U.S. patent application number 10/831978 was filed with the patent office on 2005-01-06 for nickel base superalloy and single crystal castings.
Invention is credited to Corrigan, John, Launsbach, Michael, Mihalisin, John R., Vogt, Russell G..
Application Number | 20050000603 10/831978 |
Document ID | / |
Family ID | 33519539 |
Filed Date | 2005-01-06 |
United States Patent
Application |
20050000603 |
Kind Code |
A1 |
Corrigan, John ; et
al. |
January 6, 2005 |
Nickel base superalloy and single crystal castings
Abstract
Rhenium-bearing single crystal nickel base superalloy consisting
essentially of, in weight %, about 12.5% to about 13.5% Cr, 9.0 to
about 9.9% Co, about 4.7 to about 5.1% Ti, about 2.8 to about 3.2%
Al, about 2.8 to about 4.3% W, about 1.4 to about 1.6% Mo, about
2.85 to about 3.1% Ta, about 1.0 to about 6.0% Re, about 0.08 to
about 0.11% C, about 0.010 to about 0.015% B, up to about 0.15% Nb,
up to about 0.15% Hf, up to about 0.003% Zr, and balance Ni and
incidental impurities.
Inventors: |
Corrigan, John; (Yorktown,
VA) ; Launsbach, Michael; (Yorktown, VA) ;
Vogt, Russell G.; (Yorktown, VA) ; Mihalisin, John
R.; (North Caldwell, NJ) |
Correspondence
Address: |
Mr. Edward J. Timmer
P.O. Box 770
Richland
MI
49083-0770
US
|
Family ID: |
33519539 |
Appl. No.: |
10/831978 |
Filed: |
April 26, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60482579 |
Jun 25, 2003 |
|
|
|
Current U.S.
Class: |
148/404 ;
420/444; 420/448 |
Current CPC
Class: |
C22C 19/056 20130101;
C22C 19/057 20130101; F01D 5/28 20130101; F05D 2300/607
20130101 |
Class at
Publication: |
148/404 ;
420/444; 420/448 |
International
Class: |
C22C 019/05 |
Claims
We claim:
1. Nickel base superalloy consisting essentially of, in weight %,
about 12.5% to about 13.5% Cr, 9.0 to about 9.9% Co, about 4.7 to
about 5.1% Ti, about 2.8 to about 3.2% Al, about 2.8 to about 4.3%
W, about 1.4 to about 1.6% Mo, about 2.85 to about 3.1% Ta, about
1.0 to about 6.0% Re, about 0.08 to about 0.11% C, about 0.010 to
about 0.015% B, up to about 0.15% Nb, up to about 0.15% Hf, up to
about 0.003% Zr, and balance Ni and incidental impurities.
2. The superalloy of claim 1 having a Re content of about 2 to
about 4 weight %.
3. The superalloy of claim 2 having an N.sub.v value of less than
2.37.
4. Nickel base superalloy consisting essentially of, in weight %,
about 13.0% Cr, 9.0% Co, about 4.9% Ti, about 3.0% Al, about 3.03%
W, about 1.5% Mo, about 2.95% Ta, about 3.0% Re, about 0.09% C,
about 0.012% B, up to about 0.15% Nb, up to about 0.15% Hf, up to
about 0.003% Zr, and balance Ni and incidental impurities and an
N.sub.v of about 2.33.
5. A turbine airfoil comprising the superalloy of claims 1, 2, 3,
or 4.
6. A turbine airfoil of claim 5 which is a directionally solidified
columnar grain or single crystal cast airfoil.
7. Nickel base superalloy consisting essentially of, in weight %,
about 9.5% to about 14.0% Cr, 7.0 to about 11.0% Co, about 3.0 to
about 5.0% Ti, about 3.0 to about 4.0% Al, about 3.0 to about 4.0%
W, about 1.0 to about 2.5% Mo, about 1.0 to about 4.0% Ta, about
1.0 to about 6.0% Re, up to about 0.25% C, up to about 0.015% B, up
to about 1.0% Nb, up to about 0.15% Hf, up to about 0.003% Zr, and
balance Ni and incidental impurities.
8. The superalloy of claim 7 having a Re content of about 2 to
about 4 weight %.
9. The superalloy of claim 8 having an N.sub.v value of less than
2.37.
