JP2010203258A - Repairing method of moving blade - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a repairing method of a moving blade allowing use of the repaired moving blade without problems even when the repaired moving blade is applied to a rotating machine such as a gas turbine. <P>SOLUTION: In the repairing method of the moving blade for repairing a fin 8a vertically provided on an outer surface of a tip shroud, powder building-up is carried out using a laser device 9 while supplying powder of heat resistant super alloy containing 3-5 wt.% of Al and 2-3.5 wt.% of Ti on a surface of the fin, and the damaged fin is repaired. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a moving blade repair method applied to a gas turbine or the like.

  A moving blade applied to a gas turbine includes a tip provided with a fin at a tip portion for minimizing a gap with a stationary component located outside thereof and suppressing gas leakage of combustion gas as much as possible (for example, Patent Document 1).

Japanese Patent Laid-Open No. 10-306702

However, the gap between the fin and the stationary component located outside the fin is further reduced by deformation of the stationary component side (casing side) during operation of the gas turbine, expansion of the moving blade by centrifugal force, or the like. In this case, the fin and the stationary part come into contact with each other, and the fin and the stationary part may be damaged by contact wear. And most of the damage on the blade side occurs only on the fins, and it is economical to replace the blades with new ones only by damaging the fins and discard the blades damaged only on the fins. It is not preferable from the viewpoint of viewpoint and environmental protection.
Also, with conventional repair methods, cracks occur in the repaired part during construction, and it cannot be repaired well, or even though it can be repaired apparently, the strength of the repaired part is insufficient. There is a problem that it cannot be used for rotating machines such as turbines.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for repairing a moving blade that can be used without problems even if the repaired moving blade is applied to a rotary machine such as a gas turbine. And

The present invention employs the following means in order to solve the above problems.
A blade repair method according to the present invention is a blade repair method for repairing fins erected on the outer surface of a tip shroud, wherein Al is 3 wt% or more and 5 wt% or less on the fin surface. While supplying a heat-resistant superalloy powder containing 2 wt% or more and 3.5 wt% or less, powder overlaying was performed using a laser device to repair the damaged fins.

According to the method for repairing a moving blade according to the present invention, the repaired repaired portion has sufficient strength to withstand the rotation of a rotating machine such as a gas turbine. It can be used without any problem in the rotating machine.
In addition, after repairing a rotor blade with only a damaged fin, it is reused in a rotating machine such as a gas turbine, and the frequency of replacement with a new rotor blade is greatly reduced, greatly reducing running costs. be able to.

  In the above-described method for repairing a moving blade, it is more preferable that laser light that forms a uniform heat source on the same surface or on the same line is emitted from the laser head of the laser device toward the repair portion of the fin. .

  According to such a moving blade repairing method, it is avoided that the laser beam is concentrated on one point of the repaired part, and the repaired part is heated in a planar shape or a linear shape. The temperature gradient (temperature difference) between the (irradiated) region and other regions can be minimized, the generation of thermal stress can be minimized, and the strength of the repaired part can be further improved Can do.

  In the above-described method for repairing a moving blade, it is more preferable that the repaired portion of the fin and its surroundings are carried out while preheating at a high temperature of 900 ° C. to 1100 ° C.

  According to such a moving blade repair method, the temperature gradient (temperature difference) between the area where the laser light is applied (irradiated) and other areas can be further reduced, and thermal stress is generated. Can be further reduced, and the strength of the repaired portion can be further improved.

  In the above moving blade repairing method, it is more preferable that the laser head of the laser device is automatically moved using a manipulator.

  According to such a moving blade repairing method, the welding operation is performed mechanically and automatically, so that variations in construction and strength can be eliminated.

  In the above-described method for repairing a moving blade, it is more preferable to perform solution heat treatment in the middle of multilayer welding by the powder overlaying.

  According to such a method of repairing a moving blade, residual stress in the lower layer of the repaired portion can be removed, cracking of the repaired portion can be prevented, and the repaired portion can be made sound.

  In the above-described method for repairing a moving blade, it is more preferable that a peening process is performed on a repaired part of the fin including a welded part heat-affected part before the solution heat treatment is performed.

  According to such a moving blade repairing method, it is possible to leave compressive stress on the surface of the repaired part including the heat affected part of the welded part, to prevent reheat cracking during heat treatment, Soundness can be achieved.

  In the above-described method for repairing a moving blade, it is more preferable that a ceramic coating is applied in advance to the outer surface of the tip shroud. The ceramic coating here may be a thermal spraying method or a simple spraying method (such as spray application of a release agent (BN boron nitride)).

