U.S. patent application number 11/334583 was filed with the patent office on 2006-07-20 for heat resistant alloy for exhaust valves durable at 900.degree.c and exhaust valves made of the alloy.
This patent application is currently assigned to DAIDO STEEL CO., LTD.. Invention is credited to Makoto Asami, Seiji Kurata, Toshiharu Noda, Tetsuya Shimizu, Katsuhiko Tominaga, Shigeki Ueta.
Application Number | 20060157171 11/334583 |
Document ID | / |
Family ID | 36263922 |
Filed Date | 2006-07-20 |
United States Patent
Application |
20060157171 |
Kind Code |
A1 |
Ueta; Shigeki ; et
al. |
July 20, 2006 |
Heat resistant alloy for exhaust valves durable at 900.degree.C and
exhaust valves made of the alloy
Abstract
An exhaust valve for automobile engines, which is durable at
such a high temperature as 900.degree. C., and exhibits high
fatigue strength and high oxidation resistance is disclosed. The
exhaust valve is made of a Ni-based alloy consisting essentially
of, by weight %. C: 0.01-0.15%, Si: up to 2.0%, Mn: up to 1.0%, P:
up to 0.02%, S: up to 0.01%, Co: 0.1-15%, Cr: 15-25%, one or two of
Mo: 0.1-10% and W: 0.1-5% in such amount that Mo+1/2 W; 3-10%, Al:
1.0-3.0%, Ti: 2.0-3.5%, provided that, by atomic %, Al+Ti: 6.3-8.5%
and Ti/Al ratio: 0.4-0.8, and further, by weight %, B: 0.001-0.01%,
Fe: up to 3%, and the balance of Ni and inevitable impurities by
hot forging to give the form of an exhaust valve and subjecting to
solid solution at 1000-1200.degree. C. and aging at 700-950.degree.
C.
Inventors: |
Ueta; Shigeki; (Nagoya,
JP) ; Kurata; Seiji; (Nagoya, JP) ; Shimizu;
Tetsuya; (Nagoya, JP) ; Noda; Toshiharu;
(Nagoya, JP) ; Tominaga; Katsuhiko; (Wako-shi,
JP) ; Asami; Makoto; (Wako-shi, JP) |
Correspondence
Address: |
POSZ LAW GROUP, PLC
12040 SOUTH LAKES DRIVE
SUITE 101
RESTON
VA
20191
US
|
Assignee: |
DAIDO STEEL CO., LTD.
Aichi
JP
HONDA MOTOR CO., LTD.
Tokyo
JP
|
Family ID: |
36263922 |
Appl. No.: |
11/334583 |
Filed: |
January 19, 2006 |
Current U.S.
Class: |
148/677 ;
148/410 |
Current CPC
Class: |
F01L 2301/00 20200501;
C22F 1/10 20130101; F01L 2303/00 20200501; C22C 19/055 20130101;
C22C 19/057 20130101; B21K 1/22 20130101; F01L 3/02 20130101 |
Class at
Publication: |
148/677 ;
148/410 |
International
Class: |
C22C 19/05 20060101
C22C019/05; C22F 1/10 20060101 C22F001/10 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 19, 2005 |
JP |
2005-012030 |
Nov 28, 2005 |
JP |
2005-341574 |
Claims
1. A heat resistant alloy for exhaust valves, which are durable at
900.degree. C., consisting essentially of, by weight %, C:
0.01-0.15%, Si: up to 2.0%, Mn: up to 1.0%, P: up to 0.02%, S: up
to 0.01%, Co: 0.1-15%, Cr: 15-25%, one or two of Mo: 0.1-10% and W:
0.1-5% in such an amount as Mo+1/2W: 3-10%, Al: 1.0-3.0%, Ti:
2.0-3.5%, provided that, by atomic %, Al+Ti: 6.3-8.5% and Ti/Al
ratio: 0.4-0.8, and further, by weight %, B: 0.001-0.01%, Fe: up to
3%, and the balance of Ni and inevitable impurities.
2. The heat resistant alloy for exhaust valves according to claim
1, wherein the alloy further contains, by weight %, one or more of
V: 0.2-1.0%, Nb: 0.5-1.5% and Ta: 0.5-1.5% in such an amount as, by
atomic %, Al+Ti+Nb+Ta+V: 6.3-8.5%.
