U.S. patent application number 14/768845 was filed with the patent office on 2016-01-07 for fabricable, high strength, oxidation resistant ni-cr-co-mo-al alloys.
The applicant listed for this patent is HAYNES INTERNATIONAL, INC.. Invention is credited to Lee Pike, S. Krishna Srivastava.
Application Number | 20160002752 14/768845 |
Document ID | / |
Family ID | 51656042 |
Filed Date | 2016-01-07 |
United States Patent
Application |
20160002752 |
Kind Code |
A1 |
Srivastava; S. Krishna ; et
al. |
January 7, 2016 |
Fabricable, High Strength, Oxidation Resistant Ni-Cr-Co-Mo-Al
Alloys
Abstract
Ni--Cr--Co--Mo--Al based alloys are disclosed which contain 15
to 20 wt. % chromium, 9.5 to 20 wt. % cobalt, 7.25 to 10 wt. %
molybdenum, 2.72 to 3.9 wt. % aluminum, along with typical
impurities, a tolerance for up to 10.5 wt. % iron, minor element
additions and a balance of nickel. These alloys are readily
fabricable, have high creep strength, and excellent oxidation
resistance up to as high as 2100.degree. F. (1149.degree. C.). This
combination of properties is useful for a variety of gas turbine
engine components, including, for example, combustors.
Inventors: |
Srivastava; S. Krishna;
(Kokomo, IN) ; Pike; Lee; (Kokomo, IN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HAYNES INTERNATIONAL, INC. |
Kokomo |
IN |
US |
|
|
Family ID: |
51656042 |
Appl. No.: |
14/768845 |
Filed: |
March 14, 2014 |
PCT Filed: |
March 14, 2014 |
PCT NO: |
PCT/US14/28224 |
371 Date: |
August 19, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61790137 |
Mar 15, 2013 |
|
|
|
Current U.S.
Class: |
420/443 ;
420/448; 420/449; 420/454 |
Current CPC
Class: |
C22C 19/056
20130101 |
International
Class: |
C22C 19/05 20060101
C22C019/05 |
Claims
1. A nickel-chromium-cobalt-molybdenum-aluminum based alloy having
a composition comprised in weight percent of: TABLE-US-00013 15 to
20 chromium 9.5 to 20 cobalt 7.25 to 10 molybdenum 2.72 to 3.9
aluminum up to 10.5 iron present up to 0.15 carbon up to 0.015
boron up to 0.75 titanium up to 1.5 tantalum up to 1 hafnium up to
1 manganese up to 0.6 silicon up to 0.06 zirconium
with a balance of nickel and impurities, the alloy further
satisfying the following compositional relationship defined with
elemental quantities being in terms of weight percent:
Al+0.56Ti+0.29Nb+0.15Ta.ltoreq.3.9.
2. The nickel-chromium-cobalt-molybdenum-aluminum based alloy of
claim 1, containing hafnium, tantalum, or a combination of hafnium
and tantalum, where the sum of the two elements is between 0.2 wt.
% and 1.5 wt. %.
3. The nickel-chromium-cobalt-molybdenum-aluminum based alloy of
claim 1, containing titanium, from 0.2 to 0.75 wt. %.
4. The nickel-chromium-cobalt-molybdenum-aluminum based alloy of
claim 1, containing at least one of the elements hafnium and
tantalum at a level ranging from 0.2 wt. % up to 1 and 1.5 wt. %,
respectively.
5. The nickel-chromium-cobalt-molybdenum-aluminum based alloy of
claim 1, containing traces of at least one of magnesium, calcium,
and any rare earth elements up to 0.05 wt. %.
6. The nickel-chromium-cobalt-molybdenum-aluminum based alloy of
claim 1, containing at least one of the following impurities:
copper up to 0.5 wt. %, sulfur up to 0.015 wt. %, and phosphorous
up to 0.03 wt. %.
7. The nickel-chromium-cobalt-molybdenum-aluminum based alloy of
claim 1 wherein the alloy contains in weight percent:
TABLE-US-00014 16 to 20 chromium 15 to 20 cobalt 7.25 to 9.75
molybdenum 2.9 to 3.7 aluminum
8. The nickel-chromium-cobalt-molybdenum-aluminum based alloy of
claim 1, wherein the alloy contains in weight percent:
TABLE-US-00015 17 to 20 chromium 17 to 20 cobalt 7.25 to 9.25
molybdenum 2.9 to 3.6 aluminum
9. The nickel-chromium-cobalt-molybdenum-aluminum based alloy of
claim 1, wherein the alloy contains in weight percent:
TABLE-US-00016 17.5 to 19.5 chromium 17.5 to 19.5 cobalt 7.25 to
8.25 molybdenum 3.0 to 3.5 aluminum
10. The nickel-chromium-cobalt-molybdenum-aluminum based alloy of
claim 1, wherein the alloy contains in weight percent:
TABLE-US-00017 up to 5 iron present up to 0.12 carbon up to 0.008
boron up to 0.5 silicon up to 0.04 zirconium
11. The nickel-chromium-cobalt-molybdenum-aluminum based alloy of
claim 1, wherein the alloy contains in weight percent:
TABLE-US-00018 up to 2 iron 0.02 to 0.12 carbon present up to 0.005
boron 0.2 to 0.5 titanium up to 0.5 manganese up to 0.4 silicon
present up to 0.04 zirconium
12. The nickel-chromium-cobalt-molybdenum-aluminum based alloy of
claim 1, wherein the alloy has oxidation resistance such that the
average metal affected has a value not greater than 2.5 mils/side
when tested in flowing air at 2100.degree. F. (1149.degree. C.) for
1008 hours.
13. The nickel-chromium-cobalt-molybdenum-aluminum based alloy of
claim 1, wherein the alloy has modified CHRT test ductility values
greater than 7%.
14. The nickel-chromium-cobalt-molybdenum-aluminum based alloy of
claim 1, wherein the alloy has a creep-rupture life of at least 325
hours when tested at 1800.degree. F. (982.degree. C.) under a load
of 2.5 ksi (17 MPa).
15. A nickel-chromium-cobalt-molybdenum-aluminum based alloy having
a composition comprised in weight percent of: TABLE-US-00019 15 to
20 chromium 9.5 to 20 cobalt 7.25 to 10 molybdenum 2.72 to 3.9
aluminum up to 5 iron present up to 0.15 carbon up to 0.015 boron
up to 0.75 titanium up to 1 niobium up to 1.5 tantalum up to 1
hafnium up to 2 tungsten up to 1 manganese up to 0.6 silicon up to
0.06 zirconium
with a balance of nickel and impurities, the alloy further
satisfying the following compositional relationship defined with
elemental quantities being in terms of weight percent:
Al+0.56Ti+0.29Nb+0.15Ta.ltoreq.3.9.
16. The nickel-chromium-cobalt-molybdenum-aluminum based alloy of
claim 15, containing hafnium, tantalum, or a combination of hafnium
and tantalum, where the sum of the two elements is between 0.2 wt.