  According to such a moving blade repairing method, the outer surface of the tip shroud is protected from heat. Therefore, the outer surface of the tip shroud is leaked from the peripheral edge of the repaired portion to the outer surface of the tip shroud. It is possible to prevent cracks from occurring.

  In the above-described method for repairing a moving blade, after the powder build-up is completed, the repaired portion of the fin and its periphery are heated again to 1100 ° C., held in that state for 15 minutes, and then at a rate of 10 ° C. or less per minute It is more preferable to gradually cool to 800 ° C.

  According to such a moving blade repairing method, the residual stress of the entire repaired part is removed, so that the repaired part can be prevented from cracking and the repaired part can be made sound.

  According to the method for repairing a moving blade according to the present invention, even if the repaired moving blade is applied to a rotary machine such as a gas turbine, it can be used without any problem.

It is sectional drawing which shows the structural example of a gas turbine. It is a figure which shows the structure of the moving blade applied to a gas turbine, Comprising: (a) is a top view, (b) is a side view of a front-end | tip part. It is a figure for demonstrating the outline | summary of the repair method of the moving blade which concerns on this invention. It is a chart comparing the tensile strength at room temperature. It is the chart which compared the tensile strength in 625 degreeC. It is the chart which compared the tensile strength in 850 degreeC. It is a graph which shows the result of a ballast rain test. It is a figure which shows the shape of a laser beam suitable for applying to the repairing method of the moving blade which concerns on this invention. It is a figure which shows the movement path | route (trajectory) of a laser beam suitable for applying to the repair method of the moving blade which concerns on this invention, Comprising: (a) is the figure seen from upper direction, (b) is the figure seen from the side. It is. It is a figure which shows the movement path | route (trajectory) of a laser beam suitable for applying to the repair method of the moving blade which concerns on this invention, Comprising: (a) is the figure seen from upper direction, (b) is the figure seen from the side. It is. It is a figure which shows the lamination | stacking process of the built-up part suitable for applying to the repair method of the moving blade which concerns on this invention.

Hereinafter, a method for repairing a moving blade according to an embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, the moving blade 1 includes, for example, a compression section (not shown) that compresses combustion air, and injects fuel into high-pressure air sent from the compression section and burns it. Is applied to a gas turbine 4 that includes a combustion section 2 that generates a combustion gas and a turbine section 3 that is located downstream of the combustion section 2 and is driven by the combustion gas exiting the combustion section 2. is there. Moreover, the code | symbol 5 in FIG. 1 is a casing, and the code | symbol 6 is a disk. The moving blade 1 attached to the disk 6 is rotated at high speed by the combustion gas sent from the combustion unit 2.
In addition, the white arrow in FIG. 1 has shown combustion gas.

  As shown in FIG. 2, a moving blade (also referred to as “gas turbine moving blade”) 1 includes a tip shroud provided with a tip shroud 7 at a tip portion (tip portion) opposite to the root portion embedded in the disk 6. It is a moving blade. On the outer (tip side) surface of the chip shroud 7, fins 8 for suppressing (reducing) the combustion gas flowing through the gap with the casing 5 as much as possible are provided outward. It will be repaired by the moving blade repairing method according to the invention.

  The rotor blade 1 applied to the turbine part 3 of the gas turbine 4 is exposed to high-temperature combustion gas. Therefore, the moving blade 1 applied to the turbine section 3 of the gas turbine 4 is made of a Ni-base superalloy represented by Inconel (registered trademark) 738LC (hereinafter referred to as “IN738LC”) or the like (can be done). ing).

Next, the outline of the moving blade repair method according to the present invention will be described with reference to FIG.
As shown in FIG. 3, in the method for repairing a moving blade according to the present invention, first, a material (melting material) to be a build-up material is selected, and then a construction method and construction conditions including preheating are selected.
Next, confirm the workability such as stability and reproducibility, and examine whether other contradictory events can be eliminated.
Then, it is examined whether or not the damaged portion of the fin 8 can be repaired in a defect occurrence state within an allowable defect depending on the selected material, construction method, and construction condition, and the damaged portion of the fin 8 is selected with the selected material and construction. If it is determined that repair is not possible within the permissible defects according to the method and construction conditions, the repair method is reviewed from the selection of the above materials, and the damaged portion of the fin 8 can be repaired by the above materials, construction methods and construction conditions. If it is determined, whether or not the portion repaired by the repair method has the required strength is examined. As a result, if it is determined that it does not have the required strength, review the repair method from the selection of the above materials, and if it is determined that it has the required strength, The damaged portion of the fin 8 is repaired by the repairing method (the repairing method is adopted).

