U.S. patent application number 12/227447 was filed with the patent office on 2009-09-17 for method of repairing a component, and a component.
This patent application is currently assigned to SIEMENS AKTIENGESELLSCHAFT. Invention is credited to Fathi Ahmad, Michael Dankert.
Application Number | 20090229101 12/227447 |
Document ID | / |
Family ID | 36972870 |
Filed Date | 2009-09-17 |
United States Patent
Application |
20090229101 |
Kind Code |
A1 |
Ahmad; Fathi ; et
al. |
September 17, 2009 |
Method of Repairing a Component, and a Component
Abstract
A method for the crack repair of a component having a crack on a
surface, including excavating a hollow around the crack, wherein
the hollow has two recesses and the recesses are arranged at the
height of the surface and are open at the height of the surface,
and wherein the recesses are arranged around the circumference of
the hollow and further including filling the hollow with a braze. A
component having a crack on a surface is also provided with a
hollow which is excavated around the crack, the hollow has two
recesses and the recesses are arranged at the height of the surface
and are open at the height of the surface, and the recesses are
arranged around the circumference of the hollow, wherein the hollow
is filled with the braze.
Inventors: |
Ahmad; Fathi; (Kaarst,
DE) ; Dankert; Michael; (Offenbach, DE) |
Correspondence
Address: |
SIEMENS CORPORATION;INTELLECTUAL PROPERTY DEPARTMENT
170 WOOD AVENUE SOUTH
ISELIN
NJ
08830
US
|
Assignee: |
SIEMENS AKTIENGESELLSCHAFT
Munchen
DE
|
Family ID: |
36972870 |
Appl. No.: |
12/227447 |
Filed: |
February 15, 2007 |
PCT Filed: |
February 15, 2007 |
PCT NO: |
PCT/EP2007/051475 |
371 Date: |
November 18, 2008 |
Current U.S.
Class: |
29/402.18 |
Current CPC
Class: |
B23P 6/045 20130101;
F05D 2230/237 20130101; Y02T 50/60 20130101; F05D 2230/238
20130101; B23K 2101/001 20180801; B23P 6/005 20130101; Y10T
29/49746 20150115; F05D 2230/80 20130101; F01D 5/005 20130101; B23K
1/0018 20130101 |
Class at
Publication: |
29/402.18 |
International
Class: |
B22D 19/10 20060101
B22D019/10 |
Foreign Application Data
Date |
Code |
Application Number |
May 18, 2006 |
EP |
06010253.0 |
Claims
1.-13. (canceled)
14. A method for the crack repair of a component having a crack on
a surface, comprising: excavating a hollow around the crack, the
hollow has two recesses and the recesses are arranged at a height
of the surface and are open at the height of the surface, and the
recesses are arranged around the circumference of the hollow; and
filling the hollow with a braze.
15. The method as claimed in claim 14, wherein the recesses are
arranged in pairs on opposite sides of the hollow.
16. The method as claimed in claim 14, wherein the hollow is
cuboid.
17. The method as claimed in claim 15, wherein the hollow is
cuboid.
18. The method as claimed in claim 14, wherein the hollow has a
longitudinal direction parallel to the crack direction of the
crack
19. The method as claimed in claim 14, wherein the recesses extend
transversely to a crack direction of the crack or a longitudinal
direction of the hollow and accordingly the hollow has a width at
the height of the surface greater than a width of the hollow
without a recess.
20. The method as claimed in claim 19, wherein the recesses extend
perpendicularly to a crack direction of the crack or a longitudinal
direction of the hollow.
21. The method as claimed in claim 14, wherein the recesses form a
cuboid.
22. The method as claimed in claim 14, further comprising:
arranging rods on the component, wherein the recesses are in such a
shape that the rods are arranged in the vicinity of the surface of
the component, but do not protrude beyond the surface of the
component.
23. The method as claimed in claim 21, further comprising:
arranging rods on the component, wherein the recesses are in such a
shape that the rods are arranged in the vicinity of the surface of
the component, but do not protrude beyond the surface of the
component.
24. The method as claimed in claim 14, further comprising:
arranging rods in the recesses of the hollow; and filling the
hollow with a filler material, wherein the melting temperature of
the rods is higher than the melting temperature of the filler
material.
