JP2003138334A - Ni-BASED ALLOY HAVING EXCELLENT HIGH TEMPERATURE OXIDATION RESISTANCE AND HIGH TEMPERATURE DUCTILITY - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an Ni-based alloy which has improved oxidation resistance at a high temperature and improved ductility at a high temperature. SOLUTION: The Ni-based alloy having excellent high temperature oxidation resistance and high temperature ductility has a composition containing, by mass, <=0.1% C, <=1.0% Si, <=2.0% Mn, 12 to 32% Cr, <=20% Fe, <=0.05% Ti (inclusive of zero), 0.03 to 0.5% Al, 0.001 to 0.05% Mg, and one or more kinds selected from <=0.2% rare earth elements, <=0.3% Y, <=0.2% Sc, <=0.3% Hf and <=0.4% Zr so as to control their total in <=0.5%, and in which the content of S as an impurity is <=0.002%, and also, Mg/S>=1 is satisfied, and similarly, the content of O as an impurity is limited to <=0.01%, P to <=0.005%, Pb to <=0.001%, Bi to <=0.0002%, Sb to <=0.001%, Sn to <=0.005%, and As to <=0.005%, and also, (0.1×Si+0.1×Mn+0.2×Al+2×Mg+rare earth elements+Y+Sc+Hf+ Zr)/(O+2S)>=10 is satisfied, and the balance Ni with inevitable impurities other than the above ones.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to automobile parts such as electrodes for spark plugs, parts for power generation equipment such as gas turbine nozzles, parts for heat treatment furnaces, parts for fuel cells and the like, which are exposed to an oxidizing atmosphere at high temperatures. The present invention relates to a Ni-based alloy having excellent high-temperature oxidation resistance and high-temperature ductility, which is suitable for parts and members to be used.

[0002]

2. Description of the Related Art Conventionally, Ni-18Cr-7Fe, which has excellent oxidation resistance and high temperature ductility, has been used for members exposed to an oxidizing atmosphere at high temperature.
(Alloy 600) alloy is used. Oxidation resistance is necessary to prevent loss and embrittlement due to oxidation when used at high temperature air or gas atmosphere, Alloy 600 is Cr ₂ O ₃ at high temperature
Oxidation resistance is maintained by forming a film and protecting the base material. Further, ductility at high temperature is a characteristic required for a member that undergoes a thermal cycle to prevent breakage due to deformation due to thermal expansion or thermal contraction. In recent years, various parts have been required to have oxidation resistance at a temperature higher than that in the conventional use environment, and alloys improved from Alloy 600 have been studied. As alloy 600 with improved oxidation resistance, for example, JP-A-63-153236 and JP-A-2000-336446 are proposed.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In No. 6, Y, Ce, Zr, Sc and / or La are added to Alloy 600 to improve the oxidation resistance. Then, in JP-A-2000-336446 proposed by the present inventors to improve the hot workability by adding Mg to Alloy600, based on the alloy with improved oxidation resistance without adding Ti, a rare earth element, Y, Hf and /
Alternatively, by adding Zr, the oxidation resistance is further improved. JP-A-63-153236 and JP-A-2000-336446.
The alloy described in No. 1 showed basically good oxidation resistance even at high temperatures around 1050 ° C.

However, recent automobile parts such as electrodes for spark plugs, parts for power generation equipment such as gas turbine nozzles, parts for heat treatment furnaces, parts for fuel cells and the like, which are used by being exposed to an oxidizing atmosphere at high temperature, are used. Further, the requirements for members and members are strict, and alloys having good oxidation resistance at a high temperature of 1100 ° C. are required, and the oxidation resistance of these alloys was insufficient at 1100 ° C. Further, when these alloys were continuously investigated, the test pieces produced from some ingots sometimes showed a significant decrease in oxidation resistance even at 1050 ° C.

Further, according to a study by the present inventors, it has been found that
When we investigated the ductility at high temperature for 63-153236 and JP-A-2000-336446, good properties were obtained in most of the test pieces, but ductility at high temperature was obtained in the test pieces manufactured from some ingots. Was sometimes reduced. Furthermore, JP 20
In 00-336446, an alloy containing a high Al amount of 5% or less is preferable, but when the present inventors examined in detail, an alloy with a high Al produced an Al ₂ O ₃ film at around 1100 ° C. To improve oxidation resistance, but at high temperatures, especially 700 ℃
Ductility in the vicinity is significantly reduced. These are major problems in putting alloys requiring high temperature oxidation resistance and products using them into practical use. The object of the present invention is to improve the oxidation resistance at high temperature and further improve the ductility at high temperature.
It is to provide a base alloy.