3. The heat resistant alloy for exhaust valves according to claim
1, wherein the alloy further contains, by weight %, one or more of
Mg: 0.001-0.03%, Ca: 0.001-0.03%, Zr: 0.001-0.1% and REM:
0.001-0.1%.
4. The heat resistant alloy for exhaust valves according to claim
1, wherein the alloy further contains, by weight %, Cu:
0.01-2%.
5. The heat resistant alloy for exhaust valves according to claim
1, wherein the alloy exhibits, after being treated by solid
solution and aging, 10.sup.5-cycles fatigue strength at 900.degree.
C. of 245 MPa or more, and the weight increase after being
subjected to oxidation test by keeping at 900.degree. C. for 400
hours is 5 mg/cm.sup.2 or less.
6. A method of producing an exhaust valve, which comprises
processing the alloy according to claim 1 by hot forging at
1000.degree. to 1200.degree. C. to form an intermediate product
having the form of an exhaust valve consisting of a stem and a
head, and then, subjecting the intermediate product to solid
solution treatment by heating at 1000.degree. to 1200.degree. C.,
and aging treatment by heating to 700.degree. to 950.degree. C.
7. A method of producing an exhaust valve, which comprises
consolidating a stem-tip made of a martensitic or austenitic heat
resistant steel to the stem end of the intermediate product of the
exhaust valve made by the method according to claim 6 by friction
bonding.
8. The heat resistant alloy for exhaust valves according to claim
2, wherein the alloy further contains, by weight %, one or more of
Mg: 0.001-0.03%, Ca: 0.001-0.03%, Zr: 0.001-0.1% and REM:
0.001-0.1%.
9. The heat resistant alloy for exhaust valves according to claim
2, wherein the alloy further contains, by weight %, Cu:
0.01-2%.
10. The heat resistant alloy for exhaust valves according to claim
3, wherein the alloy further contains, by weight %, Cu:
0.01-2%.
11. The heat resistant alloy for exhaust valves according to claim
2, wherein the alloy exhibits, after being treated by solid
solution and aging, 10.sup.5-cycles fatigue strength at 900.degree.
C. of 245 MPa or more, and the weight increase after being
subjected to oxidation test by keeping at 900.degree. C. for 400
hours is 5 mg/cm.sup.2 or less.
12. The heat resistant alloy for exhaust valves according to claim
3, wherein the alloy exhibits, after being treated by solid
solution and aging, 10.sup.5-cycles fatigue strength at 900.degree.
C. of 245 MPa or more, and the weight increase after being
subjected to oxidation test by keeping at 900.degree. C. for 400
hours is 5 mg/cm.sup.2 or less.
13. The heat resistant alloy for exhaust valves according to claim
4, wherein the alloy exhibits, after being treated by solid
solution and aging, 10.sup.5-cycles fatigue strength at 900.degree.
C. of 245 MPa or more, and the weight increase after being
subjected to oxidation test by keeping at 900.degree. C. for 400
hours is 5 mg/cm.sup.2 or less.
14. A method of producing an exhaust valve, which comprises
processing the alloy according to claim 2 by hot forging at
1000.degree. to 1200.degree. C. to form an intermediate product
having the form of an exhaust valve consisting of a stem and a
head, and then, subjecting the intermediate product to solid
solution treatment by heating at 1000.degree. to 1200.degree. C.,
and aging treatment by heating to 700.degree. to 950.degree. C.
15. A method of producing an exhaust valve, which comprises
processing the alloy according to claim 3 by hot forging at
1000.degree. to 1200.degree. C. to form an intermediate product
having the form of an exhaust valve consisting of a stem and a
head, and then, subjecting the intermediate product to solid
solution treatment by heating at 1000.degree. to 1200.degree. C.,
and aging treatment by heating to 700.degree. to 950.degree. C.
16. A method of producing an exhaust valve, which comprises
processing the alloy according to claim 4 by hot forging at
1000.degree. to 1200.degree. C. to form an intermediate product
having the form of an exhaust valve consisting of a stem and a
head, and then, subjecting the intermediate product to solid
solution treatment by heating at 1000.degree. to 1200.degree. C.,
and aging treatment by heating to 700.degree. to 950.degree. C.