As a material for the build-up material, a material having a low content of Al and Ti (a heat-resistant superalloy containing 0.1 to 1.5 wt% of Al and 0.1 to 3 wt% of Ti (for example, Inconel ( (Registered trademark) 625 (hereinafter referred to as “IN625”) is advantageous in that it is easy to weld.
On the other hand, as shown in FIG. 4, such a material (for example, IN625) is a heat-resistant superalloy containing 3 wt% to 5 wt% Al and 2 wt% to 3.5 wt% Ti at room temperature (room temperature). For example, although it has a tensile strength that is not much different from that of Patent No. 3957261, IN738LC), as shown in FIGS. 5 and 6, the tensile strength at high temperature is 3 wt% or more and 5 wt% or less of Al. There is a demerit that it is considerably lower (inferior) than a heat-resistant superalloy containing 2 wt% or more and 3.5 wt% or less (for example, Japanese Patent No. 3957261, IN738LC). Therefore, a material with a low content of Al and Ti (a heat-resistant superalloy containing 0.1 to 1.5 wt% of Al and 0.1 to 3 wt% of Ti (for example, IN625)) is used as a cladding material. The choice is not the best choice in terms of strength.

Therefore, it is difficult to weld, but the tensile strength at high temperature is high (excellent), a heat-resistant superalloy containing 3 wt% or more and 5 wt% or less of Al and 2 wt% or more and 3.5 wt% or less of Ti (for example, Japanese Patent No. 3957261, IN738LC) will be selected as the build-up material.
Here, in Patent No. 3957261 material containing about 3 wt% Al and about 2 wt% Ti, and IN738LC containing about 3.5 wt% Al and about 3.3 wt% Ti, the Patent No. 3957261 material is better. Since the content of Al and Ti is small, it is easier to weld than IN738LC, and as shown in FIG. 7, the result of the ballestrain test is also very good compared to IN738LC. It can be said that it is suitable (preferred).

Next, as a construction method, the damaged portion of the fin 8 and its periphery are formed at a high temperature of 900 ° C. or higher and 1100 ° C. or lower (a temperature close to the melting point of the base material forming the moving blade 1 and the moving blade 1 is formed. Powder using a laser device that forms a uniform laser beam (beam: heat source) in a rectangular shape (square shape in this embodiment) as shown in FIG. 8 while preheating at a temperature lower than the melting point of the base material After the overlaying of the powder, the overlaying part (repair part) and its surroundings are heated again to 1100 ° C. and held in that state for 15 minutes, at a rate of 10 ° C. or less per minute, A method of slow cooling to 800 ° C. is suitable (preferably).
On the other hand, the conditions of the powder overlay using a laser are: laser input power of 500 W or less, laser moving speed of 0.15 m or less per minute, and the length of one side of the laser beam of 2 mm (see FIG. 8). The supply amount of the powdered material is preferably 5 g or less per minute.

Here, it is preferable to move the laser beam automatically using a manipulator from the viewpoint of reproducibility, and it is not preferable to move the laser beam manually because it is not reproducible.
Further, the laser beam is preferably moved so as to draw the locus shown in FIG. 9 or FIG. 10 (that is, moved in the longitudinal direction while oscillating from one side edge to the other side edge of the damaged fin 8a). .
9 and 10, reference numeral 9 denotes a laser head, and reference numeral 10 denotes a laser beam.

Furthermore, as shown in FIG. 11, the overlay is preferably multilayer welding in which the second layer is stacked on the first layer and the third layer is stacked on the second layer. More preferably, a solution heat treatment (for example, a heat treatment heated at 1120 ° C. for 4.5 hours) for removing residual stress is performed before the fourth layer is stacked on the layer.
In addition, before carrying out the solution heat treatment, in order to prevent reheat cracking during the heat treatment, peening treatment (treatment for leaving compressive stress on the surface) on the overlay including the heat affected zone (HAZ portion) of the welded portion. ) Is more preferable.

  Furthermore, in order to prevent the outer surface of the chip shroud 7 from being cracked by laser light leaking from the peripheral edge of the built-up portion to the outer surface of the chip shroud 7, a ceramic coating (for example, It is preferable to apply a thermal barrier coating (only the top coat of the thermal barrier coating). The ceramic coating here may be a thermal spraying method or a simple spraying method.

  Then, when the build-up portion is stacked to a desired (predetermined) height, the build-up portion is shaved by electric discharge machining or the like so that a portion indicated by a broken line remains in the right side of FIG.

