JP2020094499A - Method for repairing turbine component and method for manufacturing repaired turbine component - Google Patents

Abstract

To provide a method for repairing a turbine component capable of performing high-quality repair efficiently and inexpensively.SOLUTION: Provided are a method for repairing a turbine component comprising: attaching a repair material by cold spray to a place where a turbine component needs to be repaired; forming an absorption layer on the surface of the attached repair material; heating the repair material to a temperature equal to or higher than a melting temperature of a brazing material constituting the repair material, to perform a diffusion heat treatment; and solidifying the liquefied brazing material, and a method for manufacturing a repaired turbine component.SELECTED DRAWING: Figure 1

Description

Embodiments of the present invention relate to a method of repairing a turbine component and a method of manufacturing a repaired turbine component.

Generally, in a gas turbine power plant, compressed air obtained by a compressor coaxial with a gas turbine is guided to a combustor and burned together with fuel in a combustor liner. At this time, the high-temperature combustion gas generated by the combustion is guided to the moving blade via the transition piece and the stationary blade, and the shaft in which the moving blade is implanted is rotationally driven to generate electric power by the coaxial generator.

Ni-based, Co-based or Ni-Fe-based superalloys are generally used in the combustor liner, transition piece, stationary blade and moving blade, which are high-temperature components of this type of gas turbine. Various damages occur with the operation of. First, since it is exposed to a high-temperature combustion gas atmosphere, its material deteriorates, and creep damage is accumulated in the moving blade due to centrifugal stress due to high-speed rotation. For stationary components such as vanes, when the gas turbine starts up, it moves from a relatively low temperature environment to a high temperature environment, and when the gas turbine stops, it moves from a high temperature environment to a low temperature environment. At the stage, thermal stress occurs and damage due to thermal fatigue accumulates. Note that these damages are accumulated and accumulated.

By the way, maintenance and management of high temperature parts of gas turbine is based on the creep or fatigue life determined at the design stage of equipment and the life set by actual operation and location environment. In some cases, the gas turbines to be taken are classified, the design life is corrected by referring to the results of the preceding machines of each classified group, and the maintenance of the subsequent machines is performed.

Then, in recent years, a maintenance management method for efficiently and accurately predicting deterioration and damage diagnosis of high temperature parts of a gas turbine is being made.

Regardless of which maintenance management method is used, repairs are usually repeated at regular inspections as necessary, and after reaching the management life, they are uniformly discarded and replaced with a very expensive new one. Here, in the repair of the gas turbine stationary blade at every regular inspection, when a crack is generated by use, the periphery of the crack is removed and repaired by welding, so that it can be reused. In addition to welding repair, there is also a brazing repair method.
The following are known examples of methods by welding repair or brazing.

JP, 11-117705, A JP, 6-234066, A JP-A-6-344129 JP, 2006-46147, A

Conventionally, when repairing cracks or other parts that require repair with brazing filler metal, to prevent the liquefied brazing filler metal from flowing out, repair the cracks and other repair parts until the liquefied brazing filler metal solidifies and repairs. I had to keep it level.

Turbine components, particularly turbine vanes and blades, have complex shapes, and the need for repairs such as cracks and wear occurs at various locations on the complex shaped turbine component.

Therefore, when performing repair, it was necessary to adjust the angle, posture, and the like of the turbine component in accordance with the angle of the repair-required portion so that the repair-required portion was horizontal and held for a certain period of time. Therefore, if there are multiple repair-required points on the same turbine part, and especially if the angles of the repair-required points are different, it may be necessary to repair each repair-required point one by one and repeat this in sequence. It was
For this reason, the repair work tends to be time-consuming, time-consuming and costly.

The turbine component repairing method according to the embodiment of the present invention solves the problems of the conventional repairing method described above.

Therefore, the method for repairing a turbine component according to the embodiment of the present invention is
A process of attaching a repair material by cold spray to the place where the turbine component needs to be repaired,
A step of forming an absorption layer on the surface of the attached repair material,
Heating the repair material to a temperature equal to or higher than the melting temperature of the brazing material constituting the repair material, and performing a diffusion heat treatment;
Solidifying the liquefied brazing material,
It is characterized by including.

Then, the method for manufacturing the repaired turbine component according to the embodiment of the present invention is
A process of attaching a repair material by cold spray to the place where the turbine component needs to be repaired,
A step of forming an absorption layer on the surface of the attached repair material,
Heating the repair material to a temperature equal to or higher than the melting temperature of the brazing material constituting the repair material, and performing a diffusion heat treatment;
Solidifying the liquefied brazing material,
It is characterized by including.

Here, “repair” means to repair irregularities in shape or size, defects, and the like. For example, by filling, overlaying or adhering a repair material on cracks, thinned portions, through or non-penetrating holes, surface scratches, etc. caused by the use of turbine components, turbine components are Restoring the shape, form and size before it is used, and at the same time restoring or maintaining strength, durability, function, etc. is included in the above-mentioned "repair".