% and 1.5 wt. %.
17. The nickel-chromium-cobalt-molybdenum-aluminum based alloy of
claim 15, containing at least one of hafnium, tantalum, and
niobium, where the sum of these elements is between 0.2 wt. % and
1.5 wt. %.
18. The nickel-chromium-cobalt-molybdenum-aluminum based alloy of
claim 15, containing titanium, from 0.2 to 0.75 wt. %.
19. The nickel-chromium-cobalt-molybdenum-aluminum based alloy of
claim 15, containing at least one of the elements niobium, hafnium,
and tantalum at a level ranging from 0.2 wt. % up to 1, 1, and 1.5
wt. %, respectively.
20. The nickel-chromium-cobalt-molybdenum-aluminum based alloy of
claim 15, containing traces of at least one of magnesium, calcium,
and any rare earth elements up to 0.05 wt. %.
21. The nickel-chromium-cobalt-molybdenum-aluminum based alloy of
claim 15, containing at least one of: copper up to 0.5 wt. %,
sulfur up to 0.015 wt. %, and phosphorous up to 0.03 wt. %.
22. A nickel-chromium-cobalt-molybdenum-aluminum based alloy having
a composition comprised in weight percent of: TABLE-US-00020 15.3
to 19.9 chromium 9.7 to 20.0 cobalt 7.5 to 10.0 molybdenum 2.72 to
3.78 aluminum 0.1 to 10.4 iron 0.085 to 0.120 carbon up to 0.005
boron up to 0.49 titanium up to 1.0 tantalum up to 0.48 hafnium up
to 0.49 silicon up to 0.02 yttrium up to 0.04 zirconium
with a balance of nickel and impurities, the alloy further
satisfying the following compositional relationship defined with
elemental quantities being in terms of weight percent:
Al+0.56Ti+0.29Nb+0.15Ta.ltoreq.3.89.
23. The nickel-chromium-cobalt-molybdenum-aluminum based alloy of
claim 22, containing up to 4.5 wt. % iron and at least one of
tungsten or niobium at a level of up to 1.94 wt. % tungsten and up
to 0.91 wt. % niobium.
24. The nickel-chromium-cobalt-molybdenum-aluminum based alloy of
claim 22, containing traces of at least one of magnesium, calcium,
and any rare earth elements up to 0.05 wt. %.
25. The nickel-chromium-cobalt-molybdenum-aluminum based alloy of
claim 22, containing one or more of the following impurities:
niobium up to 0.2 wt. %, tungsten up to 0.5 wt. %, copper up to 0.5
wt. %, sulfur up to 0.015 wt. %, and phosphorous up to 0.03 wt. %.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional Patent
Application Ser. No. 61/790,137 filed on Mar. 15, 2013, and
incorporated by reference herein.
FIELD OF THE INVENTION
[0002] This invention relates to fabricable, high strength alloys
for use at elevated temperatures. In particular, it is related to
alloys which possess excellent oxidation resistance, high
creep-rupture strength, and sufficient fabricability to allow for
service in gas turbine engine combustors and other demanding high
temperature environments.
BACKGROUND OF THE INVENTION
[0003] For sheet fabrications in gas turbine engines a variety of
commercial alloys are available. These alloys can be divided into
different families based on their key properties. Note that the
following discussion relates to alloys which are cold
fabricable/weldable, meaning that they can be produced as cold
rolled sheet, cold formed into a fabricated part, and welded.
[0004] Gamma-Prime Formers.
[0005] These include R-41 alloy, Waspaloy alloy, 282.RTM. alloy,
263 alloy, and others. These alloys are characterized by their high
creep-rupture strength. However, the maximum use temperatures of
these alloys are limited by the gamma-prime solvus temperature and
are generally not used above 1600-1700.degree. F. (871 to
927.degree. C.). Furthermore, while the oxidation resistance of
these alloys is quite good in the use temperature range, at higher
temperatures it is less so.
[0006] Alumina-Formers.
[0007] These include 214.RTM. alloy and HR-224.RTM. alloy, but not
the ODS alloys (which do not have the requisite fabricability). The
alloys in this family have excellent oxidation resistance at
temperatures as high as 2100.degree. F. (1149.degree. C.). However,
their use in structural components is limited due to poor creep
strength at temperatures above around 1600-1700.degree. F. (871 to
927.degree. C.). Note that these alloys will also form the
strengthening gamma-prime, but this phase is not stable in the
higher temperature range.
[0008] Solid-Solution Strengthened Alloys.
[0009] These include 230.RTM. alloy, HASTELLOY.RTM. X alloy, 617
alloy, and others. As their name implies, these alloys derive their
high creep-rupture strength primarily from the solid-solution
strengthening effect, as well carbide formation. This strengthening
remains effective even at very high temperatures--well above the
maximum temperature of the gamma-prime formers, for example. Most
of the solid-solution strengthened alloys have very good oxidation
resistance due to the formation of a protective chromia scale.
However, their oxidation resistance is not comparable to the
alumina-formers, particularly at the very high temperatures, such
as 2100.degree. F. (1149.degree. C.).
[0010] Nitride Dispersion Strengthened Alloys.
[0011] These include NS-163.RTM. alloy which has very high
creep-rupture strength at temperatures as high as 2100.degree. F.
(1149.degree. C.). While the creep-rupture strength of NS-163 alloy
is better than the solid-solution alloys, its oxidation resistance
is only similar. It does not have the excellent oxidation
resistance of the alumina-formers.
[0012] What is clear from the above discussion is that there is no
cold fabricable/weldable alloy commercially available which
combines both high creep-rupture strength and excellent oxidation
resistance. However, in the effort to continually push gas turbine
engine operating temperatures higher and higher, it is clear that
alloys which combine these qualities would be very desirable.
SUMMARY OF THE INVENTION
[0013] The principal object of this invention is to provide readily
fabricable alloys which possess both high creep-rupture strength
and excellent oxidation-resistance. This is a highly valuable
combination of properties not found in (or expected from) the prior
art. The composition of alloys which have been discovered to
possess these properties is: 15 to 20 wt. % chromium (Cr), 9.5 to
20 wt. % cobalt (Co), 7.25 to 10 wt. % molybdenum (Mo), 2.72 to 3.9
wt. % aluminum (Al), and carbon (C), present up to 0.15 wt. %. The
elements titanium (Ti) and niobium (Nb) may be present, for
instance to provide strengthening, but should be limited in
quantity due to their adverse effect on certain aspects of
fabricability. In particular, an abundance of these elements may
increase the propensity of an alloy for strain-age cracking. If
present, titanium should be limited to no more than 0.75 wt. %, and
niobium to no more than 1 wt. %.
[0014] The presence of the elements hafnium (Hf) and/or tantalum
(Ta) has unexpectedly been found to be associated with even greater
creep-rupture lives in these alloys. Therefore, one or both
elements may be added to these alloys to further improve
creep-rupture strength. Hafnium may be added at levels up to around
1 wt. %, while tantalum may be added at levels up to around 1.5 wt.