25. The method as claimed in claim 24, wherein the hollow is filled
with a braze.
26. The method as claimed in claim 22, wherein the rods are made of
ceramic.
27. The method as claimed in claim 24, wherein the rods are made of
ceramic.
28. The method as claimed in claim 14, further comprising:
fastening a coupon into the hollow, wherein the coupon has a shape
of the hollow with recesses.
29. The method as claimed in claim 28, wherein the coupon is brazed
in the hollow.
30. A component, comprising: a crack on a surface; a hollow which
is excavated around the crack, the hollow has two recesses and the
recesses are arranged at the height of the surface and are open at
the height of the surface, and the recesses are arranged around the
circumference of the hollow; and a braze, wherein the hollow is
filled with the braze.
31. The component as claimed in claim 30, wherein the recesses are
arranged in pairs on opposite sides of the hollow.
32. The component as claimed in claim 30, wherein the hollow is
cuboid.
33. The component as claimed in claim 30, wherein rods are arranged
on the component, wherein the recesses are in such a shape that the
rods are arranged in the vicinity of the surface of the component,
but do not protrude beyond the surface of the component.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is the US National Stage of International
Application No. PCT/EP2007/051475 filed Feb. 15, 2007, and claims
the benefit thereof. The International Application claims the
benefits of European application No. 06010253.0 EP filed May 18,
2006. Both applications are incorporated by reference herein in
their entirety.
FIELD OF INVENTION
[0002] The invention relates to a method for repairing a component
and to a component.
BACKGROUND OF INVENTION
[0003] Newly produced components, for example cast components, or
components after use, often have cracks which are repaired so that
the component can be used again.
[0004] According to the prior art, material is excavated around the
crack and it is filled with a braze or closed by welding.
[0005] So-called coupon brazing is also known from EP 0 868 253
B1.
[0006] The methods mentioned above, however, often cannot
sufficiently prevent crack growth during reuse of the
component.
SUMMARY OF INVENTION
[0007] It is therefore an object of the invention to overcome the
problem mentioned above.
[0008] The object is achieved by a method and a component as
claimed in the independent claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The invention will be explained in more detail with the aid
of the figures.
[0010] The dependent claims list other advantageous measures, which
may advantageously be combined with one another in any desired
way.
[0011] FIG. 1 shows a component surface with a crack,
[0012] FIG. 2 shows a sectional representation of FIG. 1 along the
line II-II,
[0013] FIG. 3 shows a sectional representation of a hollow,
[0014] FIG. 4 shows a surface of a component with a hollow,
[0015] FIG. 5 shows the negative of the excavated crack surface
(hollow),
[0016] FIG. 6 shows the use of rods in the further repair of the
component,
[0017] FIG. 7 shows sectional representation of FIG. 6 along the
line VII-VII,
[0018] FIGS. 8, 9, 10, 11 show other exemplary embodiments of the
invention,
[0019] FIGS. 12, 13 show another possibility for arranging rods in
the hollow,
[0020] FIG. 14 shows a gas turbine,
[0021] FIG. 15 shows a turbine blade in perspective and
[0022] FIG. 16 shows a combustion chamber in perspective.
DETAILED DESCRIPTION OF INVENTION
[0023] FIG. 1 shows a surface 4 of a component 1, which has a crack
7 with a length 1 along a crack direction 8. The crack 7 may also
extend in a curve, although in this case it also has an (averaged)
direction 8.
[0024] The component 1 is preferably a turbine blade 120, 130 (FIG.
14) or a combustion chamber element 155 (FIG. 15) of a turbine, for
example an aircraft turbine, preferably a gas turbine 100 (FIG.
13).
[0025] Particularly in the case of turbine components, a substrate
10 of the component 1 consists of a nickel- or cobalt-based
superalloy.
[0026] The method of crack repair is not however restricted to such
components, rather it also encompasses all components having
cracks, cavities, indentations which are repaired by means of
brazing or welding, and also those which consist of other
materials.
[0027] FIG. 2 shows a sectional representation of FIG. 1, from
which it may be seen that the crack 7 has a crack depth a in the
substrate 10 of the component 1, which has a thickness or wall
thickness t (a<<t).
