JP3058794B2 - Fe-Ni-Cr based super heat resistant alloy, knit mesh for engine valve and exhaust gas catalyst - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inexpensive Fe--Ni--Cr base super heat-resistant alloy having excellent high-temperature strength, and a knit mesh for an automobile engine valve and an automobile exhaust gas catalyst produced by using this alloy. It is.

[0002]

2. Description of the Related Art In recent years, with respect to the problem of environmental pollution on a global scale, energy saving and purification of exhaust gas have been required more than ever before, while resource saving of parts has been desired. For this purpose, resource saving of high-quality members such as engine valve materials and exhaust gas mesh materials which are exposed to high temperatures and high stresses in internal combustion engines of automobiles and the like is strongly desired.

Conventionally, as a material for an exhaust valve of a gasoline engine or a diesel engine, SUH35 (Fe-8.5Mn-21C) which is a high Mn austenitic steel has been used.
r-4Ni-0.5C-0.4N) has been widely used, but NCF751 (Ni-15.5Cr-1Nb-), which is a Ni-based super heat-resistant alloy, has been partly used at higher temperatures.
2.3Ti-1.2Al-7Fe) has come to be used. However, NCF751 is much more expensive than SUH35 because it contains about 70% Ni. Therefore, resources are saved more than NCF751, and NC
Alloys having high-temperature strength close to F751 and structural stability after long-time heating have been developed. As a result, for example, Japanese Patent Publication No. 1-12727, Japanese Patent Laid-Open No. 62-214149,
JP-A-58-189359, JP-A-63-21363
No. 1, JP-A-61-238942, JP-B-62-50
No. 542, Japanese Patent Publication No. 4-11613, and Japanese Patent Application Laid-Open No. Sho 60-21.
There are many proposals such as No. 1028.

[0004]

In recent years, with respect to gasoline fuel for automobile engines, measures to eliminate lead have been promoted in response to a request for purification of exhaust gas, and engines exclusively for lead-free gasoline have become mainstream. For components used especially at high temperatures among engine parts, such as automobile engine valves and knit mesh materials for exhaust gas catalysts, lead-free leads to an improved corrosive environment, as long as it has the same level of oxidation resistance as NCF751. In addition, the corrosion resistance to lead oxide, which has conventionally been regarded as a problem, has been improved without consideration. On the other hand, with the extension of the warranty period of automobiles, performance improvement has been required in terms of durability, and alloys with reduced strength reduction and embrittlement after long-term use at high temperatures have been required. It has become.

[0005] Among the resource saving materials of NCF751,
The alloys proposed in JP-A-3-213631, JP-B-4-11613 and JP-A-60-211028 are manufactured by NCF.
High temperature strength close to 751 and long-term structural stability can be obtained, but since the Ni content exceeds 50%, NCF751
Resource savings and price reductions have not yet been achieved. Also, Japanese Patent Publication No. 1-12827, Japanese Patent Application Laid-Open No. 62-21414.
No. 9 and Japanese Patent Application Laid-Open No. 58-189359 are excellent in oxidation resistance and corrosion resistance because of their high Cr content, but deteriorate the ductility at room temperature of the chromium-rich σ phase and α ′ phase. The resulting heterophase precipitates. On the other hand, JP-A-61-2389
No. 42 and Japanese Patent Publication No. Sho 62-50542 have a low Ni and low Al alloy composition, so that the γ ′ (gamma prime) phase, which is a precipitation strengthening phase, becomes coarse during long-time heating, and γ ′. Transformation from the phase to the η (eta) phase occurs, and the amount of reduction in high-temperature strength after long-time heating increases.

It is an object of the present invention to provide a resource-saving Fe-N alloy having excellent high-temperature strength and room-temperature ductility after prolonged heating and sufficient oxidation resistance, which cannot be achieved by the above-mentioned conventional alloys.
An object of the present invention is to provide an i-Cr-based super heat-resistant alloy, and further to provide a knit mesh for an engine valve and an exhaust gas catalyst manufactured using the alloy.

[0007]

As a means for predicting such material deterioration, in this study, a sample heated at 800 ° C. for 400 hours is prepared, and the tensile strength at 800 ° C. and the rotational bending fatigue strength are measured. Thus, the high-temperature strength of the alloy after long-time heating was measured. On the other hand, at room temperature (2
(0 ° C.) A U-notch Charpy impact test was performed, and the toughness of the material was evaluated from the impact value. Further, regarding the oxidation resistance, the weight change after heating at 850 ° C. for 400 hours was measured.