10. Nickel base superalloy consisting essentially of, in weight %,
about 11.75% Cr, 9.0% Co, about 4.0% Ti, about 3.5% Al, about 3.5%
W, about 1.75% Mo, about 2.5% Ta, about 3.0% Re, about 0.09% C, up
to about 0.012% B, up to about 0.15% Nb, up to about 0.15% Hf, up
to about 0.003% Zr, and balance Ni and incidental impurities and an
N.sub.v of about 2.33.
11. A turbine airfoil comprising the superalloy of claims 7, 8, 9,
or 10.
12. A turbine airfoil of claim 11 which is a single crystal cast
airfoil.
Description
[0001] This application claims the benefits and priority of Ser.
No. 60/482,579 filed Jun. 25, 2003.
FIELD OF THE INVENTION
[0002] The present invention relates to a nickel base superalloy
and to single crystal castings, such as single crystal airfoil
castings, made from the superalloy.
BACKGROUND OF THE INVENTION
[0003] Superalloys are widely used as castings in the gas turbine
engine industry for critical components, such as turbine airfoils
including blades and vanes, subjected to high temperatures and
stress levels. Such critical components oftentimes are cast using
well known directional solidification (DS) techniques that provide
a single crystal microstructure or columnar grain microstructure to
optimize properties in one or more directions.
[0004] Directional solidification casting techniques are well known
wherein a nickel base superalloy remelt ingot is vacuum induction
remelted in a crucible in a casting furnace and poured into a
ceramic investment cluster mold disposed in the furnace having a
plurality of mold cavities. During directional solidification, the
superalloy melt is subjected to unidirectional heat removal in the
mold cavities to produce a columnar grain structure or single
crystal in the event a crystal selector or seed crystal is
incorporated in the mold cavities. Unidirectional heat removal can
be effected by the well known mold withdrawal technique wherein the
melt-filled cluster mold on a chill plate is withdrawn from the
casting furnace at a controlled rate. Alternately, a power down
technique can be employed wherein induction coils disposed about
the melt-filled cluster mold on the chill plate are de-energized in
controlled sequence. Regardless of the DS casting technique
employed, generally unidirectional heat removal is established in
the melt in the mold cavities.
SUMMARY OF THE INVENTION
[0005] The present invention provides in one embodiment a nickel
base superalloy consisting essentially of, in weight %, about 12.5%
to about 13.5% Cr, about 9.0 to about 9.9% Co, about 4.7 to about
5.1% Ti, about 2.8 to about 3.2% Al, about 2.8 to about 4.3% W,
about 1.4 to about 1.6% Mo, about 2.85% to about 3.1% Ta, about 1.0
to about 6.0% Re, about 0.08 to about 0.11% C, about 0.010 to about
0.015% B, up to about 0.15% Nb, up to about 0.15% Hf, up to about
0.003% Zr, and balance Ni and incidental impurities. A preferred
range for the Re concentration is about 2% to about 4% by
weight.
[0006] A nickel base superalloy having a nominal composition
pursuant to a particular embodiment of the invention consists
essentially of, by weight, about 13.0% Cr, about 9.0% Co, about
4.9% Ti, about 3.0% Al, about 3.0% W, about 1.5% Mo, about 2.95%
Ta, about 3.0% Re, about 0.09% C, about 0.012% B, up to about 0.15%
Nb, up to about 0.15% Hf, up to about 0.003% Zr, and balance Ni and
incidental impurities. Preferably, Nb, Hf, and Zr each are
maintained at respective impurity level concentrations in the
alloy.
[0007] The present invention provides in another embodiment a
nickel base superalloy consisting essentially of, in weight %,
about 9.5% to about 14.0% Cr, about 7.0 to about 11.0% Co, about
3.0 to about 5.0% Ti, about 3.0 to about 4.0% Al, about 3.0 to
about 4.0% W, about 1.0 to about 2.5% Mo, about 1.0% to about 4.0%
Ta, about 1.0 to about 6.0% Re, up to about 0.25% C, up to about
0.015% B, up to about 1.0% Nb, up to about 0.15% Hf, up to about
0.003% Zr, and balance Ni and incidental impurities. A preferred
range for the Re concentration is about 2% to about 4% by weight.
Preferably, Nb, Hf, and Zr each are maintained at respective
impurity level concentrations in the alloy.
