NICKEL BASE SUPERALLOY COMPOSITIONS AND SUPERALLOY ARTICLES

COMPOSITIONS DE SUPERALLIAGE A BASE DE NICKEL ET ARTICLES EN SUPERALLIAGE

English Abstract

A superalloy composition comprising, in weight percent: about 6.2-6.6 Al, about 6.5-7.0 Ta, about 6.0-7.0 Cr, about 6.25-7.0 W, about 1.5-2.5 Mo, about 0.15-0.60 Hf, 0.0-1.0 Re, 6.5-9.0 Co, optionally, 0.03-0.06 C, optionally, up to about 0.004 B, optionally up to about 0.03 total of one or more rare earth elements selected from yttrium (Y), lanthanum (La), or cerium (Ce), balance nickel, such that the superalloy composition exhibits a stress rupture capability improvement of at least 15% over a base stress rupture capability of a base composition nominally comprising, in weight percent: 6.5 Al, 6.6 Ta, 6.0 Cr, 6.25 W, 1.5 Mo, 0.15 Hf, 0.0 Re, 7.5Co. Articles incorporating the superalloy composition include a gas turbine engine component such as a high pressure turbine nozzle or nozzle segment.

French Abstract

L'invention porte sur une composition de superalliage comprenant, en pourcentage en poids : environ 6,2-6,6 d'Al, environ 6,5-7,0 de Ta, environ 6,0-7,0 de Cr, environ 6,25-7,0 de W, environ 1,5-2,5 de Mo, environ 0,15-0,60 de Hf, 0,0-1,0 de Re, 6,5-9,0 de Co facultativement 0,03-0,06 de C, facultativement jusqu'à environ 0,004 de B, facultativement jusqu'à environ 0,03 au total d'un ou plusieurs éléments des terres rares choisis parmi l'yttrium (Y), le lanthane (La) ou le cérium (Ce), le complément étant constitué par du nickel, de telle sorte que la composition de superalliage présente une amélioration de la capacité de rupture sous tension d'au moins 15 % par rapport à une capacité de rupture sous tension de base d'une composition de base comprenant de manière nominale, en pourcentage en poids : 6,5 d'Al, 6,6 de Ta, 6,0 de Cr, 6,25 de W, 1,5 de Mo, 0,15 de Hf, 0,0 de Re, 7,5 de Co. Des articles incorporant la composition de superalliage comprennent un composant de moteur de turbine à gaz, tel qu'une buse ou segment de buse de turbine haute pression.

Claims

WHAT IS CLAIMED IS:
1. A superalloy composition comprising, in weight percent: about 6.2-6.6
aluminum
(Al), about 6.5-7.0 tantalum (Ta), about 6.0-7.0 chromium (Cr), about 6.25-7.0
tungsten
(W), about 1.5-2.5 molybdenum (Mo), about 0.15-0.60 hafnium (Hf), 0.0-1.0
rhenium
(Re), 6.5-9.0 cobalt (Co), optionally, 0.03-0.06 carbon (C), optionally, up to
about 0.004
boron (B,) optionally up to about 0.03 total of one or more rare earth
elements selected
from yttrium (Y), lanthanum (La), or cerium (Ce), balance nickel (Ni), such
that the
superalloy composition exhibits a stress rupture capability improvement of at
least about
15% over a base stress rupture capability of a base composition nominally
comprising, in
weight percent: 6.5 Al, 6.6 Ta, 6.0 Cr, 6.25 W, 1.5 Mo, 0.15 Hf, 0.0 Re, 7.5
Co, balance
nickel.
2. The superalloy composition according to claim 1 comprising not more than
about
0.5 weight percent rhenium.
3. The superalloy composition according to claim 1 comprising substantially 0
weight percent rhenium.
4. The superalloy composition according to claim 1 comprising about 0.5 weight
percent rhenium.
6. The superalloy composition according to claim 2 comprising from 6.5 to
about
6.6 weight percent tantalum.