17. A method of producing an exhaust valve, which comprises
consolidating a stem-tip made of a martensitic or austenitic heat
resistant steel to the stem end of the intermediate product of the
exhaust valve made by the method according to claim 14 by friction
bonding.
18. A method of producing an exhaust valve, which comprises
consolidating a stem-tip made of a martensitic or austenitic heat
resistant steel to the stem end of the intermediate product of the
exhaust valve made by the method according to claim 15 by friction
bonding.
19. A method of producing an exhaust valve, which comprises
consolidating a stem-tip made of a martensitic or austenitic heat
resistant steel to the stem end of the intermediate product of the
exhaust valve made by the method according to claim 16 by friction
bonding.
Description
TECHNICAL BACKGROUND
[0001] 1. Field in the Industry
[0002] The present invention concerns exhaust valves for internal
combustion engines, typically, automobile gasoline engines, which
are durable at such a high temperature as 900.degree. C. and
exhibit excellent fatigue properties and oxidation resistance. The
invention concerns also a heat resistant alloy used as the material
for the above-mentioned exhaust valves as well as the method of
producing exhaust valves with the alloy.
[0003] 2. Prior Art
[0004] As the material for the exhaust valves of automobile
gasoline engines there has been widely used Ni-based heat resistant
alloys such as NCF751 and NCF80A. To meet the demand for higher
strength another Ni-based alloy (Japanese Patent Disclosure
61-119640) is suitable. This alloy was proposed by the applicant
with a co-applicant, and contains, in addition to the suitable
amounts of C, Si and Mn, by wt %, Cr: 15-25%, Mo+0.5 W: 0.5-5.0%,
Nb+Ta: 0.3-3.0%, Ti: 1.5-3.5%, Al: 0.5-2.5% and B: 0.001-0.02%.
Further, there has been developed and disclosed another Ni-based
alloy, (Japanese Patent Disclosure 05-059472), which contains, in
addition to the suitable amounts of C, Si and Mn, by wt %, Co:
2.0-8.0%, Cr: 17.0-23.5%, Mo+0.5 W: 2.0-5.5%, Al: 1.0-2.0%, Ti:
2.5-5.0%, B; 0.001-0.020% and Zr: 0.005-0.15%.
[0005] As is well known, for the purpose of keeping durability of
exhaust valves it is necessary for the valves to withstand
repeatedly given bending stress. The 10.sup.8-cycles fatigue
strength of the above-mentioned newly developed alloys is, until
the using temperature is up to 850.degree. C., 245 MPa or more. In
the engines of the present days it is intended to realize
combustion under near the stoichiometry, and this sometimes
requires heat resistance of the valves at such a high temperature
as 900.degree. C. However, the fatigue strength of the known heat
resistant alloys for exhaust valves decreases to be lower than 245
MPa at 900.degree. C., and the known alloys are dissatisfactory in
regard to the strength as the material for the engines of the
desired high performance
[0006] The inventors intended to provide a heat resistant alloy
which satisfies the heat resistant condition of "10.sup.8-cycles
fatigue strength at 900.degree. C. being 245 MPa or more" and, as
the results of investigation, noted that materials for disks and
blades of gas turbines have heat resistance higher than that of
conventional alloys for exhaust valves. Detailed study on the
properties of the alloys for gas turbines revealed that they could
be generally used as the materials for the exhaust valves. The
noted heat resistant alloys are named "Waspaloy" and "Udimet 520"
having the following typical alloy compositions (by weight %):
Waspaloy Ni-19Cr-4.3Mo-14Co-1.4Al-3Ti-0.003B
Udimet 520 Ni-20Cr-6Mo-1W-12Co-2Al-3Ti-0.003B
[0007] The inventors further learned that the durability of these
alloys differs in the gas turbines and the exhaust valves of
engines and that it is necessity to confront with the difference.
More specifically, high temperature creep property is required for
the gas turbine material, while the high temperature fatigue
strength is essential for the exhaust valve materials, and
therefore, not only the alloy composition but also conditions for
processing and heat treatment must be so chosen to obtain the
desired properties.