From these evaluation results, the use of the following three techniques has led to the invention of a new alloy that does not exceed 50% and that satisfies the purpose for resource saving. (1) Atomic% in the γ 'phase composed of Ni ₃ (Al, IVa, Va)
1.8 [Al] / ([Al] + [Ti] + [Zr] + [Hf] + [V] + [Nb] + [T
By increasing the amount of a]), the γ ′ phase was stabilized (this also led to an increase in the amount of Al alone). Based on this idea, the amount of Al is set to 1.6 to 3.0% by weight, and [Al] / ([Al] + [Ti] + [Zr] + [Hf] + [ V] +
By setting the [Nb] + [Ta]) content ratio in the range of 0.45 to 0.75, the γ ′ phase during long-time heating, which has been a problem with the conventional Fe—Ni—Cr based alloy, has been reduced to η. It was possible to prevent a decrease in high-temperature strength due to transformation into a phase or a δ phase. In addition, the increase in the amount of Al
It also increases the amount of generated Al ₂ O ₃ during high-temperature heating, and also has the function of complementing the decrease in oxidation resistance due to the decrease in (3) Cr content. Fe-Ni-Cr containing less than 50% Ni and less than 20% Cr
In base superalloys, such high Al and high 1.8 [Al] /
There is no conventional alloy having the amount ([Al] + [Ti] + [Zr] + [Hf] + [V] + [Nb] + [Ta]), which is a completely new invention.

(2) A decrease in high-temperature strength due to a decrease in the amount of Ni in the matrix is compensated for by an increase in the γ 'phase. These have been achieved by adding a higher Al content in addition to the addition amounts of the IVa group and the Va group which partially overlap the conventional alloy. More specifically, the amount of γ ′ for obtaining the desired strength is expressed in atomic% ([Al] + [Ti] + [Zr] + [Hf] + [V] + [Nb] + [Ta ]), And this value is higher than the conventional forged alloy by 6.5 to 6.5.
By controlling the temperature in the range of 10.0, it was possible to improve the high-temperature strength for a short time (four times the amount becomes the calculated γ ′ amount). Such a high calculated γ 'amount has not been put to practical use in forged alloys for engine valves and the like, and this point is also a completely novel invention. In the case of a Ni-based super heat-resistant alloy having a Ni content of 50% or more, the γ 'phase is stable up to a high temperature and hot working becomes difficult at this level of γ' content. In the case of an alloy having a low [Al] / ([Al] + [Ti] + [Zr] + [Hf] + [V] + [Nb] + [Ta]) content shown in (1), the IVa Group and Va group solid solution strengthening and γ '
The increase in the lattice strain of the phase makes hot working difficult. Therefore, such a high calculated γ ′ amount is such that the Ni amount is 50%.
% And [Al] / ([Al] + [Ti] + [Zr] + [H] shown in (1)
f] + [V] + [Nb] + [Ta]) can be processed only when the amount is high.

(3) The C of the matrix is used to prevent the embrittlement phase rich in Cr such as the σ phase and the α 'phase from being precipitated even after heating for a long time.
The amount of r is kept to the minimum addition that does not deteriorate the oxidation resistance.
Further, the addition amounts of Mo and W, which are elements of the same group as Cr, were also determined as necessary by the sum total when weight% was converted to atomic%. The above (1) and (2) and the optimization of the amount of Cr are also a completely new combination, and by performing these simultaneously, it is possible to obtain an alloy having both the desired strength and ductility after long-time heating. Was.

That is, in the present invention, C is 0.15% by weight.
Below, Si 1.0% or less, Mn 3.0% or less, Ni30
-49%, Cr 10-18%, Al 1.6-3.0%, and 1.5-8.0% in total of one or more elements selected from the group IVa and Va. The remainder has a basic composition of a Fe-Ni-Cr-based super heat-resistant alloy consisting essentially of Fe, excluding impurities.
One or two kinds of not more than 3% can be contained.

A more preferable range is that C is 0.08% or less, S
i 0.5% or less, Mn 1.0% or less, Ni 30 to 49
%, Cr 13-18%, Al 1.6-3.0%, Ti
Fe-Ni-Cr containing 1.5 to 3.0%, Nb 0.3 to 2.5%, and the balance being essentially Fe, excluding impurities
It is a base super heat resistant alloy. This can also contain one or two kinds of Mo 3% or less and W 3% or less as needed, but it is more preferable to contain Mo alone 3% or less. A more desirable range is 0.08% or less by weight of C and 0.2% of Si.
%, Mn 0.5% or less, Ni 30-45%, Cr1
3.5 to 16%, Mo 0.1 to 1.0%, Al 1.8 to
2.4%, Ti 2.0-3.0%, Nb 0.5-1.5
%. 5% by weight of these alloys as required
The following Co can be included in the range of Ni + Co ≦ 49.