%. To be most effective, the sum of the tantalum and hafnium
contents should be between 0.2 wt. % and 1.5 wt. %.
[0015] To maintain fabricability, certain elements which may or may
not be present (specifically, aluminum, titanium, niobium, and
tantalum) should be limited in quantity in a manner to satisfy the
following additional relationship (where elemental quantities are
in wt. %):
Al+0.56Ti+0.29Nb+0.15Ta.ltoreq.3.9 [1]
[0016] Additionally, boron (B) may be present in a small, but
effective trace content up to 0.015 wt. % to obtain certain
benefits known in the art. Tungsten (W) may be present in this
alloy up to around 2 wt. %. Iron (Fe) may also be present as an
impurity, or may be an intentional addition to lower the overall
cost of raw materials. However, iron should not be present more
than around 10.5 wt. %. If niobium and/or tungsten are present as
minor element additions, the iron content should be further limited
to 5 wt. % or less. To enable the removal of oxygen (O) and sulfur
(S) during the melting process, these alloys typically contain
small quantities of manganese (Mn) up to about 1 wt. %, and silicon
(Si) up to around 0.6 wt. %, and possibly traces of magnesium (Mg),
calcium (Ca), and rare earth elements (including yttrium (Y),
cerium (Ce), lanthanum (La), etc.) up to about 0.05 wt. % each.
Zirconium (Zr) may be present in the alloy, but should be kept to
less than 0.06 wt. % in these alloys to maintain fabricability.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0017] We provide Ni--Cr--Co--Mo--Al based alloys which contain 15
to 20 wt. % chromium, 9.5 to 20 wt. % cobalt, 7.25 to 10 wt. %
molybdenum, 2.72 to 3.9 wt. % aluminum, along with typical
impurities, a tolerance for up to 10.5 wt. % iron, minor element
additions and a balance of nickel, which are readily fabricable,
have high creep strength, and excellent oxidation resistance up to
as high as 2100.degree. F. (1149.degree. C.). This combination of
properties is useful for a variety of gas turbine engine
components, including, for example, combustors.
[0018] Based on the understanding of the requirements of future gas
turbine engine combustors, an alloy with the following attributes
would be highly desirable: 1) excellent oxidation resistance at
temperatures as high as 2100.degree. F. (1149.degree. C.), 2) good
fabricability, such that it can be produced in wrought sheet form,
cold formed, welded, etc., 3) high temperature creep-strength as
good or better than common commercial alloys, such as HASTELLOY X
alloy, and 4) good thermal stability at elevated temperatures.
Historically, attempts to develop an alloy combining all four
properties have not been successful, and correspondingly, no
commercial alloy is available in the marketplace with all four of
these qualities.
[0019] We tested 30 experimental alloys whose compositions are set
forth in Table 1. The experimental alloys have been labeled A
through Z and AA through DD. The experimental alloys had a Cr
content which ranged from 15.3 to 19.9 wt. %, as well as a cobalt
content ranging from 9.7 to 20.0 wt. %. The molybdenum content
ranged from 5.2 to 12.3 wt. %. The aluminum content ranged from
1.93 to 4.30 wt. %. Iron ranged from less than 0.1 up to 10.4 wt.
%. Minor element additions including titanium, niobium, tantalum,
hafnium, tungsten, yttrium, silicon, carbon, and boron were present
in certain experimental alloys.
[0020] All testing of the alloys was performed on sheet material of
0.065'' to 0.125'' (1.6 to 3.2 mm) thickness. The experimental
alloys were vacuum induction melted, and then electro-slag
remelted, at a heat size of 30 to 50 lb (13.6 to 27.2 kg). The
ingots so produced were hot forged and rolled to intermediate
gauge. The sheets were annealed, water quenched, and cold rolled to
produce sheets of the desired gauge. Intermediate annealing of cold
rolled sheet was necessary during production of the 0.065'' sheet
(1.6 mm). The cold rolled sheets were annealed as necessary to
produce a fully recrystallized, equiaxed grain structure with an
ASTM grain size between 31/2 and 41/2.
TABLE-US-00001 TABLE 1 Compositions of Experimental Alloys (in wt.
%) Alloy Ni Cr Co Mo Al Fe C Si Mn Ti Y Zr B Other A Bal. 19.9 14.8
7.8 3.64 1.2 0.096 0.15 -- 0.25 0.02 0.04 0.004 B Bal. 19.8 10.1
7.7 3.56 1.3 0.088 0.14 -- 0.25 0.02 0.04 0.004 C Bal. 16.1 19.9
7.6 3.65 1.3 0.099 0.14 -- 0.24 0.02 0.04 0.004 D Bal. 16.1 19.9
7.7 3.54 5.2 0.079 0.14 -- 0.25 0.02 0.02 0.004 E Bal. 16.0 19.8
7.7 3.62 9.7 0.085 0.14 -- 0.25 0.02 0.01 0.004 F Bal. 16.0 10.1
7.7 3.46 1.2 0.097 0.14 -- 0.22 0.01 0.02 0.004 G Bal. 16.1 9.9 7.8
3.51 9.9 0.089 0.13 -- 0.23 0.01 0.02 0.005 H Bal. 16.0 19.7 9.5
3.56 1.2 0.107 0.17 -- 0.24 <0.005 0.02 0.005 I Bal. 15.8 19.3
7.5 3.60 1.0 0.110 0.18 -- 0.23 0.02 0.02 0.004 1.94 W J Bal. 16.0
9.8 9.5 3.58 9.9 0.116 0.17 -- 0.22 0.02 0.01 0.005 K Bal. 16.3
19.3 7.5 3.50 1.1 0.104 0.14 -- 0.22 0.02 0.04 0.004 0.43Hf L Bal.
