Patent Description:
Gas turbine components are subjected to high temperatures and stresses during operation. Gas turbine components may be formed of hard-to-weld materials. Mis-machined gas turbine components may have defects (e.g., recesses, grooves, or lack of material). Repair of the defects in the hard-to-weld materials of the gas turbine components may be costly and/or time consuming. Welding processes directly to the defect in the hard-to-weld material may be costly and/or difficult. Further, welding processes directly to the defect in the hard-to-weld material may negatively affect adjacent portions of the gas turbine component because the non-uniform heating and cooling during the welding process will generate thermal stress and residual stress. These stresses may result in hot cracking or strain age cracking during welding, after welding, or during post-weld heat treatment (PWHT). Brazing may be used with a vacuum furnace to heat the braze material used for the repair. However, vacuum furnaces may have limited space available for gas turbine components and may have extensive heating times for the brazing process to be completed. Further, heat treatment of the repaired gas turbine component after the vacuum furnace may further increase the cost and time to repair the gas turbine component. <CIT> discloses a brazing method for repairing a surface of a turbine component, comprising the following steps: material is removed from a damaged area of the surface of the turbine component, a prefabricated replacement element is applied on the damaged area of the surface, a powdery solder-base material mixture is applied to at least one joining surface by means of high-speed flame spraying, the replacement element is placed on the damaged area of the surface and the replacement element and the damaged area of the surface are joined together by soldering.

In an embodiment, a method includes the step of arranging a braze material on a recessed surface of a gas turbine component. Further, the method includes the step of disposing a plate on the braze material. An inner surface of the plate is proximate to the braze material, and the plate has an outer surface opposite the inner surface. Additionally, the method includes the step of heating a filler material to apply the filler material to the outer surface of the plate. Heat from applying the filler material is configured to heat the plate. Moreover, the method includes the step of bonding, via the heat from applying the filler material, the recessed surface of the gas turbine component to the inner surface of the plate with the braze material.

In certain applications, turbomachinery (e.g., turbines, compressors, and pumps) and other machinery may include components that operate in high heat environments. For example, certain turbine system components include blades, liners, rotor wheels, shafts, nozzles, and so forth. Some turbine components may have manufacturing defects (e.g., recesses, grooves, notches, etc.).

Generally, brazing may be used to restore components to operational condition. However, the brazing process may be costly and/or time consuming. For example, brazing may include using a furnace (e.g., vacuum furnace) during a brazing process. The furnace may have limited capacity to braze gas turbine components due to the size of the furnace and the size of the components. Additionally, the use of the furnace to braze the gas turbine components may have extensive heating times for the brazing process and/or have specialized operators. Additionally, furnaces heat portions of the gas turbine components in addition to the braze materials; thus, the whole repaired gas turbine component may be heat treated after brazing to restore desired material properties to the gas turbine component. Moreover, direct welding of the defect of the gas turbine component may not be effective for repairing defects in gas turbine components made of hard-to-weld material(s).

The weld-brazing techniques disclosed herein overcome current issues with brazing or welding gas turbine components. For example, the weld-brazing techniques may be used without specialized equipment (e.g., furnace) thereby reducing the costs, complexity, and/or repair times for the gas turbine components. Further, the heat applied to the gas turbine component itself by the weld-brazing techniques described herein may reduce or eliminate subsequent heat treatment of the gas turbine component, thereby reducing costs and repair times of the gas turbine component. Additionally, weld-brazing techniques may effectively repair gas turbine components having hard-to-weld materials. Thus, the weld-brazing techniques disclosed herein overcome current issues with brazing and welding of gas turbine components.

The weld-brazing techniques may also provide additional advantages over traditional brazing. Brazing may not be suitable for repairing load-bearing components. The braze material may not have desired mechanical properties (e.g., tensile strength, etc.) for load-bearing applications. Welding may be suitable for repairing load-bearing components; however, as described above, welding alone may not be effective for repairing hard-to-weld materials, such as those used in some gas turbine components. The weld-brazing techniques disclosed herein may effectively apply a material having desired load-bearing mechanical properties in addition to brazing materials. Thus, the weld-brazing techniques disclosed herein may provide more effective repair of load-bearing gas turbine components than brazing.