In the above alloy, Al is essentially added in atomic%, and one or more elements selected from the group IVa and the group Va are preferably added within a range satisfying the following relational expression. . 6.5 ≦ [Al] + [Ti] + [Zr] + [Hf] + [V] + [Nb] + [Ta] ≦ 10.0 0.45 ≦ [Al] / ([Al] + [Ti] + [Zr] + [Hf] + [V] + [Nb] + [Ta]) ≦ 0.
75 The range satisfying the more preferable relational expression is 6.5 ≦ [Al] + [Ti] + [Zr] + [Hf] + [V] + [Nb] + [Ta] ≦ 8.5 0.50 ≦ [Al] / ([ [Al] + [Ti] + [Zr] + [Hf] + [V] + [Nb] + [Ta]) ≦ 0.
60.

In the above alloy, Cr is essentially added in atomic%, and one or two of Mo and W
It is desirable to include it in the range of 3 ≦ [Cr] + [Mo] + [W] ≦ 18. These alloys may be added at 0.01
One or two kinds of B of 5% or less, Mg of 0.02% or less, and Ca of 0.02% or less, and Y of 0.1% or less and rare earth elements of 0.1% or less (hereinafter referred to as REM). ) May be appropriately included. Some of the alloys having these compositions are converted to U after heating at 800 ° C. for 400 hours.
The notch Charpy impact value is 0.5 MJ / m ² or more. Further, it is characterized in that the number of fractures in a rotary bending fatigue test at 800 ° C. and 294 MPa after heating at 800 ° C. for 400 hours is 0.5 × 10 ⁶ times or more. In addition, an engine valve for a vehicle and a knit mesh for an exhaust gas catalyst for a vehicle manufactured using these Fe—Ni—Cr-based super heat-resistant alloys have excellent characteristics which have not been achieved in the past.

[0015]

In the present invention, C is combined with Ti and Nb to form MC carbide, which helps to prevent coarsening of crystal grains and improve creep rupture ductility, so that a small amount of C must be added.
However, an excessive addition exceeding 0.15% causes a large amount of a decomposition reaction from MC carbide to M ₂₃ C ₆ carbide during heating for a long time, and lowers the ductility of grain boundaries at room temperature. Therefore, C is added at 0.15% or less. A preferable range of C is 0.08% or less.

Although Si and Mn are added as deoxidizing elements in the alloy of the present invention, excessive addition of both causes reduction in high-temperature strength, so that Si is 1.0% or less and Mn is 3.0%.
It is limited below. Preferably, Si is 0.5% or less and Mn is 1.0% or less. More preferably, S
i is 0.2% or less and Mn is 0.5% or less.

Ni stabilizes the austenite phase of the matrix and increases the high-temperature strength. Further, it is an essential additive element as a constituent element of the γ ′ phase. If the Ni content is less than 30%, the precipitation of the γ 'phase becomes insufficient, and the high-temperature strength decreases. On the other hand, if the Ni content exceeds 49%, there is no merit in price as a resource saving material of the NCF 751, so the Ni content is limited to the range of 30 to 49%. A more desirable range of Ni is 30 to 45%.

Cr is an indispensable element for imparting oxidation resistance to the alloy, and at least 10% is required to guarantee oxidation resistance as a heat-resistant part for automobiles and the like, but 18% is required.
If it exceeds, the structure becomes unstable, and a harmful embrittlement phase such as an α 'phase or a σ phase rich in Cr is generated, resulting in a decrease in creep rupture strength and room temperature ductility. A preferable Cr content is 13 to 18%, and a more desirable Cr content is
The amount is between 13.5 and 16%.

Al is an essential element in the present invention for precipitating a stable gamma-prime phase and obtaining a desired high-temperature strength as described above, and requires at least 1.6%, but 3.0%. If it exceeds, the hot workability deteriorates.
Limited to 1.6-3.0%. In addition, this high Al content increases the amount of Al ₂ O ₃ generated during high-temperature heating and contributes to the improvement of oxidation resistance. A more desirable Al content is 1.8 to 2.4%.
It is. In the category of Fe—Ni-based superalloys containing less than 50% of Ni and less than 20% of Cr, alloys with such a high amount of Al have never existed. Is one of the most characteristic features of the present invention.

In the alloys of the present invention, the elements belonging to the group IVa and Va combine with Ni in combination with Al to precipitate a gamma prime phase and increase the high-temperature strength.
It is necessary to add at least 1.5% of seeds or more. However, if the total content of these elements exceeds 8.0%, the gamma prime phase becomes unstable during high-temperature and long-time heating, and the η phase and δ
Intermetallic workpieces that are inconsistent with the γ phase such as a phase are easily formed, and the hot workability is impaired. Therefore IVa
Group or Va group elements are one or two or more in total.
Add 5 to 8.0%. A more desirable range is 3.
0 to 5.0%.