According to the method of repairing a turbine component according to the embodiment of the present invention, the repair material is attached to the repair-needed portion using cold spray. From this, for example, the repair material can be efficiently and surely filled up to the deep portion of the crack of the turbine component and can be retained inside the crack. In addition, it is easy to attach the repair material to the thin-walled region of the turbine component in a precise, reliable and uniform manner.
Further, since the repair material is attached by using cold spray, the repair material can be efficiently and surely attached and held even if the repair-needed portion is not horizontal.

Further, according to the embodiment of the present invention, the absorption layer is formed so as to cover the attached repair material, and the repair material in which the absorption layer is melted can be absorbed and held. For this reason, the molten repair material does not flow out even if the repair required portion of the turbine component is not horizontal. Therefore, even if there are a plurality of repair-needed parts having different inclinations in the same turbine component, it is possible to simultaneously perform the diffusion heat treatment on each repair-needed part.

Further, according to the embodiment of the present invention, not only “a plurality of repair-needed portions existing in the same turbine component” but also “a plurality of repair-needed portions existing in each of a plurality of different turbine components” It is also possible to perform the diffusion heat treatment simultaneously, or continuously.

Then, according to the method for repairing a turbine component according to the embodiment of the present invention, an absorption layer is formed so as to cover the attached repair material, and the absorption layer functions as a morphological stabilization layer of the repair material. There is. From this, for example, even when the repair material attached to the curved surface of a turbine vane or the like is liquefied or fluidized for diffusion heat treatment, the liquefied repair material may flow out or become uneven. , Is effectively suppressed by the presence of this absorption layer. Further, for example, in the cooling/solidifying process after the repair material is melted, even if an angle change or vibration from the outside is received, the morphological change of the repair material in the melting/solidification process is suppressed.

From this, it is possible to easily perform high-quality, high-strength repair according to the desired repair mode and shape.
Therefore, according to the method for repairing a turbine component according to the embodiment of the present invention, high quality repair can be performed efficiently and inexpensively.

The schematic diagram which shows the preferable repair method of the turbine component of this invention. The schematic diagram which shows the preferable repair method of the turbine component of this invention. The schematic diagram which shows the preferable repair method of the turbine component of this invention. The cross-sectional schematic diagram of the 1st stage stationary blade repaired by the repair method of the preferable turbine component of this invention. The cross-sectional schematic diagram of the 1st stage stationary blade repaired by the repair method of the preferable turbine component of this invention. The drawing which shows the result of the low cycle fatigue test of the 1st stage stationary blade repaired by the repair method of the preferable turbine component of this invention. The cross-sectional schematic diagram of the 2nd stage stator blade repaired by the repair method of the preferable turbine component of this invention. The cross-sectional schematic diagram of the 2nd stage stator blade repaired by the repair method of the preferable turbine component of this invention. The drawing which shows the result of the low cycle fatigue test of the 2nd stage stationary blade repaired by the repair method of the preferable turbine component of this invention.

Embodiment of the invention

[Repair method of turbine parts]
A method of repairing a turbine component according to an embodiment of the present invention is
A process of attaching a repair material by cold spray to the place where the turbine component needs to be repaired,
A step of forming an absorption layer on the surface of the attached repair material,
A step of heating the repair material to a temperature equal to or higher than a melting temperature of a brazing material constituting the repair material, performing diffusion heat treatment, and performing repair;
Solidifying the liquefied brazing material,
Is included.

FIG. 1 is a diagram showing an outline of a preferred turbine component repair method according to the present embodiment.
FIG. 1 shows a stationary blade of a gas turbine as a specific example of a turbine component. The stationary blade 1 of the gas turbine shown in FIG. 1A is a stationary blade 1 of a gas turbine that is used for operation and has a crack 30 and a reduced-thickness portion 31 on a blade surface 2 as a portion 3 requiring repair. is there.

A turbine component repair method according to an embodiment of the present invention uses a cold spray device (not shown) at a portion 3 of the gas turbine vane 1 where repair is required, as shown in FIG. 1B. The material 4 is attached (the attached repair material is shown as a repair material 4').

The cold spray device is preferably supplied with a "mixed powder material" containing "powder material 4a that does not melt during diffusion heat treatment" and "wax material 4b that melts during diffusion heat treatment", This mixed powder material is sprayed and attached to a portion 3 where the stationary blade 1 of the gas turbine needs to be repaired. The attached repair material 4'consists of "powder material 4a' that does not melt during diffusion heat treatment" and "brazing material 4b' that melts during diffusion heat treatment", and both materials are evenly and tightly bonded to each other. At the same time, the surface portion of the stationary blade 1 of the gas turbine (including the surface of the stationary blade 1 inside the crack 30) is closely adhered.

