U.S. patent application number 09/737901 was filed with the patent office on 2002-10-31 for nickel diffusion braze alloy and method for repair of superalloys.
Invention is credited to Chesnes, Richard Patrick, Xu, Raymond Ruiwen.
Application Number | 20020157737 09/737901 |
Document ID | / |
Family ID | 24965751 |
Filed Date | 2002-10-31 |
United States Patent
Application |
20020157737 |
Kind Code |
A1 |
Chesnes, Richard Patrick ;
et al. |
October 31, 2002 |
NICKEL DIFFUSION BRAZE ALLOY AND METHOD FOR REPAIR OF
SUPERALLOYS
Abstract
A braze alloy powder mixture that includes a low-melt powder
composition and a high-melt powder composition. The low-melt powder
composition is made of one or more low-melt powders and includes
50-70% Ni, 8-20% Cr, 8-15% Ta, 4-10% Co, 2-7% Al, and up to 2.25%
B. The high-melt powder composition is made of one or more
high-melt powders and includes 50-70% Ni, 2-10% Cr, 2-10% Ta, 5-15%
Co, 2-10% Al, 2-10% W, and up to about 3% each of Re, Mo and Hf. Up
to about 1% Ti, W, Mo, Re, Nb, Hf, Pd, Pt, Ir, Ru, C, Si, and/or Zr
may be included in the low-melt powder, while the high-melt powder
may include up to about 1% each of Ti, Nb, C, B, Si, and Zr.
Inventors: |
Chesnes, Richard Patrick;
(Cincinnati, OH) ; Xu, Raymond Ruiwen; (Carmel,
IN) |
Correspondence
Address: |
Timothy N. Thomas
WOODARD EMHARDT NAUGHTON MORIARTY & McNETT
111 Monument Circle, Suite 3700
Indianapolis
IN
48204
US
|
Family ID: |
24965751 |
Appl. No.: |
09/737901 |
Filed: |
December 15, 2000 |
Current U.S.
Class: |
148/528 ;
75/255 |
Current CPC
Class: |
B23K 35/0244 20130101;
C22C 19/056 20130101; C22C 19/058 20130101; B23K 2101/001 20180801;
B23K 1/0018 20130101; B22F 1/0003 20130101; B23K 35/3033 20130101;
B23K 35/304 20130101; C22C 19/057 20130101; C22C 1/0433
20130101 |
Class at
Publication: |
148/528 ;
75/255 |
International
Class: |
C22F 001/10 |
Claims
What is claimed is:
1. A braze alloy powder composition comprising: (a) at least one
low-melt alloy powder, and (b) at least one high-melt alloy powder;
wherein said at least one low-melt alloy powder comprises 50-70%
Ni, 8-20% Cr, 8-15% Ta, 4-10% Co, 2-7% Al, and up to 2.25% B, and
wherein said at least one high-melt alloy powder comprises 50-70%
Ni, 2-10% Cr, 2-10% Ta, 5-15% Co, 2-10% Al, 2-10% W, 2-4% Re, and
up to 3% each of Mo and Hf.
2. A braze alloy powder composition according to claim 1 wherein
said at least one low-melt alloy powder also comprises up to about
1% each of one or more members selected from the group consisting
of: Ti, W, Mo, Re, Nb, Hf, Pd, Pt, Ir, Ru, C, Si, and Zr.
3. A braze alloy powder composition according to claim 1 wherein
said at least one high-melt alloy powder also comprises up to about
1% each of one or more members selected from the group consisting
of: Ti, Nb, C, B, Si, and Zr.
4. A braze alloy powder composition according to claim 1 wherein
said at least one low-melt powder comprises about 57% Ni, about 17%
Cr, about 12% Ta, about 6% Co, about 3.5% Al, and about 1.5% B.
5. A braze alloy powder composition according to claim 1 wherein
said at least one low-melt powder comprises a mixture of three
low-melt alloy powders, including: (a) about 35% of a first
low-melt powder comprising about 74% Ni, about 6% Cr, about 6% Al,
about 12% Co, and about 2% B; (b) about 45% of a second low-melt
powder comprising about 42% Ni, about 31% Cr, about 26% Ta, and
about 1% B; and (c) about 20% of a third low-melt powder comprising
about 6% Ni, about 6% Al, about 8% Co, about 4% W, about 4% Ta,
about 3% Si, about 1% Re, about 1% Nb, and about 1% B.
6. A braze alloy powder composition according to claim 1 wherein
said at least one high-melt powder composition comprises about 58%
Ni, about 7% Cr, about 6% Ta, about 12% Co, about 6% Al, about 3%
Re, about 1.5% Hf, and about 5% W.
7. A braze alloy powder composition according to claim 1 wherein
said composition comprises about 45% of said at least one low-melt
alloy powder and about 55% of said at least one high-melt alloy
powder.
8. A braze alloy powder composition according to claim 1 wherein
said composition comprises about 45% of said at least one low-melt
alloy powder and about 55% of said at least one high-melt alloy
powder, wherein said at least one low-melt alloy powder comprises a
mixture of three low-melt alloy powders, including: (a) about 35%
of a first low-melt powder comprising about 74% Ni, about 6% Cr,
about 6% Al, about 12% Co, and about 2% B; (b) about 45% of a
second low-melt powder comprising about 42% Ni, about 31% Cr, about
26% Ta, and about 1% B; and (c) about 20% of a third low-melt
powder comprising about 65% Ni, about 6% Al, about 8% Co, about 4%
W, about 4% Ta, about 3% Si, about 0.5% to 1.5% each of Re, Nb, Hf,
and B; and wherein about 55% of a high-melt alloy powder comprising
about 59% Ni, about 7% Cr, about 6% Ta, about 12% Co, about 6% Al,
about 3% Re, about 1.5% Hf, and about 5% W.