<FIG> is a cross-sectional view of a turbine system <NUM>. During operation of the turbine system <NUM>, a fuel such as natural gas or syngas, may be routed to the turbine system <NUM> through one or more fuel nozzles <NUM> into a combustor <NUM>. Air may enter the turbine system <NUM> through an air intake section <NUM> and may be compressed by a compressor <NUM>. The compressor <NUM> may include a series of stages <NUM>, <NUM>, and <NUM> that compress the air. Each stage may include one or more sets of stationary vanes <NUM> and blades <NUM> that rotate to progressively increase the pressure to provide compressed air. The blades <NUM> may be attached to rotating wheels <NUM> connected to a shaft <NUM>. The compressed discharge air from the compressor <NUM> may exit the compressor <NUM> through a diffuser section <NUM> and may be directed into the combustor <NUM> to mix with the fuel. For example, the fuel nozzles <NUM> may inject a fuel-air mixture into the combustor <NUM> in a suitable ratio for optimal combustion, emissions, fuel consumption, and power output. In certain examples, the turbine system <NUM> may include multiple combustors <NUM> disposed in an annular arrangement. Each combustor <NUM> may direct hot combustion gases into a turbine <NUM>.

The turbine <NUM> may include multiple includes three separate stages <NUM>, <NUM>, and <NUM> surrounded by a liner <NUM>. Each stage <NUM>, <NUM>, and <NUM> includes a set of turbine blades or buckets <NUM> coupled to a respective rotor wheel <NUM>, <NUM>, and <NUM>, which are attached to a shaft <NUM>. Further, each stage may include a set of nozzles <NUM>. Hot gases from the combustor <NUM> may be directed in a flow direction <NUM> through the turbine <NUM>. As the hot combustion gases flowing through the turbine <NUM> cause rotation of turbine blades <NUM>, the shaft <NUM> rotates to drive the compressor <NUM> and any other suitable load, such as an electrical generator. Eventually, the turbine system <NUM> diffuses and exhausts the combustion gases in the flow direction <NUM> through an exhaust section <NUM>. Turbine components, such as the fuel nozzles <NUM>, intake <NUM>, compressor <NUM>, stationary nozzles <NUM>, blades <NUM>, wheels <NUM>, shaft <NUM>, diffuser <NUM>, stage <NUM>, stage <NUM>, and stage <NUM>, turbine blades <NUM>, nozzles <NUM>, shaft <NUM>, liner <NUM>, and exhaust section <NUM>, may use the disclosed embodiments to repair defects, cracks, or gaps, as described in more detail with respect to <FIG> below.

<FIG> is a cross-sectional view of a gas turbine component <NUM> having an external defect <NUM>. The gas turbine component <NUM> may be the nozzle <NUM> of the gas turbine of <FIG>. However, the gas turbine component <NUM> may be another hot-gas component of the gas turbine system <NUM> (e.g., blades <NUM>, diffusers <NUM>, liners <NUM>, etc.). In some embodiments, the techniques disclosed herein may be applied to other components of the gas turbine system <NUM> or other components generally (e.g., steam turbine components, automotive components, etc.). The external defect <NUM> of the gas turbine component <NUM> may be a recessed portion <NUM> (e.g., notch, groove, crack, gap, etc.). The external defect <NUM> may be a cosmetic defect (e.g., a defect in a non-load bearing portion of the hot gas component), such as a groove or notch in a base of the turbine nozzle <NUM> or turbine blade <NUM>. In another embodiment, the external defect <NUM> may be a structural defect, such that the gas turbine component <NUM>, at the external defect <NUM>, may have minimum acceptable mechanical properties (e.g., tensile strength, etc.). The external defect <NUM> may be disposed on a surface <NUM> of the gas turbine component <NUM> that may interface with the hot gas during operation of the gas turbine system <NUM>.