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7. A superalloy composition consisting of, in weight percent: about 6.2-6.6
aluminum (Al), about 6.5-7.0 tantalum (Ta), about 6.0 chromium (Cr), about
6.25-7.0
tungsten (W), about 2.0 molybdenum (Mo), about 0.6 hafnium (Hf), from 0.0 to
0.5
rhenium (Re), about 7.5 cobalt (Co), optionally, 0.03-0.06 carbon (C),
optionally, up to
about 0.004 boron (B), optionally up to about 0.03 total of one or more rare
earth
elements selected from yttrium (Y), lanthanum (La), or cerium (Ce), and a
balance of
nickel (Ni) and incidental impurities.
8. The superalloy composition according to claim 7 consisting of about 6.5 to
about
6.6 weight percent tantalum.
9. The superalloy composition according to claim 7 consisting of substantially
0
weight percent rhenium.
10. The superalloy composition according to claim 7 consisting of about 0.5
weight
percent rhenium.
11. The superalloy composition according to claim 7, consisting of, in weight
percent: about 6.3 aluminum (Al), about 6.5 tantalum (Ta), about 6.0 chromium
(Cr),
from about 6.25 to about 7 tungsten (W), about 2.0 molybdenum (Mo), about 0.60
hafnium (Hf), substantially 0.0 rhenium (Re), about 7.5 cobalt (Co),
optionally, 0.03-0.06
carbon (C), optionally, up to about 0.004 boron (B), optionally up to about
0.03 total of
one or more rare earth elements selected from yttrium (Y), lanthanum (La), or
cerium
(Ce), and a balance of nickel and incidental impurities.
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12. An article formed of a superalloy composition according to claim 1.
13. The article according to claim 12 comprising a gas turbine engine
component.
14. The article according to claim 13 comprising a high pressure turbine
nozzle or
nozzle segment.
15. An article formed of a superalloy composition according to claim 7.
16. The article according to claim 15 comprising a gas turbine engine
component.
17. The article according to claim 16 comprising a high pressure turbine
nozzle or
nozzle segment.
18. An article formed of a superalloy composition according to claim 11.
19. The article according to claim 18 comprising a gas turbine engine
component.
20. The article according to claim 19 comprising a high pressure turbine
nozzle or
nozzle segment.
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Description

CA 02766552 2011-12-22
WO 2011/002605 PCT/US2010/038640
240858-2
NICKEL BASE SUPERALLOY COMPOSITIONS AND
SUPERALLOY ARTICLES
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This Application claims priority and benefit of U.S. Provisional Patent
Application Serial No. 61/221,946, filed June 30, 2009, the disclosure of
which is
incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] This invention relates generally to nickel-base superalloy compositions
and superalloy articles and more particularly to such alloys for use in high
pressure
turbine (HPT) nozzle applications.
[0003] Currently known no-rhenium superalloys may exhibit inadequate stress
rupture capability. Other known superalloys that provide desired stress
rupture capability
may include relatively high amounts of rhenium. It is desirable to provide an
alloy able
to provide sufficient stress rupture capability with a reduced rhenium level.
SUMMARY OF THE INVENTION
[0004] The above-mentioned need or needs may be met by exemplary
embodiments that provide nickel-base superalloy compositions for use in high
temperature applications. Exemplary embodiments exhibit sufficient stress
rupture
capability, at relatively low- or no- rhenium levels.
[0005] In an exemplary embodiment, a superalloy composition comprises, in
weight percent: about 6.2-6.6 aluminum (Al), about 6.5-7.0 tantalum (Ta),
about 6.0-7.0
chromium (Cr), about 6.25-7.0 tungsten (W), about 1.5-2.5 molybdenum (Mo),
about
0.15-0.60 hafnium (Hf), 0.0-1.0 rhenium (Re), 6.5-9.0 cobalt (Co), optionally,
0.03-0.06
carbon (C), optionally, up to about 0.004 boron (B,) optionally up to about
0.03 total of
one or more rare earth elements selected from yttrium (Y), lanthanum (La), or
cerium
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(Ce), balance nickel (Ni), such that the superalloy composition exhibits a
stress rupture
capability improvement of at least about 15% over a base stress rupture
capability of a
base composition nominally comprising, in weight percent: 6.5 Al, 6.6 Ta, 6.0
Cr, 6.25
W, 1.5 Mo, 0.15 Hf, 0.0 Re, 7.5 Co, balance nickel.