[0006]

The present inventors have examined the problem of oxidation resistance at high temperatures. First, among the improved alloys of Alloy 600 shown in JP-A-63-153236 and JP-A-2000-336446, a test piece subjected to an oxidation resistance test at 1100 ° C. was examined, and a small amount of Al was found to be an oxide film. It was found that it contributes to the adhesiveness and suppresses the peeling of the oxide film, which has a good effect on the oxidation resistance.

Further, when a test piece having good oxidation resistance at 1050 ° C. was examined, the rare earth elements, Y, Sc, Hf, and Zr act effectively, and these elements cause the growth and peeling of the oxide film. In order to suppress, good oxidation resistance was exhibited even at 1100 ° C. Next, among the improved alloys of Alloy 600 shown in JP-A-63-153236 and JP-A-2000-336446, the material whose oxidation resistance was lowered even at 1050 ° C. was investigated, and it was surprising that the impurity element The contents of O and S are
It has been found that the oxidation resistance at high temperatures tends to decrease as the content of c, Hf and Zr increases.

As a result of a further detailed study by the present inventors, the alloys containing a large amount of O and S, which have low oxidation resistance even at 1050 ° C., contain rare earth elements, Y, Sc, Hf and Zr. , O
Rare earth elements, Y, Sc, Hf, and Zr, which are solid-solved in the form of oxides and sulfides that bind to S and S, respectively, may not be sufficient to contribute to oxidation resistance. Therefore, in order to suppress the formation of oxides containing rare earth elements, Y, Sc, Hf, and Zr as the main components, the O content should be sufficiently reduced before adding these elements during dissolution. I found that it was necessary to put it. For that purpose, vacuum melting and deoxidation with C, Si and Mn are essential, and Mg and a small amount of A
It was found that the addition of l also has an effect, and it is necessary to add rare earth elements, Y, Sc, Hf and Zr to the molten metal sufficiently deoxidized by these additions.

Further, in order to suppress the formation of sulfides of rare earth elements, Y, Sc, Hf and Zr, Mg is added to the molten metal.
It is necessary to remove S and fix S in the alloy with Mg. As described above, after adding a small amount of Al, rare earth elements contained in the alloy, Y, Sc, to suppress the oxide formation and sulfide formation of Hf and Zr, to effectively contribute to the oxidation resistance. , O and S are limited to a specific amount or less, and by using a special relational expression, Si, Mn, Al, Mg, rare earth elements, Y, Sc, Hf, and Zr are equal to or more than a certain amount with respect to O and S. It has been found that it is necessary to include it.

Next, the present inventors investigated ductility at high temperature. Examination of the above-mentioned test piece that the ductility at high temperature has decreased, Pb, Bi, which is an impurity element more than expected,
Finding that the content of Sb, Sn and As is high,
It was found that the high temperature ductility was reduced due to the excessive amounts of these impurities remaining in the ingot, and Pb,
It was found that Bi, Sb, Sn and As can be kept low.

Further, when Al is positively added in the range of 5% or less as in JP-A-2000-336446, the oxidation resistance is improved as the added amount of Al is increased, but the temperature is about 700 ° C. Addition of excessive Al deteriorates the high temperature ductility because it forms a γ'phase in the region and significantly reduces the ductility. However,
Since oxidation resistance is insufficient if Al is kept low, Al
In order to maintain good oxidation resistance even with a low
It was found that the above-mentioned addition of rare earth elements, Y, Sc, Hf and / or Zr is necessary in addition to Al addition. As described above, (1) low Al content, (2) addition of rare earth element, oxidation resistance improving element of Y, Sc, Hf and / or Zr, (3) addition of O and S to make it act effectively It has been found that by simultaneously combining reduction (4) and reduction of impurity elements (1) to (4) that further lowers high temperature ductility, both oxidation resistance and high temperature ductility can be achieved at the same time.