The attached repair material 4 ′ is filled only in the internal space of the crack 30 and can be attached only there. However, the method for repairing the turbine component according to the embodiment is not limited to the mode in which the repair material 4 ′ is strictly controlled in the adhesion position and the adhesion amount in this way to fill only the internal space of the crack 30. For example, as shown in FIG. 1B, the inner space of the crack 30 is filled, and the opening of the crack 30 of the stationary blade 1 of the gas turbine (that is, the opening of the crack 30 in the plane of the blade surface 2). It is easier and preferable that the repair material 4 ′ be attached to the peripheral portion 32 of) and the repair material 4 ′ is raised more than the opening portion of the crack 30. Similarly, the repair material 4 ′ may be adhered only in an amount corresponding to the thinned volume of the thinned portion 31, but as shown in FIG. 1B, in the thinned region of the stationary blade 1 of the gas turbine, It is easier and preferable to attach the repair material 4'to the peripheral portion 32 and to an amount equal to or larger than the reduced volume.

Then, in the repair method according to the present embodiment, as shown in FIG. 1C, a step of forming an absorption layer 5′ on the surface of the attached repair material 4′, preferably the entire surface of the attached repair material 4′. A step of forming an absorption layer 5′ so as to cover the.

The absorbent layer 5′ is preferably a porous body, and has pores opened on the inner surface side of the absorbent layer 5′ (that is, the surface on the side of the repair material 4′), particularly, a plurality of pores. Those in which several are connected are preferable.

Next, in the repairing method according to the present embodiment, a step of performing the diffusion heat treatment by heating to a temperature equal to or higher than the melting temperature of the "brazing material 4b' that melts during the diffusion heat treatment" that constitutes the repair material 4'is performed. In this step, the "brazing filler metal 4b'" is heated to a temperature equal to or higher than its melting temperature to melt and liquefy. The "liquefied brazing material 4b'" surrounds each particle of the "powder material 4a' that does not melt during the diffusion heat treatment", and also inside the crack 30 of the stationary blade 1 of the gas turbine or the stationary blade 1 of the gas turbine. The diffusion heat treatment is performed while penetrating or contacting the microcracks or the metal structure existing on the surface of the thinned portion 31 and the peripheral portion 32 thereof. Further, a part of the liquefied brazing material 4b'" is absorbed in the absorption layer 5'and held in the absorption layer 5'. The presence of the absorbing layer 5 ′ prevents the “liquefied brazing material 4 b ′” and the “powder material 4 a ′ that does not melt during the diffusion heat treatment” from flowing out of the crack 30. Here, the "diffusion heat treatment" means a heat treatment for diffusing the element of each material.

Then, this liquefied brazing filler metal is solidified by the step of solidifying the liquefied brazing filler metal, and is integrated with the constituent material of the vane 1 of the gas turbine, as indicated by 4b″ in FIG. 1D. Of a gas turbine in which cracks or wall thinning are repaired by a matrix structure in which "the powder material 4a" which does not melt during diffusion heat treatment is a dispersed phase and "the solidified brazing material 4b"" is a continuous phase The vane 1 is obtained.

The turbine component repair method according to the present embodiment can be performed by performing a series of steps on these. This allows repaired turbine components according to embodiments of the present invention to be manufactured.

<Turbine parts>
A method for repairing a turbine component according to an embodiment of the present invention includes various turbine components used for operation, preferably, for example, a vane of a gas turbine, a moving blade, a combustor liner, a transition piece, a shroud segment, and a compressor. It can be applied when repairing. Especially applied when repairing one or more damages (eg, cracks, fractures, wear or thinning areas) that have occurred on the blade part, inner wall part, or outer wall part of a gas turbine stationary blade. be able to.

The turbine component repair method according to the embodiment of the present invention can be applied when repairing turbine components made of various metal materials. In particular, it can be applied when repairing a gas turbine stationary blade made of a Ni-based, Co-based, or Ni-Fe-based alloy. Particularly preferably, it contains Cr 28.5 to 30.5%, C 0.2 to 0.3%, Ni 9.5 to 11.5%, W 6.5 to 7.5% and B 0.005 to 0.01%. Turbine parts made of Co-based alloy material, or Co 18 to 20%, W 1.5 to 2.5%, Cr 20 to 24%, Al 1.0 to 1.5%, Ta 0.8 to 1.2%, Nb 0.6 -1.0%, Hf0-0.2%, Ti2.0-2.5%, Mo0-0.2%, C0.05-0.15%, Zr0.002-0.05% and B0.01. It can be used when repairing a turbine component made of a Ni-based alloy material containing 0.02% to 0.02%. It should be noted that the turbine component may be formed of only a single metallic material, or may be a combination of several components made of different metallic or non-metallic materials.

<Repair material and process of attaching repair material>
In the method of repairing a turbine component according to the embodiment of the present invention, a step of attaching a repair material by cold spray is performed. For example, as shown in FIG. 1, it is preferable to use a cold spray to fill the crack 30 with a repair material, or to reduce the thickness reduction (wear) portion 31 caused by the use of a turbine component. In order to restore the shape to the one before, the repairing material is attached to the thinned area to cover it. Here, in the present specification, the term "cold spray" refers to "a metal powder is accelerated by a high-speed gas flow having a temperature lower than a melting point and is collided with a substrate at a high speed in a solid phase state, mainly for the base material and particles "Technology for attaching metal powder by plastic deformation".

