Repair methods for sealing fins

Abstract

A method for repairing the sealing fins of a steam turbine rotor includes: a welding step, which welds onto the damaged portion of the sealing fin to form an additional fin at the damaged portion; and a tempering step, which uses an electric arc discharge or laser to heat the heat-affected zone of the sealing fin caused by the welding, thereby tempering the heat-affected zone.

Description

Technical Field

[0001] This invention relates to a method for repairing sealing fins. This case asserts priority based on Japan Patent Application No. 2024-200272 filed with the Japan Patent Office on November 18, 2024, the contents of which are incorporated herein by reference. Prior Technology

[0002] The sealing fins of a steam turbine rotor are exposed to high temperatures during turbine operation, and thus can be damaged over time due to contact with components on the casing side or oxidation. Patent Document 1 discloses a method for repairing damage to the sealing fins at the leading end of a turbine rotor blade, which involves welding over the damaged area of ​​the fin, sandblasting the boundary between the fin and the weld, and then performing a melt-processing treatment. [Previous Technical Documents] [Patent Literature]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2009-191716 Summary of the Invention

[0004] [The problem the invention aims to solve] The repair method for the sealing fins described in Patent Document 1 requires electrical discharge machining to remove the unevenness or deteriorated layer that accompanies the sandblasting process, which increases the number of repair steps and easily leads to a long repair period.

[0005] In view of the above, at least one embodiment of the present invention aims to provide a method for repairing sealing fins, which can repair the sealing fins of a steam turbine rotor in a short period of time. [Technical means to solve the problem]

[0006] To achieve the above objectives, at least one embodiment of the present invention provides a method for repairing sealing fins. This is a repair method for the sealing fins of the rotor of a steam turbine, which includes: The welding step involves welding over the damaged area of ​​the aforementioned sealing fins, thereby forming additional fins at the damaged area; and The tempering process involves applying heat to the heat-affected zone of the aforementioned sealing fins caused by the aforementioned weld overlay using an electric arc discharge or laser, thereby tempering the aforementioned heat-affected zone. [Effects of the Invention]

[0007] According to at least one embodiment of the present invention, a method for repairing sealing fins is provided, which can repair the sealing fins of a steam turbine rotor in a short period of time. Simple Explanation of the Diagram

[0008] [Figure 1] A diagram illustrating the applicable object of a repair method for a sealing fin 8 in one embodiment. [Figure 2] is a flowchart showing a repair method for a sealing fin 8 in one embodiment. [Figure 3] A diagram used to illustrate an example of weld overlay. [Figure 4] A diagram used to illustrate one example of tempering treatment. [Figure 5] A diagram used to illustrate another example of tempering treatment. [Figure 6] is an example of a graph showing the relationship between the parameter d of the damage amount of the sealing fin 8 and the heat input. [Figure 7] A diagram illustrating the applicable objects of the repair method for the sealing fin 8 in other embodiments. Implementation

[0009] Hereinafter, several embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, and relative arrangements of the constituent parts described or shown as embodiments are not intended to limit the scope of the present invention, but are merely illustrative examples. For example, the relative or absolute configuration of "in a certain direction", "along a certain direction", "parallel", "orthogonal", "center", "concentric" or "coaxial" does not strictly represent only this configuration, but also includes tolerances, or the state of relative displacement with angles or distances that can achieve the same function. For example, the expression of the state of equality of things such as "same", "equal" and "homogeneous" does not strictly represent only the state of equality, but also includes tolerance, or the existence of a state where there is a difference in the degree to which the same function can be obtained. For example, the representation of shapes such as square shapes or cylindrical shapes does not only represent the shapes of square shapes or cylindrical shapes in a strict geometric sense, but also includes shapes with concave or convex parts or chamfered parts within the range that can achieve the same effect. On the other hand, expressions such as "having", "possessing", "having", "containing", or "having" a constituent element are not expressions of exclusivity that exclude the existence of other constituent elements.