That is, in the present invention, C: 0.1% or less by mass%, Si: 1.
0% or less, Mn: 2.0% or less, Cr: 12 to 32%, Fe: 20% or less, Ti: 0.
05% or less (including 0), Al: 0.03 to 0.5%, Mg: 0.001 to 0.05%,
And 0.5% or less in total of one or more selected from the group of (rare earth element: 0.2% or less, Y: 0.3% or less, Sc: 0.2% or less, Hf: 0.3% or less, Zr: 0.4% or less) And is an impurity
S is 0.002% or less and satisfies Mg / S ≧ 1, and similarly, impurities O: 0.01% or less, P: 0.005% or less, Pb: 0.001% or less,
Bi: 0.0002% or less, Sb: 0.001% or less, Sn: 0.005% or less, As:
Limit to less than 0.005% and (0.1 x Si + 0.1 x Mn + 0.2 x Al +
2 × Mg + rare earth element + Y + Sc + Hf + Zr) / (O + 2S) ≧ 10,
The balance is a Ni-based alloy consisting of Ni and unavoidable impurities other than the above, which has excellent high-temperature oxidation resistance and high-temperature ductility.

In the present invention, among the above Ni-based alloys excellent in high temperature oxidation resistance and high temperature ductility, the preferable ranges of Cr and Fe are as follows: Cr: 12-20% by mass%, Fe: 3% or more. It is a Ni-based alloy with excellent high temperature oxidation resistance and high temperature ductility of up to 10%. More preferably, La: 0.2% or less and Zr: 0.4% in mass%
One or two of the following are included and their sum is 0.
It is a Ni-based alloy excellent in high temperature oxidation resistance and high temperature ductility of 5% or less.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, an important feature of the present invention is an optimum composition capable of combining sufficient oxidation resistance at high temperature and good hot ductility. The action of each element will be described below. C has a function of forming a carbide by being combined with Cr and the like and preventing coarsening of crystal grains, and it is necessary to add a small amount. It is also an element necessary for deoxidation.
However, excessive addition causes a decrease in cold workability due to the formation of a large amount of carbide and a deficiency of Cr in the matrix (matrix), so the content is limited to 0.1% or less. Si is an element that exerts a strong deoxidizing action on the molten metal. Further, it has an effect of improving castability. Further, SiO ₂ is formed between the oxide film and the base material and prevents the oxide film from peeling. For these reasons, Si is added, but excessive addition causes a decrease in oxidation resistance, so the upper limit of Si is 1.0%. Mn has the same deoxidizing effect as Si and has the effect of improving the castability, but excessive addition causes a decrease in oxidation resistance, so the upper limit of Mn is 2.0%.

Since Cr is present in the matrix, it forms a Cr ₂ O ₃ film on the surface of the material at a high temperature to improve the oxidation resistance. In order to form a continuous oxide film at high temperature and to impart sufficient oxidation resistance, the lower limit needs to be 12% or more. However, excessive addition lowers the workability and causes peeling of the Cr ₂ O ₃ coating, so the upper limit of Cr was 32%. A desirable range for more reliably obtaining the effect of Cr is 12 to 20%. Fe is
It is an element that lowers the high temperature strength, and if it is not added, the hot workability will be significantly deteriorated. Therefore, it is an element necessary for manufacturing. However, excessive addition, on the contrary, lowers the strength at high temperature and also slightly lowers the oxidation resistance. Therefore, the upper limit of the amount of Fe added is set to 20% or less. A desirable range for more reliably obtaining the effect of Fe is more than 3% and up to 10%.

When Ti is added, Ti oxide is formed from the oxide film toward the inside of the material along the grain boundaries. As a result, the oxide film is easily peeled off and the oxidation resistance is deteriorated. However, if it is a small amount, the amount of exfoliation at the time of oxidation is small, and it also has a deoxidizing effect on the molten metal, so that it may be added if it is an extremely small amount. Therefore, the upper limit of the Ti content is 0.05% or less, and the Ti content may not be added (0%). Al
Is an element that precipitates γ ′ at around 700 ° C. if excessively added, and is an element that reduces ductility, and it is necessary to suppress it to a low level, but addition of a small amount improves oxidation resistance and does not affect ductility, Furthermore, since it has a deoxidizing action in the molten metal, addition of a small amount of Al is effective. Therefore, Al is set to 0.03 to 0.5% or less.