The gas turbine component <NUM> may include a hard-to-weld (HTW) material, such as iron-based, martensitic stainless steel, precipitated-hardening stainless steel, chromium molybdenum steel, high alloy steel, tool steel, non-ferrous alloys (e.g., aluminum, copper, brass, zinc, and zirconium), or some combination thereof. Further, HTW materials may be superalloys (e.g., nickel-based superalloys) having a high fraction of a "gamma prime" strengthening phase. Specifically, the HTW material may have a gamma-prime (γ') between <NUM> and <NUM>. In some embodiments, the HTW material may have a gamma-prime (γ') between <NUM> and <NUM>. In another example, the HTW material may have a gamma-prime (γ') between <NUM> and <NUM>. A higher gamma-prime (γ') fraction may increase the oxidization resistance and creep resistance of the HTW material, such that the gas turbine component <NUM> of the HTW material may operate in a high heat environment of the gas turbine system <NUM>. In some embodiments, the HTW material may be a superalloy, such as Hastelloy, Inconel, Waspaloy, GTD, or Rene alloys. Examples of specific HTW materials include Rene <NUM>, Rene N5, GTD <NUM>, and GTD <NUM>. In some embodiments, the HTW material may include cobalt, iron, niobium, tantalum, molybdenum, tungsten, vanadium, and titanium to strengthen the superalloy.

In another embodiment, the HTW material may be a nickel-base superalloy. Nickel-based superalloys can be classified into three categories: solid-solution strengthened, precipitated strengthened, and specialty alloys. Although, solid-solution strengthened nickel-base superalloys, such as Ni-Cu, Ni-Mo, Ni-Fe, Ni-Cr-Fe, Ni-Cr-Mo-W, Ni-Fe-Cr-Mo, Ni-Cr-Co-Mo (i.e., Inconel <NUM>, Inconel <NUM>, Haynes <NUM>, etc.) are generally not considered HTW materials; however, the precipitation-strengthened and specialty nickel-base superalloys are generally considered HTW materials. Precipitation-strengthened nickel-base superalloys include titanium, aluminum, and/or niobium that forms a strengthening precipitate with nickel after an appropriate heat treatment. The gamma prime volume fraction of precipitation-strengthened nickel-base superalloys may range from less than <NUM>% (e.g., Nimonic <NUM>) to above <NUM>% (e.g., Rene <NUM>). For precipitation-strengthened nickel-base superalloys, if the gamma prime is less than <NUM>% (e.g., GTD222 and Rene <NUM>), it usually shows excellent weldability, such that the precipitation-strengthened nickel-base superalloy is an ETW material. However, if the gamma prime of the precipitation-strengthened nickel-base superalloy is above <NUM>% in volume (e.g., Rene <NUM>, Inconel <NUM>, GTD111), it usually exhibits poor weldability, such that the precipitation-strengthened nickel-base superalloy is a HTW superalloys. Thus, the gas turbine component <NUM> in the hot gas path may be made with HTW materials, such as Rene <NUM>, Inconel <NUM>, GTD111. Specialty alloys generally include nickel-aluminum intermetallics and Oxide dispersion strengthened alloys. Examples of specialty alloys include oxide dispersion strengthened alloys (e.g., MS6000, MA754), and nickel-aluminides (e.g., NiAl or Ni3Al compound). Specialty alloys generally have high strength and corrosion resistance, and are considered a HTW material because of their low ductility at high temperatures (e.g., high temperature creep strength). Accordingly, the gas turbine component <NUM> may be made of a specialty alloy.

As discussed above, the external defect <NUM> may be disposed on a surface <NUM> of the gas turbine component <NUM> that may interface with the hot gas during operation of the gas turbine system <NUM>. A braze material <NUM> may be applied to the external defect <NUM> of the gas turbine component <NUM>. In the illustrated embodiment, the braze material <NUM> may be inserted into the recessed portion <NUM> (e.g., on a recessed surface <NUM> of the recessed portion <NUM>). However, in some embodiments, the braze material may be disposed on the gas turbine component <NUM> to create a protrusion, or other missing feature, to repair a defect in the gas turbine component caused by a lack of material. The braze material <NUM> may be a tape having a thickness <NUM> between. <NUM> and <NUM> (e.g.,. <NUM> and <NUM> mil). The tape of the braze material <NUM> may be placed on <NUM>-<NUM>%, <NUM>-<NUM>%, and/or <NUM>-<NUM>% of the recessed surface <NUM>. In some embodiments, the braze material <NUM> may be a powder, foil, or pre-form that may be positioned at least partially within the recessed portion <NUM>. The braze material <NUM> may be configured to fill the recessed portion <NUM> up to or beyond the surface <NUM> of the gas turbine component <NUM>. In some embodiments, the braze material <NUM> may be configured to only partially fill the recessed portion <NUM>.