In the cold spray device, as the repair material 4, preferably, a "mixed powder material" including "a powder material 4a that does not melt during the diffusion heat treatment" and "a brazing material 4b that melts during the diffusion heat treatment". Is supplied. Here, "the brazing material 4b that melts during the diffusion heat treatment" is a powder under the conditions before the diffusion heat treatment (for example, normal temperature conditions), but melts under the temperature condition where the diffusion heat treatment is performed. A brazing material that is in a state.

In the above-mentioned “mixed powder material”, the mixing ratio (weight ratio) of “powder material 4a that does not melt during diffusion heat treatment” and “brazing material 4b that melts during diffusion heat treatment” is Ni-based molten alloy. Powder material: Co based non-melting alloy powder material, preferably 20 to 80:80 to 20, particularly preferably 30 to 70:70 to 30.

As the above-mentioned "powder material 4a that does not melt during the diffusion heat treatment", preferably, for example, a material containing a Co-based alloy powder material and a Ni-based alloy powder material can be mentioned. Particularly preferable specific examples of the Co-based non-molten alloy powder material include, for example, Co—Ni—Cr containing Cr 15 to 25%, Ni 15 to 25%, Ta 5 to 10%, C 0.05% or less, and W 0.1% or less. -Based alloy powder material (melting temperature 1380 to 1425° C.) and Co 10 to 15%, Cr 15 to 20%, Al 1 to 1.5%, Ti 0.5 to 1%, Ta 0.05 to 0.15%, Mo 8 to 10 %, Nb 0.2 to 0.4%, and C 0.02 to 0.08% (based on the melting temperature of 1300 to 1400° C.).

The preferable particle size of the “powder material 4a” is 70 μm or less, and the particularly preferable particle size is 50 μm or less. Here, the particle size is based on JIS Z2510. With such a particle size, the element can be easily diffused.

On the other hand, as the above-mentioned "brazing material 4b that melts during the diffusion heat treatment", preferably, for example, particles containing a Ni-based alloy powder material can be mentioned. As a particularly preferable specific example of the Ni-based alloy powder material, for example, a Ni-Cr-Co-Si-B based alloy powder material containing 10 to 15% Cr, 15 to 25% Co, 3 to 5% Si, and 2 to 5% B. (Melting temperature of 1000 to 1090° C.).

The preferable particle diameter of the "brazing material 4b" is 70 μm or less, and the particularly preferable particle diameter is 50 μm or less. Here, the particle size is based on JIS Z2510. With such a particle size, melting can be easily performed and elements can be diffused.

It is preferable that the "brazing material 4b that melts during the diffusion heat treatment" has good wettability with respect to the metal material that constitutes the turbine component when it is subjected to the diffusion heat treatment and then melted after being attached. Here, the "wettability" is defined in "JIS Z3191 and evaluated by a spread test and a gap test. When the wettability is good, the inner wall surface of the crack 30 at the repair required portion 3 of the turbine component is determined. Of the absorption layer 5'(details described later), the absorption layer 5'can be quickly and sufficiently absorbed, so that the effect of the absorption layer can be more easily achieved.

According to the method for repairing a turbine component according to the embodiment of the present invention, a repair material can be applied to a plurality of repair-required points at the same time or sequentially using a cold spray (here, “a plurality of repair-needs are required”). The "location" means not only "a plurality of repair-required locations existing in the same turbine component" but also "a plurality of repair-required locations existing in a plurality of different turbine components". When adhering, it is not necessary that the inclination of each repair required portion is horizontal.

When the repair material 4 is filled in the crack 30 with cold spray or when the thinned portion 31 is covered, the opening of the crack 30 (that is, the opening of the crack 30 on the surface of the blade surface 2). It is preferable to attach the repair material 4′ so that the repair material 4′ rises or the volume of the metal thinned portion 31 is equal to or more than the volume reduction amount. Then, it is preferable that the repair material 4 ′ is simultaneously attached to the peripheral portion 32 of the crack 30 or the peripheral portion 32 of the thinned region 31. The repair material 4′ applied by cold spray is melted, for example, in the subsequent diffusion heat treatment, and a part thereof is absorbed by the absorption layer 5′, or the repair material 4′ applied by cold spray is contained in the repair material 4′. This is because the encapsulated components may separate during the subsequent diffusion heat treatment, and the volume of the repair material 4′ after coagulation and drying may be smaller than immediately after cold spraying.

Cold spraying can be performed in air, but in some cases, can be performed in a non-oxidizing gas atmosphere such as an inert gas.

<Absorption layer and step of forming absorption layer>
In the method for repairing a turbine component according to the embodiment of the present invention, a step of forming an absorption layer 5′ on the surface of the repair material 4′ attached by the above steps is performed.

This step can be performed, for example, by applying the forming material to be the absorbing layer 5'to the surface of the repair material 4'using a roller, a brush or the like, or using a conventional general sprayer or the like. However, in the embodiment of the present invention, it is preferable to employ the cold spray used when the repair material 4 is attached.

At this time, as a material for forming the absorbing layer 5', a film capable of forming a film on the surface of the repair material by cold spray, and the absorbing layer 5'is formed in contact with the surface of the repair material 4'. After that, it is preferable to use a material that does not melt under the temperature condition of the thermal diffusion treatment described later.