[0010] Figure 1 is a diagram illustrating the applicable object of a repair method for a sealing fin 8 in one embodiment. As partially shown in Figure 1, the following describes a method for repairing the sealing fins 8 located at the leading edge 6a of the rotor 6 of a steam turbine 2. In the example shown in Figure 1, the sealing fins 8 are located at the leading edge 6a of the rotor 6 to suppress leakage through the gap between the housing (not shown) housing the rotor 4 and the leading edge 6a of the rotor 6. The sealing fins 8 can be made of metal materials such as high-chromium steel, low-chromium steel, low-alloy steel, or nickel-based alloys. The sealing fins 8 located on the rotor 4 of the steam turbine 2 are exposed to high-temperature environments during the operation of the steam turbine 2, and may become damaged over time due to contact with components on the housing side (not shown) or oxidation. Several examples of methods for repairing the damaged portion 8a of the sealing fins 8 will be described below using Figures 2 to 5.

[0011] Figure 2 is a flowchart illustrating a repair method for the sealing fin 8 in one embodiment. Figure 3 is a diagram illustrating an example of weld overlay. Figure 4 is a diagram illustrating an example of tempering treatment. Figure 5 is a diagram illustrating another example of tempering treatment.

[0012] As shown in Figure 2, in S101, the damaged portion 8a of the sealing fin 8 (refer to Figure 1) is treated before welding. For example, foreign matter, welding material, coatings, etc., adhering to the damaged portion 8a are removed. Furthermore, in cases where the amount of damage varies depending on the position along the length of the sealing fin 8 (for example, where the height of the sealing fin 8 deviates due to its position along the length of the sealing fin 8), the height of the sealing fin 8 can be fixed at all positions along its length, and machining can be applied to the front end of the sealing fin 8. This suppresses welding defects and allows for proper repair of the sealing fin 8. Also, the length direction of the sealing fin 8 can be the axial direction of the rotor 4, and the height direction of the sealing fin 8 can be the radial direction of the rotor 4. Moreover, the damaged portion 8a of the sealing fin 8 refers to the portion where the height of the sealing fin 8 is reduced from its initial height h0 at the start of its use.

[0013] In S102, as shown in Figure 3, the damaged portion 8a of the sealing fin 8 is welded, thereby forming an additional fin 9 at the damaged portion 8a (welding step). The welding performed in S102 can be MIG welding (Metal Insert Gas Welding), and the welding metal used can be a cobalt-based alloy, a nickel-based alloy, or a Worsfield stainless steel. Furthermore, the welding in S102 can be extremely low heat input welding, which is MIG welding performed under extremely low heat input conditions. Also, the heat input Q1 of the welding in S102 can be, for example, 9.0 (kJ / cm) or less, preferably 6.0 (kJ / cm) or less, and more preferably 3.0 (kJ / cm) or less. Here, the heat input Q1 refers to the electrical energy consumed per unit length of welding, which is determined by the following formula (a). Q1=(I×V×60) / (v×1000)···(a)

[0014] Furthermore, in the above formula (a), Q1 is the heat input of the welding process (kJ / cm), I is the current (A) flowing through the electrode wire 14 of the welding torch 12 during welding, V is the arc voltage (V) supplied to the electrode wire 14 of the welding torch 12 during welding, and v is the moving speed of the welding torch 12 during welding (cm / min).

[0015] When welding is performed on the damaged area 8a of the sealing fin 8 in S102, a heat-affected zone 8c will be generated in the base material 8b of the sealing fin 8 due to the heat input of the welding. The heat-affected zone 8c is the part of the base material 8b whose metal structure changes due to the heat input of the welding. Compared with other parts of the base material 8b, it has higher hardness and is more prone to brittleness.

[0016] Therefore, in S103, the heat-affected zone 8c generated in the sealing fin 8 is subjected to heat input by arc discharge or laser, thereby performing a tempering treatment on the heat-affected zone 8c (tempering treatment step). For example, as shown in FIG4, a welding torch 22 equipped with a tungsten electrode 20 can be used to perform a tempering treatment on the heat-affected zone 8c by arc discharge from the tungsten electrode 20. In this case, the welding torch 22 can also be a welding torch for TIG welding (Tungsten Inert Gas Welding), or a tempering welding caused by TIG welding that can perform fine heat input management. Furthermore, instead of using the above-mentioned welding torch 22, as shown in FIG5, a laser processing head 32 equipped with a lens 30 (for example, a laser processing head for laser welding) can be used to perform a tempering treatment on the heat-affected zone 8c by laser input through the lens 30. Furthermore, the welding of the damaged area 8a in S102 is equivalent to quenching, and the tempering treatment in S103 is carried out after the additional fins 9 formed on the damaged area 8a have cooled.