9. A braze alloy mixture consisting essentially of 50-70% Ni,
10-15% Cr, 8-10% Ta, 8-10% Co, 4-6% Al, 2-4% W, and about 1% each
of Mo, Re, and Hf.
10. A braze alloy mixture consisting essentially of about 58% Ni,
about 11% Cr, about 9% Ta, about 9% Co, about 5% Al, about 3% W,
and about 1% each of Mo, Re, and Hf.
11. A braze alloy mixture according to claim 8 wherein said mixture
also comprises up to about 1% each of one or more members selected
from the group consisting of: Ti, Nb, Pd, Pt, Ir, Ru, C, Si, B, and
Zr.
12. A method of repairing an article made of a nickel-based
superalloy material, said method comprising: (a) providing a braze
alloy powder composition comprising: (i) at least one low-melt
alloy powder, and (ii) at least one high-melt alloy powder; wherein
said at least one low-melt alloy powder comprises 50-70% Ni, 8-20%
Cr, 8-15% Ta, 4-10% Co, 2-7% Al, and up to 2.25% B; and wherein
said at least one high-melt alloy powder comprises 50-70% Ni, 2-10%
Cr, 2-10% Ta, 5-15% Co, 2-10% Al, 2-10% W, and up to 3% each of Mo,
Re, and Hf; (b) brazing a damaged portion of the article with said
braze alloy powder composition, wherein said brazing is done at
temperatures of between about 2150.degree. F. and about
2350.degree. F.
13. The method of claim 12 and further comprising the step of
exposing the brazed article to a stepped diffusion cycle at
temperatures of between about 1900.degree. F. and about
2100.degree. F.
14. The method of claim 12 wherein said providing step comprises
providing a braze alloy powder composition comprising about 45% of
at least one low-melt alloy powder and about 55% of at least one
high-melt alloy powder, wherein said at least one low-melt alloy
powder comprises a mixture of three low-melt alloy powders,
including: (a) about 35% of a first low-melt powder comprising
about 74% Ni, about 6% Cr, about 6% Al, about 12% Co, and about 2%
B; (b) about 45% of a second low-melt powder comprising about 42%
Ni, about 31% Cr, about 26% Ta, and about 1% B; and (c) about 20%
of a third low-melt powder comprising about 64% Ni, about 6% Al,
about 8% Co, about 4% W, about 4% Ta, about 3% Si, about 1% Re,
about 1% Nb, and about 1% B, and about 55% of a high-melt alloy
powder comprising about 58% Ni, about 7% Cr, about 6% Ta, about 12%
Co, about 6% Al, 2-4% Re, 1-2% Hf, and about 5% W.
15. The method of claim 14 and further including the step of
exposing the brazed article to a stepped diffusion cycle as
follows: a. Heat part to 1800-2000.degree. F. and hold for 0.5-4
hours; b. Heat part to 1900-2100.degree. F. and hold for 1-4 hours;
c. Heat part to 1950-2150.degree. F. and hold for 1-4 hours; d.
Heat part to 2000-2200.degree. F. and hold for 6 to 24 hours; and
e. Cool to ambient temperature.
16. The method of claim 15 wherein the heating is preferably
accomplished at a rate such that the first heating step is
performed at a rate of about 20-40.degree. F. per minute, the
second heating step is performed at a rate of about 10-30.degree.
F. per minute, the third heating step is performed at a rate of
about 5-20.degree. F. per minute, the fourth heating step is
performed at a rate of about 5-20.degree. F. per minute.
17. The method of claim 15 wherein said stepped diffusion cycles is
as follows: a. Heat to 1900.degree. F. at 30.degree. F. per minute
and hold for 1 hour; b. Heat to 2000.degree. F. at 20.degree. F.
per minute and hold for 2 hours; c. Heat to 2050.degree. F. at
10.degree. F. per minute and hold for 2 hours; d. Heat to
2100.degree. F. at 10.degree. F. per minute and hold for 8 to 18
hours; e. Cool at a rate effective to avoid thermal distortion.
Description
[0001] The present invention relates generally to compositions and
methods for repairing superalloys, and more particularly to
compositions and methods for the braze repair of nickel- and/or
cobalt-based superalloy parts.
BACKGROUND OF THE INVENTION
[0002] Nickel- and/or cobalt-based superalloys are commonly used by
the aerospace and power industries for components such as turbine
vanes that will be subjected to high temperatures and stress. While
such alloys are inherently strong and resistant to damage, cracks
and ruptures occasionally occur. When the damage is relatively
minor, repairs can be made, such as, for example, by braze
repair.
[0003] High temperature diffusion braze technology is normally used
to repair turbine vanes made of Ni- and Co-based superalloys. The
braze alloy mixture typically includes two powdered constituents.
The first constituent (the base metal powder) is a high temperature
powder with a chemistry the same as, or similar to, the component
being repaired. The second constituent (the braze alloy powder)
consists of a high temperature diffusion braze alloy that has a
melting temperature well below that of the base metal powder. This
braze alloy powder is used to join the base metal powder particles
together, and to join the composite powder mixture to the areas of
the component being repaired.
[0004] Diffusion braze alloy powders typically contain melting
point depressants such as boron and/or silicon of elements.