[0006] In an exemplary embodiment, a superalloy composition consists of, in
weight percent: about 6.2-6.6 aluminum (Al), about 6.5-7.0 tantalum (Ta),
about 6.0
chromium (Cr), about 6.25-7.0 tungsten (W), about 2.0 molybdenum (Mo), about
0.6
hafnium (Hf), from 0.0 to 0.5 rhenium (Re), about 7.5 cobalt (Co), optionally,
0.03-0.06
carbon (C), optionally, up to about 0.004 boron (B), optionally up to about
0.03 total of
one or more rare earth elements selected from yttrium (Y), lanthanum (La), or
cerium
(Ce), and a balance of nickel (Ni) and incidental impurities.
[0007] In an exemplary embodiment, an article formed from an exemplary
superalloy composition is provided. The article may be a high pressure turbine
nozzle,
nozzle segment, or other gas turbine engine component.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The subject matter which is regarded as the invention is particularly
pointed out and distinctly claimed in the concluding part of the
specification. The
invention, however, may be best understood by reference to the following
description
taken in conjunction with the accompanying drawing figures in which:
[0009] FIG. 1 is a perspective view of a component article such as a gas
turbine
engine high pressure turbine (HPT) nozzle segment.
DETAILED DESCRIPTION OF THE INVENTION
[0010] Referring now to the drawings, FIG. 1 depicts an HPT nozzle segment
including at least one vane 12. In an exemplary embodiment, the nozzle segment
10
comprises a single crystal nickel-base superalloy composition as disclosed
herein.
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Articles incorporating the disclosed superalloy composition include HPT
nozzles or
nozzle segments and may include other gas turbine engine components.
[0011 ] Exemplary nickel-base superalloy composition comprise reduced levels
of rhenium (Re), defined herein as being from 0 up to about 0.5 weight %.
Increased
amounts of other strengthening alloying elements such as tantalum (Ta),
tungsten (W)
and molybdenum (Mo) may be utilized to offset the lower levels of Re. For
example,
tantalum may be present in amounts from about 6.5 to about 7.0 weight %,
molybdenum
may be present in amounts from about 1.5 to about 2.5 weight %, and tungsten
may be
present in amounts from about 6.25 to about 7.0 weight %. In other exemplary
embodiments, tantalum may be present at levels of from about 6.5 to about 6.6
weight %.
All percentages presented herein are percentages by weight, unless noted
otherwise.
[0012] Table 1 provides a series of exemplary compositions. A theoretical
stress rupture prediction generated by computer modeling for the compositions
was
compared with the predicted stress rupture (in hours) of a base, no-rhenium
superalloy
composition. As evidenced in Table 1, each of the enumerated compositions
provided an
improved predicted stress rupture, presented as % improvement.
[0013] Certain of the exemplary compositions presented in Table 1 are
highlighted. These exemplary compositions exhibit excellent improvement in the
predicted stress rupture as compared to the Base composition. These exemplary
compositions may provide desired outcomes with reduced rhenium levels (0.0-0.5
weight
%). Other exemplary compositions include rhenium in levels up to about 1.0
weight %.
[0014] Alloys 25 and 27 listed in Table 1 are provided as comparative examples
and include about 1.5 weight % rhenium. Exemplary embodiments disclosed herein
consider the contributions of various alloying elements to the thermal
mechanical
properties and oxidation resistance of the superalloy composition.
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[0015] Certain exemplary embodiments disclosed herein include from about 6.2
to about 6.6 weight percent aluminum. In other exemplary embodiments, the
aluminum
may be present in amounts from about 6.3 to about 6.5 percent.
[0016] Certain embodiments disclosed herein include at least about 6 to about
7
weight % chromium (Cr) sufficient to provide hot corrosion resistance, but not
high
enough to detrimentally lead to TCP phase instability and poor cyclic
oxidation
resistance.