[0008] Another nickel base superalloy having a nominal composition
pursuant to a particular embodiment of the invention consists
essentially of, by weight, about 11.75% Cr, about 9.0% Co, about
4.0% Ti, about 3.5% Al, about 3.5% W, about 1.75% Mo, about 2.5%
Ta, about 3.0% Re, about 0.09% C, about 0.012% B, up to about 1.0%
Nb, up to about 0.15% Hf, up to about 0.003% Zr, and balance Ni and
incidental impurities.
[0009] A nickel base superalloy pursuant to embodiments of the
invention possesses improved castability and improved mechanical
properties.
[0010] Other advantages, features, and embodiments of the present
invention will become apparent from the following description.
DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a graph representing the Larson-Miller parameter
for invention alloys A and B pursuant to embodiments of the
invention and for comparison CompSX, CMSX-4, PWA 1484, and Rene'N5
nickel base superalloys.
[0012] FIG. 2 is a graph representing the Larson-Miller parameter
for invention alloy B pursuant to an embodiment of the invention
and for comparison CompSX nickel base superalloy.
[0013] FIG. 3 is a bar graph showing stress rupture life for
invention alloys A and B pursuant to embodiments of the invention
and for comparison CompSx nickel base superalloy.
[0014] FIG. 4 is a bar graph representing the Larson-Miller
parameter at different stress levels for invention alloys A and B
pursuant to embodiments of the invention and for comparison CompSX
nickel base superalloy.
[0015] FIG. 5 is a graph of ultimate tensile strength (UTS) versus
temperature for invention alloy A pursuant to an embodiment of the
invention and for comparison CompSX, CMSX-4, PWA 1484, and Rene'N5
nickel base superalloys.
[0016] FIG. 6 is a graph of 0.2% yield stress versus temperature
for invention alloy A pursuant to an embodiment of the invention
and for comparison CompSX, PWA 1484, and Rene'N5 nickel base
superalloys.
[0017] FIG. 7 is a graph of percent elongation versus temperature
for invention alloy A pursuant to an embodiment of the invention
and for comparison CompSX, CMSX-4, PWA 1484, and Rene'N5 nickel
base superalloys.
[0018] FIG. 8 is a graph of percent reduction in area versus
temperature for invention alloy A pursuant to an embodiment of the
invention and for comparison CompSX, CMSX-4, PWA 1484, and Rene'N5
nickel base superalloys.
DESCRIPTION OF THE INVENTION
[0019] The present invention provides a nickel base superalloy
which is useful in directional solidification processes to make gas
turbine engine components subjected to high temperatures and stress
levels, such as turbine airfoils including blades and vanes,
although the invention is not limited to use in such processes or
to make such components. The nickel base superalloy is especially
useful in directional solidification processes to make columnar
grain castings or single crystal castings.
[0020] Pursuant to an embodiment of the invention, the nickel base
superalloy consists essentially of, in weight %, about 12.5% to
about 13.5% Cr, about 9.0 to about 9.9% Co, about 4.7 to about 5.1%
Ti, about 2.8 to about 3.2% Al, about 2.8 to about 4.3% W, about
1.4 to about 1.6% Mo, about 2.85% to about 3.1% Ta, about 1.0 to
about 6.0% Re, about 0.08 to about 0.11% C, about 0.010 to about
0.015% B, up to about 0.15% Nb, up to about 0.15% Hf, up to about
0.003% Zr, and balance Ni and incidental impurities. Such nickel
base superalloy typically will exhibit a Pha Comp (N.sub.v) value
of about 2.37 or less.
[0021] The Pha Comp value corresponds to the electron vacany number
(N.sub.v), which is described in U.S. Pat. No. 6,054,096, the
teachings of which are incorporated herein by reference to this
end. The N.sub.v value represents the propensity of the superalloy
microstructure to be microstructurally unstable under elevated
temperature and time service conditions where the instability
relates to formation of brittle extraneous phases in the superalloy
microstructure under the extended service conditions. Such
extraneous phases are often referred to as TCP (topologically
closed packed) phases, such as for example sigma phase and mu
phase.
[0022] The concentrations of Cr, Co, W, and Mo are closely
controlled within the above ranges to achieve the above PhaC Comp
(N.sub.v) value so as to improve microstructural stability of the
superalloy in service at anticipated elevated temperatures and
times experienced by airfoils in a gas turbine engine.
[0023] The Re alloying element preferably is present in amount of
about 2% to about 4% by weight and more preferably about 3.0% Re.
Re is present in the superalloy to increase strength of single
crystal castings made of the superalloy. Preferably, Nb, Hf, and Zr
each are maintained at respective impurity level concentrations in
the alloy.