By adding a small amount of rare earth elements, Y, Sc, Hf and Zr, the oxidation resistance is remarkably improved without lowering the ductility at high temperature. Addition of an appropriate amount of rare earth element is effective for oxidation resistance, but among them, preferable rare earth elements are La and Ce. Rare earth elements such as La and Ce, Y, S
Each element of c, Hf, and Zr has the effect of improving the adhesion of the oxide film and suppressing the growth rate of the oxide film, but excessive addition deteriorates the hot workability. Therefore, the addition amount of rare earth elements 0.2% or less, Y 0.3% or less, Sc 0.2% or less, Hf 0.3% or less, Z
One or more of r0.4% or less is included, and the total of them is 0.5% or less. Further, in the present invention, among the above-mentioned rare earth elements, Y, Sc, Hf, and Zr, La and Zr are particularly effective in improving the adhesion of the film and improving the oxidation resistance. Therefore, rare earth elements, Y, Sc, Hf, Zr particularly desirable additional elements and addition amount include one or two of La 0.2% or less and Zr 0.4% or less and their total is 0.5% or less. Is.

Mg is an element necessary for removing or fixing S by combining with S to form a compound. However, since Mg has a small solid solubility limit in Ni, excessive addition forms Ni ₂ Mg at the grain boundaries. Therefore, a eutectic of Ni and Ni ₂ Mg is generated at the grain boundary, and the grain boundary becomes brittle during hot working.
Hot workability and hot ductility are reduced. Therefore, the addition of Mg is 0.001 to 0.05%. Then, it is necessary to adjust the Mg within the range of 0.001 to 0.05% and then set the ratio of Mg / S by mass to 1 or more in order to reliably remove or fix S.

Next, the impurities to be restricted in the present invention will be described in detail. Impurity S forms a sulfide with rare earth elements, Y, Sc, Hf, and Zr, which are essential elements for improving the oxidation resistance, because the solid solution limit in Ni is very small and therefore only a small amount is contained. The effect of improving the oxidation resistance of rare earth elements, Y, Sc, Hf and Zr is reduced. Also, Ni ₃ S ₂ segregates at the grain boundaries, and a eutectic of Ni and Ni ₃ S ₂ is generated. The eutectic has a very low melting point and becomes very brittle in the temperature range of hot working. Therefore, S is an element that weakens the grain boundaries during hot working, causes cracks, and reduces hot workability and hot ductility. Therefore, S is 0.002% or less. More preferably, it should be limited to 0.001% or less, and even more preferably 0.001%.
It is within the range of 05% or less.

O is an impurity element that binds to the rare earth elements, Y, Sc, Hf and Zr to form an oxide, and inhibits the oxidation resistance improving effect of these elements, so the upper limit of O is set to 0.01%. did. More preferably, it should be limited to 0.003% or less. Here, in order to sufficiently exert the effect of the rare earth element effective for oxidation resistance, Y, Sc, Hf, and Zr, O is sufficiently added before the addition of the rare earth element, Y, Sc, Hf, and Zr during melting. It is good to reduce it. Specifically, vacuum melting and deoxidation with C, Si, and Mn are effective, and addition of Mg and a very small amount of Al is also effective. After sufficiently reducing O in the molten metal by adding the above deoxidizing element, rare earth elements, Y, Sc, Hf, and Zr are added, the rare earth elements, Y, Sc, Hf, and Zr elements are effective. It can function and impart excellent oxidation resistance.

As described above, in order to suppress oxide formation and sulfide formation of rare earth elements, Y, Sc, Hf and Zr contained in the alloy and effectively contribute to oxidation resistance, Si, M
It is necessary that n, Mg, rare earth elements, Y, Sc, Hf, and Zr be contained in a certain amount or more with respect to O and S. Therefore, these elements are (0.1 × Si + 0.1 × Mn) within the specified addition amount range.
+ 2 × Mg + rare earth element + Y + Sc + Hf + Zr) / (O + 2S) ≧ 10 must be satisfied.

Since P is an impurity element that impairs hot workability and may cause embrittlement in a temperature range near 500 ° C., P is also limited as an impurity element in the present invention. P
The content of 0.005% or less in the range that does not impair hot workability. It is preferably 0.003% or less.