[0008] From the view to achieve the high fatigue strength the
inventors sought the ways for improving the properties of the gas
turbine materials, and discovered that, by choosing the Mo-- and
W-- contents to such a relatively high ranges as Mo+W: 3-10%,
choosing the Co-content to a suitable amount, and arranging the
amounts of Al and Ti to be, by atomic %, Al+Ti: 6.3-8.5%, and the
Ti/Al ratio to be 0.4-0.8, the above requirement for the fatigue
strength, 10.sup.8-cycles bending fatigue strength is 245 MPa or
more, can be satisfied. The inventors also discovered that addition
of a small amount of Cu is effective for improving the oxidation
resistance at 900.degree. C.
SUMMARY OF THE INVENTION
[0009] The general object of the present invention is to provide,
based on the above knowledge which the inventors obtained, a heat
resistant alloy for exhaust valves which can be used at such a high
temperature as 900.degree. C. and having high fatigue strength as
well as oxidation resistance. The specific object of the present
invention is to provide a heat resistant alloy having particularly
high fatigue strength, in other words, an alloy exhibiting many
more cycles of test at the same required strength level. To provide
a method of producing exhaust valves with the present heat
resistant alloy is also the object of the present invention.
[0010] The heat resistant alloy for the exhaust valves achieving
the above object, durable at the temperature of 900.degree. C.,
according to the invention consists essentially of, by weight %, C;
0.01-0.15%, Si: up to 2.0%, Mn: up to 1.0%, P: up to 0.02%, S: up
to 0.01%, Co: 0.1-15%, Cr: 15-25%, one or two of Mo: 0.1-10% and W:
0.1-5% in such amount as Mo+1/2W: 3-10%, Al: 1.0-3.0%, Ti:
2.0-3.5%, provided that, by atomic %, Al+Ti: 6.3-8.5% and Ti/Al
ratio: 0.4-0.8, and further, by weight %, B: 0.001-0.01%, Fe: up to
3%, and the balance of Ni and inevitable impurities.
[0011] The method of producing the exhaust valves using the
above-mentioned heat resistant alloy as the material comprises
processing the material to form an exhaust valve consisting of a
stem and a head by hot forging at 1000-1200.degree. C., and
subjecting the processed intermediate product to solid solution
treatment at 1000-1200.degree. C., and aging treatment at
700-950.degree. C.
PREFERRED EMBODIMENTS OF THE INVENTION
[0012] The heat resistant alloy for exhaust valves according to the
invention may contain, in addition to the above-mentioned basic
alloy components, by weight %, one or more of V: 0.5-1.5%, Nb:
0.5-1.5% and Ta; 0.5-1.5% in such amount that, by atomic %,
Al+Ti+Nb+TA+V: 6.3-8.5%. The strength of the alloy will be enhances
by addition of the element or elements.
[0013] The heat resistant alloy for exhaust valves of the invention
may further contain, in addition to the above mentioned components,
one or more of Mg: 0.001-0.03%. Ca: 0.001-0.03%, Zr: 0.001-0.1% and
REM: 0.001-0.1%. By adding the element or elements, hot workability
of the alloy will be improved. REM improves, in addition to this
effect, oxidation resistance of the alloy.
[0014] The present heat resistant alloy for exhaust valves may
further contain Cu: 0.01-2%. Addition of Cu enhances the oxidation
resistance of the product valves.
[0015] The following explains the reasons for selecting the
above-described composition of the heat resistant alloy for the
exhaust valves according to the invention in the order of the
essential elements and the optionally added elements. C:
0.01-0.15%
[0016] Carbon combines with Ti, Nb and Ta to form MC carbides, and
with Cr. Mo and W to form M.sub.23C.sub.6, M.sub.6C carbides, which
are useful for preventing coarsening of the grains and enhancing
the grain boundaries. To obtain these merits at least 0.01% of
carbon is necessary. Too much carbon forms too large amount of
carbides, which lowers the workability at forming the valves, the
toughness and the ductility of the alloy. Thus, 0.15% is the upper
limit of C-content. Si: up to 2.0%
[0017] Silicon is an element used as the deoxidizing agent at
melting and refining the alloy, and may be used if necessary.
Silicon is also useful for increasing oxidation resistance of the
alloy. However, too high a content of Si lowers the toughness and
the workability of the alloy, and the addition should be in an
amount up to 2.0%.
Mn: up to 1.0%
[0018] Manganese also takes the role of deoxidizing agent like
silicon, and may be added if necessary. Too much addition damages
the workability and the high temperature oxidation resistance of
the alloy, and therefore, the amount of addition should be chosen
in the range up to 1.0%.