According to the moving blade repairing method of the present embodiment, the heat-resistant superalloy powder containing Al 3 wt% or more and 5 wt% or less and Ti 2 wt% or more and 3.5 wt% or less is supplied to the surface of the damaged fin 8a. On the other hand, powder deposition is performed using a laser device to repair the damaged fins 8a.
As a result, the repaired repaired portion has sufficient strength to withstand the rotation of the gas turbine, so that the repaired moving blade can be used for the gas turbine without any problem.
In addition, since the blades in which only the fins 8 are damaged are repaired and reused in the gas turbine, the frequency of replacement with new blades is greatly reduced, so that the running cost can be greatly reduced. .

Further, a laser beam that forms a uniform heat source in a rectangular shape (on the same surface) is emitted from the laser head 9 of the laser device toward the surface of the damaged fin 8a.
As a result, it is avoided that the laser beam is concentrated on one point of the repaired part, and the repaired part is heated in a planar shape, so that the region irradiated with the laser beam (irradiated) and other regions The temperature gradient (temperature difference) can be minimized, the generation of thermal stress can be minimized, and the strength of the repaired portion can be further improved.

Furthermore, the fin repaired part and its periphery are carried out while preheating at a high temperature of 900 ° C. or higher and 1100 ° C. or lower.
As a result, the temperature gradient (temperature difference) between the region where the laser light is applied (irradiated) and other regions can be further reduced, and the generation of thermal stress can be further reduced, The strength of the repaired part can be further improved.

Furthermore, the laser head 9 of the laser apparatus is automatically moved using a manipulator.
Thereby, since welding work is performed mechanically and automatically, it is possible to eliminate variations in construction and variations in strength.

Furthermore, solution heat treatment is performed in the middle of multilayer welding by powder overlaying.
Thereby, the residual stress of the lower layer of a repair part can be removed, the crack of a repair part can be prevented, and the soundness of a repair part can be aimed at.

Furthermore, before performing the solution heat treatment, the peening process is performed on the repaired portion of the fin including the heat affected zone of the weld.
Thereby, compressive stress can be left on the surface of the repaired part including the heat affected part of the welded part, reheat cracking during heat treatment can be prevented, and the repaired part can be made sound.

Furthermore, a ceramic coating is applied in advance to the outer surface of the chip shroud 7. The ceramic coating here may be a thermal spraying method or a simple spraying method.
As a result, the outer surface of the tip shroud 7 is protected from heat, so that the laser light leaking from the peripheral edge of the repaired portion to the outer surface of the tip shroud 7 causes the outer surface of the tip shroud 7 to crack. Can be prevented.

Furthermore, after the powder build-up is completed, the repaired part of the fin and its surroundings are heated again to 1100 ° C., held in that state for 15 minutes, and then gradually cooled to 800 ° C. at a rate of 10 ° C./min I have to.
Thereby, since the residual stress of the whole repair part is removed, the crack of a repair part can be prevented and the soundness of a repair part can be aimed at.

In addition, this invention is not limited to embodiment mentioned above, In the range which does not deviate from the summary of this invention, it can change suitably.
The blade repair method according to the present invention is not only applicable to gas turbine blades mounted on gas turbines, but is mounted on other rotating machines (steam turbines, exhaust turbine superchargers, etc.). It can also be applied to a moving blade.

1 Rotor 7 Chip shroud 8 Fin 9 Laser head 10 Laser light

Claims (8)

A method of repairing a moving blade for repairing a fin erected on an outer surface of a tip shroud,
While spraying a powder of a heat-resistant superalloy containing 3 wt% or more and 5 wt% or less of Al and 2 wt% or more and 3.5 wt% or less of Ti on the surface of the fin, powder overlaying is performed using a laser device, A method for repairing a moving blade, comprising repairing the damaged fin.   The repair of a moving blade according to claim 1, wherein a laser beam forming a uniform heat source is emitted on the same surface or on the same line from the laser head of the laser device toward the repair portion of the fin. Method.   The method of repairing a moving blade according to claim 1 or 2, wherein the repair portion of the fin and its periphery are preheated at a high temperature of 900 ° C or higher and 1100 ° C or lower.   The method of repairing a moving blade according to any one of claims 1 to 3, wherein the laser head of the laser device is automatically moved using a manipulator.   5. The blade repair method according to claim 1, wherein a solution heat treatment is performed in the middle of the multi-layer welding by the powder overlaying.   The blade repair method according to claim 5, wherein a peening process is performed on the repaired portion of the fin including the heat affected zone of the fin before the solution heat treatment is performed.   The method of repairing a moving blade according to any one of claims 1 to 6, wherein a ceramic coating is applied in advance to an outer surface of the tip shroud. After completion of the powder build-up, the repaired portion of the fin and its surroundings are heated again to 1100 ° C., held in that state for 15 minutes, and then gradually cooled to 800 ° C. at a rate of 10 ° C. or less per minute. The method for repairing a moving blade according to any one of claims 1 to 7, characterized in that:

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