Next, Pb, Bi, Sb, Sn and As are impurity elements that reduce the ductility of the alloy at high temperatures of 500 ° C. or higher, and the content of these five impurity elements is limited to a specified amount or less. As a result, good ductility can be realized.
Therefore, the content to be limited is Pb: 0.001% or less, Bi: 0.
0002% or less, Sb: 0.001% or less, Sn: 0.005% or less, As: 0.005%
It is the following. If even one of them falls outside the above range, the ductility of the alloy may be deteriorated. Therefore, it is necessary to limit all of the above five elements within the range defined by the present invention. By the way, as a method of limiting these five elements, Pb, B
The elements of i, Sb, Sn and As can be reduced.

Next, the following elements, which are not particularly specified in the present invention, can be added to the alloy of the present invention within the following ranges. Mo and W have a solid solution strengthening effect and can be added when strength is required at room temperature or high temperature. However, excessive addition hinders hot and cold workability, so the addition amount is 3% or less of Mo and 6% or less of W. Nb and Ta have the function of forming carbides and suppressing the crystal grain growth in addition to the solid solution strengthening effect, and can be added when high strength or grain refinement is required. However, excessive addition deteriorates ductility at high temperature, so the addition amount is Nb 0.5% or less and Ta 0.5% or less. V also has an effect of suppressing crystal grain growth, and can be added when crystal grain refinement is required. However, excessive addition impairs cold workability, so the addition amount is 0.5% or less.

Ca can be added to fix and remove S, and it is effective to add when it is desired to remove S by an element other than Mg. However, excessive addition deteriorates the hot workability, so the addition amount is 0.02% or less. Co is an element that improves strength at room temperature and high temperature, and can be added when strength is required at room temperature or high temperature. However, excessive addition causes an increase in cost, so the addition amount is 2
% Or less. N is an element that suppresses crystal grain coarsening and improves strength, and can be added when higher strength or finer crystal grains are required. However, excessive addition deteriorates cold workability, so the addition amount is 0.05% or less. B is an element that suppresses crystal grain coarsening, and can be added when crystal grain refining is required. However, excessive addition lowers the oxidation resistance, so the addition amount is 0.01% or less.

In addition, the Ni-based alloy of the present invention described above is 1100.
Shows good oxidation resistance in the temperature range up to ° C. As an indicator of its excellent oxidation resistance, at any temperature of 500 ~ 1100 ℃, when held in the atmosphere for 100 h, peeling of the oxide film does not substantially occur, and the unit area of the test piece (m ² It can be specified that the amount of increase in oxidation per) is 20 g or less. Alloys with properties within this range are exposed to oxidizing atmospheres at high temperatures such as automobile parts such as electrodes for spark plugs, parts for power generation equipment such as gas turbine nozzles, parts for heat treatment furnaces and parts for fuel cells. It is possible to prevent the components and members used for the purpose from being lost due to peeling of the oxide film, and to avoid embrittlement of the components themselves due to oxidation. Here, the oxidation weight increase per unit area is 500 to 1100 ° C, and the difference between the weight of the test piece including the oxide film after heating and the weight of the test piece before heating is maintained for 100 hours in the atmosphere. It is divided by the surface area of the test piece before heating.

Further, the Ni-based alloy of the present invention is excellent in ductility at normal temperature and high temperature. The alloy of the present invention is heated from room temperature to 1100 ° C
When it is subjected to a tensile test at any temperature, it exhibits excellent ductility with a breaking elongation of 35% or more. In the temperature range from this room temperature to 1100 ° C., the alloy of the present invention, which has the characteristic that the elongation at break is 35% at any temperature, is used for automobile parts such as electrodes for spark plugs, parts for power generation equipment such as gas turbine nozzles, Due to repeated heating and cooling of parts and members that are used by being exposed to an oxidizing atmosphere at high temperatures, such as parts for heat treatment furnaces and parts for fuel cells, each time they are deformed by thermal expansion or contraction. It has sufficient properties to avoid the fracture.

[0028]

EXAMPLES The present invention will be described in detail below with reference to examples. 10kg of Ni-based alloy with composition shown in Table 1 by vacuum melting
The ingot was melted. At this time, the alloy of the present invention is C, Si, Mn, Mg and a small amount of Al in order to prevent deterioration of the oxidation resistance, the molten metal sufficiently deoxidized by adding a rare earth element,
Y, Sc, Hf and Zr are added, and rare earth elements, Y, Sc, Hf and
The formation of Zr oxide was suppressed. Further, in the alloy of the present invention, the molten raw materials were analyzed in order to improve the ductility at high temperature, and the carefully selected raw materials were used to prevent the inclusion of impurities such as Pb, Bi, Sb, Sn and As.