P: up to 0.02%, S: up to 0.01%
[0019] Phosphor and sulfur are inevitable impurities of the
Ni-alloy of the invention and undesirable, because they lower the
hot workability of the alloy. Particularly, the practical range of
processing conditions of hot working of the alloy of the invention
is, due to the low Ni-content, narrow. From the view to ensure the
hot workability the allowable limits of P and S are determined as
above.
Co: 0.1-15%
[0020] Cobalt stabilizes .gamma.' phase at high temperature and
strengthen the matrix to contribute to improvement of fatigue
strength. On the other hand, addition of much amount of cobalt
results in increased costs, and moreover, excess cobalt makes the
austenite phase unstable. Thus, amount of adding cobalt is in the
above range, preferably 2-15%, more preferably, 8-14%.
Cr: 15-25%
[0021] Chromium is essential for increasing the heat resistance of
the alloy, and the necessary amount of addition for this purpose is
at least 15%. Because addition of Cr exceeding 20% causes
precipitation of .sigma.-phase, which results in decrease in
toughness and high temperature strength, an amount up to 25% should
be chosen. Preferable amount of Cr is in a relatively low range,
15-20%.
One or both of Mo: 0.1-10% and W: 0.1-5%, provided that Mo+0.5 W:
3-10%
[0022] Both molybdenum and tungsten are the elements which improve
the high temperature strength of the alloy by enhancing solid
solution of the matrix, and therefore, important components for
high fatigue strength at 900.degree. C. intended by the inventors.
To achieve this purpose both the elements are added in the
respective amounts of at least 0.1%. Addition of large amounts
causes increased costs and decreased workability, and thus, the
upper limits as above are given. Preferable amount of Mo is usually
in the higher range of 5-10%. However, excess addition is not
advantageous due to decreased oxidation resistance.
Al: 1.0-3.0%, Ti: 2.0-3.5%
[0023] Aluminum is an important element in combining with nickel to
form .gamma.'-phase. At an Al-content less than 1.0% precipitation
of .gamma.'-phase is so insufficient that the desired high
temperature strength cannot be obtained. On the other hand, at an
Al-content exceeding 3.0% hot workability of the alloy is low.
[0024] Titanium also combines with nickel to form .gamma.'-phase
which is useful for improving the high temperature strength. In
case where the Ti-content is so small as less than 2.0%, solid
solution temperature of the .gamma.'-phase becomes low, and as the
result, sufficient high temperature strength cannot be obtained.
Addition of Ti to such a large amount as more than 3.5% lowers the
workability, and causes precipitation of .eta.-phase (Ni.sub.3Ti),
which lowers the high temperature strength and the toughness of the
alloy. Also, hot processing of the alloy becomes difficult.
By atomic %, Al+Ti: 6.3-8.5%: Ti/Al ratio: 0.4-0.8
[0025] As seen from the above, the amount of Al+Ti(+Nb) is a
measure for the amount of .gamma.'-phase at 900.degree. C. In case
where the amount of Al+Ti(+Nb) is small, the fatigue strength of
the alloy is low, while in case where the amount is large, hot
processing becomes difficult. This is the reason why the range, by
atomic %, 6.3-8.5% is chosen.
[0026] The Ti/Al ratio is an important factor for stabilizing the
.gamma.'-phase at 900.degree. C. and increasing the fatigue
strength. At such a low value of the ratio as less than 0.4, aging
effect is so small that the sufficient strength may not be
obtained. On the other hand, such a high value as more than 0.8
causes precipitation of the .eta.-phase and the strength of the
alloy will be low. Preferable ratio in the above range is 0.6-0.8,
in which the intended improvement in the fatigue strength will be
effectively achieved.
B: 0.001-0.01%
[0027] Boron contributes to improvement in the hot workability of
the alloy, and further, improves the fatigue strength by
segregating at the grain boundaries to enhance the strength of the
grain boundaries. Thus, B is added in an amount of 0.001% or more
at which the above effects can be obtained. Excess addition of B
lowers the melting point of the matrix to damage the hot
workability, and therefore, addition amount should be up to
0.01%.
Fe: up to 3%
[0028] Iron is a component which, depending on the choice of the
materials, inevitably comes into the product alloy. If the
Fe-content is large, then the strength of the alloy will be low,
and therefore, a lower Fe-content is preferable. As the permissible
limit the above 3% is given. It is recommended to limit the
Fe-content to be less than 1%, which can be done by selecting the
materials.