Additionally, a plate <NUM> may be disposed over the recessed portion <NUM> and the braze material <NUM> such that the braze material <NUM> is disposed between the recessed surface <NUM> and an inner surface <NUM> of the plate. As discussed below, heat may be applied to an outer surface <NUM> of the plate <NUM> to heat the braze material <NUM> and bond the plate <NUM> with the gas turbine component <NUM> having an external defect <NUM> and the plate <NUM>. In some embodiments, heat may be applied to the outer surface <NUM> of the plate <NUM> via application of a filler material to the outer surface <NUM> of the plate.

In some embodiments, the plate <NUM> is configured to fully cover the recessed portion <NUM>. As such, the inner surface <NUM> of the plate may have a larger surface area than an area spanning across the recessed portion <NUM>. However, in some embodiments, the external defect <NUM> may have a non-uniform shape. Thus, the dimensions of the plate <NUM> may be configured such that the inner surface <NUM> of the plate fully covers the recessed portion <NUM>. For example, the plate <NUM> may have a rectangular shape. A length <NUM> of the plate <NUM> may be longer than an overall longest distance across the recessed portion <NUM>, and a width of the plate may be longer than a longest distance across the recessed portion in a direction orthogonal to the overall longest distance across the recessed portion. Thus, the plate <NUM> may fully cover the recessed portion <NUM> having a non-uniform shape. The plate <NUM> may have any shape suitable for covering the recessed portion <NUM>. In some embodiments, the plate <NUM> may be formed having a shape based on the shape of the recessed portion <NUM>. That is, the plate <NUM> may be formed with a complementary shape to the recessed portion <NUM>. Further, the plate <NUM> may fully cover the braze material <NUM>.

In some embodiments, the plate <NUM> may be configured to be larger than the recessed portion <NUM> by a predetermined amount such that the plate <NUM> has an excess portion <NUM> (e.g., portions of the plate extending beyond the recessed portion <NUM>). In some embodiments, the plate <NUM> may be configured to have at least a minimum amount of excess portion <NUM> along a perimeter of the recessed portion <NUM>. For example, the plate <NUM> may extend at least <NUM> to <NUM>, <NUM> to <NUM>, or <NUM> to <NUM> beyond the recessed portion <NUM>. In some embodiments, the excess portion <NUM> extends beyond both the recessed portion <NUM> and the braze material <NUM>. The excess portion <NUM> of the plate <NUM> may be used as a weld run-on or run-off tabs for starting or stopping a weld respectively.

In some embodiments, portions of the inner surface <NUM> of the plate may contact an exterior surface <NUM> of the gas turbine component <NUM>. In another embodiment, the thickness <NUM> of the braze material <NUM> (i.e., before or after application of the filler material to melt the braze material) may be greater than a depth <NUM> of the recessed portion <NUM> such that portions of the plate <NUM> may rest on the braze material <NUM> and not contact the exterior surface <NUM> of the gas turbine component <NUM> upon disposing the plate <NUM> above the recessed portion <NUM>. If a surface <NUM> of the braze material <NUM> is uneven, the plate <NUM> may shift with respect to the recessed portion <NUM> and/or the braze material <NUM>. Accordingly, in some embodiments, to prevent shifting, the plate <NUM> may be fixed to the gas turbine component before applying the filler material to the outer surface <NUM>.

The plate <NUM> may include an easy-to-weld (ETW) material. The ETW material may include, but is not limited to steel, stainless steel, nickel-based superalloy, cobalt-based superalloy, or another suitable metallic material. Examples of specific ETW materials include solid-solution strengthened alloys, such as Inconel <NUM>, Inconel <NUM>, Haynes <NUM>, and precipitated strengthened alloys, such as GTD222, GTD262, GTD292, Rene <NUM>. In some embodiments, the ETW alloys in the precipitated strengthened alloy category have a gamma prime (γ') less than <NUM>%. In another embodiment, the ETW has a gamma prime (γ') less than <NUM>%.

