than that of the comparative alloy. In this case, the elongation at 720 ° C. by adding Mg is
It can be seen that the elongation in the temperature range of 820 ° C. or more is particularly improved by the addition of B.

The alloy of the present invention and the comparative alloy both have a solid solution index within a desirable range of 1.2 to 1.35, and a target rupture life is obtained. The solid solution index was 1.11, which resulted in failure to obtain a rupture life. Next, No. 12-No. No. 17 described above. 1 to No. A creep rupture test was performed under the same conditions as in Example 11, and the elongation is shown in Table 4.

[0040]

[Table 4]

From Table 4, it can be seen that by setting B to 0.2% by mass, the elongation of the alloy is Cr, Al, Ti, Mo, W,
Even when the elements such as Nb and Mg were changed, the values were higher than those of the comparative alloy, and the results also showed that the fracture life satisfied the target value.

As described above, the alloy of the present invention satisfies the target values in both the rupture life and the elongation at break in creep rupture characteristics. It turns out there is. As described above, since the alloy of the present invention can be applied to a lean burn engine used in a severe environment, it is natural that the alloy of the present invention has sufficient durability even when used for a turbine wheel as a component of a general turbocharger. Needless to say, the sex is obtained.

[0043]

The alloy of the present invention does not contain expensive alloying elements such as Co, Ta, Hf, etc.
oy713C is as inexpensive, but has a solid solution index and LM
% By adjusting its creep rupture characteristics to Al
loy 713C or more, and further the addition of B or Mg can improve its ductility and further improve the durability as a turbine wheel, and can be applied to lean burn engines.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Toshihiro Uehara 2107-2 Yasugi-cho, Yasugi-shi, Shimane F-term in the Metallurgical Research Laboratory, Hitachi Metals, Ltd. 3G002 EA06 3G005 EA04 EA16 FA13 GB79 GB81 KA00 KA07

Claims (5)

[Claims] 1. Cr: 7.0 to 9.5% by mass ratio, A
l: 2.5 to 5.5%, W: 8.0 to 13.0%, M
o: 1.0 to 5.0% (W + 2Mo is 14 to 1
9), Nb: 0.5-3.5%, C: 0.02-
0.2%, B: 0.05-0.35%, Mg: 0.02
% Or less (excluding 0%), Zr: 0.1% or less,
Si: 1.0% or less, Mn: 1.0% or less, 2Mo / (W + 2Mo) satisfies 0.20 to 0.55, and (W + 2Mo) / Nb satisfies 1 to 10, the balance being Ni
And a Ni-based super heat-resistant cast alloy comprising an unavoidable impurity. 2. Cr: 7.0 to 9.5% by mass ratio, A
l: 2.5 to 5.5%, W: 8.0 to 13.0%, M
o: 1.0 to 5.0% (W + 2Mo is 14 to 1
9), Nb: 0.5-3.5%, C: 0.02-
0.2%, B: 0.05-0.35%, Mg: 0.02
% (But not including 0%), Ti: 3.0% or less,
Zr: 0.1% or less, Si: 1.0% or less, Mn: 1.
0% or less, and 2Mo / (W + 2Mo) is 0.1%.
20 to 0.55, and (W + 2Mo) / (Nb + 2T)
i) satisfying 1 to 10, with the balance being Ni and unavoidable impurities. 3. Cr: 7.0 to 9.5% by mass ratio, A
l: 2.5 to 5.5%, W: 8.0 to 13.0%, M
o: 1.0 to 5.0% (W + 2Mo is 14 to 1
9), Nb: 0.5-3.5%, C: 0.02-
0.2%, B: 0.01-0.05%, Mg: 0.00
4 to 0.02%, Zr: 0.1% or less, Si: 1.0%
Hereinafter, Mn: 1.0% or less, and 2Mo / (W
+ 2Mo) is 0.20 to 0.55, and (W + 2Mo)
/ Nb satisfies 1 to 10, with the balance being Ni and unavoidable impurities. 4. Cr: 7.0 to 9.5% by mass ratio, A
l: 2.5 to 5.5%, W: 8.0 to 13.0%, M
o: 1.0 to 5.0% (W + 2Mo is 14 to 1
9), Nb: 0.5-3.5%, C: 0.02-
0.2%, B: 0.01-0.05%, Mg: 0.00
4 to 0.02%, Ti: 3.0% or less, Zr: 0.1%
Hereinafter, Si: 1.0% or less, Mn: 1.0% or less, and 2Mo / (W + 2Mo) is 0.20 to 0.5.
5, and (W + 2Mo) / (Nb + 2Ti) is 1 to 10
And a balance consisting of Ni and inevitable impurities. 5. A turbine wheel made of a Ni-base super heat-resistant alloy, comprising the Ni-base super heat-resistant cast alloy according to any one of claims 1 to 4.