[0017] In S103, the above-mentioned tempering treatment can be performed on the heat-affected part 8c without adding solder to the damaged part 8a. In this case, during the heat input to the heat-affected part 8c by arc discharge or laser in S103, the melt flow welding of the sealing fin 8 and the additional fin 9 is performed without adding solder to the damaged part 8a.

[0018] Furthermore, regarding the tempering treatment of the heat-affected zone 8c of S103, the heat input Q2 of the arc discharge or laser during the tempering treatment can be determined based on the parameter d of the damage amount of the sealing fin 8. Also, the parameter d of the damage amount of the sealing fin 8, as shown in Figure 1, can be the reduction in the height of the sealing fin 8 based on its initial height h0 at the start of use. Specifically, it can be the difference (=h0-h1) between the initial height h0 of the sealing fin 8 at the start of use and the height h1 of the sealing fin 8 at the current repair stage (e.g., after the pre-welding treatment of S101 and before the welding of S102). Moreover, the heat input Q2 here refers to the electrical energy (kJ / cm) consumed per unit length of the tempering treatment by arc discharge or laser. In the case of using arc discharge, it is determined by equation (b), and in the case of using laser, it is determined by equation (c). Q2=(I×V×60) / (v×1000)···(b) Q2 = W / v ···(c)

[0019] Furthermore, in equation (b) above, Q2 is the heat input of the arc discharge during the tempering process (kJ / cm), I is the current (A) flowing through the tungsten electrode 20 of the welding torch 22 during the tempering process, V is the arc voltage (V) supplied to the tungsten electrode 20 of the welding torch 22 during the tempering process, and v is the moving speed (cm / min) of the welding torch 22 during the tempering process. Also, in equation (c) above, Q2 is the heat input of the laser during the tempering process (kJ / cm), W is the output of the laser during the tempering process (W), and v is the moving speed (cm / min) of the laser processing head 32 during the tempering process.

[0020] Regarding the tempering treatment of the heat-affected zone 8c in S103, the heat input Q2 of the arc discharge or laser during the tempering treatment is determined based on the parameter d of the damage amount of the sealing fin 8. Alternatively, the heat input Q2 of the arc discharge or laser during the tempering treatment in S103 can be determined based on the parameter d of the damage amount of the sealing fin 8 and the predetermined related information R (see Figure 6) (heat input determination step). Here, the related information R indicates the relationship between the parameter d of the damage amount of the sealing fin 8 and the heat input Q2 of the arc discharge or laser during the tempering treatment. In this case, in S103, the heat input Q2 of the arc discharge or laser during the tempering treatment is controlled based on the heat input Q2 determined in the aforementioned heat input determination step. Furthermore, in the example shown in Figure 6, the aforementioned related information R indicates that the larger the parameter d of the damage amount of the sealing fin 8, the smaller the heat input Q2. Based on the aforementioned information R, the heat input Q2 is determined to suppress excessive heat input to the moving wing 6, thereby alleviating the stress in the heat-affected zone 8c. Furthermore, from the viewpoint of suppressing defects such as cracking in the heat-affected zone 8c, the heat input Q2 of the arc discharge or laser during tempering is even smaller than the heat input Q1 of the weld overlay.

[0021] Next, in S104, post-weld processing is performed. Specifically, this includes removing the welding plates or fixtures used for welding. Then, in S105, the surfaces of the moving wing 6 and the repaired sealing fins 8 are inspected for defects such as cracks. For example, fluorescent penetrant testing is used for this inspection.

[0022] Here, the effect of the repair method using the sealing fin 8 as illustrated in Figure 2 will be explained. According to the above-described repair method for the sealing fin 8, after forming an additional fin 9 at the damaged area 8a of the sealing fin 8 by welding in S102, the heat-affected zone 8c generated in the sealing fin 8 is tempered in S103 by arc discharge or laser heat input, thereby reducing the hardness of the heat-affected zone 8c and alleviating the internal stress of the heat-affected zone 8c, thus suppressing damage to the repaired sealing fin 8. Furthermore, compared to the repair method for the sealing fin described in Patent Document 1, it does not require sandblasting or removal of unevenness or deteriorated layers accompanying sandblasting, thus reducing the number of repair steps required and allowing the repair of the sealing fin 8 to be performed in a short period of time.