16.2 20.0 7.8 3.48 1.0 0.106 0.22 -- 0.23 0.02 0.02 0.005 0.71Ta M
Bal. 16.6 10.1 7.7 3.75 10.4 0.108 0.15 -- 0.23 0.02 0.03 0.004
0.38Hf N Bal. 16.7 10.2 7.8 3.64 10.2 0.110 0.19 -- 0.23 0.02 0.02
0.005 0.78Ta O Bal. 16.0 19.9 7.5 3.60 1.1 0.107 0.17 -- 0.23 0.02
0.02 0.004 0.35Nb, 0.69Ta P Bal. 16.0 9.9 7.5 3.63 10.0 0.107 0.19
-- 0.23 0.02 0.02 0.004 1.93 W Q Bal. 16.2 10.1 7.6 3.65 10.2 0.112
0.18 -- 0.22 0.02 0.02 0.005 0.35Nb, 0.71Ta R Bal. 15.3 20 10.0
3.32 <0.1 0.114 0.19 0.20 0.22 0.01 0.04 0.004 S Bal. 15.9 9.9
9.5 3.78 1.0 0.107 0.47 0.19 0.02 0.011 0.04 0.004 T Bal. 16.0 9.9
7.6 2.72 4.5 0.120 0.17 0.20 0.22 0.015 0.04 0.004 1.89 W, 0.91 Nb
U Bal. 19.5 19.9 7.6 3.36 1.1 0.103 0.17 0.20 0.49 0.013 0.04 0.005
V Bal. 19.0 9.9 8.0 3.40 1.0 0.090 0.18 0.15 0.21 0.011 0.04 0.005
0.48 Hf W Bal. 18.9 19.9 7.5 3.31 1.0 0.086 0.18 0.14 0.21 0.009
0.03 0.004 1.0 Ta X Bal. 19.2 19.9 7.7 3.40 1.0 0.088 0.17 0.13
0.21 0.011 0.04 0.004 0.45 Hf Y Bal. 16.4 10.2 7.8 2.81 1.1 0.108
0.49 0.50 0.22 0.010 0.04 0.004 Z Bal. 19.0 10 7.4 3.19 1.0 0.091
0.18 0.16 0.21 0.008 0.03 0.004 1.0 Ta AA Bal. 19.2 20 5.2 3.37 1.0
0.107 0.18 0.20 0.24 0.012 0.04 0.004 BB Bal. 19.3 20 12.3 3.67 1.0
0.099 0.51 0.53 0.42 0.011 0.04 0.004 CC Bal. 19.4 10 9.6 1.93 1.0
0.107 0.19 0.21 0.24 <0.002 <0.01 0.004 DD Bal. 18.9 10 9.5
4.30 1.0 0.117 0.49 0.21 0.43 0.005 0.05 0.004
[0021] To evaluate the key properties (oxidation resistance,
fabricability, creep strength, and thermal stability) four
different types of tests were performed on experimental alloys to
establish their suitability for the intended applications. The
results of these tests are described in the following sections.
Oxidation Resistance
[0022] Oxidation resistance is a key property for an advanced high
temperature alloy. Temperatures in the combustor of a gas turbine
engine can be very high and there is always a push in the industry
for higher and higher use temperatures. An alloy having excellent
oxidation resistance at as high as 2100.degree. F. (1149.degree.
C.) would be a good candidate for a number of applications. The
oxidation resistance of nickel-base alloys is strongly affected by
the nature of the oxides which form on the surface of the alloy
upon thermal exposure. It is generally favorable to form a
protective surface layer, such as chromium-rich and aluminum-rich
oxides. Alloys which form such oxides are often referred to as
chromia or alumina formers, respectively. The vast majority of
wrought high temperature nickel alloys are chromia formers.
However, a few alumina-formers are commercially available. One such
example is HAYNES.RTM. 214.RTM. alloy. The 214 alloy is well known
for its excellent oxidation resistance.
[0023] For the purpose of determining the oxidation resistance of
the experimental alloys, oxidation testing was conducted on most of
the alloys in flowing air at 2100.degree. F. (1149.degree. C.) for
1008 hours. Also tested alongside these samples were five
commercial alloys: HAYNES 214 alloy, 617 alloy, 230 alloy, 263
alloy, and HASTELLOY X alloy. Samples were cycled to room
temperature weekly. At the conclusion of the 1008 hours the samples
were descaled and submitted for metallographic examination.
Recorded in Table 2 are the results of the oxidation tests. The
recorded value is the average metal affected, which is the sum of
the metal loss plus the average internal penetration of the
oxidation attack. Details of this type of testing can be found in
International Journal of Hydrogen Energy, Vol. 36, 2011, pp.
4580-4587. For the purposes of this invention, an average metal
affected value of 2.5 mils/side (64 .mu.m/side) or less was the
preferred objective and an appropriate indication of whether a
given alloy could be considered as having "excellent" oxidation
resistance. Indeed, metallographic examination of the alloys with
less than this level of attack confirm their desirable oxidation
behavior. Certain minor elements/impurities could possibly result
in somewhat reduced (but still acceptable) oxidation resistance,
therefore the average metal affected value could probably be as
high as 3 mils/side (76 .mu.m/side) while still maintaining
excellent oxidation resistance.
TABLE-US-00002 TABLE 2 2100.degree. F. (1149.degree. C.) Oxidation
Test Results Average Metal Affected Alloy (mils/side) (.mu.m/side)
A 0.9 23 B 0.9 23 C 0.7 18 D 1.0 25 E 0.6 15 F 0.9 23 G 0.9 23 H
0.4 10 I 0.6 15 J 0.6 15 K 1.8 46 L 0.7 18 M 1.5 38 N 0.5 13 O 0.6
15 P 0.5 13 Q 0.4 10 R 0.9 23 S 0.6 15 T 1.1 28 U 1.4 36 V 2.3 58 W
0.5 13 X 1.6 41 Z 0.5 13 CC 4.4 112 263 16.5 419 214 1.3 33 617 5.1
130 230 4.8 122 HASTELLOY X 12.0 305
[0024] The results of the oxidation testing of the experimental
alloys were very impressive. All of the tested experimental alloys
(with the exception of alloy CC) had an average metal affected of
2.3 mils/side (58 .mu.m) or less. Therefore, all of these alloys
(with the exception of alloy CC) had acceptable oxidation
resistance for the purposes of this invention. Considering the
commercial alloys, the experimental alloys were all comparable to
the alumina-forming HAYNES 214 alloy, which had an average metal
affected value of 1.3 mils/side (33 .mu.m). In contrast, the
chromia-forming 617 alloy, 230 alloy, HASTELLOY X alloy, and 263
alloy all had much higher levels of oxidation attack, with average
metal affected values of 5.1, 4.8, 12.0, and 16.5 mils/side (130,
122, 305, and 419 .mu.m), respectively. The excellent oxidation
resistance of the experimental alloys is believed to derive from a
critical amount of aluminum, which was 2.72 wt. % or greater for
all of the experimental alloys other than alloy CC. Alloy CC had an
Al value of only 1.93 wt. %, illustrating that this is too low an
Al level for the desired excellent oxidation resistance. Similarly,
the Al levels of the four chromia-forming commercial alloys were
quite low (the highest being 617 alloy with 1.2 wt. % Al). In
contrast, the alumina forming 214 alloy has an Al content of 4.5
wt. %. In summary, all of the nickel-base alloys tested in this
program with an Al level of 2.72 wt. % or more were found to have
excellent oxidation resistance, while those with lower Al levels
did not. Therefore, to be considered an alloy of the present
invention the Al level of the alloy should be greater than or equal
to 2.72 wt. %.
[0025] Fabricability
[0026] One of the requirements of the alloys of this invention is
that they are fabricable. As discussed previously, for alloys
containing significant amounts of certain elements (such as
aluminum, titanium, niobium, and tantalum), having good
fabricability is closely tied to the alloy's resistance to
strain-age cracking. The resistance of the experimental alloys to
strain-age cracking was measured using the modified CHRT test
described by Metzler in Welding Journal supplement, October 2008,
pp. 249s-256s. This test was developed to determine an alloy's
relative resistance to strain-age cracking. It is a variation of
the test described in U.S. Pat. No. 8,066,938. In the modified CHRT
test, the width of the gauge section is variable and the test is
performed on a dynamic thermo-mechanical simulator rather than a
screw-driven tensile unit. The results of the two different forms
of the test are expected to be qualitatively similar, but the
absolute quantitative results will be different. The results of the
modified CHRT testing performed on our experimental alloys are
shown in Table 3. The testing was conducted at 1450.degree. F.