[0029]

[Table 1]

No. 1 to No. 19 shown in Table 1 are alloys of the present invention, and No. 20 to No. 26 are comparative alloys. Note that No. 24 alloy is Al-free because it is based on the improved alloy of Alloy 600 shown in JP-A-63-153236, and this alloy does not take special consideration for deoxidation and In order to investigate the effect, O was made extremely high, Mg was not added, and P, Pb, Bi, Sb,
In order to investigate the effects of Sn and As as well, the raw materials were selected so that these elements were also extremely high. Further, improved alloys of Alloy 600 included in JP 2000-336446 A are shown as No. 25 and No. 26. No.25 alloy is also Al-free and O, P, Pb, B
In order to investigate the effects of i, Sb, Sn and As, these elements were melted so as to be high, and the No. 26 alloy has a large amount of Al added.

This ingot was forged into a 30 mm square bar. This rod was subjected to solution treatment by air cooling at 950 ° C. for 1 hour. However, Nos. 22 and 24 were cracked and could not be forged. A sample was cut from the material that had been subjected to forging and solution treatment, and subjected to an oxidation resistance test and a tensile test at 700 ° C. For the oxidation resistance test, a φ10 mm × 20 mm test piece was tested at 1100 ° C ×
After heating for 100 hours, the amount of oxide film peeling and the increase in oxidation were determined. If the amount of oxide film peeling is 0, it means that there is substantially no peeling of the oxide film, and if the amount of increased oxidation is 20 g / m ² or less, the oxidation resistance is good. Tensile tests were performed to evaluate ductility at high temperatures. High temperature tensile test is ASTM: E21 at 700 ℃
And the elongation at break was measured. The elongation at break at high temperature is good if it is 35% or more. However, since No. 22 and 24 could not be forged, cut out steel pieces for collecting various test pieces from the ingot, subject them to solution treatment under the same conditions as above, and subject them to oxidation-resistant test pieces and high temperature. Tensile test pieces were prepared.

[0032]

[Table 2]

The alloy of the present invention showed very good oxidation resistance in the oxidation resistance test at 1100 ° C. × 100 hr with little increase in oxidation and no peeling of oxide film. The alloy of the present invention had a good ductility at 700 ° C and exhibited a breaking elongation of 35% or more. Also,
Since the alloy of the present invention has good hot workability, problems such as forging cracking did not occur.

On the other hand, when the Cr content of the comparative material is less than 12%,
(No. 20) A Cr ₂ O ₃ film is non-uniformly formed at a high temperature and does not act as a protective film, so the amount of oxidation increase after the oxidation resistance test increases and the oxide peels off. If Cr exceeds 32% (N
o.21) Cr ₂ O ₃ peeling occurs, so the amount of oxidation increase is large. When Mg was less than 0.001% and Mg / S <1 (No. 22), the hot workability deteriorated and cracking occurred during forging, making it impossible to forge. Further, since (0.1 × Si + 0.1 × Mn + 0.2 × Al + 2 × Mg + rare earth element + Y + Sc + Hf + Zr) / (O + 2S) <10, the oxidation resistance is poor. If the rare earth elements, Y, Sc, Hf and Zr are not added (No. 23), the oxide film grows rapidly and the oxide film peels off, resulting in a large increase in oxidation.

The alloy of No. 24 had Mg / S <1 without addition of Mg, so that cracking occurred during forging. Also, in addition to the fact that the adhesion of the oxide film is poor because Al is not added, S
Is higher than 0.002, O is higher than 0.01, and (0.1 × Si + 0.1
× Mn + 0.2 × Al + 2 × Mg + Rare earth element + Y + Sc + Hf + Zr) / (O + 2S)
Since it is <10, Y forms an oxide and a sulfide and does not sufficiently contribute to the oxidation resistance, so the amount of oxidation increase is large. Furthermore, Pb> 0.001%, Bi> 0.0002%, Sb> 0.001
%, Sn> 0.005%, As> 0.005%, so the elongation at break at 700 ° C is small. No. 24 alloy is JP 63-15
It is an alloy in the range included in No. 3236, which contains O, S, Pb, Bi, Sb, Sn, and As in an extremely large amount in order to investigate the effects of As.