<FIG> is a top view of a gas turbine component <NUM> and the plate <NUM>. A filler material may be applied to an outer surface <NUM> of the plate <NUM> along a weld path <NUM> to heat the braze material and bond the plate <NUM> with the gas turbine component <NUM> having an exterior defect and the plate <NUM>. The weld path <NUM> may direct the filler material to be applied as parallel weld beads. In some embodiments, the weld path <NUM> may direct the filler material to be applied, such that the weld beads are overlapped or separated on the outer surface <NUM> of the plate <NUM>. The weld path <NUM> may direct the filler material to be applied in various patterns. The filler material may be applied to a portion of the plate <NUM> disposed above the recessed portion <NUM>. In some embodiments, the filler material is applied to both the portion of the plate <NUM> disposed above the recessed portion <NUM> and to the excess portion <NUM> of the plate <NUM>. In another embodiment, the filler material is only applied to a portion of the plate <NUM> disposed above the braze material.

In some embodiments, the plate <NUM> and the gas turbine component <NUM> are fixed together before applying the filler material to the outer surface <NUM>. The plate <NUM> and gas turbine component <NUM> may be fixed together at locations <NUM> via at least one weld, adhesive, clamping device, or other suitable mechanism for securing the plate <NUM> and brazing material to the gas turbine component <NUM>. In some embodiments, the plate <NUM> and turbine component <NUM> may be fixed together using fusion and/or resistance weld processes. The weld process may weld the components together at locations <NUM>. However, in another embodiment, the weld process is configured to melt the braze material, disposed between the plate <NUM> and the gas turbine component <NUM>, at locations <NUM> to fix the plate <NUM> to the gas turbine component <NUM>. The plate <NUM> may be fixed to the exterior surface <NUM> of the gas turbine component <NUM>, such that the weld <NUM> is not applied above the recessed portion <NUM>. Fixing the plate <NUM> and gas turbine component <NUM> together may decrease shifting and rotating, as well as increase heat conduction between at least the plate <NUM> and the braze material <NUM>.

<FIG> a cross-sectional view of a filler material <NUM> applied to an outer surface <NUM> of the plate <NUM> to heat the braze material <NUM> and bond the plate <NUM> with the gas turbine component <NUM> having an exterior defect and the plate <NUM>. The plate <NUM> is disposed over the recessed portion <NUM> and the braze material <NUM> such that the braze material <NUM> is disposed between the recessed surface <NUM> and the inner surface <NUM> of the plate <NUM>. At least a first portion of the inner surface <NUM> of the plate <NUM> is in contact the braze material <NUM>, and the braze material <NUM> is in contact with the recessed surface <NUM> of the recessed portion <NUM>.

The filler material <NUM> may be applied to the outer surface <NUM> of the plate <NUM>. The application of filler material <NUM> to the plate <NUM> heats the plate <NUM>, which heats the braze material <NUM>. Placement of the filler material <NUM> may be dependent on the size of the external defect <NUM> (e.g., depth <NUM> and breadth of the recessed portion <NUM>). For example, the recessed portion <NUM> may be a long and narrow groove that has a shallow end and a deep end. As such, more braze material <NUM> may be applied to the deep end. Thus, more filler material <NUM> may be applied to the plate <NUM> above the deep end than to the plate <NUM> above the shallow end to melt the braze material <NUM> in both the deep end and the shallow end.

The filler material <NUM> may be applied to the outer surface <NUM> of the plate <NUM> via a welding process. The welding process may be a tungsten inert gas (TIG), metal inert gas (MIG), stick, laser, electron beam (EB), plasma, flux-cored arc welding (FCAW), laser beam (LB) fusion welding, another type of suitable welding process, or some combination thereof. A shielding gas may be used during application of the filler material <NUM> to prevent oxidation. Application of the filler material <NUM> to the outer surface <NUM> of the plate <NUM> heats the plate <NUM>. The application of the filler material <NUM> and a thickness <NUM> of the plate <NUM> are configured to heat the braze material <NUM> to the brazing temperature. Although the plate <NUM> is disposed between the braze material <NUM> and the filler material <NUM>, the filler material <NUM> may be heated prior to or during application to the plate <NUM>. Heat from the filler material <NUM> may be conducted from the filler material <NUM>, through the plate <NUM>, and to the braze material <NUM>. The thickness <NUM> of the plate <NUM> may affect heating of the braze material (e.g., the braze material <NUM> may not melt if the thickness <NUM> of the plate <NUM> is too thick). The thickness <NUM> of the plate <NUM> may be between <NUM> to <NUM>. Additionally, heat from the filler material <NUM> may be radiated to the braze material <NUM>.