Unfortunately though, the use of boron and silicon in braze alloys
can have a negative impact on the mechanical and/or environmental
properties of the repaired area of the part. In particular, large,
blocky or script-like brittle phases are formed which decrease the
ability of the material to resist rupture from stress. These
brittle phases are composed of refractory elements, chromium,
and/or titanium combined with boron, silicon and carbon. For the
braze repair of directional solidified (DS) superalloys with
columnar-grained (CG) and single-crystal (SC) microstructure, B and
Si are particularly detrimental to the mechanical properties and
oxidation resistance.
[0005] A need therefore exists for improved braze repair alloy
powders with minimal amounts of B and/or Si, that can be used for
repairing superalloys such as those found in jet engine turbine
vanes. The present invention addresses that need.
SUMMARY OF THE INVENTION
[0006] Briefly describing one aspect of the present invention,
there is provided a braze alloy powder mixture comprising a
low-melt powder composition and a high-melt powder composition. The
low-melt powder composition may be made from a single low-melt
alloy powder, or it may be a mixture of more than one low-melt
alloy powder. In either event, the low-melt powder composition
preferably comprises, by weight, 50-70% Ni, 8-20% Cr, 8-15% Ta,
4-10% Co, 2-7% Al, and up to about 2.25% B. Similarly, the
high-melt powder composition may be made from a single high-melt
alloy powder, or it may be a mixture of more than one high-melt
alloy powder. In either event, the high-melt powder composition
preferably comprises, by weight, 50-70% Ni, 2-10% Cr, 2-10% Ta,
5-15% Co, 2-10% Al, 2-10% W, and up to about 3% each Re, Mo and/or
Hf.
[0007] In the most preferred embodiments the low-melt powder
composition also comprises up to about 1% each of any or all of the
following: Ti, W, Mo, Re, Nb, Hf, Pd, Pt, Ir, Ru, C, Si, and Zr,
and the high-melt powder composition also comprises up to about 1%
each of any or all of the following: Ti, Nb, C, B, Si, and Zr.
[0008] Accordingly, the braze alloy mixture (that is, the
combination of low-melt and high-melt powders) preferably comprises
50-70% Ni, 10-15% Cr, 8-10% Ta, 8-10% Co, 4-7% Al, 2-4% W, about
1-2% Re, and about 0.5-1% each of Mo and Hf. In the most preferred
embodiments the braze alloy mixture also comprises up to about 1%
each of any or all of the following: Ti, Nb, Pd, Pt, Ir, Ru, C, B,
Si, and Zr.
[0009] One object of the present invention is to provide braze
alloy powders useful for the braze repair of Ni- and/or Co-based
superalloys.
[0010] Other objects and advantages will be apparent from the
following description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a graph showing the results of a stress rupture
test performed on an article repaired with the inventive braze
repair alloy powders of one preferred embodiment of the present
invention.
[0012] FIG. 2 is a graph showing the results of a low cycle fatigue
test performed on an article repaired with the inventive braze
repair alloy powders of one preferred embodiment of the present
invention.
[0013] FIG. 3 is a graph showing the specific weight change during
a cyclic furnace oxidation test performed on an article repaired
with the inventive braze repair alloy powders of one preferred
embodiment of the present invention.
[0014] FIG. 4A shows an engine vane segment with fine cracks in the
vane.
[0015] FIGS. 4B and 4C show cracks in an engine vane segment such
as that shown in FIG. 4A, after repair with the inventive braze
repair alloy powders of the present invention.
[0016] FIGS. 5A and 5B show leading and trailing edge sides of a
vane segment prior to (5A) and after (5B) braze repair using the
inventive braze repair alloy powders of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0017] For the purposes of promoting an understanding of the
principles of the invention, reference will now be made to certain
preferred embodiments and specific language will be used to
describe the same. It will nevertheless be understood that no
limitation of the scope of the invention is thereby intended, such
alterations and further modifications in the illustrated device,
and such further applications of the principles of the invention as
illustrated therein being contemplated as would normally occur to
one skilled in the art to which the invention relates.
[0018] As indicated above, one aspect of the present invention
relates to powders useful for the braze repair of superalloy
components such as turbine vanes. In a preferred embodiment one or
more low-melt alloy powders is mixed with one or more high-melt
alloy powders to form a powdered braze alloy mixture that can be
used for the repair.
[0019] Another aspect of the invention relates to methods of
repairing superalloy components by using the subject braze alloy
mixtures at braze temperatures of about 2300.degree. F., followed
by a stepped, diffusion heat treatment cycle at temperatures
ranging from about 1900.degree. F. to about 2100.degree. F.
[0020] 1. Substrates
[0021] The braze repair compositions and methods of the present
invention can be used to repair a wide variety of substrates,
including nickel- or cobalt-based alloy substrates. Specific
examples of alloys that can be repaired with the compositions and
methods of the present invention include, but are not limited to:
nickel-based alloys such as Mar-M246, Mar-M247; single crystal
nickel alloys such as CMSX-3, CMSX-4, and CM-186; and cobalt-based
alloys such as Mar-M509 and X40.
[0022] 2. Braze Alloy Powders, and Mixtures Thereof
[0023] The braze alloy powder mixtures of the present invention
include both a low-melt powder composition and a high-melt powder
composition. The low-melt alloy powder composition is an alloy, or
a mixture of alloys, that substantially melts below the braze
temperature (hence the name "low-melt"). In contrast, the high-melt
alloy powder composition is an alloy, or a mixture of alloys, that
remains substantially unmelted at braze temperatures because the
composition has a melting temperature above the braze temperature
(hence the name "high-melt").
[0024] In the preferred embodiments of braze repair mixtures used
to repair Ni-based superalloys such as MAR-M247 or CMSX-3, the
low-melt powder composition is preferably made from a mixture of
alloys that melt below about 2250.degree. F., with the combination
of alloys being selected so that the low-melt powder composition as
a whole substantially melts in the range of about 2100.degree.