In the group IVa element, the addition of Ti is most preferable.
It is in the range of 5 to 3.0%. A more desirable range of Ti is 2.0 to 3.0%. Further, Zr and Hf have a lower solid solubility in the γ phase than Ti, and cannot be added in a larger amount than Ti. On the other hand, a part thereof segregates at the crystal grain boundary, and also has an effect of increasing the grain boundary strength in a high temperature region. Further, among the elements of the Va group, addition of Nb is most preferable, and the preferable addition amount of Nb is in the range of 0.3 to 2.5%. More desirable N
The range of b is 0.5 to 1.5%. On the other hand, in the case of V, the solid solution strengthening action is weaker than that of Nb, and the oxidation resistance is also reduced. Therefore, excessive addition is not preferable. Also, T
In the case of a, the γ ′ phase is solid-solution strengthened more than Nb. However, rare resources may significantly increase the price, so that it cannot be added in a large amount.

Mo and W are the same group VIa elements as Cr,
Both have the effect of solid solution strengthening the austenite matrix and increasing the high temperature fatigue strength and high temperature creep rupture strength. For this purpose, if necessary, one or two of Mo and W
% Can be added. However, Mo is more desirable in terms of alloy price and specific gravity, and in that case, M is more desirable.
The o content is 0.1 to 1.0%. In addition, since the total of the three elements in atomic% together with the amount of Cr is effective for the precipitation of the α ′ phase and the σ phase, the addition amounts of Mo and W, which are homologous to Cr, may be changed as necessary. It is desirable to keep the sum when the weight% is converted into the atomic% constant. Therefore, the amount of [Cr] + [Mo] + [W] expressed in atomic% is desirably 13 to 18. A more desirable range is a range of 15.0 to 17.5. Co forms a solid solution in the austenite matrix and promotes solid solution of the γ 'phase in the hot working region to improve workability, while increasing the amount of the γ' phase precipitated in the practical temperature range to improve high-temperature strength. Enhance. For this reason, Co can be added as necessary in the form of substituting the amount of Ni in the range of Ni + Co ≦ 49. However, since Co is an expensive element as compared with Ni, the upper limit is 5.0%. Good to be.

In order to achieve the object of the present invention, Al and IV
It is important not only that the group a element and the group Va element each independently satisfy the above-mentioned component ranges, but also, as the gamma prime constituent elements, it is important that the total sum of the respective elements and the ratio of Al be within appropriate ranges. . As described above, in the γ 'phase composed of Ni ₃ (Al, IVa, Va), [Al] / ([Al] + [Ti] + [Zr] + [Hf] + [V] expressed in atomic%. + [Nb] + [Ta]) can stabilize the γ ′ phase.
If the ratio of [Al] / ([Al] + [Ti] + [Zr] + [Hf] + [V] + [Nb] + [Ta]) is less than 0.45, γ ′ The high-temperature strength tends to decrease due to the transformation from the phase to the η phase or the δ phase. On the other hand, if this ratio exceeds 0.75, the γ 'phase is not sufficiently solid-solution strengthened, and the room-temperature strength is reduced. Therefore, [Al]
The ratio of / ([Al] + [Ti] + [Zr] + [Hf] + [V] + [Nb] + [Ta]) is 0.45
A range of 0.75 is desirable. More preferably 0.50
It is in the range of 0.60.

Further, in order to compensate for the decrease in high-temperature strength due to the decrease in the amount of Ni in the matrix by increasing the amount of the γ ′ phase, the amount is expressed in atomic% ([Al] + [Ti] + [Zr] + [Hf] + [ [V] + [Nb] + [Ta]) amount is also preferably controlled to an appropriate range. This value is 6.5
If the Ni content is less than 50%, the strength of a conventional Fe-Ni-Cr-based super heat-resistant alloy in which the Ni content exceeds 50% will not reach the strength, whereas if it exceeds 10, the hot working for engine valves and the like will be difficult. Therefore, it is expressed in atomic% ([Al] + [Ti] + [Zr] + [Hf] + [V] + [N
b] + [Ta]) is 6.5 to 1 higher than the conventional forged alloy.
By controlling to a range of 0.0, short-time high-temperature strength can be improved. A more preferred range is from 7.0 to 8.5. Such a high calculated γ 'amount has not been put to practical use in forged alloys for engine valves and the like, and this point is also a completely novel invention. In the case of a Ni-based super heat-resistant alloy having a Ni content of 50% or more, the γ 'phase is stable up to a high temperature, and it is difficult to perform high-strength hot working of an engine valve or the like with this level of γ'.