(788.degree. C.), and the reported CHRT ductility values were
measured as elongation over 1.5 inches (38 mm). The modified CHRT
test ductility of the experimental alloys ranged from 5.9% for
alloy DD to 17.9% for alloy X.
[0027] Also shown in Table 3 are the modified CHRT test results for
three commercial alloys as published by Metzler in Welding Journal
supplement, October 2008, pp. 249s-256s. The modified CHRT test
ductility values for R-41 alloy and Waspaloy were both less than
7%, while the value for 263 alloy was 18.9%. The R-41 alloy and
Waspaloy alloy, while weldable, are both known to be susceptible to
strain-age cracking, whereas 263 alloy is considered readily
weldable. For this reason, alloys of the present invention should
possess modified CHRT test ductility values greater than 7%. Of the
experimental alloys only alloys 0 and DD had a modified CHRT test
ductility value less than 7%; therefore alloys 0 and DD cannot be
considered alloys of the present invention.
TABLE-US-00003 TABLE 3 Results of the Modified CHRT test Alloy
Modified CHRT Test Ductility (%) A 13.0 B 11.6 C 7.7 D 13.3 E 13.6
F 8.9 G 10.3 H 8.7 I 9.4 J 10.2 K 8.6 L 8.0 M 9.7 N 10.0 O 6.3 P
9.3 Q 10.2 R 10.8 S 9.4 T 9.9 U 9.5 V 15.1 W 16.3 X 17.9 Y 13.5 Z
11.9 AA 10.5 BB 8.9 CC 15.3 DD 5.9 R-41 6.9 WASPALOY 6.8 263
18.9
[0028] It was discovered that for these Ni--Cr--Co--Mo--Al based
alloys, the resistance to strain age cracking could be associated
with the total amount of the gamma-prime forming elements Al, Ti,
Nb, and Ta. Therefore, the combined amount of these elements
present in the alloy should satisfy the following relationship
(where the elemental quantities are given in weight %):
Al+0.56Ti+0.29Nb+0.15Ta.ltoreq.3.9 [1]
The values of the left-hand side of equation 1 are shown in Table 4
for all of the experimental alloys. All alloys where
Al+0.56Ti+0.29Nb+0.15Ta was less than or equal to 3.9 can be seen
to have greater than 7% modified CHRT test ductility and therefore
pass the strain-age cracking resistance requirement of the present
invention. Only alloys 0, Q, and DD were found to have values
greater than 3.9. For alloys 0 and DD, the values of 3.93 and 4.54
can be correlated with poor modified CHRT test ductility. On the
other hand, alloy Q was found to have acceptable modified CHRT test
ductility. It is believed that this is a result of the alloy's high
Fe content. Fe additions are known to suppress the formation of
gamma-prime and could therefore help to improve the modified CHRT
test ductility. Nevertheless, a lower amount of gamma-prime forming
elements is generally beneficial for fabricability. Therefore, the
value of Al+0.56Ti+0.29Nb+0.15Ta should be kept to less than or
equal to 3.9 for all alloys of the present invention. Note that one
implication of this is that the maximum aluminum content of the
alloys of this invention must be 3.9 wt. % (which corresponds to
the case where titanium, niobium, and tantalum are all absent).
TABLE-US-00004 TABLE 4 Experimental Alloys - Eq. [1] value
(left-hand side) Alloy Al + 0.56Ti + 0.29Nb + 0.15Ta A 3.78 B 3.70
C 3.78 D 3.68 E 3.76 F 3.58 G 3.64 H 3.69 I 3.73 J 3.70 K 3.62 L
3.72 M 3.88 N 3.89 O 3.93 P 3.76 Q 3.98 R 3.44 S 3.79 T 3.11 U 3.63
V 3.52 W 3.58 X 3.52 Y 2.93 Z 3.46 AA 3.50 BB 3.90 CC 2.06 DD
4.54
Creep-Rupture Strength
[0029] The creep-rupture strength of the experimental alloys was
determined using a creep-rupture test at 1800.degree. F.
(982.degree. C.) under a load of 2.5 ksi (17 MPa). Under these
conditions, the creep-resistant HASTELLOY X alloy is estimated
(based on interpolated data from Haynes International, Inc.
publication #H-3009C) to have a creep-rupture life of 285 hours.
For the purposes of this invention, a minimum creep-rupture life of
325 hours was established as the requirement, which would be a
marked improvement over HASTELLOY X alloy. It is useful to note
that the test temperature of 1800.degree. F. (982.degree. C.) is
greater than the predicted gamma-prime solvus temperature of the
experimental alloys, thus any effects of gamma-prime phase
strengthening should be negligible.
[0030] The creep-rupture life of the experimental alloys is shown
in Table 5 along with those of several commercial alloys. Alloys A
through 0, R through Z, and BB, were all found to have
creep-rupture lives greater than 325 hours under these conditions,
and therefore meet the creep-rupture requirement of the present
invention. Alloys P, Q, AA, CC and DD were found to fail the
creep-rupture requirement. Considering the commercial alloys, 617
alloy and 230 alloy had acceptable creep-rupture lives of 732.2 and
915.4 hours, respectively. Conversely, the 214 alloy had a
creep-rupture life of only 196.0 hours--well below that of the
creep-rupture life requirement which defines alloys of the present
invention.
TABLE-US-00005 TABLE 5 Creep-Rupture Life at 1800.degree. F.
(982.degree. C.)/2.5 ksi (17 MPa) Alloy Rupture Life (hours) A
1076.7 B 534.7 C 486.1 D 447.0 E 331.9 F 402.8 G 722.0 H 2051.1 I
360.0 J 1785.7 K 5645.5 L 566.7 M 1317.4 N 1197.3 O 340.3 P 134.3 Q
254.4 R >500 S >500 T >330 U >500 V 1624.0 W 693.8 X
>500 Y >500 Z 909.4 AA 276.0 BB >500 CC 224.3 DD 138.6 617
732.2 214 196.0 230 915.4 HASTELLOY X 285 (estimated)
[0031] Certain experimental alloys containing either hafnium or
tantalum, were found to exhibit surprisingly greater creep-rupture
lives than many of the other experimental alloys. For example, the
hafnium-containing Alloy K has a creep-rupture life of 5645.5
hours, and the tantalum-containing alloy N has a creep-rupture life
of 1197.3 hours. A comparison of alloys with and without hafnium
and tantalum additions is given in Table 6. For comparative
purposes, the alloys are grouped according to their nominal base
composition. A clear benefit of hafnium and tantalum additions on
the creep-rupture life can be seen for all base compositions.
However, any beneficial effect of tantalum on the creep-rupture
strength must be weighed against any negative effects on the
fabricability as described previously in this document.