F.+/-100.degree. F. The high-melt alloy powder composition used in
such embodiments is preferably made of a single high-melt alloy
that doesn't melt until it gets above about 2400.degree. F.
[0025] In the most preferred embodiments the low-melt powder
composition accordingly comprises one or more alloy powders and has
a resulting composition of about 50-70% Ni, 8-20% Cr, 8-15% Ta,
4-10% Co, 2-7% Al, and up to about 2.25% B and/or Si, by weight,
and has a compositional melting range of between about 2000.degree.
F. and 2250.degree. F. In certain preferred embodiments the
low-melt powder composition also comprises up to about 1% each of
any or all of the following: Ti, W, Mo, Re, Nb, Hf, Pd, Pt, Ir, Ru,
C, and Zr.
[0026] Most preferably, the alloys used to prepare the low-melt
alloy powders each contain between about 0.65 and about 2.25% B,
with the total amount of B in the low-melt powder composition
preferably being between about 1% and 2%. The low-melt alloy
powders each also preferably contain up to about 3% Si, with the
total amount of Si in the low-melt powder preferably being between
about 0.5% and 1%.
[0027] The high-melt powder composition preferably is an alloy (or
mixture of alloys) with a chemistry that is the same or
substantially the same as the alloy in the substrate to be
repaired. Accordingly, to repair Ni-based superalloy components
such as those made of MAR-M246 or 247, or CMSX-3 or -4, the
high-melt powder composition typically comprises about 50-70% Ni,
2-10% Cr, 2-10% Ta, 5-15% Co, 2-10% Al, 2-10% W, 2-4% Re, and up to
about 3% each of Mo and Hf. In the most preferred embodiments the
high-melt powder composition also comprises up to about 1% each of
any or all of the following: Ti, Nb, C, B, Si, and Zr.
[0028] The low-melt alloy composition and the high-melt alloy
composition are generally combined at ratios of about 1:3 to about
3:1 low-melt:high-melt powder, with ratios of 1:2 to 2:1 being more
preferred. In the most preferred embodiments, the ratio of low-melt
powder to high-melt powder is typically in the range of 1:1 to
1:1.5.
[0029] In testing to date, compositions comprising about 40-50%
low-melt alloy powder, and about 50-60% high-melt powder has been
preferred for repairing Ni-based superalloy parts such as vanes
made of CMSX-3. A ratio of about 45:55 low-melt:high-melt powders
has been most preferred for those Ni-based superalloy repairs.
[0030] In selecting the proportions of components used in the
invention, it should be recognized that higher weight percentages
of high-melt powder typically provide better mechanical properties
in view of their reduced levels of boron and/or silicon. Similarly,
higher percentages of low-melt powders typically have improved
braze flow. As can be appreciated by persons skilled in the art, a
proper balance between mechanical properties and braze flow must be
established, as dictated by the demands of a particular
application.
[0031] Higher Al content is also desired in some embodiments
because Al-rich compositions improve high-temperature oxidation
properties. Further, increasing the Ta content in the mixtures
improves the braze joint mechanical properties. In particular, Ta
additions strengthen the gamma and gamma prime phases by increasing
lattice mismatches.
[0032] In view of the above, it can be seen that the final braze
alloy repair mixture preferably comprises 50-70% Ni, 10-15% Cr,
8-10% Ta, 8-10% Co, 4-7% Al, 2-4% W 1-2% Re, and about 1% each of
Mo and Hf, and most preferably also comprises up to about 1% each
of any or all of the following: Ti, Nb, Pd, Pt, Ir, Ru, C, B, Si,
and Zr.
[0033] As indicated above, in certain preferred embodiments the
low-melt alloy powder comprises a mixture of two or more low-melt
alloys. In one preferred embodiment particularly useful for
repairing Ni-based superalloy parts, the low-melt alloy powder
comprises: (a) about 35% of a first low-melt powder comprising
about 74% Ni, about 6% Cr, about 6% Al, about 12% Co, and about 2%
B, with a liquidus temperature of about 2050.degree. F.; (b) about
45% of a second low-melt powder comprising about 42% Ni, about 31%
Cr, about 26% Ta, and about 1% B, with a liquidus temperature of
about 2250.degree. F.; and (c) about 20% of a third low-melt powder
comprising about 64% Ni, about 6% Al, about 8% Co, about 4% W,
about 4% Ta, about 3% Si, about 1% Re, about 1% Nb, and about 1% B,
with a liquidus temperature of about 2000.degree. F.
[0034] In one preferred embodiment the high-melt powder composition
comprises about 55-60% Ni, about 7% Cr, about 6% Ta, about 12% Co,
about 6% Al, about 3% Re, about 1.5% Hf, and about 5% W.
[0035] Table 1 below shows the compositions, by weight %, of three
potential low-melt alloys (ADB-01, ADB-02, and ADB-03) and one
potential high-melt alloy (HMA-01). In the most preferred
embodiments these alloys are combined such that the low-melt alloy
powder comprises about 35% ADB-01, about 45% ADB-02, and about 20%
ADB-03. One preferred braze repair powder comprises 45% of this
mixture of low-melt powders, and 55% of this preferred high-melt
powder.
[0036] Table 2 below shows other low-melt and high-melt alloy
powders that may be used in the present invention. (It is to be
appreciated that Table 2 is for illustrative purposes, and that not
all low-melt or high-melt powders are shown in Table 2.) Table 3
shows braze repair alloy mixtures of those low-melt and high-melt
alloy powders. (It is also to be appreciated that Table 3 is for
illustrative purposes, and that not all mixtures of low-melt and
high-melt powders are shown in Table 3.)