When the material for forming the absorption layer 5'is supplied to the cold spray device, it is preferable to supply it as a powder material having a particle diameter of 150 to 300 µm, particularly preferably 200 to 250 µm.

As a preferable specific example of the material for forming the absorption layer 5′, for example, Ni 10 to 40%, Cr 10 to 20%, and other Ni—Cr alloy powder material containing Si and Fe (melting temperature 1050 to 1100° C.) are used. Can be mentioned.

It is preferable that the material for forming the absorbing layer 5'has good wettability with respect to the brazing material melted during the thermal diffusion treatment. .

The absorption layer 5 ′ can be formed so as to cover the surface of the repair material 4 ′ attached to the turbine component 1. In particular, as shown in FIG. 1D, the absorbent layer 5 covers the surface of the turbine component 1 in addition to covering substantially all of the surface of the repair material 4 ′ attached to the turbine component 1. In addition to the peripheral portion 32 to which the repair material 4'is attached, the peripheral portion 33 to which the repair material 4'is not attached is preferably formed so as to be continuously covered. The thickness of the absorbent layer 5'is preferably about 2 to 3 mm, and is as thin as possible.

Thus, the absorption layer 5′ itself has a portion directly attached to the surface of the turbine component 1 (that is, a portion directly attached without the repair material 4′ (ie, the peripheral portion 33)). By doing so, the adhesive strength of the absorbent layer 5'is further improved, and the function of the absorbent layer 5'as a morphological stabilization layer for the repair material 4'is improved.

As a result, even if the repair-required portion 3 such as a crack is inclined, the molten brazing material 4b″ is absorbed by the absorbing layer 5′, and the absorbing layer 5′ is firmly attached to the turbine component. Therefore, the “molten brazing material 4b″” and the “powder material 4a′ that does not melt during the diffusion heat treatment” are prevented from flowing out from the repair-needed portion 3.

In particular, the absorbent layer 5′ is preferably a porous body, and has pores opened on the inner surface side of the absorbent layer 5′ (that is, the surface on the side of the repair material 4′), particularly, a plurality of pores. Those in which some of them are connected and linked are preferable.

Since the absorbent layer 5'having good wettability with respect to the brazing material and having a porous structure as described above has a good absorbing property for the molten brazing material 4b" and a high retaining ability for the brazing material b", It is possible to effectively prevent the repair material 4 ′ attached to the crack 30, the thinned portion 31, the peripheral portion 32 and the like from flowing out due to the inclination of the turbine component.

<Diffusion heat treatment>
In the method for repairing a turbine component according to the embodiment of the present invention, after the absorption layer 5'is formed, the repair material 4'is heated to a temperature equal to or higher than the melting temperature of the brazing material 4b' constituting the repair material 4'. A step of performing diffusion heat treatment is performed.

The temperature of the diffusion heat treatment can be appropriately determined depending on the content of the repair material 4', for example, the type of "the brazing material 4b' that melts during the diffusion heat treatment" and the like.

The temperature of the diffusion heat treatment is, for example, a Co-Ni-Cr alloy powder or a Ni-based alloy powder as the "powder material 4a' that does not melt during the diffusion heat treatment", and the "brazing material 4b that melts during the diffusion heat treatment" is used. When the Ni-Cr-Co-Si-B alloy powder is used as "", the temperature is 1050 to 1150°C, preferably 1070 to 1100°C. The temperature of the heat treatment for strengthening is preferably constant at a predetermined temperature within the above temperature range, but may be varied within the above temperature range.

The duration of the diffusion heat treatment is generally 10 minutes or longer and 30 minutes or shorter, preferably 15 minutes or longer and 20 minutes or shorter. If the diffusion heat treatment is not performed for a sufficient period of time, unmelting occurs. On the other hand, if the diffusion heat treatment is performed for an excessively long time, the number of steps is increased, which is not preferable.

After completion of the diffusion heat treatment, a step of solidifying the liquefied brazing material is performed. This step can be carried out, for example, by leaving the repaired turbine component in the air as it is, or by leaving it in a vacuum or in an atmosphere of a non-oxidizing gas such as an inert gas, or by blowing an inert gas. It can be cooled to room temperature by applying it.

According to the method for repairing a turbine component according to the embodiment of the present invention, the repair material applied to the “plurality of repair required points” can be simultaneously subjected to diffusion heat treatment, if necessary. In this diffusion heat treatment, it is not necessary that the inclination of each repair required portion is horizontal. Therefore, as in the prior art, for example, a molten brazing filler metal is filled in the crack, or a granular repair material filled in the crack, as compared with a repairing method consisting of heating and fluidizing it thereafter, Repair work can be performed extremely efficiently.