[Al] / ([A
l] + [Ti] + [Zr] + [Hf] + [V] + [Nb] + [Ta]), the solid solution strengthening of elements such as Ti, Nb, Ta and γ ' The increase in the lattice strain of the phase makes hot working difficult. Therefore, for such a high calculated γ ′ amount, the Ni amount does not exceed 50% and [Al] / ([Al] + [Ti] + [Zr] + [Hf] + [V] + [Nb] + [Ta]) Hot working is possible only when the quantity ratio is high. Of the atomic% represented by the above relational expression, the element without addition is calculated as zero.

B is effective in increasing the high-temperature strength and ductility by the grain boundary strengthening action in the present invention, and can be added in an appropriate amount to the alloy of the present invention. The effect starts with a small amount of addition, but if it exceeds 0.015%, the initial melting temperature at the time of heating is lowered and the hot workability is deteriorated.
It is good to make it 15%. Mg and Ca serve as powerful deoxidizing and desulfurizing elements to enhance the cleanliness of the alloy, and also contribute to improving ductility during high-temperature tensile and creep deformation and during hot working, so that one or two of them can be added in an appropriate amount. The effect starts with a small amount of addition, but Mg and Ca are each added at 0.1%.
If it exceeds 02%, the initial melting temperature at the time of heating decreases and the hot workability deteriorates. Therefore, the upper limits of Mg and Ca are preferably set to 0.02%.

In the present invention, Y and REM are effective for increasing the high-temperature oxidation resistance, and one or two or more of them can be added to the alloy of the present invention in an appropriate amount. The effect starts with a small amount of addition. However, if Y and REM each exceed 0.1%, the initial melting temperature during heating decreases and hot workability deteriorates, so the upper limits of Y and REM are: 0.1 each
% Is good. In addition, based on the alloy of the present invention, in order to increase the oxidation resistance to the limit, it is easy to determine the optimum addition ratio from the lanthanoid element group, and such an operation is beyond the scope of the present invention. Not something.

Although not mentioned in the claims,
May be added to the alloy of the present invention in a range of 2.0% or less because it strengthens the austenite matrix in solid solution, promotes precipitation of the γ ′ phase at the same time, and effectively acts on high-temperature corrosion resistance. However,
There is no need to add excessively, because the price of the alloy is greatly increased with scarce resources. Fe is an element effective for forming an inexpensive austenite matrix as a resource saving alloy. In addition, since the matrix is softened in a higher temperature range than Ni, hot working can be performed even if the above-mentioned strengthened alloy element content is included. For the above reasons, Fe is the remainder except for inevitable impurities.
Further, among the impurities, the following elements may be included in the alloy of the present invention as long as they are in the following ranges. P ≦ 0.04%, S ≦ 0.02%, O ≦ 0.02
%, N ≦ 0.05% More preferably, it is in the following range. P ≦ 0.02%, S ≦ 0.005%, O ≦ 0.01
%, N ≦ 0.01% The above-mentioned Fe-Ni-Cr based superalloy is a single vacuum melt
Alternatively, an ingot obtained through a refining process such as electroslag remelting or vacuum arc remelting after vacuum melting can be finished into a primary product through a working process such as hot forging or hot rolling.

These materials are put to practical use after being subjected to a solution treatment at 900 to 1100 ° C. and an aging treatment at 600 to 800 ° C., which are generally used for γ ′ precipitation-strengthened superalloys. When hot working also serves as solution treatment, aging treatment may be directly performed after hot working. This alloy can also exhibit sufficient room temperature toughness and ductility even after long-term heat treatment simulating practical use, for example, after long-time heating at 800 ° C. for about 400 hours. This is the conventional high C
In the case of r-Fe-Ni-Cr-based super heat-resistant alloy, the characteristic could not be obtained, and as a specific numerical value, a Charpy impact value of 0.5 MJ / m ² or more can be obtained.