1TABLE 1 BRZAE ALLOY COMPOSITIONS by weight percent Alloy Ni Cr Al
Ti Co W Mo Re Ta Nb Hf ADB-01 BAL. 5.75-6.25 6.15-6.35 .01 max
11.25-12.25 .01 max .01 max .01 max .01 max .01 max .01 max ADB-02
BAL. 30.8-31.2 .01 max .01 max .05 max .01 max .01 max .01 max
25.8-26.2 .01 max .01 max ADB-03 BAL. 5.9-6.10 6.15-6.35 .01 max
7.72-8.25 3.25-3.75 .01 max 1.00-1.50 4.00-4.50 1.00-1.50 0.40-0.60
HMA-01 BAL. 6.60-7.00 5.94-6.30 0.02 max 11.45-12.05 4.70-5.10
1.30-1.70 2.60-3.00 6.20-6.50 0.10 max 1.30-1.70 Alloy C B Si Pd Pt
Zr Ir Ru Y La ***Ce ADB-01 **.02 max 2.00-2.25 .05 max .01 max .01
max .01 max .01 max .01 max .005 max .005 max .005 max ADB-02 **.02
max .85-1.15 .05 max .01 max .01 max .01 max .01 max .01 max .005
max .005 max .005 max ADB-03 **.02 max 1.20-1.40 2.75-3.25 .005 max
.005 max .005 max .02 max .02 max .005 max .005 max .005 max HMA-01
.10-.14 .01-.02 .06 max .30 max .030 max Alloy Mn O S P Fe V Cu Mg
N ADB-01 .01 max #.0300 max .0010 max .015 max .1 max .1 max .1 max
.01 max .0300 max ADB-02 .01 max #.0300 max .0010 max .015 max .1
max .1 max .1 max .01 max .0300 max ADB-03 .01 max .0100 max .0002
max .015 max .1 max .1 max .1 max .01 max .0300 max HMA-01 .01 max
#.0300 max .0040 max .010 max .1 max .2 max .1 max .0035 max
[0037]
2TABLE 2 BRZAE ALLOY COMPOSITIONS by weight percent ALLOY Ni Cr Al
Ti Co W Mo Re Ta Nb Hf ADB-101 BAL. 6.75-7.25 4.75-5.25 .01 max
10.75-11.26 1.76-2.25 .01 max .01 max 7.75-8.25 .10 max .1 max
ADB-102 BAL. 6.25-6.75 4.75-5.25 .01 max 9.75-10.25 1.0.1.5 .01 max
0.3-05 9.75-10.25 .4-.6 .01 max ADB-103 BAL. 6.25-6.75 4.75-5.25
.01 max 10.75-11.25 1.76-2.25 .01 max .01 max 10.75-11.25 .10 max
.01 max ADB-104 BAL. 6.25-5.75 4.75-5.25 .01 max 11.25-12.25
1.25-1.75 .01 max .01 max 10.75-11.25 .10 max 0.8-1.2 ADB-10B BAL.
6.25-6.75 6.15-6.35 .01 max 11.25-12.25 .01 max .01 max .01 max
6.25-6.50 .10 max .01 max ADB-01 BAL. 5.75-6.25 6.16-6.35 .01 max
11.25-12.25 .01 max .01 max .01 max .01 max .01 max .01 max ADB-108
BAL. .01 max 54.75-55.25 .01 max .05 max .01 max .01 max .01 max
.01 max .01 max .01 max ADB-02 BAL. 30.8-31.2 .01 max. .01 max .06
max .01 max .01 max .01 max 25.8-26.2 .01 max .01 max ADB-110 .05
max .01 max .01 max. .01 max BAL. .01 max .01 max .01 max 29.8-30.2
.01 max .01 max ADB-111 BAL. 6.25-6.75 6.15-6.35 .01 max
11.25-12.25 .01 max .01 max .01 max 6.25-6.50 .01 max .01 max
ADB-03 BAL. 5.0-6.10 6.15-6.35 .01 max 7.75-8.25 3.25-3.75 .01 max
1.00-1.60 4.00-4.50 1.00-1.50 0.40-0.60 ADB-114 BAL. .01 max .01
max .01 max .01 max .01 max .01 max .01 max .01 max .01 max .01 max
RCT-4 BAL. 6 6 4 2 4 2 ALLOY Pd Pt Ir Ru C B Si Zr Y La ***Ce Mn
ADB-101 2.75-3.25 .005 max .01 max .01 max .08-.12 .45-.55 5.0-5.5
.005 max .005 max .005 max .005 max .01 max ADB-102 .25-.75 .25-.75
.01 max .01 max .01 max 1.0-1.25 3.0-3.5 .005 max .005 max .005 max
.005 max .01 max ADB-103 .005 max .005 max .01 max .01 max .01 max
.08-.12 .45-.55 5.5-6.0 .005 max .005 max .005 max .01 max ADB-104
5.75-6.25 .005 max .01 max .01 max .04-.08 1.20-1.50 3.25-3.75 .005
max .005 max .005 max .005 max .01 max ADB-10B .25-.75 .005 max .01
max .01 max **.02 max 2.40-2.60 .05 max .005 max .005 max .005 max
.005 max .01 max ADB-01 .01 max .01 max .01 max .01 max **.02 max
2.00-2.25 .05 max .01 max .005 max .005 max .005 max .01 max
ADB-108 .01 max .01 max .01 max .01 max **.02 max .01 max .05 max
.01 max .005 max .005 max .005 max .01 max ADB-02 .01 max .01 max
.01 max .01 max **.02 max .85-1.15 .05 max .01 max .005 max .005
max .005 max .01 max ADB-110 .01 max .01 max .01 max .01 max **.02
max 1.60-1.80 .05 max .01 max .005 max .006 max .005 max .01 max
ADB-111 .01 max .005 max .01 max .01 max .02-.04 .01 max .05 max
.005 max .005 max .005 max .005 max .01 max ADB-03 .005 max .005
max .01 max .01 max **.02 max 1.20-1.40 2.75-3.25 .005 max .005 max
.005 max .005 max .01 max ADB-114 59.5-60.5 .01 max .01 max .01 max
.02-.04 .01 max .05 max .005 max .01 max RCT-4 0.062 3 0.015 ALLOY