<Other processing steps>
In the method for repairing a turbine component according to the embodiment of the present invention, other processing steps can be carried out, if necessary, prior to the above-mentioned repair step. Examples of such other processing steps include cleaning processing, oxidation or corrosive substance removal processing, solution treatment, and the like. Here, the oxidizing or corrosive substance removing process is specifically a process step of removing a layer containing oxides and corrosive substances existing on the surface of the turbine component before repairing the damage. This removing step can be performed by, for example, mechanical polishing such as a blasting method including spraying fine particles, a grinding method using a grinder, or a reduction treatment using a reducing gas (for example, hydrogen gas or hydrogen fluoride). By carrying out this removal treatment step, it is possible to improve the flowability and permeability of the brazing material, the brazing strength, the welding strength and the like. Further, the solution treatment is, specifically, before the damage is repaired, the surface portion of the turbine component is heated to the solution temperature to homogenize and modify the metal structure forming the turbine component. It can be carried out. By carrying out this solution treatment, the weldability can be improved. The treatment temperature of the solution treatment is preferably 1150 to 1190°C, particularly preferably 1160 to 1180°C, and the treatment time is preferably 30 to 480 minutes, particularly preferably 120 to 240 minutes.

In the turbine component repairing method according to the embodiment of the present invention, after repairing, for example, the repaired portion of the turbine component in FIG. 1 is flattened or the function as the turbine component is restored or improved, if necessary. In order to do so, a shape correction process such as polishing can be performed. Examples of the polishing include mechanical polishing such as a blasting method including spraying fine particles and a grinding method using a grinder.

[Method for manufacturing repaired turbine parts]
A method of manufacturing a repaired turbine component according to an embodiment of the present invention comprises:
A process of attaching a repair material by cold spray to the place where the turbine component needs to be repaired,
A step of forming an absorption layer on the surface of the attached repair material,
A step of heating the repair material to a temperature equal to or higher than a melting temperature of a brazing material constituting the repair material, performing diffusion heat treatment, and performing repair;
Solidifying the liquefied brazing material,
Is included.

The step of adhering the repair material in the method of manufacturing the repaired turbine component, the step of forming the absorbent material layer, and the step of performing the repair are respectively substantially the same as the steps in the repair method of the turbine component described above. It is a thing. Each of these steps is as described in detail in the above section [Method for repairing turbine parts].

Although the method for repairing a turbine component and the method for manufacturing a repaired turbine component according to some embodiments of the present invention have been described above, these embodiments are presented as examples and limit the scope of the invention. Not a thing. These embodiments can be implemented in various other forms, and various omissions, replacements, changes or additions can be made without departing from the spirit of the invention. These embodiments and their modified examples are included in the scope and the gist of the invention, and are also included in the invention described in the claims and the equivalent scope thereof.

An embodiment of a method for repairing diffusion brazing for cracking and thinning a gas turbine high temperature component according to the present invention will be described below with reference to the drawings.
FIG. 2 schematically shows the flow of a particularly preferable repair method according to this embodiment.

The repair method shown in FIG. 2 is an acceptance inspection 11, removal of an oxidation/corrosion layer 12, adhesion of repair material using cold spray 13, absorption formation using cold spray 14, diffusion heat treatment 15, removal of absorption layer. This is a method in which the steps 16 and the pre-shipment inspection 17 are performed in this order.

<Example 1>
In Example 1, an experiment was carried out for repairing the above-mentioned cracks and wall thinning by using the same material as that of the stationary blade of the actual machine and using a material simulating the cracks in a laboratory. Since the laboratory test material is used, the acceptance inspection, removal of the oxidation/corrosion layer, removal of the absorption layer, and pre-shipment inspection shown in FIG. 2 are omitted. The turbine component to be repaired is made of Co-based superalloy FSX414 shown in Table 1 below.

Here, as shown in FIG. 3, a groove 19 was formed by wire cutting in order to simulate a crack in the substrate-shaped turbine component 18 (FIG. 3A) (FIG. 3B). Next, after degreasing and cleaning the entire material in advance to remove oil and dirt during processing, the repair material was attached by cold spray to the groove 19 created above (FIG. 3C). The repair material used was a mixture of Ni-based molten alloy powder and Co-based non-melting alloy powder. The adhered Ni-based molten alloy powder 20' is a Ni-Cr-Co-Si-B system, and the adhered Co-based non-molten alloy powder 21' is a Co-Ni-Cr system. On top of that, in order to prevent the repair material from flowing out during the diffusion heat treatment, a Ni—Cr alloy powder having a melting point equal to or higher than the diffusion heat treatment temperature is cold sprayed to form an absorption layer 22′ having a porous structure. Formed (FIG. 3D).

Next, the test material prepared as described above was charged into a vacuum heat treatment furnace, subjected to diffusion heat treatment at 1090° C., and then the cross section of the repaired portion was observed. FIG. 3 shows a schematic view of a cross section along with the cross section in each process.

After the diffusion heat treatment, the repaired part has a structure in which the Co-based non-melting alloy powder 21′ and the solidified product 20″ of the melt derived from the Ni-based melting alloy powder 20′ are uniformly mixed, and voids and the like are present. It was confirmed that there was no sound repair part (FIG. 3E), and after the diffusion heat treatment, the Ni-base molten alloy showed a form of seeping into the gaps of the absorption layer 22′. 'Becomes a liquid, and it is thought that it became such a form due to the capillary phenomenon.

