JP2012055949A - Alloy for brazing material and method for braze repair - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an alloy for brazing material, which can prevent a brazing material from being melted when a heat treatment is performed by making the solidus temperature of the brazing material after brazing higher than the solidus temperature of a brazing material before brazing, and to provide a method for braze repair.SOLUTION: The alloy for brazing material comprises, by mass: 15-30% Cr; 0.2-5% B; and a balance comprising Ni and inevitable impurities.

Description

  Embodiments of the present invention relate to a brazing alloy and a brazing repair method using the brazing alloy, for example, used for repairing gas turbine components.

  In a gas turbine power plant, air compressed by driving a compressor provided coaxially with a gas turbine is introduced into a combustor to mix and burn fuel, and the generated high-temperature combustion gas is introduced into a moving blade. The rotor blades are driven to rotate, and power is generated by a generator connected to the rotating shaft of the rotor blades. Here, the combustion gas discharged | emitted from the combustor is guide | induced to the moving blade of a gas turbine through a transition piece and a stationary blade.

  If cracks or wear occur in the stationary blades, combustor liners, transition pieces, blades, etc., which are high-temperature parts exposed to such high-temperature combustion gas, repair welding or diffusion brazing repairs are performed. Continued use. In these repairs, heat treatment during welding and heat treatment for removing residual stress are performed as necessary.

  Among the stationary blades that are high-temperature parts, the first-stage stationary blade disposed at the entrance of the turbine is exposed to the hottest combustion gas, and inevitably many cracks are inevitably generated due to thermal fatigue during start and stop. . Therefore, a Co-based alloy having excellent heat resistance and repairability has been mainly used for the first stage stationary blade.

  When repairs such as cracks, oxidation erosion, and wear are performed by repair welding, for example, TIG welding repairs are performed. However, as the temperature of the gas turbine increases, the repair amount increases. Deformation may occur in the stator blades due to the thermal effects and residual stresses. The amount of deformation has reached a state where it is difficult to repair by subsequent deformation correction.

  When repairing cracks, oxidation erosion, wear, etc. by diffusion brazing, a brazing material in which a melting point lowering material such as Si or B is added to a material having a chemical composition similar to the chemical composition constituting the substrate ( Brazing repair is performed at a temperature lower than the melting point of the base material using a repair material obtained by mixing a molten alloy powder) and a composition material (non-molten alloy powder) having a base equivalent strength at a predetermined mixing ratio. .

JP-A-4-254544

  For example, Co-base alloy FSX414 (manufactured by General Electric), Ni-base alloy IN939 (manufactured by Inco), GTD222 (manufactured by General Electric), or the like is used as the stationary blade of the gas turbine. After repairing a part of the crack generated in the stationary blade by the conventional diffusion brazing described above, when repairing another crack, the already melted alloy of the repaired material melts again and flows out from the repaired part. There was a problem. Further, when solution heat treatment is performed after repair, there is a problem that the molten alloy of the repair material already brazed melts again and flows out from the repair site.

  Therefore, the present invention has a higher solidus temperature of the brazing material after brazing than the solidus temperature of the brazing material before brazing, and can prevent melting of the brazing material during heat treatment or the like. An object of the present invention is to provide a brazing alloy and a brazing repair method.

  In order to achieve the above object, the brazing alloy of the embodiment according to the present invention contains, by mass%, Cr: 15-30, B: 0.2-5, the balance being Ni and inevitable impurities. Become.

It is a block diagram for demonstrating the process of brazing repairing the defect which arose in the base material using the brazing repair material of 2nd Embodiment which concerns on this invention.

  Embodiments of the present invention will be described below.

(First embodiment)
The alloy for brazing filler metal in the first embodiment according to the present invention contains, by mass%, Cr: 15-30, B: 0.2-5, and the balance is made of Ni and inevitable impurities.

  In addition to the above chemical composition, the alloy for brazing filler metal in the first embodiment according to the present invention may further contain 7% by mass or less of Si. Further, in addition to the above-described chemical composition (including the case of containing Si), Co may further be contained in an amount of less than 15% by mass.

  In addition, among the inevitable impurities in the brazing alloy described above, it is preferable that at least Fe is suppressed to 5 mass% or less, Mn is 1 mass% or less, and C is suppressed to 0.3 mass% or less.

  In the brazing alloy according to the first embodiment having the above chemical composition range, the solidus temperature of the brazing alloy after brazing is equal to the solidus temperature of the brazing alloy before brazing (hereinafter referred to as the solidus temperature). The solidus temperature Tb before brazing).

  When ordinary brazing is performed using the brazing alloy of the first embodiment having the chemical composition range described above, the B concentration of the brazing material is halved by diffusion (the B concentration after brazing is reduced). It is in a state where it is reduced to about 50% or less of the B concentration before brazing. Further, the solidus temperature of the brazing alloy after brazing tends to increase as the B concentration decreases, and in the brazing alloy of the first embodiment, the B concentration after brazing. By setting the B concentration to 50% or less of the B concentration before brazing, the solidus temperature of the brazing alloy after brazing exceeds the maximum strength maintenance temperature Tm and the solution heat treatment temperature of the substrate, which will be described later. It can be.