TABLE-US-00006 TABLE 6 Effects of Hafnium and Tantalum Additions on
Creep-Rupture Life 1800.degree. F. (982.degree. C.)/2.5 ksi (17
MPa) Creep- Rupture Nominal Base Composition Alloy Addition Life
(h) Ni--16Cr--20Co--7.5Mo--3.5Al--1Fe C -- 486.1 L 0.43Hf 5645.5 K
0.71Ta 566.7 Ni--16Cr--10Co--7.5Mo--3.5Al--10Fe P -- 134.3 M 0.38Hf
1317.4 N 0.78Ta 1197.3 Ni--19.5Cr--10Co--7.5Mo--3.5Al--1Fe B --
534.7 V 0.48Hf 1624.0 Z 1Ta 909.4
[0032] As mentioned above, the experimental alloys P and Q, both of
which contain around 10 wt. % iron, failed the creep-rupture
requirement. These alloys contained minor element additions of
tungsten and niobium, respectively. It is useful to compare these
alloys to alloy G which is similar to these two alloys, but without
a tungsten or niobium addition. Alloy G was found to have
acceptable creep-rupture life. Therefore, when alloys from this
family are at their upper end of the iron range (.about.10 wt. %)
the elements tungsten and niobium appear to have a negative effect
on the creep-rupture life. However, when the iron content is lower,
for example alloys I and T, tungsten additions do not result in
unacceptable creep-rupture lives. Similarly, niobium additions do
not result in unacceptable creep-rupture lives when the iron
content is lower (alloy T). For these reasons, the alloys of this
invention are limited to 5 wt. % iron or less when tungsten or
niobium are present as minor element additions. For alloys with
greater than 5 wt. % iron, niobium and tungsten should be
controlled to impurity level only (approximately 0.2 wt. % and 0.5
wt. % for niobium and tungsten, respectively).
[0033] Also mentioned above, alloys AA, CC, and DD failed the
creep-rupture requirement. Alloy AA has a Mo level below that
required by the present invention, while all the other elements
fall within their acceptable ranges. Therefore, it was found that a
critical minimum Mo level was necessary for the requisite
creep-rupture strength. Similarly, alloys CC and DD both have Al
levels which are outside the range of this invention, while all the
other elements fall within their acceptable ranges. The mechanisms
responsible for the low creep-rupture strength when the Al level is
outside the ranges defined by this invention are unclear.
[0034] Thermal Stability
[0035] The thermal stability of the experimental alloys was tested
using a room temperature tensile test following a thermal exposure
at 1400.degree. F. (760.degree. C.) for 100 hours. The amount of
room temperature tensile elongation (retained ductility) after the
thermal exposure can be taken as a measure of an alloy's thermal
stability. The exposure temperature of 1400.degree. F. (760.degree.
C.) was selected since many nickel-base alloys have the least
thermal stability around that temperature range. To have acceptable
thermal stability for the applications of interest, it was
determined that a retained ductility of greater than 10% is a
necessity. Preferably the retained ductility should be greater than
15%. Of the 30 experimental alloys described here, 28 of them had a
retained ductility of 17% or more--comfortably above the preferred
minimum. Alloys BB and DD were the exceptions, both having a
retained ductility of less than 10%. Alloy BB has a Mo level
greater than the maximum for the alloys of the present invention,
while all the other elements fell within their acceptable ranges.
Thus, it is believed that this high Mo level was responsible for
the poor thermal stability. Similarly, alloy DD had an Al level
greater than the maximum for the alloys of the present invention,
while all the other elements fell within their acceptable ranges.
Thus, the high Al level is believed responsible for the poor
thermal stability.
TABLE-US-00007 TABLE 7 Thermal Stability Test % Elongation
(retained ductility) Alloy after 1400.degree. F. (760.degree.
C.)/100 hours A 24 B 25 C 23 D 25 E 25 F 23 G 23 H 23 I 21 J 19 K
24 L 22 M 20 N 22 O 23 P 20 Q 20 R 21 S 17 T 23 U 23 V 21 W 23 X 21
Y 23 Z 20 AA 22 BB 2 CC 29 DD 7
[0036] Summarizing the results of the testing for the four key
properties (oxidation resistance, fabricability, creep-rupture
strength, and thermal stability), alloys A through N, alloys R
through X, and alloy Z, (22 in all) were found to pass all four key
property tests and are thus considered alloys of the present
invention. Also considered part of the present invention is alloy
Y, which passed the creep-rupture, modified CHRT, and thermal
stability tests, but was not tested for oxidation resistance (its
aluminum level indicates that alloy Y would have excellent
oxidation resistance as well according to the teaching of this
specification). Alloys 0 and DD failed the modified CHRT test and
thus were determined to have insufficient fabricability (due to
poor resistance to strain age cracking). Alloys P, Q, AA, CC, and
DD were found to fail the creep-rupture strength requirement. Alloy
CC failed the oxidation requirement. Finally, alloys BB and DD
failed the thermal stability requirement. Therefore, alloys 0, P,
Q, AA, BB, CC, and DD (7 in all) are not considered alloys of the
present invention. These results are summarized in Table 8.
Additionally, seven different commercial alloys were considered
alongside the experimental alloys. All seven commercial alloys were
found to fail one or more of the key property tests.
TABLE-US-00008 TABLE 8 Experimental Alloy Summary Alloy of the
Present Alloy Failed Key Property Test(s) Invention A YES B YES C
YES D YES E YES F YES G YES H YES I YES J YES K YES L YES M YES N
YES O Modified CHRT NO P Creep-Rupture NO Q Creep-Rupture NO R YES
S YES T YES U YES V YES W YES X YES Y YES Z YES AA Creep-Rupture NO
BB Thermal Stability NO CC Oxidation, Creep-Rupture NO DD Modified
CHRT, Creep-Rupture, NO Thermal Stability
[0037] The acceptable experimental alloys contained (in weight
percent): 15.3 to 19.9 chromium, 9.7 to 20.0 cobalt, 7.5 to 10.0
molybdenum, 2.72 to 3.78 aluminum, less than 0.1 up to 10.4 iron,
0.085 to 0.120 carbon, as well as minor elements and impurities.
The acceptable alloys further had values of the term
Al+0.56Ti+0.29Nb+0.15Ta which ranged from 2.93 to 3.89.
[0038] Perhaps the most critical aspect of this invention is the
very narrow window for the element aluminum. A critical aluminum
content of at least 2.72 wt. % is required in these alloys to
promote the formation of the protective alumina scale--requisite
for their excellent oxidation resistance. However, the aluminum
content must be controlled to 3.9 wt. % or less to maintain the
fabricability of the alloys as defined, in part, by the alloys'
resistance to strain-age cracking. This careful control of the
aluminum content is a necessity for the alloys of this invention.
The narrow aluminum window was also found to be important for the
creep-strength of these alloys, as well as the thermal stability.