According to the first embodiment, the crack can be filled with the repair material, and even if the repair surface is inclined, the repair material preferentially penetrates into the gap of the absorbent layer 22', so that the repair material can be prevented from flowing out.

<Example 2>
Here, an example is shown in which the stationary blade used in the actual plant is a Co-based superalloy gas turbine first-stage stationary blade that is equivalent to the material shown in Table 1. The repair method here was performed according to the procedure shown in FIG.

Since this first stage stationary blade has been used for a long time in an actual machine, an oxide film has been formed on the surface of the crack 23 to be repaired, and in this state the brazing material does not get wet, so in a hydrogen atmosphere Then, the oxide on the crack surface was removed by heat treatment.

As the repair material, a mixture of Ni-based molten alloy powder and Co-based non-molten alloy powder was used. The Ni-based molten alloy powder is a Ni-Cr-Co-Si-B system, and the Co-based non-molten alloy powder is a Co-Ni-Cr system. These were sprayed by cold spray to the inside and the periphery of the crack 23 of the blade portion 24 of the first stage stationary blade.

In addition, in order to prevent the repair material from flowing out during the diffusion heat treatment, a Ni—Cr alloy powder having a melting point equal to or higher than the diffusion heat treatment temperature is cold sprayed to form an absorption layer 25′ having a porous structure. Formed.

Next, the test material prepared as described above was charged into a vacuum heat treatment furnace, subjected to diffusion heat treatment under the condition of 1080° C., and then the cross section of the repaired portion was observed. FIG. 4 shows a schematic view of the cross section.

After the diffusion heat treatment, the repaired part has a structure in which the Co-based non-melting alloy powder 26′ and the solidified product 27″ of the melt derived from the Ni-based melting alloy powder are uniformly mixed, and there is no cavity and the like. It was confirmed that the Ni-based molten alloy powder permeated into the gaps of the absorption layer 25' after the diffusion heat treatment. It is considered that such a shape is caused by the phenomenon.In addition, the crack 23 penetrates to the opposite surface, and the repair material is also used for the inner wall portion 28 and the outer wall portion 29 of the stationary blade in which the repair surface is vertical. No outflow was observed.

FIG. 5 is a schematic diagram when the absorbent layer 25 ′ and the bulging portion of the repair material of FIG. 4 are removed by a grinder to finish the surface, and after visual inspection, the repair portion is cut and a cross-section is observed. No defects were found inside or on the surface of the repaired part, confirming that the repair was sound.

Next, the high temperature strength of the repaired part was confirmed. FIG. 6 shows the number of repeated cycles of failure of the test piece 40 (3 samples) including the repaired portion of the repaired vane by the low cycle fatigue test in comparison with the equivalent value of the unused vane 41 (3 samples). Although there is some variation in the test data, the number of repeated damages of the repair material 40 was almost the same as that of the unused stationary blade 41.

According to the second embodiment, even if the crack penetrates in any direction, the crack is filled with the repair material, and the repair object is not deformed, and the temperature is the same as that of the material not repaired. It can be repaired for strength and can be reused. In addition, the repair material is not limited to cracks, but the present method is also effective for repairing a damaged damaged portion that is thinned by oxidation or erosion.

<Example 3>
Here, an example in which the second stage stationary blade of a gas turbine used in an actual plant is a repair target is shown. This vane is made of a Ni-base superalloy shown in Table 2 below.

The repair method here was performed according to the procedure shown in FIG.

Since this second stage stationary blade has been used for a long time in an actual machine, an oxide film has been formed on the surface of the crack 43 to be repaired, and in this state the brazing material does not get wet, so in a hydrogen fluoride atmosphere. Heat treatment was performed to remove the oxide on the crack surface. When the heat treatment in a hydrogen fluoride atmosphere cannot be performed, the oxide layer around the crack can be mechanically removed by a grinder or the like.

As the repair material, a mixture of Ni-based molten alloy powder and Ni-based non-molten alloy powder having a similar component to the metal material forming the stationary blade was used. The Ni-based molten alloy powder is Ni-Cr-Co-Si-B system, and the Ni-based non-molten alloy powder is Ni-Co-Cr system. These were sprayed by cold spray to the inside and the periphery of the crack 43 of the blade portion 44 of the second stage stationary blade.

In addition, in order to prevent the repair material from flowing out during the diffusion heat treatment, a Ni—Cr alloy powder having a melting point equal to or higher than the diffusion heat treatment temperature is cold sprayed to form an absorption layer 45′ having a porous structure. Formed.

Next, the test material prepared as described above was charged into a vacuum heat treatment furnace, subjected to diffusion heat treatment at 1090° C., and then the cross section of the repaired portion was observed. FIG. 7 shows a schematic view of the cross section.