One or more of V: 0.2-1.0%, Nb: 0.5-1.5% and Ta: 0.5-1.5%, by
atomic %. Al+Ti+Nb+Ta+V: 6.3-8.5%
[0029] Niobium, tantalum and vanadium all combine with Al and Ni to
strengthen the .gamma.'-phase. Vanadium also contributes to
solution hardening. If these effects are expected, it is
recommended to add one or more of these elements in an amount or
amounts of the above lower limit or more. Because excess content or
contents will decrease the toughness of the alloy, the addition
should be made in the amount or amounts up to the respective upper
limits and not exceeding the limited total amount.
One or more of Mg: 0.001-0.03%, Ca: 0.001-0.03%, Zr: 0.001-0.1% and
REM: 0.001-0.1%
[0030] Addition of these elements improves the hot workability of
the alloy. Zirconium also exhibits the effect of enhancing the
grain boundaries by segregating at the grain boundaries. REM (Rare
earth metals) improve, not only the hot workability, but also the
oxidation resistance of the alloy. In order to obtain these merits
it is recommended to add the element or elements in an amount or
amounts of at least the lower limit or limits. Excess contents
makes the temperature at which melting of the alloy begins lower,
resulting in the lowered hot workability, and therefore, addition
should be so made that the amount or amounts of the element or
elements do not exceed the respective upper limits.
Cu: 0.01-2%
[0031] As mentioned above, addition of copper increases oxidation
resistance of the alloy and improves the durability of the product
valves. Addition in the amount of 0.01% or more is recommended.
Excess addition of Cu results in decreased hot workability, and
therefore, addition must be up to 2.0%
[0032] The heat resistant alloy for exhaust valves according to the
present Invention exhibits, after being subjected to the solution
treatment and the aging, 10.sup.8-cycles fatigue strength at
900.degree. C. of 245 MPa or more, and the weight increase after
being subjected to oxidation test by keeping at 900.degree. C. for
400 hours is 5 mg/cm.sup.2 or less. The exhaust valves made of the
present alloy can withstand against such a high temperature as
900.degree. C. that the valves made of the conventional materials
cannot withstand. Thus, the valves have high durability given by
high fatigue strength and high oxidation resistance, and meet the
demand for increased performance of automobile engines.
EXAMPLES
[0033] Ni-based alloys having the alloy compositions shown in Table
1 (Working Examples) and Table 2 (Control Examples) were prepared
in a 50 kg HF-induction furnace and cast into ingots. The Ni-based
alloys prepared for the comparison are those used or proposed for
the material of the conventional exhaust valves, which are of the
following steel marks. [0034] Control 1: NCF751 [0035] Control 2:
NCF80 [0036] Control 3: Ni-based alloy disclosed in Japanese Patent
Disclosure 61-119640 [0037] Control 4: Ni-based alloy disclosed in
Japanese Patent Disclosure 05-059472
[0038] The respective ingots were forged and rolled to rods of
diameter 16 mm. The rods were subjected to solid solution treatment
of heating at 1050.degree. C. for 1 hour followed by water
quenching, and aging by heating at 750.degree. C. for 4 hours
followed by air cooling. The obtained materials were subjected to
tensile test and rotary bending fatigue test at 900.degree. C. and
continuous oxidation test for 400 hours. The results are shown in
Table 3 (Working Examples) and Table 4 (Control Examples) together
with the values of Ti/Al ratios and atomic % of Al+Ti.