In addition to the narrow aluminum window, there are other factors
crucial to this invention. These include the cobalt and molybdenum
additions, which contribute greatly to the creep-rupture
strength--a key property of these alloys. In particular, it was
found that a critical minimum level of molybdenum was necessary in
this particular class of alloys to ensure sufficient
creep-strength. Chromium is also crucial due to its contribution to
oxidation resistance. Certain minor element additions can provide
significant benefits to the alloys of this invention. This includes
carbon, a critical (and required) element for imparting creep
strength, grain refinement, etc. Also, boron and zirconium, while
not required to be present, are preferred to be present due to
their beneficial effects on creep-rupture strength. Likewise, rare
earth elements, such as yttrium, lanthanum, cerium, etc. are
preferred to be present due to their beneficial effects on
oxidation resistance. Finally, while all alloys of this invention
have high creep-rupture strength, those with hafnium and/or
tantalum additions have been found to have unexpectedly pronounced
creep-rupture strength.
[0039] The criticality of certain elements to the ability of the
alloys of this invention to meet the combination of the four key
material properties is illustrated by comparison of the present
invention to that described by Gresham in U.S. Pat. No. 2,712,498
which overlaps the present invention. In the Gresham patent wide
elemental ranges are described which cover vast swaths of
compositional space. No attempt is made to describe alloys which
possess the combination of the four key material properties
required by the present invention. In fact, the Gresham patent
describes many alloys which do not meet the requirements of the
present invention. For example, the commercial 263 alloy was
developed by Rolls-Royce Limited (to whom this patent was assigned)
and has been used in the aerospace industry for decades. However,
this alloy does not have the excellent oxidation resistance
required by the present invention--as was shown in Table 2 above.
Furthermore, there is no teaching by Gresham et al. that a critical
minimum aluminum level is necessary for oxidation resistance.
Another example is alloy DD described in Table 1. This alloy falls
within the ranges of the Gresham patent. However, this alloy fails
three of the four requirements of the present invention:
creep-rupture, resistance to strain-age cracking (as measured by
the modified CHRT test), and thermal stability. The failure of
alloy DD to pass the strain-age cracking requirement, for example,
has been shown in the present specification to be a result of the
aluminum level being too high. There is no teaching by Gresham et
al. that there is a critical maximum aluminum level (or a maximum
combined level of the elements Al, Ti, Nb, and Ta) to avoid
susceptibility to strain-age cracking. A third example is that
Gresham does not describe the need to limit the maximum molybdenum
level to avoid poor thermal stability. In short, Gresham describes
alloys which do not meet the combination of four key material
properties described herein and does not teach anything about the
critical compositional requirements necessary to combine these four
properties, including for example, the very narrow acceptable
aluminum range.
[0040] The alloys of the present invention must contain (in weight
percent): 15 to 20 chromium, 9.5 to 20 cobalt, 7.25 to 10
molybdenum, 2.72 to 3.9 aluminum, an amount of carbon up to 0.15,
and the balance nickel plus impurities minor element additions. The
ranges for the major elements are summarized in Table 9. In
addition to carbon, the minor element additions may also include
iron, silicon, manganese, titanium, niobium, tantalum, hafnium,
zirconium, boron, tungsten, magnesium, calcium, and one or more
rare earth elements (including, but not limited to, yttrium,
lanthanum, and cerium). The acceptable ranges of the minor elements
are described below and summarized in Table 10.
TABLE-US-00009 TABLE 9 Major Element Ranges (in wt. %) Intermediate
Intermediate Element Broad range range #1 range #2 Narrow Ni
balance balance balance balance Cr 15 to 20 16 to 20 17 to 20 17.5
to 19.5 Co 9.5 to 20 15 to 20 17 to 20 17.5 to 19.5 Mo 7.25 to 10
7.25 to 9.75 7.25 to 9.25 7.25 to 8.25 Al 2.72 to 3.9 2.9 to 3.7
2.9 to 3.6 3.0 to 3.5
[0041] The elements titanium and niobium may be present, for
instance to provide strengthening, but should be limited in
quantity due to their adverse effect on certain aspects of
fabricability. In particular, an abundance of these elements may
increase the propensity of an alloy for strain-age cracking. If
present, titanium should be limited to no more than 0.75 wt. %, and
niobium to no more than 1 wt. %. If not present as intentional
additions, titanium and niobium could be present as impurities up
to around 0.2 wt. % each.
[0042] The presence of the elements hafnium and/or tantalum has
unexpectedly been found to be associated with even greater
creep-rupture lives in these alloys. Therefore, one or both
elements may optionally be added to these alloys to further improve
creep-rupture strength. Hafnium may be added at levels up to around
1 wt. %, while tantalum may be added at levels up to around 1.5 wt.
%. To be most effective, the sum of the tantalum and hafnium
contents should be between 0.2 wt. % and 1.5 wt. %. If not present
as intentional additions, hafnium and tantalum could be present as
impurities up to around 0.2 wt. % each.
[0043] To maintain fabricability, certain elements which may or may
not be present (specifically, aluminum, titanium, niobium, and
tantalum) should be limited in quantity in a manner to satisfy the
following additional relationship (where elemental quantities are
in wt. %):
Al+0.56Ti+0.29Nb+0.15Ta.ltoreq.3.9 [1]
[0044] Additionally, boron may be present in a small, but effective
trace content up to 0.015 wt. % to obtain certain benefits known in
the art. Tungsten may be added up to around 2 wt. %, but if present
as an impurity would typically be around 0.5 wt. % or less. Iron
may also be present as an impurity at levels up to around 2 wt. %,
or may be an intentional addition at higher levels to lower the
overall cost of raw materials. However, iron should not be present
more than around 10.5 wt. %. If niobium and/or tungsten are present
as minor element additions, the iron content should be further
limited to 5 wt. % or less. To enable the removal of oxygen and
sulfur during the melting process, these alloys typically contain
small quantities of manganese up to about 1 wt. %, and silicon up
to around 0.6 wt. %, and possibly traces of magnesium, calcium, and
rare earth elements (including yttrium, cerium, lanthanum, etc.) up
to about 0.05 wt. % each. Zirconium may be present in the alloy as
an impurity or intentional addition (for example, to improve
creep-rupture life), but should be kept to 0.06 wt. % or less in
these alloys to maintain fabricability, preferably 0.04 wt. % or
less.