[0028] The crack 7 according to FIGS. 1, 2 is excavated as in the
prior art, so as to create a hollow 11 which according to the prior
art comprises an indentation which is rectangular (FIGS. 3, 4, 5)
or triangular (FIGS. 8, 9) in cross section. Other cross-sectional
shapes may be envisaged. The hollow 11 is preferably of cuboid
shape.
[0029] However, the hollow 11 additionally comprises at least three
recesses 13, 13', 16, 16', 19, 19'.
[0030] FIG. 4 shows a plan view of such a hollow 11.
[0031] The recesses 13, 13', . . . may be arranged arbitrarily
along the direction 8 around the circumference of the hollow 11.
The recesses 13, 13', . . . are preferably arranged lying directly
opposite in pairs (FIGS. 4, 5, 6, 9, 10).
[0032] The distances between the recesses 13, 13', 16, 16'', . . .
, and in particular also from the start or end 17 of the hollow 11,
are preferably equidistant (FIGS. 5, 6). In the exemplary
embodiment according to FIG. 4, the recesses 13, 13' are present at
the end 17 of the hollow 11.
[0033] FIG. 5 represents the negative of the excavated inner
surface of the hollow 11 with recesses 13, 13', . . .
[0034] Here the recesses 13, 13' are not arranged at the end 17 of
the hollow 11, rather they lie at a distance from the end 17 of the
hollow 11 along the direction 8.
[0035] The excavated hollow 11 has a height a', which is equal or
essentially corresponds to the crack depth a according to FIG. 3
(a.ltoreq.a'). The hollow 11 has a length l' along the crack
direction 8, which is equal or essentially corresponds to the
length l of the crack 7 (FIG. 1) (l.ltoreq.l').
[0036] Furthermore, the hollow 11 (without recesses) has a width b
which is wide enough so that the crack 7 and attacked surfaces on
the crack surface have been removed.
[0037] The recesses 13, 16, 19, which preferably have recesses 13',
16', 19' lying opposite, in particular perpendicularly to the crack
direction 8, substantially represent cuboids transversely to the
direction 8 (see dashed indication) which have a length b+greater
than the width b of the hollow 11.
[0038] The recesses 13, 13', . . . are for example of cuboid (or
cubic) shape here and have a length f along the direction 8, a
depth g in the direction of the depth a' and a width e in the
direction of the width b. The width e of the recess is preferably
much less than the width b of the hollow 11, the length f is much
less than the length l' of the hollow 11 and the depth g is
preferably much less than the depth a' of the hollow 11.
[0039] In FIG. 5, the recesses 13, 13', . . . are of cubic or
cuboid shape. The recesses 13, 13', . . . may likewise have other
shapes (round or triangular in cross section).
[0040] After the crack has been excavated according to FIG. 5, rods
22', 22'', 22''' are placed into the recesses 13, 13', . . . (FIG.
6), the melting temperature of these rods being higher than the
melting temperature of the filler material, which constitutes in
particular a braze 25, with which the hollow 11 to be filled is
then also filled (FIG. 7). The hollow 11 may also be closed by
welding.
[0041] The recesses 13, 13' are preferably configured so that the
rods 22', 22'', 22''' can be put into them from above, i.e. the
recesses 13, 13', . . . are open at the height of the surface 4,
and they do not protrude from the hollow 11 beyond the surface 4.
The depth g of the recesses 13, 13', . . . is preferably configured
here (FIG. 5) so that the rod 22', 22'', 22''' is arranged close to
the surface 4 of the component 1.
[0042] The rods 22', 22'' are preferably arranged in a plane, i.e.
at one height. The height of the rods 22', 22'' between one
another, i.e. the depth g of the respective recesses 13, 13', . . .
, may also be selected arbitrarily so that there is a larger
distance from the surface 4.
[0043] The material of the rods 22', 22'', 22''' preferably
consists of a ceramic material.
[0044] The effect of the rods is that a crack, which is often
formed on the surface 4 and propagates through the braze, meets the
ceramic rods 22', 22'', 22''' where it is prevented from growing
further in them owing to the greater toughness of the rods 22',
22'', 22'''.