[0023] Furthermore, in S103, when heat input to the heat-affected zone 8c is achieved through arc discharge from a tungsten electrode (in the case of tempering the heat-affected zone 8c via TIG welding), precise heat input management can be implemented for the heat input to the heat-affected zone 8c. Therefore, the hardness of the heat-affected zone 8c after welding is easily adjusted, effectively suppressing damage to the repaired sealing fin 8. Moreover, in the tempering process of S103, it is not necessary to add solder to the damaged area 8a during the heat input to the heat-affected zone 8c via arc discharge or laser, thus simplifying the repair method for the sealing fin 8.

[0024] Furthermore, by using the relevant information R, which represents the relationship between the parameter d of the sealing fin 8 regarding the amount of damage and the heat input of the arc discharge or laser during tempering, the heat input of the arc discharge or laser during tempering is determined. In this way, the heat-affected part 8c can be tempered with an appropriate heat input corresponding to the amount of damage to the sealing fin 8. Therefore, the hardness of the heat-affected part 8c after welding can be appropriately adjusted, and damage to the repaired sealing fin 8 can be effectively suppressed.

[0025] Furthermore, the solder used for S102 overlay is a cobalt-based alloy, a nickel-based alloy, or a ferrosilicon stainless steel, which can suppress hardening after heat input.

[0026] Furthermore, the sealing fins 8 formed at the front end 6a of the moving wing 6 can suppress damage to the repaired sealing fins 8, thus stably suppressing leakage flow in the gap between the front end 6a of the moving wing 6 and the casing (stationary wall) of the steam turbine 2 (not shown).

[0027] Furthermore, the welding of S102 is a low heat input welding process, which can suppress the hardening of the heat-affected zone 8c caused by the welding, thus improving the effect of suppressing damage to the repaired sealing fin 8.

[0028] The present invention is not limited to the above-described embodiments, but also includes modifications to the above-described embodiments and appropriate combinations of such embodiments.

[0029] For example, in Figure 1, although the sealing fin 8 formed at the front end of the moving blade 6 of the steam turbine 2 is shown as an example, the repair method of the sealing fin 8 illustrated in Figure 2, as shown in Figure 7, can also be applied to the sealing fin 8 formed at the position opposite to the stationary blade 5 of the steam turbine 2 on the outer peripheral surface 4a of the rotor 4.

[0030] Furthermore, in the above embodiment, although the method of tempering TIG welding for fine heat input management of the heat-affected part 8c is exemplified in S103, it is not particularly limited to the welding method implemented in S103 as long as fine heat input management of the heat-affected part 8c can be achieved.

[0031] Furthermore, in the above embodiment, although an example is given of a method in which the sealing fin 8 and the additional fin 9 are welded without adding solder to the damaged part 8a during the heat input to the heat-affected part 8c by arc discharge or laser in S103, as long as the heat input to the heat-affected part 8c can be properly managed, the heat input to the heat-affected part 8c caused by arc discharge or laser can also be performed while adding solder to the damaged part 8a in S103.

[0032] The contents recorded in the above-mentioned implementation forms can be understood as follows, for example.

[0033] [1] A method for repairing sealing fins according to at least one embodiment of the present invention, A method for repairing sealing fins (e.g., sealing fin 8) on the rotor (e.g., rotor 4) of a steam turbine (e.g., the steam turbine 2 described above), comprising: The welding step involves welding over the damaged portion of the aforementioned sealing fin (e.g., damaged portion 8a) to form an additional fin (e.g., additional fin 9) at the damaged portion; and The tempering process involves applying heat to the heat-affected portion (e.g., the heat-affected portion 8c) of the aforementioned sealing fins caused by the aforementioned weld overlay, using an electric arc discharge or laser to perform tempering treatment on the aforementioned heat-affected portion.

[0034] According to the sealing fin repair method described above [1], after additional fins are formed at the damaged part of the sealing fin by welding, the heat-affected zone generated by welding is tempered by arc discharge or laser heat input, thereby reducing the hardness of the heat-affected zone and easing the internal stress of the heat-affected zone, which can suppress the damage of the repaired sealing fin. Moreover, compared with the sealing fin repair method described in Patent Document 1, sandblasting or removal of uneven or deteriorated layers accompanied by sandblasting is not required, so the number of repair processes can be reduced and the sealing fin can be repaired in a short period of time.