TABLE-US-00010 TABLE 10 Minor Element Additions (in wt. %) Element
Broad range Intermediate Narrow range C present up to 0.15 present
up to 0.12 0.02 up to 0.12 Fe up to 10.5 up to 5 up to 2 Si up to
0.6 up to 0.5 up to 0.4 Mn up to 1 up to 1 up to 0.5 Ti up to 0.75
up to 0.75 0.2 to 0.5 Nb.sup.a up to 1 up to 1.sup.c up to 1.sup.d
Ta up to 1.5 up to 1.5.sup.c up to 1.sup.d Hf up to 1 up to 1.sup.c
up to 0.5.sup.d Zr up to 0.06 up to 0.04 present up to 0.04 B up to
0.015 up to 0.008 present up to 0.005 W.sup.a up to 2 up to 2 up to
0.5 Mg up to 0.05 up to 0.05 up to 0.05 Ca up to 0.05 up to 0.05 up
to 0.05 REE.sup.b up to 0.05 each up to 0.05 each one or more
present up to 0.05 each .sup.aAlloys with Nb or W present at higher
than impurity levels should also contain .ltoreq.5 wt. % Fe
.sup.bRare earth elements (REE) include one or more of Y, La, Ce,
etc. .sup.cIn the intermediate range, at least one of niobium,
tantalum, and hafnium should be present, and the sum should be
between 0.2 and 1.5 .sup.dIn the narrow range, at least one of
tantalum and hafnium should be present, and the sum should be
between 0.2 and 1.5
[0045] A summary of the tolerance for certain impurities is
provided in Table 11. Some elements listed in Table 11 (tantalum,
hafnium, boron, etc.) may be present as intentional additions
rather than impurities; if a given element is present as an
intentional addition it should be subject to the ranges defined in
Table 10 rather than Table 11. Additional unlisted impurities may
also be present and tolerated if they do not degrade the key
properties below the defined standards.
TABLE-US-00011 TABLE 11 Impurity Tolerances (in wt. %) Impurity
Maximum Tolerance Fe 2* Si 0.4* Mn 0.5* Ti 0.2* Nb* 0.2* Ta 0.2* Hf
0.2* Zr 0.05* B 0.005* W* 0.5* Cu 0.5 S 0.015 P 0.03 *May be higher
if an intentional addition (see Table 10)
[0046] From the information presented in this specification we can
expect that the alloy compositions set forth in Table 12 would also
have the desired properties.
TABLE-US-00012 TABLE 12 Other Alloy Compositions Alloy Ni Cr Co Mo
Al Fe C Si Ti Y Zr B Other 1 Bal. 16 15 8 3.9 1 0.1 0.1 -- 0.02
0.04 0.004 2 Bal. 16 15 7.25 3.3 1 0.1 0.1 0.25 0.02 0.04 0.004 0.5
Ta 3 Bal. 16 15 8 3.3 1 0.02 0.1 0.25 0.02 0.04 0.004 0.5 Ta 4 Bal.
16 15 8 3.3 1 0.15 0.1 0.25 0.02 0.04 0.004 0.5 Ta 5 Bal. 15 15 8
3.3 1 0.1 0.1 0.25 0.02 0.04 0.004 0.5 Ta 6 Bal. 20 15 8 3.3 1 0.1
0.1 0.25 0.02 0.04 0.004 0.5 Ta 7 Bal. 16 15 8 3.3 1 0.1 -- 0.25
0.02 0.04 0.004 0.5 Ta 8 Bal. 16 9.5 8 3.3 1 0.1 0.1 0.25 0.02 0.04
0.004 0.5 Ta 9 Bal. 16 15 8 3.3 1 0.1 0.1 -- 0.02 0.04 0.004 0.5 Ta
10 Bal. 16 15 8 3.3 1 0.1 0.1 0.25 0.02 -- 0.004 0.5 Ta 11 Bal. 16
15 8 3.3 1 0.1 0.1 0.25 0.02 0.04 -- 0.5 Ta 12 Bal. 16 15 8 3.3 1
0.05 0.1 0.25 0.02 0.04 0.004 0.5 Ta 13 Bal. 16 15 8 3.3 1 0.1 0.1
0.25 0.02 0.04 0.015 0.5 Ta 14 Bal. 16 15 8 3.3 1 0.1 0.1 0.75 0.02
0.04 0.004 0.5 Ta 15 Bal. 16 15 8 3.3 1 0.1 0.1 0.25 0.02 0.04
0.004 1 Nb 16 Bal. 16 15 8 3.3 1 0.1 0.1 0.25 0.02 0.04 0.004 1 Hf
17 Bal. 16 15 8 3.3 1 0.1 0.1 0.25 0.02 0.04 0.004 1.5 Ta 18 Bal.
16 15 8 3.3 10.5 0.1 0.1 0.25 0.02 0.04 0.004 0.5 Ta 19 Bal. 16 15
8 3.3 1 0.1 0.1 0.25 0.02 0.04 0.004 1 Mn, 0.5 Ta 20 Bal. 16 15 8
3.3 1 0.1 0.5 0.25 0.02 0.04 0.004 0.5 Ta 21 Bal. 16 15 8 3.3 1 0.1
0.6 0.25 0.02 0.04 0.004 0.5 Ta 22 Bal. 16 15 8 3.3 1 0.1 0.1 0.25
0.02 0.06 0.004 0.5 Ta 23 Bal. 16 15 8 3.3 1 0.1 0.1 0.25 0.02 0.04
0.008 0.5 Ta 24 Bal. 16 15 8 3.3 1 0.1 0.1 0.5 0.02 0.04 0.004 0.5
Ta 25 Bal. 16 15 8 3.3 1 0.1 0.1 0.25 0.02 0.04 0.004 0.5 Hf 26
Bal. 16 15 8 3.3 1 0.1 0.1 0.25 0.02 0.04 0.004 0.5 Ta, 0.2 W 27
Bal. 16 15 8 3.3 1 0.1 0.1 0.25 0.02 0.04 0.004 0.5 Ta, 0.05 Mg 28
Bal. 16 15 8 3.3 1 0.1 0.1 0.25 0.02 0.04 0.004 0.5 Ta, 0.05 Ca 29
Bal. 16 15 8 3.3 1 0.1 0.1 0.25 0.02 0.04 0.004 0.5 Ta, 0.05 La 30
Bal. 16 15 8 3.3 1 0.1 0.1 0.25 0.02 0.04 0.004 0.5 Ta, 0.05 Ce 31
Bal. 16 15 8 3.3 1 0.1 0.1 0.25 0.05 0.04 0.004 0.5 Ta 32 Bal. 16
15 8 3.5 1 0.1 0.1 0.45 0.05 0.04 0.004 1 Ta
[0047] In addition to the four key properties described above,
other desirable properties for the alloys of this invention would
include: high tensile ductility in the as-annealed condition, good
hot cracking resistance during welding, good thermal fatigue
resistance, and others.
[0048] Even though the samples tested were limited to wrought
sheet, the alloys should exhibit comparable properties in other
wrought forms (such as plates, bars, tubes, pipes, forgings, and
wires) and in cast, spray-formed, or powder metallurgy forms,
namely, powder, compacted powder and sintered compacted powder.
Consequently, the present invention encompasses all forms of the
alloy composition.
[0049] The combined properties of excellent oxidation resistance,
good fabricability, and good creep-rupture strength exhibited by
this alloy make it particularly useful for fabrication into gas
turbine engine components and particularly useful for combustors in
these engines. Such components and engines containing these
components can be operated at higher temperatures without failure
and should have a longer service life than those components and
engines currently available.
[0050] Although we have disclosed certain preferred embodiments of
the alloy, it should be distinctly understood that the present
invention is not limited thereto, but may be variously embodied
within the scope of the following claims.
* * * * *