The heat transferred from the filler material <NUM>, via conduction and/or radiation, to the braze material <NUM> may be sufficient to liquefy (e.g., melt) the braze material <NUM>. The filler material applied to the outer surface of the plate may have a temperature of <NUM> degrees Celsius (<NUM> degrees Fahrenheit). The plate <NUM> may be heated such that a temperature at an interface <NUM> between the plate <NUM> and the braze material <NUM> has a temperature above the liquidus temperature of the braze material. In some embodiments, the braze material <NUM> has a liquidus temperature between <NUM> and <NUM> degrees Celsius (<NUM> and <NUM> degrees Fahrenheit). Thus, the heat transferred to the braze material <NUM> from the filler material <NUM> via the plate <NUM> may heat the plate <NUM> at the interface <NUM> to a temperature above <NUM> degrees Celsius, such that the braze material <NUM> melts. After the filler material <NUM> cools and the temperature of the braze material <NUM> falls below the liquidus temperature of the braze material <NUM>, the braze material <NUM> will solidify. Heating the braze material <NUM> above the liquidus temperature, then cooling the braze material <NUM> below the liquidus temperature is configured to trigger a bonding process for the braze material <NUM>. The bonding process includes the braze material <NUM> bonding with the gas turbine component <NUM> and the plate <NUM> during liquefaction and re-solidification of the braze material <NUM>.

The braze material <NUM> is indirectly heated via application of the filler material <NUM> to the plate <NUM>, thereby enabling the plate <NUM> to be brazed with the gas turbine component <NUM> without putting the gas turbine component <NUM> in a furnace (e.g., vacuum furnace). Although brazing typically uses a vacuum furnace to perform a brazing process without formation of oxidation, the bonding process disclosed herein does not use a vacuum furnace. The plate <NUM> is configured to cover the recessed portion <NUM> and the braze material <NUM>, and during the bond process, the braze material <NUM> is configured to liquefy between the plate <NUM> and the recessed portion <NUM> such that oxidation does not occur. Thus, the bonding process may be accomplished without specialized brazing equipment, such as a furnace or a gas flame torch.

In some embodiments, the application of the filler material <NUM> to the outer surface <NUM> of the plate <NUM> is configured to heat the braze material <NUM> to the brazing temperature without heating the gas turbine component <NUM> above a heat threshold. The heat threshold may be dependent on the material properties of the gas turbine component <NUM>. The heat threshold may be a maximum temperature that a material of the gas turbine component <NUM> may be heated before altering the microstructure of the material to an extent that the gas turbine component <NUM> is unsuitable for its intended use without being heat treated. If the temperature of the gas turbine component <NUM> exceeds the heat threshold, heat treating the gas turbine component <NUM> may restore the material of the gas turbine component <NUM> to a desired microstructure for its intended use, but heat treating may be time consuming and costly.

In some embodiments, a portion of the filler material <NUM> is removed after the bonding process is complete. For example, the filler material <NUM> may be removed above a line <NUM>. A portion of the filler material <NUM> removed may be fifty percent or more of the filler material <NUM> applied to the outer surface <NUM> of the plate <NUM>. A surface <NUM> of the filler material <NUM> may be rough or uneven. Machining the filler material to the line <NUM> may smooth the surface of the filler material <NUM>. Machining the filler material to the line <NUM> may also remove cracks or other imperfections, which may prevent crack propagation. In some embodiments, the filler material <NUM> is removed and a portion of the plate <NUM> is removed via machining of the plate to a line <NUM>. In some embodiments, the filler material <NUM>, plate <NUM>, and/or braze material <NUM> may be machined to be even with the exterior surface <NUM> of the gas turbine component <NUM> and to restore the gas turbine component <NUM> to manufactured dimensions. That is, the line <NUM> or the line <NUM> may be even (e.g., coplanar) with the exterior surface <NUM>. In some embodiments, a portion of the filler material <NUM> and/or the plate <NUM> may extend beyond an edge <NUM> of the gas turbine component. The portion of the filler material <NUM> and/or the plate <NUM> extending beyond the edge <NUM> of the gas turbine component <NUM> may be removed via machining to the line <NUM>.