[0045] The recesses 13, 13', 16, 16', 19, 19' may likewise extend
over the entire height a' of the hollow 11, as is represented in
FIG. 10. Plates instead of rods are then preferably inserted into
these recesses 13, 13', . . . , the plates extending over the
entire width b+. The plates may have the height a', although they
may also be of smaller size.
[0046] Instead of plates, fine- or coarse-latticed meshes may also
be inserted so that the filler material or the braze can enclose
the mesh during the brazing and the mesh acts as crack prevention
over the entire depth of the hollow 11.
[0047] Fiber bundles may also be inserted into the hollow 11
instead of the rods 22', 22'', 22''', and fiber mats may also be
inserted instead of the plates.
[0048] A coupon may also be brazed or welded into the hollow 11,
the coupon having a shape according to FIG. 5 while having smaller
dimensions than the hollow 11, so that it can be fitted into
it.
[0049] FIG. 11 shows another exemplary embodiment of an arrangement
of the rods 22', 22'', 22''' in the hollow 11.
[0050] The rods 22', 22'', . . . do not extend perpendicularly to
the crack direction 8 or to the longitudinal direction of the
hollow 11 here, rather they are arranged obliquely. The rods 22'',
22''' may likewise cross over, i.e. either they are arranged at
different heights in the hollow 11 or a cross in the form of an "X"
is placed into the recesses 16, 16', 19, 19', in which case the
rods 22'', 22''' may form one part.
[0051] Further arrangement possibilities for the rods 22', 22''
with respect to one another, or the combination of rods and fiber
mats (FIG. 10), may be envisaged.
[0052] Instead of the recesses, which adjoin the surface 4 of the
component 1, there may also be recesses 13, 13', . . . below the
surface 4 on the inner surfaces of the hollow 11. The rods 22, . .
. must then be flexible enough to be bent (FIG. 12) so that they
can be inserted into the hollow 11, in which case the rods must
have a length >b so that their two ends rest in the indentations
13, 13' (FIG. 13).
[0053] FIG. 14 shows a gas turbine 100 by way of example in a
partial longitudinal section.
[0054] The gas turbine 100 internally comprises a rotor 103, which
will also be referred to as the turbine rotor, mounted so as to
rotate about a rotation axis 102 and having a shaft 101.
[0055] Successively along the rotor 103, there are an intake
manifold 104, a compressor 105, an e.g. toroidal combustion chamber
110, in particular a ring combustion chamber, having a plurality of
burners 107 arranged coaxially, a turbine 108 and the exhaust
manifold 109. The ring combustion chamber 110 communicates with an
e.g. annular hot gas channel 111. There, for example, four
successively connected turbine stages 112 form the turbine 108.
Each turbine stage 112 is formed for example by two blade rings. As
seen in the flow direction of a working medium 113, a guide vane
row 115 is followed in the hot gas channel 111 by a row 125 formed
by rotor blades 120.
[0056] The guide vanes 130 are fastened on an inner housing 138 of
a stator 143 while the rotor blades 120 of a row 125 are fitted on
the rotor 103, for example by means of a turbine disk 133. Coupled
to the rotor 103, there is a generator or a work engine (not
shown).
[0057] During operation of the gas turbine 100, air 135 is taken in
and compressed by the compressor 105 through the intake manifold
104. The compressed air provided at the end of the compressor 105
on the turbine side is delivered to the burners 107 and mixed there
with a fuel. The mixture is then burnt to form the working medium
113 in the combustion chamber 110. From there, the working medium
113 flows along the hot gas channel 111 past the guide vanes 130
and the rotor blades 120. At the rotor blades 120, the working
medium 113 expands by imparting momentum, so that the rotor blades
120 drive the rotor 103 and the work engine coupled to it.
[0058] During operation of the gas turbine 100, the components
exposed to the hot working medium 113 experience thermal loads.
Apart from the heat shield elements lining the ring combustion
chamber 110, the guide vanes 130 and rotor blades 120 of the first
turbine stage 112, as seen in the flow direction of the working
medium 113, are heated the most.