[0030] These are characteristics that have been renewed attention because the need for improving the durability of each component material has emerged with the increase in the warranty period of automobiles. Or when the impact value after heating for 400 hours at 800 ° C. as a valve member for an automobile engine is rotated rapidly to a high temperature in the engine cold regions after long-term use when less than 0.5 mJ / m ^2, a toughness not Sufficient may lead to breakage of the valve. Therefore, if necessary, the impact value of the alloy of the present invention after heating at 800 ° C. for 400 hours is preferably set to 0.5 MJ / m ² or more. Also, the present alloy can obtain a sufficient fatigue strength even after being heated at 800 ° C. for 400 hours. In a member that repeatedly acts at a high temperature, such as an engine valve, the biggest factor that determines the life is fatigue. With the extension of the warranty period of an automobile, in order to guarantee the performance of the valve, 400 ° C. is required at 800 ° C. 800 ° C-294 after heating for hours
The number of rotation bending fatigue rupture under the test conditions of MPa is 0.5
× 10 ⁶ times or more is better. A more desirable number of breaks is 2.5 × 10 ⁶ or more. The alloy of the present invention can satisfy these fatigue strengths under optimal heat treatment conditions.

The alloy of the present invention can achieve both excellent room-temperature toughness after high-temperature heating for a long time and high-temperature fatigue strength. This is a performance that could not be achieved with a conventional Fe-Ni-Cr-based super heat-resistant alloy, and is a numerical value that specifically indicates the excellent properties of the alloy of the present invention. In addition, after cutting the hot-rolled bar made of this alloy to the required dimensions, the engine valve for automobiles formed by hot upsetting and hot extrusion has high-temperature fatigue strength, high-temperature hardness, microstructure stability, and oxidation resistance. In addition, it is an inexpensive resource-saving valve that does not require build-up of the valve face portion and has excellent normal and high-temperature strength after long-time heating, and can greatly contribute to the economy of automobiles. The engine valve may be used after being subjected to surface nitriding by various processes or various hard plating. Further, it can be used as a joint valve in which various heat-resistant steels or high-hardness alloy tool steels are welded to the shaft side. In addition, durability is further improved when used as a hollow engine valve by various processing methods.

Further, the hot-rolled bar made of the present alloy is processed into a wire having a minimum diameter of about 0.2 mm by repeatedly performing cold or warm working and annealing from a solution treatment state to a wire having a minimum diameter of about 0.2 mm. When formed into a supporting knit mesh, it has better oxidation resistance and higher temperature strength than stainless steel such as SUS310S, which is a conventional knit mesh material, so that a knit mesh excellent in reliability and durability can be obtained.

[0033]

【Example】

(Example 1) An alloy having a composition shown in Table 1 was made into a 10 kg ingot by vacuum induction melting, and then hot-worked to 3 kg.
A 0 mm square bar was prepared (REM was added as misch metal). After the solution was kept at 1050 ° C. for 30 minutes and then subjected to a solution treatment of water cooling and a solution of 750 ° C. for 4 hours and then subjected to an aging treatment of air cooling, the standard heat treatment was carried out and further from this state, 80%
Room temperature hardness after holding at 0 ° C. × 400 hours, room temperature Charpy impact test, tensile test at room temperature and 800 ° C., 800 ° C.
A rotational bending fatigue test was performed under the condition of -294 MPa. Further, the oxidation resistance during heating at 850 ° C. for 400 hours was also investigated. Room temperature hardness was measured by a Rockwell hardness tester. The Charpy impact test was conducted at a test temperature of 20 ° C.
It was measured using a 2U notch No. 3 test piece by the IS method. The tensile test was performed by the ASTM method using a parallel part diameter of 6.
It measured at 35 mm and elongation 4D. Rotating bending fatigue test is J
In accordance with IS Z2274, using a test piece having a diameter of a parallel portion of 8 mm, the number of times until the test piece was broken at 3,600 rotations was determined. Oxidation resistance test is 10mm in diameter and 20 in length
The change in oxidized weight by weight measurement before and after heating at 850 ° C. × 400 hours was evaluated using a round bar test piece of mm. Table 2 shows the results of various tests.

[0034]

[Table 1]

[0035]

[Table 2]

No. 1 in Table 1. 1 to 21 are alloys of the present invention, N
o. Nos. 31 to 33 are comparative alloys. 41 is Tokuho 4-1
No. 1613 is a conventional alloy. The A value, B value, and C value, which are described together with the various chemical compositions in Table 1, are each expressed in atomic% [Al] + [Ti] + [Zr] + [Hf] + [V] + [Nb] + [Ta]
Amount, [Al] / ([Al] + [Ti] + [Zr] + [Hf] + [V] + [Nb] + [Ta]) amount, and [Cr] + [Mo] + [W] amount It is. In addition, in these calculations, the addition amount of REM used the atomic weight of La as a representative value. FIG. 1 shows the relationship between the A value and the B value. Various mechanical properties and oxidation resistance of the alloy of the present invention are as follows.
Conventional alloy No. Excellent characteristics equal to or higher than 41 were obtained, and it is clear how the alloy of the present invention is a heat-resistant alloy with excellent resource saving.