In addition, in the No. 25 alloy, Al was not added and the adhesion of the oxide film was poor, and in addition, O was 0.01
It is higher and (0.1 × Si + 0.1 × Mn + 2 × Mg + 0.2 × Al + rare earth element + Y + Sc + Hf + Zr) / (O + 2S) <10, so La forms an oxide. However, since it does not contribute to the oxidation resistance, the increase in oxidation amount is large. Furthermore, Pb> 0.001%, Bi> 0.0002%, Sb> 0.0
Since it is 01%, Sn> 0.005% and As> 0.005%, the breaking elongation at 700 ° C is small. No. 25 alloy is JP 2000-
O, S, Pb, Bi, Sb, Sn in alloys in range 336446
It is an alloy containing a large amount of these elements in order to investigate the effect of Al and As. Furthermore, the alloy of No. 26 has a high Al content, so 700
The elongation at break at ° C is significantly reduced. No.26
The above alloy is also within the range included in JP-A-2000-336446. As described above, it is understood that the alloy which can withstand use at high temperature, can be forged, and has good ductility at high temperature can be obtained only when each element is included in the scope of the present invention.

Finally, among the alloys of the present invention, five No. 1 composition alloys were melted in an amount of 10 kg in the same manner as in the above-mentioned embodiment, and the ingot was wrought into a 30 mm square bar and air-cooled at 950 ° C. for 1 hr. Was subjected to solution treatment, and oxidation resistance test pieces and tensile test pieces were sampled to investigate the variation in properties. As a result, no variation was confirmed in oxidation resistance and high temperature tensile ductility.

[0038]

According to the present invention, automobile parts such as electrodes for spark plugs, parts for power generation equipment such as gas turbine nozzles, parts for heat treatment furnaces and parts for fuel cells are exposed to an oxidizing atmosphere at high temperatures. It is possible to produce a Ni-based alloy having excellent high-temperature oxidation resistance and high-temperature ductility, which is suitable for parts and members to be used as such.

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[Procedure amendment]

[Submission date] November 14, 2001 (2001.11.
14)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

As described above, in order to suppress oxide formation and sulfide formation of rare earth elements, Y, Sc, Hf and Zr contained in the alloy and effectively contribute to oxidation resistance, Si, M
It is necessary that n, Mg, rare earth elements, Y, Sc, Hf, and Zr be contained in a certain amount or more with respect to O and S. Therefore, these elements are (0.1 × Si + 0.1 × Mn) within the specified addition amount range.
+ 0.2 × Al + 2 × Mg + rare earth element + Y + Sc + Hf + Zr) / (O + 2S) ≧ 10 must be satisfied.

Claims (3)

[Claims] 1. Mass% C: 0.1% or less, Si: 1.0% or less, Mn:
2.0% or less, Cr: 12 to 32%, Fe: 20% or less, Ti: 0.05% or less (including 0), Al: 0.03 to 0.5%, Mg: 0.001 to 0.05%, and (rare earth element: 0.2% or less , Y: 0.3% or less, Sc: 0.2% or less, Hf: 0.3%
(Zr: 0.4% or less) contains 0.5% or less in total of one kind or two or more kinds selected from the group of), and S as an impurity is 0.002%.
Is less than or equal to and satisfies Mg / S ≧ 1, and also O of impurities: 0.
01% or less, P: 0.005% or less, Pb: 0.001% or less, Bi: 0.0002% or less, Sb: 0.001% or less, Sn: 0.005% or less, As: limited to 0.005% or less, and (0.1 × Si + 0.1 × Mn + 0.2 × Al + 2 × Mg + rare earth element + Y + Sc + Hf + Zr) / (O + 2S) ≧ 10, the balance is Ni and inevitable impurities other than the above, high temperature acid resistance Ni-based alloy with excellent chemical resistance and hot ductility. 2. Cr: 12-20% by mass%, Fe: 3% over 10%
The Ni-based alloy excellent in high temperature oxidation resistance and high temperature ductility according to claim 1, characterized in that 3. The composition according to claim 1 or 2, characterized in that it contains one or two kinds of La: 0.2% or less and Zr: 0.4% or less in mass% and the total thereof is 0.5% or less. Ni-based alloy with excellent high temperature oxidation resistance and high temperature ductility.