  Therefore, here, as an evaluation index of the solidus temperature of the brazing alloy after brazing, the B concentration is reduced by half by diffusion (the B concentration after brazing is 50% of the B concentration before brazing). The solidus temperature in the brazing material (hereinafter referred to as post-brazing solidus temperature Ta) will be described. As described above, the post-brazing solidus temperature Ta is set higher than the solution heat treatment temperature of a base material such as a stationary blade to be brazed.

  Here, the solidus temperature Ta after brazing was prepared by preparing a sample in which only B of the chemical component of the brazing alloy has a half content, and differential scanning calorimetry (DSC) for this sample. ) Is measured. Further, the solidus temperature Tb before brazing is also measured by performing differential scanning calorimetry (DSC).

  Since the solidus temperature Ta after brazing is higher than the solidus temperature Tb before brazing, for example, even when repairing defects such as cracks and thinning formed in other parts of the base material, It is possible to prevent the brazing material alloy of the repaired portion already brazed from melting and flowing out.

  The solidus temperature Tb before brazing is the temperature at which the tensile strength (tensile strength or proof stress (JIS Z 2241)) of the base material to be brazed is reduced by 10% with respect to the tensile strength at normal temperature ( Hereinafter, it is preferable that the temperature is not more than the maximum strength maintenance temperature Tm.

  Here, high temperature parts such as a stationary blade in a gas turbine are exposed to a high temperature combustion gas and cause defects such as cracks and thinning, so that brazing repair is performed. The stationary blade in the gas turbine is mainly composed of, for example, a Co-based alloy such as FSX414 (manufactured by General Electric). Table 1 shows the chemical composition of FSX414.

  As described above, the alloy for brazing filler metal according to the first embodiment has a basic chemical composition containing Cr and B in Ni. In the brazing step, B diffuses into, for example, the base material. The B concentration decreases and the solidus temperature (in other words, the melting point) increases. From the viewpoint of promoting the diffusion of B and improving the fluidity of the repair material so that the repair material such as the brazing alloy penetrates to the tip of the crack, the brazing temperature is preferably higher. For example, in FSX414, fine carbides are precipitated in a three-dimensional network corresponding to a solidified structure (dendrites) in the manufacturing process. From the above viewpoint, a higher brazing temperature is preferable. However, if brazing is performed on this FSX414 at a temperature exceeding 1210 ° C., for example, for 30 minutes or more, the three-dimensional network structure of carbide collapses due to element diffusion. As a result, the strength characteristics of the material deteriorate.

  For this reason, brazing is preferably performed at a temperature equal to or lower than the maximum strength maintenance temperature Tm. Therefore, the brazing alloy needs to be melted at a temperature equal to or lower than the maximum strength maintaining temperature Tm. Therefore, the solidus temperature Tb before brazing of the brazing alloy may be equal to or lower than the maximum strength maintaining temperature Tm. preferable.

  For example, when using a base material made of FSX414, it is preferable that the maximum strength maintenance temperature Tm is 1210 ° C., and the pre-brazing solidus temperature Tb of the brazing alloy is 1210 ° C. or less. It also increases the workability of brazing (allows brazing at a lower temperature), increases the fluidity of the brazing material during brazing, or reduces the effect on the substrate due to exposure to the brazing temperature In view of the above, it is more preferable that the solidus temperature Tb before brazing of the brazing alloy is 1100 ° C. or lower.

  Further, by using the brazing alloy of the first embodiment, as described above, the post-brazing solidus temperature Ta becomes higher than the solution heat treatment temperature of the base material. Therefore, for example, when a base material made of FSX414 is used, since the solution heat treatment temperature of FSX414 is 1150 to 1180 ° C, at least the post-brazing solidus temperature Ta is 1150 ° C (solution heat treatment of FSX414). When the temperature is 1150 ° C.), the temperature is preferably set to a temperature exceeding the maximum strength maintenance temperature Tm.

  Next, the reasons for limiting each chemical composition range in the alloy for brazing filler metal according to the first embodiment of the present invention described above will be described. In the following description, “%” indicating the chemical composition content is “% by mass” unless otherwise specified.

(1) Cr (chromium)
Cr has an effect of improving the corrosion resistance. When the Cr content is less than 15%, the above-described effects are not exhibited. When the Cr content exceeds 30%, the melting point increases, and brazing at a maximum strength maintaining temperature Tm or less is difficult. Become. Therefore, the Cr content is determined to be 15 to 30%. In addition, it lowers the melting point of the brazing material, increases the workability of brazing (allows brazing at a lower temperature), increases the flowability of the brazing material during brazing, or exposes to the brazing temperature. From the viewpoint of reducing the influence on the base material due to the content of Cr, it is more preferable that the Cr content is 15 to 23%.