After the diffusion heat treatment, the repaired part has a structure in which the Ni-based non-melting alloy powder 46′ and the solidified material 47″ of the melt derived from the Ni-based melting alloy powder are uniformly mixed, and there is no void and the like. It was confirmed that the Ni-based molten alloy powder permeated into the gaps of the absorption layer 45′ after the diffusion heat treatment. It is considered that such a shape is caused by the phenomenon.In addition, the crack 43 penetrates to the opposite surface, and the repair material is also used for the inner wall portion 48 and the outer wall portion 49 of the stationary blade in which the repair surface is vertical. No outflow was observed.

FIG. 8 is a schematic diagram when the absorbent layer 45 ′ and the bulging portion of the repair material in FIG. 7 are removed by a grinder to finish the surface and after visual inspection, the repair portion is cut and a cross-section is observed. No defects were found inside or on the surface of the repaired part, confirming that the repair was sound.

Next, the high temperature strength of the repaired part was confirmed. FIG. 9 shows the number of repetitions of breakage by the low cycle fatigue test in the test piece 50 (3 samples) including the repaired portion of the repaired vane in comparison with the value of the unused vane 51 (3 samples). Although there was some variation in the test data, the number of repeated damages of the repair material was almost the same as that of the unused stationary blade 43.

According to the third embodiment, the cracks in any direction are filled with the repair material even if the crack penetrates, and the high temperature equivalent to that of the material that is not repaired is obtained without deforming the repair object. It can be repaired for strength and can be reused. In addition to the cracks, this method is also effective for repairing not only cracks but also recessed damaged parts thinned by oxidation or erosion.

〔Effect of the invention〕
As described above, in the crack of the gas turbine high temperature component according to the present invention, the diffusion brazing repair method for reducing the wall thickness and the high temperature component thereof, cracks in different directions, even cracks that have penetrated are filled with the brazing repair material, and repaired. There was no outflow of material, and it was confirmed that the high temperature strength was almost the same as the base material. In addition, it was not necessary to carry out the diffusion brazing process in multiple times, and rational repairs could be achieved.

DESCRIPTION OF SYMBOLS 1... Turbine stationary blade, 2... Blade surface, 3... Location requiring repair, 30... Crack, 31... Thinned portion, 32... Peripheral portion, 4'... Attached repair agent, 4a'... Adhesion of powder material that does not melt during diffusion heat treatment, 4b'... Adhesion of brazing material that melts during diffusion heat treatment, 4b"... Solidified brazing material, 5'... Absorption layer, 11... Acceptance inspection , 12...removal of oxidation/corrosion layer, 13...adhesion of repair material using cold spray, 14...adhesion of absorption using cold spray, 15...diffusion heat treatment, 16...absorption layer removal, 17...pre-shipment inspection , 18... Turbine parts, 19... Grooves, 20'... Adhering Ni-based molten alloy powder, 21'... Adhering Co-based non-melting alloy powder, 22'... Absorption layer, 23... Crack, 24... Wing portion, 25 '... Absorption layer, 26'... Co-based non-melting alloy powder, 27"... Solidification product of melt derived from Ni-based melting alloy powder, 28... Inner wall part, 29... Outer wall part, 40... Repaired stationary blade , 41... Unused stationary blade, 43... Crack, 44... Wing portion, 45'... Absorption layer, 46'... Ni-based non-melting alloy powder and 47"... Solidified material, 48... Inner wall portion, 49... Outer wall portion, 50... Repaired stationary blade, 51... Unused stationary blade

Claims (9)

A process of attaching a repair material by cold spray to the place where the turbine component needs to be repaired,
A step of forming an absorption layer on the surface of the attached repair material,
Heating the repair material to a temperature equal to or higher than the melting temperature of the brazing material forming the repair material, and performing a diffusion heat treatment;
Solidifying the liquefied brazing material,
A method of repairing a turbine component, comprising: The method for repairing a turbine component according to claim 1, wherein the absorption layer is formed by using cold spray. The method for repairing a turbine component according to claim 1 or 2, wherein the repair material includes a brazing material that melts during the diffusion heat treatment and a powder material that does not melt during the diffusion heat treatment. The method of repairing a turbine component according to claim 3, wherein the brazing filler metal that melts during the diffusion heat treatment contains a powder material of a Ni-based alloy. The method for repairing a turbine component according to claim 3 or 4, wherein the powder material that does not melt during the diffusion heat treatment includes a Co-based alloy powder material or a Ni-based alloy powder material. The portion requiring repair of the turbine component is a crack or through hole generated by the use of the turbine component, or a metal thinning region caused by wear. 7. How to repair turbine parts. The said absorption layer has a porous structure, The repair method of the turbine component of any one of Claims 1-6. The turbine component according to any one of claims 1 to 7, wherein the turbine component is selected from a vane of a gas turbine, a moving blade, a combustor liner, a transition piece, a shroud segment, and a compressor. Repair method. A process of attaching a repair material by cold spray to the place where the turbine component needs to be repaired,
A step of forming an absorption layer on the surface of the attached repair material,
Heating the repair material to a temperature equal to or higher than the melting temperature of the brazing material constituting the repair material, and performing a diffusion heat treatment;
Solidifying the liquefied brazing material,
A method of manufacturing a repaired turbine component, comprising:

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