[0035] [2] In several embodiments, the repair method for the sealing fins described in [1] above is used. The aforementioned welding process is MIG welding.

[0036] According to the repair method of the sealing fins described above [2], electrodes that become solder can be continuously supplied, which can improve the efficiency of the welding operation. Moreover, MIG welding is carried out under extremely low heat input conditions, thereby reducing the hardened area of ​​the heat-affected zone after welding.

[0037] [3] In several embodiments, the repair method for the sealing fins described in [1] or [2] above is used. In the aforementioned tempering process, heat is applied to the heat-affected part by an electric arc discharge from the tungsten electrode, thereby tempering the heat-affected part.

[0038] According to the repair method of the sealing fin described above [3], the heat input to the heat-affected zone can be finely managed, so the hardness of the heat-affected zone after welding is easy to adjust, and the damage to the repaired sealing fin can be effectively suppressed.

[0039] [4] In several embodiments, the repair method for the sealing fins described in any of [1] to [3] above is used. During the aforementioned tempering process, no additional solder is applied to the aforementioned damaged area during the heat input to the aforementioned heat-affected zone via arc discharge or laser.

[0040] According to the repair method of the sealing fin described above [4], since the additional fin has been formed in the welding step, it is not necessary to add solder in the tempering step, thus simplifying the repair method of the sealing fin.

[0041] [5] In several embodiments, the repair method for the sealing fins described in any of [1] to [4] above is used. It also includes a heat input determination step, which determines the heat input amount (e.g., the heat input amount Q2) of the arc discharge or laser before the tempering process based on parameters of the aforementioned sealing fins regarding the amount of damage (e.g., parameter d), relevant information indicating the relationship between the parameters of the aforementioned sealing fins regarding the amount of damage and the heat input amount of the aforementioned arc discharge or laser before the aforementioned tempering process (e.g., relevant information R). In the aforementioned tempering process, the heat input of the aforementioned arc discharge or the aforementioned laser is controlled based on the heat input determined in the aforementioned heat input determination process.

[0042] According to the repair method of the sealing fin described above [5], the heat-affected part can be tempered by an appropriate amount of heat input corresponding to the amount of damage to the sealing fin. Therefore, the hardness of the heat-affected part after welding can be adjusted appropriately, which can effectively suppress the damage to the repaired sealing fin.

[0043] [6] In several embodiments, the method for repairing the sealing fins described in any of [1] to [5] above is used. The welding material used in the aforementioned welding process is a cobalt-based alloy, a nickel-based alloy, or a Worsfield stainless steel.

[0044] According to the repair method of the sealing fin described above [6], as the welding material for overlay welding, cobalt-based alloys, nickel-based alloys or Worsfield stainless steel are used, thereby suppressing hardening after heat input.

[0045] [7] In several embodiments, the method for repairing the sealing fins described in any of [1] to [6] above is used. The aforementioned sealing fins are formed at the front end (e.g., the aforementioned front end 6a) of the aforementioned rotor's moving blade (e.g., the aforementioned moving blade 6).

[0046] According to the repair method of the sealing fins described above [7], the damage to the repaired sealing fins can be effectively suppressed for the sealing fins formed at the front end of the rotor blades, thus the leakage flow between the front end of the rotor blades and the casing (stationary wall) of the steam turbine can be stably suppressed.

[0047] [8] In several embodiments, the method for repairing the sealing fins described in any of [1] to [6] above is used. The aforementioned sealing fins are formed on the outer peripheral surface of the aforementioned rotor (e.g., the aforementioned outer peripheral surface 4a) at a position opposite to the aforementioned stationary blade of the steam turbine (e.g., the aforementioned stationary blade 5).

[0048] According to the repair method of the sealing fins described above [8], the damage to the repaired sealing fins can be effectively suppressed for the sealing fins formed on the outer peripheral surface of the rotor at the position opposite to the stationary blade of the aforementioned steam turbine. Therefore, the leakage flow between the outer peripheral surface of the rotor and the stationary blade can be stably suppressed.

[0049] [9] In several embodiments, the method for repairing the sealing fins described in any of [1] to [8] above is used. The aforementioned welding process is a low-heat-input welding process.