TABLE-US-00001 TABLE 1 Alloy Composition (Working Examples Weight
%, balance Ni) Nb + Mo + No. C Si Mn P S Cr Co Mo W Al Ti Ta B Zr,
V, Mg, Ca Fe Cu 1/2 W A 0.03 0.23 0.56 0.005 0.003 18.3 13.1 4.4 --
1.9 2.6 -- 0.004 -- 0.1 -- 4.4 B 0.05 0.05 0.09 0.004 0.002 16.1
5.8 6.3 -- 2.1 2.3 1.3 0.003 Mg 0.003 Ca 0.002 1.3 -- 6.3 C 0.04
0.13 0.24 0.003 0.001 20.5 9.9 5.6 1.7 1.8 2.1 0.9 0.003 Zr 0.03 Mg
0.003 Ca 0.001 0.7 -- 6.5 D 0.08 0.18 0.15 0.001 0.001 15.8 12.0
4.9 -- 1.8 2.4 -- 0.005 -- 0.1 0.9 4.9 E 0.03 0.07 0.12 0.002 0.001
19.2 14.3 3.5 2.1 2.3 2.6 0.6 0.002 Zr 0.03 V 0.2 Mg 0.002 0.3 --
4.6 F 0.06 0.10 0.21 0.003 0.002 22.4 8.1 2.6 1.5 2.7 2.1 -- 0.004
Zr 0.05 0.2 -- 3.4 G 0.05 0.26 0.18 0.004 0.001 17.6 3.5 5.4 -- 1.6
2.2 1.1 0.003 Ca 0.002 0.5 1.3 5.4 H 0.04 0.14 0.20 0.002 0.003
21.7 8.9 2.3 2.6 1.8 2.2 0.5 0.003 Zr 0.06 Mg 0.003 1.6 -- 3.6 I
0.07 0.09 0.17 0.001 0.001 19.0 10.1 1.8 2.6 2.1 2.0 -- 0.003 V 0.3
0.9 -- 3.1 J 0.04 0.11 0.08 0.003 0.002 18.9 4.6 3.7 1.3 2.2 2.5
0.8 0.004 Zr 0.05 Mg 0.005 0.7 -- 4.4 K 0.03 0.22 0.18 0.002 0.001
23.1 13.6 5.5 -- 2.3 3.1 -- 0.005 Ca 0.002 1.0 -- 5.5 L 0.05 0.15
0.13 0.002 0.001 20.2 8.2 6.1 0.9 1.8 2.3 -- 0.003 Mg 0.003 REM
0.002 0.5 -- 6.6
[0039] TABLE-US-00002 TABLE 2 Alloy Composition (Control Examples,
Weight %, Balance Ni) Nb + Mo + No. C Si Mn P S Cr Co Mo W Al Ti Ta
B Zr, V, Mg, Ca Fe Cu 1/2 W 1 0.05 0.15 0.17 0.002 0.001 16.3 -- --
-- 1.2 2.5 -- 0.003 -- 7.1 -- -- 2 0.06 0.23 0.18 0.003 0.002 20.5
-- -- -- 1.4 2.6 -- 0.004 -- 0.6 -- -- 3 0.05 0.12 0.16 0.002 0.002
18.7 -- 1.2 1.4 1.4 2.5 -- 0.005 -- 3.2 -- 1.9 4 0.08 0.05 0.09
0.002 0.001 19.6 -- 0.9 -- 1.9 2.6 1.0 0.005 -- 5.1 -- 0.9
[0040] TABLE-US-00003 TABLE 3 Test results, Working Examples
900.degree. C. 900.degree. C. .times. 400 hours Ti/Al Al + Ti +
900.degree. C. 10.sup.8-cycles Weight increase Atomic (Nb + Ta + V)
Tensile Strength Fatigue Strength by oxidation No. ratio (Atomic %)
(MPa) (MPa) (mg/cm.sup.2) A 0.77 7.05 582 270 1.4 B 0.62 8.01 609
284 1.7 C 0.66 6.93 571 265 1.3 D 0.75 6.64 548 250 1.8 E 0.64 8.42
620 294 1.3 F 0.44 8.05 583 265 1.2 G 0.75 6.26 624 294 1.6 H 0.69
6.67 546 250 1.2 I 0.54 6.91 557 250 1.4 J 0.64 8.09 585 274 1.4 K
0.76 8.41 627 299 1.1 L 0.72 6.56 556 252 1.4
[0041] TABLE-US-00004 TABLE 4 Test results, Control Examples
900.degree. C. 900.degree. C. .times. 400 hours Ti/Al Al + Ti +
900.degree. C. 10.sup.8-cycles Weight increase Atomic (Nb + Ta + V)
Tensile Strength Fatigue Strength by oxidation No. ratio (Atomic %)
(MPa) (MPa) (mg/cm.sup.2) 1 1.18 5.41 333 89 1.7 2 1.05 5.91 380
104 1.4 3 1.01 5.89 436 142 1.5 4 0.77 7.55 479 196 1.5
* * * * *