[0017] Certain embodiments disclosed herein include from about 6.5% to about
9%, and more preferably about 7% to about 8% cobalt (Co). Lower amounts of
cobalt
may reduce alloy stability. Greater amounts may reduce the gamma prime solvus
temperature thus impacting high temperature strength and oxidation resistance.
[0018] Certain embodiments disclosed herein include molybdenum (Mo) in
amounts from about 1.5 to 2.5 weight %. The minimum value is sufficient to
impart
solid solution strengthening. Amounts exceeding the maximum may lead to
surface
instability. Greater amounts of Mo may also negatively impact both hot
corrosion and
oxidation resistance.
[0019] Certain embodiments disclosed herein include tungsten (W) in amounts
from about 6.25 to about 7.0 weight %. Lower amounts of W may decrease
strength.
Higher amounts may produce instability with respect to TCP phase formation.
Higher
amounts may also reduce oxidation capability.
[0020] Certain embodiments disclosed herein provide reduced levels of
rhenium, preferably from 0.0 to about 1.0 weight percent, and more preferably
not greater
than about 0.5 weight %. It is contemplated that some or all of the rhenium
may be
provided as revert from scrap material. Compositions 25 and 27 illustrate
significant
improvement in predicted stress rupture capability with the addition of 1.5
weight %
rhenium. It is desired to provide improved performance at reduced rhenium
levels.
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[0021] Hafnium (Hf) may be included at relatively low levels of about 0.15
weight % up to higher levels of about 0.6 weight %. Hafnium can improve
oxidation
resistance and the adherence of thermal barrier coatings when utilized.
However,
hafnium can degrade the corrosion resistance of uncoated alloys. Hafnium
additions of
about 0.7% can be satisfactory, but additions of greater than about 1%
adversely impact
stress rupture properties and the incipient melting temperature.
[0022] Optional additions may include about 0.03-0.06 weight % carbon (C), up
to about 0.004 weight % boron (B), or up to about 0.03 weight% of one or more
rare
earth elements such as yttrium (Y), lanthanum (La), and cesium (Ce).
[0023] Boron provides strength for low angle boundaries and enhanced
acceptability limits for components having low angle grain boundaries. The
lower limit
for carbon provides sufficient carbon to improve alloy cleanliness since
carbon provides
de-oxidation. Beyond the upper 0.06% amount, the carbide volume fraction
increases,
reducing fatigue life. Rare earth additions, i.e., yttrium (Y), lanthanum
(La), and cerium
(Ce), may be provided in certain embodiments in amounts up to about 0.03%.
These
additions may improve oxidation resistance by enhancing the retention of the
protective
alumina scale. Greater amounts may promote mold/metal reaction at the casting
surface,
increasing the component inclusion content.
[0024] Exemplary embodiments disclosed herein include each of the
enumerated compositions in Table 1 with the exception of the base composition,
and
comparative alloys 25 and 27. Additionally, exemplary embodiments disclosed
herein
include compositions employing the endpoints of disclosed ranges and all
intermediate
values. For example, a range of aluminum from about 6.2 to about 6.6 weight
percent is
defined to include 6.2 weight percent, 6.6 weight percent, and any intervening
percentage
between 6.2 and 6.6 weight percent.
[0025] Exemplary embodiments disclosed herein provide improved stress
rupture capability of at least 15% as compared to a base stress rupture
capability of a base
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composition nominally comprising, in weight percent: 6.5 Al, 6.6 Ta, 6.0 Cr,
6.25 W, 1.5
Mo, 0.15 Hf, 0.0 Re, 7.5Co, balance Ni, identified as "Base" in Table 1.