On the other hand, among the comparative alloys, In No. 31, a crack occurred during hot forging, and the evaluation test was not performed. This is because the sum of the IVa group and the Va group in Table 1 was as high as 8.2%, and the A value was too high. In addition, No. 3
2, as shown in FIG. 1, the A value and the B value are at the same level as the alloy of the present invention, and the mechanical properties after standard heat treatment are excellent, but tensile drawing at room temperature after long-time heating, and Charpy impact The value has dropped significantly. This is because the σ phase was precipitated at the crystal grain boundaries because the Cr content and the C value were too high. In addition, No. No. 33 has excellent mechanical properties after standard heat treatment, but has a lower high-temperature tensile strength after long-time heating and the number of times of rotational bending fatigue fracture compared to the alloy of the present invention, and a decrease in tensile drawing and Charpy impact value at room temperature. Is big. These are because the Al content and the B value as shown in FIG. 1 were low, and during the long-time heating, the γ ′ phase became coarse and the γ ′ phase was transformed into the η phase.

(Example 2) The alloy No. 1 of the present invention shown in Table 1 was used. 2 by hot forging, cutting and grinding
Round bar. Further, one end of the round bar was formed into a shape of an engine valve by hot upsetting. This engine valve and the conventional alloy mass-produced engine valve disclosed in Japanese Patent Publication No. 4-11613 were subjected to the standard heat treatment described in Example 1, and then a bench test was performed using an engine tester of unleaded gasoline specification. The test conditions were a high-speed high-temperature continuous endurance test.
The condition of 30 ° C. was selected, and the continuous operation was performed for 400 hours. After the test was completed, the shape change and the corrosion state of the cross section of the alloy valves of the present invention and the conventional alloy were checked.

(Example 3) The alloy No. 2 of the present invention of Example 2 was used.
The 6mm round bar made of 2 is repeatedly drawn and annealed to obtain a diameter
After being processed into a 0.25 mm wire, it was formed into a knit mesh of a ceramic carrier for an exhaust gas catalyst. This catalyst unit was incorporated at the same time as the bench test in Example 2 to investigate the performance as a knit mesh. Although the temperature of the knit mesh is higher than the temperature of the valve, after the test, the knit mesh made of the alloy of the present invention does not cause creep deformation or abnormal oxidation, and is found to have excellent performance as an exhaust gas knit mesh. Was.

[0040]

According to the present invention, excellent structural stability equal to or higher than that of a Ni-based super heat-resistant alloy containing 50% or more of Ni used for engine valves and the like, and excellent room temperature and high temperature after long-time heating. -Saving and inexpensive Fe-Ni-C with tensile properties, high-temperature oxidation resistance, excellent high-temperature fatigue properties and corrosion resistance
An r-base super heat-resistant alloy is obtained, and when a knit mesh for an engine valve or an exhaust gas catalyst using this alloy is used for an automobile engine, a highly reliable engine excellent in economy and durability can be manufactured.

[Brief description of the drawings]

FIG. 1 [Al] + [Ti] + [Zr] + [Hf] + [V] + [Nb] + [Ta] and [Al] of the compositions of the present invention alloy, comparative alloy and conventional alloy /
It is a figure which plotted the relationship of ([Al] + [Ti] + [Zr] + [Hf] + [V] + [Nb] + [Ta]).

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Tsutomu Saka 1-4-1 Chuo, Wako-shi, Saitama Examiner at Honda R & D Co., Ltd. Kengo Koyanagi (56) Reference JP-A-6-271993 (JP, A JP-A-6-271992 (JP, A) JP-A-3-260034 (JP, A) JP-A-49-13018 (JP, A) JP-A-60-234938 (JP, A) JP-A-60-234 46343 (JP, A) JP-A-51-110414 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C22C 30/00 B01J 8/02 C22C 38/00 302 F01L 3/02

Claims (17)