[0024] The invention contemplates a nickel base superalloy having a
nominal composition that consists essentially of, by weight, about
13.0% Cr, about 9.0% Co, about 4.9% Ti, about 3.0% Al, about 3.0%
W, about 1.5% Mo, about 2.95% Ta, about 3.0% Re, about 0.09% C,
about 0.012% B, up to about 0.15% Nb, up to about 0.15% Hf, up to
about 0.003% Zr, and balance Ni and incidental impurities. Such
nickel base superalloy typically exhibits a Pha Comp (N.sub.v)
value of about 2.37.
[0025] Pursuant to another embodiment of the invention, the nickel
base superalloy consists essentially of, in weight %, about 9.5% to
about 14.0% Cr, about 7.0 to about 11.0% Co, about 3.0 to about
5.0% Ti, about 3.0 to about 4.0% Al, about 3.0 to about 4.0% W,
about 1.0 to about 2.5% Mo, about 1.0% to about 4.0% Ta, about 1.0
to about 6.0% Re, up to about 0.25% C, up to about 0.015% B, up to
about 1.0% Nb, up to about 0.15% Hf, up to about 0.003% Zr, and
balance Ni and incidental impurities. A preferred range for the Re
concentration is about 2% to about 4% by weight. Preferably, Nb,
Hf, and Zr each are maintained at respective impurity level
concentrations in the alloy.
[0026] The invention contemplates another nickel base superalloy
having a nominal composition pursuant to a particular embodiment of
the invention consisting essentially of, by weight, about 11.75%
Cr, about 9.0% Co, about 4.0% Ti, about 3.5% Al, about 3.5% W,
about 1.75% Mo, about 2.5% Ta, about 3.0% Re, about 0.09% C, about
0.012% B, up to about 1.0% Nb, up to about 0.15% Hf, up to about
0.003% Zr, and balance Ni and incidental impurities. Such nickel
base superalloy typically exhibits a Pha Comp (N.sub.v) value of
about 2.20.
[0027] The nickel base superalloys pursuant to the invention will
be production-castable from the standpoint that it can be cast into
complex single crystal shapes including solid and/or hollow
components, such as single crystal gas turbine engine airfoils
including blades and vanes. The castings will be generally free
from casting scale that is formed on single crystal castings made
from low carbon single crystal nickel base superalloys.
[0028] Single crystal test bars for mechanical property testing
were cast using a superalloy pursuant to an embodiment of the
invention having the nominal composition, in weight %, 13.3% Cr,
9.1% Co, 4.83% Ti, 3.06% Al, 2.99% W, 1.49% Mo, 2.97% Ta, 2.98% Re,
0.087% C, 0.012% B, 0.0012% Nb, 0.0007% Hf, 0.0001% Zr, and balance
Ni and incidental impurities (designated invention alloy A).
[0029] Additional single crystal test bars for mechanical property
testing were cast using a superalloy pursuant to an embodiment of
the invention having the nominal composition, in weight %, 13.9%
Cr, 9.4% Co, 4.9% Ti, 3.0% Al, 3.85% W, 1.58% Mo, 2.94% Ta, 0.09%
C, 0.012% B, LAP Zr, LAP Nb, LAP Hf, and balance Ni and incidental
impurities wherein LAP is low as possible impurity level
(designated invention alloy B).
[0030] The single crystal test bars were made by casting the
above-described invention alloys A and B at a temperature of alloy
melting point plus 350-400 degrees F. into a shell mold preheated
to 2750-2850 degrees F. The superalloy test bars were solidified as
single crystal test bars using the conventional directional
solidification withdrawal technique and a pigtail crystal selector
in the shell molds. Directional solidification processes for making
single crystal castings are described in U.S. Pat. Nos. 3,700,023;
3,763,926; and 4,190,094. The solidified as-cast test bars of both
invention alloys A and B were subjected to a primary aging heat
treatment at 2050 degrees F. for 2 hours, gas fan cooled at greater
than 75 degrees F./minute to a final aging heat treatment at 1550
degrees F. for 16 hours and then gas fan cooled at greater than 25
degrees F./minute to room temperature for mechanical property
testing.