[0026] EXAMPLES
TABLE 1
Alloy Al Ta Cr W Mo Hf Re Co % Improved
Base 6.5 6.6 6.0 6.25 1.5 0.15 0.0 7.5 ---
1 6.3 6.5 6.0 6.25 2.0 0.60 1.0 7.5 154
2 6.3 6.5 6.0 6.25 2.0 0.60 0.5 7.5 117
6 6.5 6.6 6.0 6.25 1.5 0.15 0.5 7.5 33
7 6.5 6.6 6.0 6.25 1.5 0.15 1.0 7.5 70
8 6.5 6.6 6.0 6.25 1.5 0.60 0.5 7.5 83
9 6.5 6.6 6.0 6.25 1.5 0.60 1.0 7.5 135
6.5 6.6 6.0 6.25 1.5 0.60 0.0 7.5 40
11 6.3 6.5 7.0 6.25 2.0 0.60 1.0 7.5 114
12 6.3 6.5 7.0 6.25 2.0 0.60 0.5 7.5 94
13 6.5 6.6 7.0 6.25 1.5 0.15 0.5 7.5 52
14 6.5 6.6 7.0 6.25 1.5 0.15 1.0 7.5 84
6.5 6.6 7.0 6.25 1.5 0.60 0.5 7.5 104
16 6.5 6.6 7.0 6.25 1.5 0.60 1.0 7.5 122
17 6.5 6.6 7.0 6.25 1.5 0.60 0.0 7.5 74
18 6.3 6.5 6.5 6.25 2.0 0.60 1.0 7.5 139
19 6.3 6.5 6.5 6.25 2.0 0.60 0.5 7.5 81
6.5 6.6 6.5 6.25 1.5 0.15 0.5 7.5 45
21 6.5 6.6 6.5 6.25 1.5 0.15 1.0 7.5 78
22 6.5 6.6 6.5 6.25 1.5 0.60 0.5 7.5 103
23 6.3 6.6 6.5 6.25 1.5 0.60 1.0 7.5 143
24 6.5 6.6 6.5 6.25 1.5 0.60 0.0 7.5 61
*25 6.3 6.5 7.0 6.25 2.0 0.60 1.5 7.5 128
26 6.5 6.6 7.0 6.25 1.5 0.15 0.0 7.5 24
*27 6.3 6.5 6.5 6.25 2.0 0.60 1.5 7.5 160
28 6.5 6.6 6.5 6.25 1.5 0.15 0.0 7.5 15
29 6.3 6.5 6.0 7.00 2.0 0.60 0.0 7.5 102
6.3 6.5 7.0 7.00 2.0 0.60 0.0 7.5 76
31 6.3 6.5 6.0 7.00 2.0 0.60 0.5 7.5 138
32 6.3 6.5 7.0 7.00 2.0 0.60 0.5 7.5 92
33 6.3 6.5 6.0 7.00 2.5 0.60 0.0 7.5 87
34 6.3 6.5 7.0 7.00 2.5 0.60 0.0 7.5 51
6.3 6.5 6.0 7.00 2.5 0.60 0.5 7.5 122
36 6.3 6.5 7.0 7.00 2.5 0.60 0.5 7.5 83
37 6.3 6.5 6.0 6.50 2.0 0.60 0.0 7.5 87
38 6.3 6.5 7.0 6.25 2.0 0.60 0.0 7.5 71
39 6.3 6.5 6.0 6.50 2.0 0.60 0.5 7.5 124
6.3 6.5 7.0 6.50 2.0 0.60 0.5 7.5 94
41 6.3 6.5 6.0 6.50 2.5 0.60 0.0 7.5 78
42 6.3 6.5 7.0 6.50 2.5 0.60 0.0 7.5 46
43 6.3 6.5 6.0 6.50 2.5 0.60 0.5 7.5 115
44 6.3 6.5 7.0 6.50 2.5 0.60 0.5 7.5 77
All: Balance Ni *Alloys 25 and 27 include 1.5 weight % Rhenium as comparative
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[0027] This written description uses examples to disclose the invention,
including the best mode, and also to enable any person skilled in the art to
make and use
the invention. The patentable scope of the invention is defined by the claims,
and may
include other examples that occur to those skilled in the art. Such other
examples are
intended to be within the scope of the claims if they have structural elements
that do not
differ from the literal language of the claims, or if they include equivalent
structural
elements with insubstantial differences from the literal languages of the
claims.
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Representative Drawing