[0050] According to the repair method of the sealing fin described above [9], since the welding step is a low heat input welding, the hardening of the heat-affected zone caused by welding can be suppressed, thereby improving the effect of suppressing damage to the repaired sealing fin.

[0051]

[10] In several embodiments, the method for repairing the sealing fins described in any of [1] to [9] above is used. The heat input of the aforementioned welding process is below 9.0 (kJ / cm).

[0052] By making the heat input of the weld overlay small as described above

[10] , the hardening of the heat-affected zone caused by the weld overlay can be suppressed, thus improving the effect of suppressing damage to the repaired sealing fins.

[0053]

[11] In several embodiments, the repair method for the sealing fins described in

[10] above is used. The heat input of the aforementioned welding process is below 6.0 (kJ / cm).

[0054] By making the heat input of the weld overlay to a small amount as described above

[11] , the hardening of the heat-affected zone caused by the weld overlay can be further suppressed, thus improving the effect of suppressing damage to the repaired sealing fins.

[0055]

[12] In several embodiments, the repair method for the sealing fins described in

[11] above is used. The heat input of the aforementioned welding process is below 3.0 (kJ / cm).

[0056] By making the heat input of the weld overlay to a small amount as described above

[12] , the hardening of the heat-affected zone caused by the weld overlay can be further suppressed, thus improving the effect of suppressing damage to the repaired sealing fins.

[0057] 2: Steam turbine 4: Rotor 4a: outer peripheral surface 5:Jingyi 6: Moving Wing 6a: Frontend 8: Sealing fins 8a: Damaged site 8b: Base Material 8c: Heat-affected zone 9:Add fins 12,22: Welding torch 14: Electrode wire 20: Tungsten electrode 30: Lens 32: Laser processing head

Claims

1. A method for repairing sealing fins, specifically for repairing sealing fins on the rotor of a steam turbine, comprising: a welding overlay step, wherein welding is performed on a damaged portion of the sealing fin to form an additional fin at the damaged portion; a tempering treatment step, wherein heat is applied to the heat-affected zone of the sealing fin caused by the welding overlay using an electric arc discharge or laser to perform tempering treatment on the heat-affected zone; and a heat input amount determination step, wherein the heat input amount of the electric arc discharge or laser before the tempering treatment is determined based on parameters relating to the amount of damage to the sealing fin, and related information relating the parameters relating to the amount of damage to the sealing fin to the heat input amount of the electric arc discharge or laser before the tempering treatment, wherein the heat input amount of the electric arc discharge or laser before the tempering treatment is controlled based on the heat input amount determined in the heat input amount determination step in the tempering treatment step.

2. The method for repairing the sealing fins as described in claim 1, wherein, The aforementioned welding process is MIG welding.

3. The method for repairing the sealing fins as described in claim 1, wherein, In the aforementioned tempering process, heat is applied to the aforementioned heat-affected part by an electric arc discharge from the tungsten electrode, thereby tempering the aforementioned heat-affected part.

4. The method for repairing the sealing fins as described in claim 1, wherein, During the aforementioned tempering process, no additional solder is applied to the aforementioned damaged area during the period when heat is applied to the aforementioned heat-affected zone by the aforementioned arc discharge or the aforementioned laser.

5. The method for repairing the sealing fins as described in claim 1, wherein, The solder used in the aforementioned welding process is a cobalt-based alloy, a nickel-based alloy, or a Worsfield stainless steel.

6. The method for repairing the sealing fins as described in claim 1, wherein, The aforementioned sealing fins are formed at the front end of the moving blade of the aforementioned rotor.

7. The method for repairing the sealing fins as described in claim 1, wherein, The aforementioned sealing fins are formed on the outer circumferential surface of the aforementioned rotor at a position opposite to the stationary blades of the aforementioned steam turbine.

8. The method for repairing the sealing fins as described in claim 1, wherein, The aforementioned welding process is a low-heat-input welding process.

9. The method for repairing the sealing fins as described in claim 1, wherein, The heat input of the aforementioned welding process is below 9.0 (kJ / cm).

10. The method for repairing the sealing fins as described in claim 9, wherein, The heat input of the aforementioned welding process is below 6.0 (kJ / cm).

11. The method for repairing the sealing fins as described in claim 10, wherein, The heat input of the aforementioned welding process is below 3.0 (kJ / cm).

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