(57) [Claims] 1. The method according to claim 1, wherein C is 0.15% or less by weight and Si is 1.0% or less.
% Or less, Mn 3.0% or less, Ni 30 to 49%, Cr1
0 to 18%, Al 1.6 to 3.0%, and 1.5 to 8.0% in total of one or more elements selected from the group IVa and the group Va, and the remainder contains impurities. A Fe-Ni-Cr-based super heat-resistant alloy characterized by being essentially made of Fe except for Fe. 2. The method according to claim 1, wherein the content of C is not more than 0.15% by weight,
% Or less, Mn 3.0% or less, Ni 30 to 49%, Cr1
0% to 18%, Mo 3% or less and W 3% or less 1 or 2
Species, containing 1.6 to 3.0% of Al, and a total of 1.5 or more of one or more elements selected from the IVa group and the Va group.
A Fe-Ni-Cr-based super heat-resistant alloy containing 8.0%, with the balance being essentially Fe, excluding impurities. 3. The method according to claim 1, wherein the content of C is not more than 0.08% by weight,
%, Mn 1.0% or less, Ni 30-49%, Cr1
3-18%, Al 1.6-3.0%, Ti 1.5-3.
0-%, Nb 0.3-2.5%, and the balance is essentially Fe, excluding impurities.
Cr-based super heat resistant alloy. 4. The method according to claim 1, wherein C is 0.08% or less by weight, and Si0.5
%, Mn 1.0% or less, Ni 30-49%, Cr1
One or two of 3 to 18%, Mo 3% or less and W 3% or less
Seed, Al 1.6-3.0%, Ti 1.5-3.0%, N
b. Fe-Ni-Cr based super heat resistant alloy containing 0.3 to 2.5%, with the balance essentially consisting of Fe excluding impurities. 5. The method according to claim 1, wherein the content of C is not more than 0.08% by weight,
%, Mn 1.0% or less, Ni 30-49%, Cr1
3 to 18%, Mo 3% or less, Al 1.6 to 3.0%, T
A Fe-Ni-Cr-based super heat-resistant alloy containing 1.5 to 3.0% of i and 0.3 to 2.5% of Nb, with the balance being essentially Fe except for impurities. 6. The composition according to claim 6, wherein C is less than 0.08% by weight,
%, Mn 0.5% or less, Ni 30-45%, Cr1
3.5 to 16%, Mo 0.1 to 1.0%, Al 1.8 to
2.4%, Ti 2.0-3.0%, Nb 0.5-1.5
%, With the balance being essentially Fe, excluding impurities. 7. The method according to claim 6, wherein 5% by weight or less of Co is converted to Ni + Co.
The Fe-Ni-Cr-based super heat-resistant alloy according to any one of claims 1 to 6, wherein the content is in the range of ≤ 49. 8. The method according to claim 1, wherein Al is essentially added in atomic%, and one or more elements selected from the group IVa and Va satisfy the following relational expression. The Fe-Ni-Cr based super heat resistant alloy according to any one of the above. 6.5 ≦ [Al] + [Ti] + [Zr] + [Hf] + [V] + [Nb] + [Ta] ≦ 10.0 0.45 ≦ [Al] / ([Al] + [Ti] + [Zr] + [Hf] + [V] + [Nb] + [Ta]) ≦ 0.
75 9. The method according to claim 1, wherein Al is essentially added in atomic%, and one or more elements selected from the group IVa and Va satisfy the following relational expression. The Fe-Ni-Cr based super heat resistant alloy according to any one of the above. 6.5 ≦ [Al] + [Ti] + [Zr] + [Hf] + [V] + [Nb] + [Ta] ≦ 8.5 0.50 ≦ [Al] / ([Al] + [Ti] + [Zr] + [Hf] + [V] + [Nb] + [Ta]) ≦ 0.
60 10. Cr is essentially added at atomic%, and one or two of Mo and W are 13 ≦ [Cr] +
10. The Fe—Ni—Cr according to claim 1, wherein [Mo] + [W] ≦ 18.
Super heat resistant alloy. 11. The Fe—Ni—Cr based super heat-resistant alloy according to claim 1, further comprising 0.015% by weight or less of B in weight%. 12. The Fe— according to any one of claims 1 to 11, comprising one or two kinds by weight of 0.02% or less of Mg and 0.02% or less of Ca. Ni
-Cr based super heat resistant alloy. 13. Y and 0.1% by weight, not more than 0.1%.
% Fe-Ni-Cr according to any one of claims 1 to 12, comprising one or two kinds of REM of not more than%.
Super heat resistant alloy. 14. 20 hours after heating at 800 ° C. for 400 hours.
Fe-Ni-Cr-base superalloy according to any one of claims 1 to 13, U-notch Charpy impact value is equal to or is 0.5 mJ / m ² or more at ° C.. 15. After heating at 800 ° C. for 400 hours, 80
The Fe-Ni-Cr-based super heat-resistant alloy according to any one of claims 1 to 14, wherein the number of breaks in a rotary bending fatigue test at 0 ° C-294 MPa is 0.5 × 10 ⁶ or more. 16. The F according to claim 1, wherein
An automobile engine valve manufactured using an e-Ni-Cr based super heat resistant alloy. 17. The F according to claim 1, wherein
A knit mesh for an exhaust gas catalyst for automobiles manufactured using an e-Ni-Cr-based super heat-resistant alloy.