[0059] In order to withstand the temperatures prevailing there,
they may be cooled by means of a coolant. Substrates of the
components may likewise comprise a directional structure, i.e. they
are monocrystalline (SX structure) or comprise only longitudinally
directed grains (DS structure). Iron-, nickel- or cobalt-based
superalloys used as material for the components, in particular for
the turbine blades 120, 130 and components of the combustion
chamber 110. Such superalloys are known for example from EP 1 204
776 B1, EP 1 306 454, EP 1 319 729 A1, WO 99/67435 or WO 00/44949;
with respect to the chemical composition of the alloys, these
documents are part of the disclosure.
[0060] The guide vane 130 comprises a guide vane root (not shown
here) facing the inner housing 138 of the turbine 108, and a guide
vane head lying opposite the guide vane root. The guide vane head
faces the rotor 103 and is fixed on a fastening ring 140 of the
stator 143.
[0061] FIG. 15 shows a perspective view of a rotor blade 120 or
guide vane 130 of a turbomachine, which extends along a
longitudinal axis 121.
[0062] The turbomachine may be a gas turbine of an aircraft or of a
power plant for electricity generation, a steam turbine or a
compressor.
[0063] The blade 120, 130 comprises, successively along the
longitudinal axis 121, a fastening region 400, a blade platform 403
adjacent thereto as well as a blade surface 406 and a blade tip
415. As a guide vane 130, the vane 130 may have a further platform
(not shown) at its vane tip 415.
[0064] A blade root 183 which is used to fasten the rotor blades
120, 130 on a shaft or a disk (not shown) is formed in the
fastening region 400. The blade root 183 is configured, for
example, as a hammerhead. Other configurations as a fir-tree or
dovetail root are possible. The blade 120, 130 comprises a leading
edge 409 and a trailing edge 412 for a medium which flows past the
blade surface 406.
[0065] In conventional blades 120, 130, for example solid metallic
materials, in particular superalloys, are used in all regions 400,
403, 406 of the blade 120, 130. Such superalloys are known for
example from EP 1 204 776 B1, EP 1 306 454, EP 1 319 729 A1, WO
99/67435 or WO 00/44949; with respect to the chemical composition
of the alloy, these documents are part of the disclosure. The
blades 120, 130 may in this case be manufactured by a casting
method, also by means of directional solidification, by a forging
method, by a machining method or combinations thereof.
[0066] Workpieces with a monocrystalline structure or structures
are used as components for machines which during operation are
exposed to heavy mechanical, thermal and/or chemical loads. Such
monocrystalline workpieces are manufactured, for example, by
directional solidification from the melts. These are casting
methods in which the liquid metal alloy is solidified to form a
monocrystalline structure, i.e. to form the monocrystalline
workpiece, or is directionally solidified. Dendritic crystals are
in this case aligned along the heat flux and form either a rod
crystalline grain structure (columnar, i.e. grains which extend
over the entire length of the workpiece and in this case, according
to general terminology usage, are referred to as directionally
solidified) or a monocrystalline structure, i.e. the entire
workpiece consists of a single crystal. It is necessary to avoid
the transition to globulitic (polycrystalline) solidification in
these methods, since nondirectional growth will necessarily form
transverse and longitudinal grain boundaries which negate the
beneficial properties of the directionally solidified or
monocrystalline component. When directionally solidified structures
are referred to in general, this is intended to mean both single
crystals which have no grain boundaries or at most small-angle
grain boundaries, and also rod crystal structures which, although
they do have grain boundaries extending in the longitudinal
direction, do not have any transverse grain boundaries. These
latter crystalline structures are also referred to as directionally
solidified structures. Such methods are known from U.S. Pat. No.
6,024,792 and EP 0 892 090 A1; with respect to the solidification
method, these documents are part of the disclosure.
[0067] The blades 120, 130 may likewise have coatings against
corrosion or oxidation, for example (MCrAlX; M is at least one
element from the group iron (Fe), cobalt (Co), nickel (Ni), X is an
active element and stands for yttrium (Y) and/or silicon and/or at
least one rare earth element, or hafnium (Hf)). Such alloys are
known from EP 0 486 489 B1, EP 0 786 017 B1, EP 0 412 397 B1 or EP
1 306 454 A1 which, with respect to the chemical composition of the
alloy, are intended to be part of this disclosure. The density may
preferably be 95% of the theoretical density. A protective aluminum
oxide layer (TGO=thermal grown oxide layer) is formed on the MCrAlX
layer (as an interlayer or as the outermost layer).