O S P Fe V Cu Mg N ADB-101 .0100 max .0002 max .015 max .1 max .1
max .1 max .01 max .0300 max ADB-102 .0100 max .0002 max .015 max
.1 max .1 max .1 max .01 max .0300 max ADB-103 .0100 max .0002 max
.015 max .1 max .1 max .1 max .01 max .0300 max ADB-104 .0100 max
.0002 max .015 max .1 max .1 max .1 max .01 max .0300 max ADB-100
#.0300 max #.0010 max .015 max .1 max .1 max .1 max .01 max .0300
max ADB-01 #.0300 max #.0010 max .015 max .1 max .1 max .1 max .01
max .0300 max ADB-108 #.0300 max #.0010 max .015 max .1 max .1 max
.1 max .01 max .0300 max ADB-02 #.0300 max #.0010 max .015 max .1
max .1 max .1 max .01 max .0300 max ADB-110 #.0300 max #.0010 max
.015 max .1 max .1 max .1 max .01 max .0300 max ADB-111 #.0300 max
#.0010 max .015 max .1 max .1 max .1 max .01 max .0300 max ADB-03
.0100 max .0002 max .015 max .1 max .1 max .1 max .01 max .0300 max
ADB-114 #.0300 max #.0010 max .015 max .1 max .1 max .1 max .01 max
.0300 max **With no carbon additions
[0038]
3TABLE 3 BRAZE ALLOY MIXTURES AND TEST NOTES Mixture # Alloy
Mixture Comments MM-29 Mar-M247/ADB-03 50/50 Alloy densified.
Bright shiny silver surface. Good wet-out. 100% slot fill. MM-36
Mar-M247/ADB-03/ADB-106 40/30/30 Alloy densified. Bright shiny
silver surface. Good wet-out. 100% slot fill. MM-37
247/ADB-03/AMS4782 40/40/20 Alloy densified. Bright shiny silver
surface. Good wet-out. 100% slot fill. MM-39
Mar-M247/ADB-03/ADB-104 40/30/30 Alloy densified. Bright shiny
silver surface. Good wet-out. 100% slot fill. MM-45
Mar-M247/SXCX-4/ADB-03/ADB-104 20/20/30/30 Alloy densified. Bright
shiny silver surface. Good wet-out. 100% slot fill. MM-47
MAR-M247/ADB-03 40/60 Alloy densified. Bright shiny silver surface.
Good wet-out. 100% slot fill. MM-51 Mar-M247/ADB-03/ADB-114
60/20/20 Less slot fill than MM-50. MM-52 Mar-M247/ADB-03/ADB-114
40/35/25 Alloy densified. Bright shiny silver surface. Excellent
wet-out. 100% slot fill. MM-69 Mar-M247/ADB-02 40/60 Excellent flow
and complete slot fill. MM-70 Mar-M247/ADB-02/ADB-114 50/40/10
Excellent flow and complete slot fill. MM-72 Mar-M247/ADB-02/ADB-03
50/40/10 Excellent flow and complete slot fill. MM-73
Mar-M247/ADB-02/B-28 50/40/10 Excellent flow and complete slot
fill. MM-74 Mar-M247/ADB-02/B-28/ADB-114 50/35/10/5 Excellent flow
and complete slot fill. MM-75 Mar-M247/ADB-02/ADB-03/ADB-114
50/35/10/5 Excellent flow and complete slot fill. MM-106
Mar-M247/ADB-01/ADB-02 50/40/10 Excellent flow and complete slot
fill. MM-122 HMA-01/ADB-01/ADB-02 50/30/20 RX in SX-3 near braze;
Excellent flow and complete slot fill. MM-123 HMA-01/RCT-4/ADB-02
50/30/20 Excellent flow and complete slot fill. MM-124
HMA-01/ADB-01/ADB-02 50/20/30 Excellent flow and complete slot
fill. MM-127 HMA-01/ADB-01/ADB-02 60/20/20 Sluggish flow and
complete slot fill. 5-10% voids in bead MM-128 HMA-01/ADB-01/ADB-02
60/30/10 Excellent flow and complete slot fill. 100% RX in SX-3
interface. MM-129 HMA-01/ADB-01/ADB-02 60/10/30 Excellent flow and
complete slot fill. A lot voids in bead. MM-130
HMA-01/ADB-01/ADB-02 65/25/10 Excellent flow and complete slot
fill. 100% RX in SX-3 interface. MM-131 HMA-01/ADB-01/AOB-02
60/25/15 Excellent flow and complete slot fill. 100% RX in SX-3
interface. MM-133 HMA-01/ADB-01 60/40 Excellent flow and complete
slot fill. MM-135 HMA-01/ADB-01 70/30 Excellent flow and complete
slot fill. MM-136 HMA-01/ADB-01/ADB-02/ADB-03 50/15/20/15 Excellent
flow and complete slot fill. MM-137 HMA-01/ADB-01/ADB-02/ADB-03
55/15/20/10 Excellent flow and complete slot fill. MM-140
HMA-01/ADB-03 60/40 Excellent flow and complete slot fill. MM-141
HMA-01/ADB-106/ADB-03 60/20/20 Excellent flow and complete slot
fill. MM-142 HMA-01/RCT-4/ADB-02 60/20/20 Excellent flow and
complete slot fill. MM-143 HMA-01/RCT-4/ADB-02 60/30/10 Good flow
and complete slot fill. MM-144 HMA-01/RCT-4/ADB-02 60/35/5 Good
flow and complete slot fill. MM-145 HMA-01/RCT-12/ADB-110 60/30/10
Excellent flow and complete slot fill.