[0031] Similar single crystal comparison test bars were made from a
known comparison CompSX nickel base superalloy, PWA 1484 nickel
base superalloy, N5 nickel base superalloy, and CMSX-4 nickel base
superalloy also using the conventional directional solidification
withdrawal technique. These nickel base superalloys are in
commercial use in the manufacture of single crystal airfoil
castings for use in gas turbine engines. The CompSX nickel base
superalloy is described in U.S. Pat. No. 6,416,596; the PWA 1484
nickel base superalloy is described in U.S. Pat. No. 4,719,080; the
N5 nickel base superalloy is described in U.S. Pat. No. 6,074,602;
and the CMSX-4 nickel base superalloy is described in U.S. Pat. No.
4,643,782. The CMSX-4 nickel base superalloy limits carbon to a
maximum of 60 ppm by weight. The CompSX nickel base superalloy used
in the mechanical property testing had a nominal composition, in
weight %, 13.9% Cr, 9.4% Co, 4.9% Ti, 3.0% Al, 3.85% W, 1.58% Mo,
2.94% Ta, 0.09% C, 0.012% B, less than 50 ppm by weight Zr, LAP Nb,
LAP Hf, and balance Ni and incidental impurities wherein LAP is low
as possible impurity level. The CompSX test bars were single
crystal cast and heat treated in the same manner as the invention
alloy A and B test bars.
[0032] The test bars were tested at different elevated temperatures
for stress rupture resistance using test procedure ASTM E139 and
tensile tested at room temperature and elevated temperatures for
ultimate tensile strength (UTS), 0.2% yield strength, percent
elongation, and reduction in area using ASTM test procedure ASTM E8
for room temperature tests and ASTM E21 for elevated
temperatures.
[0033] Referring to FIGS. 1 and 2, comparison of the Larson-Miller
parameters for the invention alloy A and B test bars pursuant to
the invention and the comparison CompSX, PWA 1484, N5, and CMSX-4
nickel base superalloys is shown. The Larson-Miller parameter, P,
is used to compare stress rupture characteristics of the nickel
base superalloys shown in FIGS. 1 and 2. The Larson-Miller
parameter is a time-temperature dependent parameter, P=T(.degree.
K.)(20+log t)1000 where T is test temperature and t is time to
rupture, widely used to extraplote stress rupture data as described
in MECHANICAL METALLURGY, section 3-13, pages 483-486, Copyright
1961, 1976 by McGraw-Hill, Inc. FIGS. 1, 2 and 3 reveal that the
invention alloy A pursuant to the invention is an improvement over
the CompSX test bars with either a single crystal or equiaxed grain
structure. FIG. 1 also includes several commercially available
third generation single crystal superalloy data points as a
reference. It is important to point out the data provided on the
superalloy systems including PWA 1484, N5, and CMSX-4, represent a
fully solutioned microstructure obtained by heat treatments that
have been optimized over time to enhance the mechanical properties
of those superalloys.
[0034] FIG. 3 is a bar graph comparing the stress rupture lives for
the invention alloys A and B pursuant to the invention and the
comparison CompSX nickel base superalloy. It is apparent that the
invention alloy A pursuant to the invention exhibited a dramatic
increase in stress rupture life compared to the comparison CompSX
nickel base superalloy under all testing conditions shown in FIG.
3.
[0035] Referring to FIGS. 4, 5, 6, and 7, the tensile testing data
is shown for the invention alloy A pursuant to the invention and
the comparison CompSX, PWA 1484, N5, and CMSX-4 nickel base
superalloys. It is apparent that the invention alloy A pursuant to
the invention is comparable to the comparison nickel base
superalloys in tensile strength (e.g. ultimate tensile strength-UTS
and 0.2% yield stress-0.2% YS), elongation, and reduction of area
over the temperatures tested (e.g. room temperature to 1100.degree.
C.).
[0036] The nickel base superalloys pursuant to the invention
exhibited reduced casting scale and reduced non-metallic inclusions
as a result of the inclusion of the carbon concentrations of 0.087
weight %. For example, the invention alloy A and B investment cast
test bars pursuant to the invention had reduced casting scale and
reduced non-metallic inclusion levels as compared to the CMSX-4
nickel base superalloy and exhibited improved castability from the
standpoint that vacuum investment cast test bars pursuant to the
invention exhibited less exterior scale as compared to vacuum
investment cast test bars of the comparison CMSX-4 nickel base
superalloy.
[0037] Although the invention has been shown and described with
respect to detailed embodiments thereof, it will be understood by
those skilled in the art that various changes in form and detail
thereof may be made without departing from the spirit and scope of
the claimed invention.
* * * * *