[0068] On the MCrAlX, there may furthermore be a thermal barrier
layer, which is preferably the outermost layer and consists for
example of ZrO.sub.2, Y.sub.2O.sub.3--ZrO.sub.2, i.e. it is not
stabilized or is partially or fully stabilized by yttrium oxide
and/or calcium oxide and/or magnesium oxide. The thermal barrier
layer covers the entire MCrAlX layer. Rod-shaped grains are
produced in the thermal barrier layer by suitable coating methods,
for example electron beam deposition (EB-PVD). Other coating
methods may be envisaged, for example atmospheric plasma spraying
(APS), LPPS, VPS or CVD. The thermal barrier layer may comprise
porous, micro- or macro-cracked grains for better thermal shock
resistance. The thermal barrier layer is thus preferably more
porous than the MCrAlX layer.
[0069] The blade 120, 130 may be designed to be hollow or solid. If
the blade 120, 130 is intended to be cooled, it will be hollow and
optionally also comprise film cooling holes 418 (indicated by
dashes).
[0070] FIG. 16 shows a combustion chamber 110 of a gas turbine 100.
The combustion chamber 110 is designed for example as a so-called
ring combustion chamber in which a multiplicity of burners 107,
which produce flames 156 and are arranged in the circumferential
direction around a rotation axis 102, open into a common combustion
chamber space 154. To this end, the combustion chamber 110 as a
whole is designed as an annular structure which is positioned
around the rotation axis 102.
[0071] In order to achieve a comparatively high efficiency, the
combustion chamber 110 is designed for a relatively high
temperature of the working medium M, i.e. about 1000.degree. C. to
1600.degree. C. In order to permit a comparatively long operating
time even under these operating parameters which are unfavorable
for the materials, the combustion chamber wall 153 is provided with
an inner lining formed by heat shield elements 155 on its side
facing the working medium M.
[0072] Owing to the high temperatures inside the combustion chamber
110, a cooling system may also be provided for the heat shield
elements 155 or for their retaining elements. The heat shield
elements 155 are then hollow, for example, and optionally also have
film cooling holes (not shown) opening into the combustion chamber
space 154.
[0073] Each heat shield element 155 made of an alloy is equipped
with a particularly heat-resistant protective layer (MCrAlX layer
and/or ceramic coating) on the working medium side, or is made of
refractory material (solid ceramic blocks). These protective layers
may be similar to the turbine blades, i.e. for example MCrAlX
means: M is at least one element from the group iron (Fe), cobalt
(Co), nickel (Ni), X is an active element and stands for yttrium
(Y) and/or silicon and/or at least one rare earth element, or
hafnium (Hf). Such alloys are known from EP 0 486 489 B1, EP 0 786
017 B1, EP 0 412 397 B1 or EP 1 306 454 A1 which, with respect to
the chemical composition of the alloy, are intended to be part of
this disclosure.
[0074] On the MCrAlX, there may furthermore be an e.g. ceramic
thermal barrier layer which consists for example of ZrO.sub.2,
Y.sub.2O.sub.3--ZrO.sub.2, i.e. it is not stabilized or is
partially or fully stabilized by yttrium oxide and/or calcium oxide
and/or magnesium oxide.
[0075] Rod-shaped grains are produced in the thermal barrier layer
by suitable coating methods, for example electron beam deposition
(EB-PVD). Other coating methods may be envisaged, for example
atmospheric plasma spraying (APS), LPPS, VPS or CVD. The thermal
barrier layer may comprise porous, micro- or macro-cracked grains
for better thermal shock resistance.
[0076] Refurbishment means that turbine blades 120, 130 and heat
shield elements 155 may need to have protective layers taken off
(for example by sandblasting) after their use. The corrosion and/or
oxidation layers or products are then removed. Optionally, cracks
in the turbine blade 120, 130 or the heat shield element 155 are
also repaired by the method. The turbine blades 120, 130 or heat
shield elements 155 are then recoated and the turbine blades 120,
130 or the heat shield elements 155 are used again.
* * * * *