[0039] 3. Methods of Use
[0040] The following steps are typical for the braze repair
processes of the present invention. It is to be appreciated that
certain steps may be adjusted, or even omitted, depending on the
nature of the component being repaired.
[0041] The first steps normally involve the inspection and cleaning
of the component. Initially, chemical and mechanical cleaning
processes are generally used to remove dirt, debris, grease, oils,
and loose scale from the component. Following that, chemical
stripping may be required to remove any coatings that may be
present. Then, fluoride ion cleaning (FIC) may need to be used to
remove complex oxides from the surface and from inside cracks.
Finally, high-temperature vacuum cleaning may be required to remove
residual oxides and fluoride ions from the FIC process. All of
these methods are generally known to the art, and can be
incorporated into the inventive process on an "as needed" basis
without undue experimentation.
[0042] Following cleaning, the high temperature braze repair is
begun. In that process, the braze repair alloy powder is made into
a slurry (preferably using a binder effective to hold the powders
together and to help hold the powders on the surface being
repaired) and is applied to the surface. The component is then
heated in a vacuum or in an inert gas to a temperature effective to
melt the low-melt alloy so that the braze material fills the crack
being repaired. In the preferred embodiments the braze temperature
is between 2150.degree. F. and 2350.degree. F., with braze
temperatures of about 2300.degree. F. being most preferred. The
braze time may vary from about 10 minutes to about 40 minutes, with
braze times of about 20 to 30 minutes being most commonly used.
[0043] Following the brazing itself, the component is subjected to
a diffusion heat treatment cycle to homogenize the repaired region.
The diffusion heat treatment is preferably performed at
temperatures 0-400.degree. F. below the braze temperature, and for
times of up to about 24 hours. A vacuum or inert atmosphere is
preferably used for the diffusion heat treatment.
[0044] In certain preferred embodiments the heat diffusion cycle is
performed for a time and at temperatures effective to break down
the script-like silicide phases into fine discrete particles. The
cycle also preferably is performed for a time and at temperatures
effective to reduce the size and quantity of brittle boride
phases.
[0045] In one preferred embodiment the diffusion cycle is a stepped
heat cycle, as follows:
[0046] a. Heat part to 1800-2000.degree. F. and hold for 0.5-4
hours;
[0047] b. Heat part to 1900-2100.degree. F. and hold for 1-4
hours;
[0048] C. Heat part to 1950-2150.degree. F. and hold for 1-4
hours;
[0049] d. Heat part to 2000-2200.degree. F. and hold for 6 to 24
hours; and
[0050] e. Cool to ambient temperature.
[0051] The heating is preferably accomplished at a rate such that
the first heating step is performed at a rate of about
20-40.degree. F. per minute, the second heating step is performed
at a rate of about 10-30.degree. F. per minute, the third heating
step is performed at a rate of about 5-20.degree. F. per minute,
the fourth heating step is performed at a rate of about
5-20.degree. F. per minute.
[0052] In the most preferred embodiment the diffusion cycle is a
stepped heat cycle, as follows:
[0053] a. Heat part to about 1900.degree. F. at about 30.degree. F.
per minute and hold for 1 hour;
[0054] b. Heat part to about 2000.degree. F. at about 20.degree. F.
per minute and hold for 2 hours;
[0055] c. Heat part to about 2050.degree. F. at about 10.degree. F.
per minute and hold for 2 hours;
[0056] d. Heat part to about 2100.degree. F. at about 10.degree. F.
per minute and hold for 8 to 18 hours;
[0057] e. Vacuum or inert gas furnace cool to about 1200.degree. F.
at a rate which is slow enough to avoid thermal distortion; and
[0058] f. Inert gas fan cool to about 150.degree. F. or less.
[0059] Reference will now be made to specific examples using the
processes described above. It is to be understood that the examples
are provided to more completely describe preferred embodiments, and
that no limitation to the scope of the invention is intended
thereby.
EXAMPLE 1
Braze Alloy Repair
[0060] A braze repair alloy mixture is prepared by combining: (a)
about 15% of a first low-melt alloy powder comprising 5.75-6.25%
Cr, 6.15-6.35% Al, 11.25-12.25% Co, 2-2.25% B, and the balance Ni
(with only trace amounts (i.e., less than 0.1%) of other components
and/or impurities); (b) about 20% of a second low-melt alloy powder
comprising 30.8-31.2% Cr, 25.8-26.2% Ta, 0.85-1.15% B, and the
balance Ni (with only trace amounts (i.e., less than 0.1%) of other
components and/or impurities); (c) about 10% of a third alloy
powder comprising 5.9% Cr, 6.15-6.35% Al, 7.75-8.25% Co, 3.25-3.75%
W, 1-1.5% Re, 4-4.5% Ta, 1-1.5% Nb, 0.4-0.6% Hf, 1.2-1.4% B,
2.75-3.25% Si, and the balance Ni (with only trace amounts (i.e.,
less than 0.1%) of other components and/or impurities); and (d)
about 55% of a high-melt powder comprising 6.6-7% Cr, 5.9-6% Al,
11.4-12.1% Co, 4.7-5.1% W, 1.3-1.7% Mo, 2.6-3% Re, 6.2-6.5% Ta,
1.3-1.7% Hf, and the balance Ni (with only trace amounts (i.e.,
less than 0.1%) of other components and/or impurities).