The filler material <NUM> may include either an ETW material, a HTW material, or some combination thereof. In some embodiments, the filler material <NUM> is an ETW material when the filler material <NUM> is configured to be removed after application via a machining process. Although HTW material may have preferable mechanical properties, ETW filler material may be easier and/or cheaper to apply to the plate <NUM> than HTW filler material. Further, the ETW filler material may be easier to obtain a defect-free weld than the HTW filler material. Accordingly, the ETW material may be used when the filler material <NUM> is configured to be fully removed because the preferable mechanical properties of the HTW material may only increase the difficulty in removing the filler material <NUM>. However, in some embodiments, the filler material <NUM> may include ETW material when a portion of the filler material <NUM> is configured to remain on the gas turbine component <NUM> after machining. In other embodiments, the filler material <NUM> may include a HTW material when at least a portion of the filler material <NUM> is configured to remain on the gas turbine component <NUM> after machining to increase oxidation resistance, temperature corrosion, creep resistance, and or mechanical strength of the filler material <NUM>.

<FIG> illustrates an embodiment of a method <NUM> suitable for performing a weld-braze, as described above with respect to <FIG>. The method includes arranging (block <NUM>) a braze material on a recessed surface of a recessed portion of a gas turbine component. The braze material may be a powder, foil, tape, or pre-form. For example, an operator may fill the recessed portion with powder braze material. The operator may partially fill the recessed portion. However, the operator may completely fill or overfill the recessed portion with the braze material. In some embodiments, the operator may arrange the braze material on the external surface of the gas turbine component in addition to the recessed surface.

The method also includes disposing (block <NUM>) a plate on the braze material, such that an inner surface of the plate is proximate to the braze material. The plate may be disposed above the recessed portion. In some embodiments, the plate is disposed partially within the recessed portion and above the braze material such that the braze material is positioned between the recessed surface and the plate. In another embodiment, the plate is disposed entirely within the recess portion. The plate may be substantially the same size as an opening of the recessed portion, such that the plate spans across the recessed portion. In some embodiments, the method includes the step of applying (block <NUM>) a tack weld to the plate prior to heating the filler material to apply the filler material. The tack weld may be configured to hold the plate in place while applying the filler material as described below.

As described above, the plate has an outer surface opposite the inner surface. The method further includes heating (block <NUM>) a filler material to apply the filler material to the outer surface of the plate. The heat from the applied filler material is configured to heat the plate and the braze material. Moreover, the method includes bonding (block <NUM>), via the heat from applying the filler material, the recessed surface of the gas turbine component to the inner surface of the plate with the braze material. Heat from the filler material may be transferred through the plate to heat the braze material to a temperature above the liquidus temperature of the braze material such that the braze material melts. As the heat applied from the filler material dissipates, the braze material cools and solidifies. Melting then solidifying the braze material, while the braze material is in contact with both the recessed surface and the plate may cause bonding (block <NUM>) of the braze material to both the recessed surface and the plate.

In some embodiments, the method further includes machining (block <NUM>) the gas turbine component to remove portions of the filler material, plate, braze material, or some combination thereof. However, the method does not include the step of heat treating the gas turbine component and/or the braze material in a furnace, vacuum furnace, etc..

The technical effects of the weld-brazing techniques disclosed herein include enabling faster repairs at a reduced cost by eliminating steps of a traditional brazing process, as well as providing improved repairs to load-bearing components having hard-to-weld materials.

Claim 1:
A method comprising:
arranging a braze material (<NUM>) on a recessed surface of a gas turbine component (<NUM>);
disposing a plate (<NUM>) on the braze material, wherein an inner surface of the plate is proximate to the braze material, and the plate comprises an outer surface (<NUM>) opposite the inner surface;
heating a filler material (<NUM>) to apply the filler material to the outer surface of the plate,
characterised in that heat from applying the filler material is configured to heat the plate; and in that the method comprises the step of:
bonding, via the heat from applying the filler material, the recessed surface of the gas turbine component to the inner surface of the plate with the braze material.