[0061] The braze repair alloy powder is made into a slurry using a
commercially available binder, and is then applied to a clean
surface of a Ni-based superalloy material and the component is
heated in a vacuum to a braze temperatures of about 2300.degree. F.
for about 20 minutes.
[0062] Following brazing, a stepped diffusion heat cycle is used,
as follows:
[0063] a. Heat to 1900.degree. F. at 30.degree. F. per minute and
hold for 1 hour.
[0064] b. Heat to 2000.degree. F. at 20.degree. F. per minute and
hold for 2 hours.
[0065] c. Heat to 2050.degree. F. at 10.degree. F. per minute and
hold for 2 hours.
[0066] d. Heat to 2100.degree. F. at 10.degree. F. per minute and
hold for 8 to 18 hours.
[0067] e. Cool to 1200.degree. F. at a rate effective to avoid
thermal distortion, and hold for at least 5 minutes.
[0068] f. Cool to 150.degree. F. or less.
EXAMPLE 2
Stress Rupture Testing
[0069] Stress rupture (S/R) tests were performed on representative
base metals, and on articles repaired using a preferred embodiment
of the inventive powder mixture and repair process. In one aspect
of the test, base metal materials such as MAR-M247 and CMSX-3 were
subjected to heat treatments corresponding to the steps used in the
present invention (e.g., heating to braze temperature, followed by
a typical stepped heat diffusion cycle) to test the effect of the
inventive method on the base materials themselves. The test
conditions for the base metal tests were 1800.degree. F. and 36
Ksi.
[0070] In another aspect of the S/R test, repaired parts were
tested to determine the mechanical properties of parts repaired by
the inventive process. The test conditions for repaired parts were
2000.degree. F. and 5 Ksi for parts in which a 0.005-inch gap was
repaired, and 2000.degree. F. and 3 Ksi for parts in which a
0.040-inch gap was repaired.
[0071] The test results indicate that the braze repair process of
the present invention does not cause any significant negative
impact on the mechanical properties of the base metal, such as
CMSX-3. Moreover, the repaired parts exhibited mechanical
properties comparable to unrepaired superalloys such as
MAR-M247.
[0072] For example, the average time to stress rupture for repaired
parts that had a 0.005" gap (test at 2000.degree. F. and 5 Ksi) was
46.98 hours for uncoated parts and 186.48 hours for parts coated
with standard Pt/Al coatings. The time to rupture for coated
0.04"-gap parts was 153.34 hours (test at 2000.degree. F. and 3
Ksi). This compares favorably to the performance of undamaged parts
made from MAR-M247, whether uncoated or coated with standard Pt/Al
coatings.
[0073] FIG. 1 shows the results of S/R testing. As can be seen from
the graph, the mechanical performance of parts repaired by the
compositions and methods of the present invention compares
favorably with the mechanical performance of undamaged MAR-M247
parts.
EXAMPLE 3
Low Cycle Fatigue Testing
[0074] Low cycle fatigue (LCF) tests were performed on
representative base metals, and on articles repaired using a
preferred embodiment of the inventive powder mixture and repair
process. For the low cycle fatigue (LCF) tests, the test conditions
were 1900.degree. F., R=0,0.53% strain, and a frequency of 20 CPM
for.
[0075] FIG. 2 shows the results of the LCF testing. As can be seen
from the graph, the mechanical performance of parts repaired by the
compositions and methods of the present invention compares
favorably with the mechanical performance of undamaged MAR-M247
parts.
EXAMPLE 4
Cyclic Oxidation Testing
[0076] Cyclic oxidation tests were also performed on the brazed
specimens using a cyclic oxidation test cycle of 2075.degree. F.
for 50 minutes and fan cool at room temperature for 10 minutes. The
specimens consisted of base material and brazed samples, both with
compatible PtAl coatings.
[0077] The inventive braze alloy mixtures performed much better
than prior art braze mixtures during the tests. The most preferred
embodiments achieved a more than 10-fold improvement of oxidation
properties over diffusion braze alloy systems due to the lower
percentage of boron and the higher percentage of aluminum.
[0078] FIG. 3 shows the specific weight change during cyclic
furnace oxidation test at 2075.degree. F. for 500 cycles. (Five
hundred cycles was selected to as a reasonable approximation of
target engine flight life.) Sample weight changes were in weight
gain or weight positive gain but decreasing weight. The samples
gain weight due to the formation of protective oxides, which are
primarily aluminum oxides. Some oxide spelling-off could result in
reduction in weight. But protective layers still remain on the
surface and Al can diffuse from the braze mixture to the surface to
form new protective oxide. Negative weight gain is not desirable,
and almost never occurred in the 500 cycle tests.
[0079] As shown by the above, it is to be appreciated that the
microstructure of joints brazed with the technology of the present
invention contains very few, if any, phases that would be
detrimental to the joint mechanical and oxidation properties. The
inventive mixtures also possess acceptable level of braze voids
after brazing process.
[0080] While the invention has been illustrated and described in
detail in the drawings and foregoing description, the same is to be
considered as illustrative and not restrictive in character, it
being understood that only the preferred embodiment has been shown
and described and that all changes and modifications that come
within the spirit of the invention are desired to be protected.
* * * * *