(2) B (boron)
B lowers the solidus temperature (melting point) of the brazing alloy and improves the workability of brazing. When the B content is less than 0.2%, the above-described effects are not exhibited and the melting point of the brazing alloy is too high. On the other hand, if the B content exceeds 5%, borides are formed and the strength and corrosion resistance of the brazing alloy are impaired. Therefore, the B content is determined to be 0.2 to 5%. Further, when the B content is 4.5 or less, the tendency to form borides is weak, and sufficient strength and corrosion resistance can be obtained. When the B content is 1.5 or more, the workability of brazing is improved. In order to improve further, it is more preferable that the B content is 1.5 to 4.5%.

(3) Si (silicon)
Si improves the workability of brazing and raises the solidus temperature of the brazing alloy in the chemical composition range of the brazing alloy of the first embodiment according to the present invention. When the Si content exceeds 7%, silicide is formed to inhibit the strength and corrosion resistance of the brazing alloy and the solidus temperature of the brazing alloy becomes too high. Therefore, the Si content is set to 7% or less. Further, from the viewpoint of suppressing the formation of silicide, the Si content is more preferably 4% or less. In order to exhibit the above-described effect of Si, the lower limit value of the Si content is preferably 1% or more.

(4) Co (cobalt)
Co has the effect of increasing the stability of the structure at and near the contact portion with a Co-based alloy such as FSX414. When the Co content is 15% or more, the effect of increasing the solidus temperature due to B diffusion is rapidly reduced. Therefore, the Co content is set to less than 15%. Further, the smaller the Co content, the greater the increase in the solidus temperature Ta after brazing, and since Co is an expensive element, the Co content is more preferably 10% or less. . In order to exhibit the effect of Co described above, the lower limit value of the Co content is preferably 5% or more.

(5) Fe (iron), Mn (manganese) and C (carbon)
Fe, Mn and C are classified as inevitable impurities in the alloy for brazing filler metal of the first embodiment according to the present invention. It is desirable that the residual content of these inevitable impurities is as close to 0% as possible. In addition, these inevitable impurities are suppressed to a content that does not affect the properties of the brazing alloy, Fe is 5% or less, Mn is 1% or less, and C is 0.3% or less. Is preferred.

  Here, a method for manufacturing the alloy for brazing filler metal according to the first embodiment of the present invention will be described.

  The alloy for brazing filler metal according to the first embodiment of the present invention is produced by melting a material having a chemical composition constituting the alloy for brazing filler metal and forming a powder by an atomizing method. Further, a binder may be added to this powder to form a paste.

  Further, a brazing alloy may be produced by melting a material having a chemical composition constituting the brazing alloy and casting it into a plate shape or a rod shape. Further, this plate-like or rod-like alloy for brazing filler metal may be processed into a foil shape or a line shape.

  According to the brazing material alloy of the first embodiment described above, the post-brazing solidus temperature Ta can be made higher than the pre-brazing solidus temperature Tb. After repairing the portion, when repairing other defects, it is possible to prevent the brazing alloy already brazed from melting and flowing out. Moreover, since the solidus temperature Ta after brazing is higher than the solution heat treatment temperature of the base material to be brazed, the solution heat treatment can be performed without melting and flowing out the brazed brazing alloy. it can.

(Second Embodiment)
In the second embodiment according to the present invention, it will be a mixture in which the molten alloy powder made of the alloy for the brazing material of the first embodiment described above and the non-molten alloy powder that does not melt when brazing will be mixed. A brazing repair material and a brazing repair method using the brazing repair material will be described.

  As described above, the non-molten alloy powder is composed of a material that does not melt when brazed, and can be composed of, for example, a material having the same chemical composition as the base material to be brazed. In addition, for example, when the base material is made of a Co-based alloy, the melting point of the non-molten alloy powder may be drastically lowered due to the diffusion of B from the molten alloy made of the brazing alloy. There is. Therefore, as the non-molten alloy powder, the chemical composition other than B is the same as the chemical composition of the molten alloy powder, and the B content in the non-molten alloy powder is smaller than the B content in the molten alloy powder, Or a material that is zero can be used.

  For example, when using a non-molten alloy powder having a chemical composition other than B that is the same as that of the molten alloy powder and having a B content of zero in the non-molten alloy powder, the non-molten alloy powder The brazing repair material is preferably configured with a mass ratio of 1: 1 to molten alloy powder of 1: 1. In this case, when the diffusion of B from the base material to be brazed is not taken into consideration, the B concentration in the repaired portion is an alloy having a uniform composition in which the B concentration of the molten alloy powder is reduced by half. Therefore, as in the case of the brazing alloy of the first embodiment, the solidus temperature of the molten alloy after brazing becomes higher than the solidus temperature of the molten alloy before brazing. Further, the solidus temperature of the molten alloy after brazing can be made higher than the solution heat treatment temperature of the base material such as a stationary blade to be brazed.

  Further, in order to reduce the B concentration by diffusion and increase the solidus temperature of the molten alloy after brazing, for example, the mass ratio of the non-molten alloy powder to the molten alloy powder is adjusted, You may reduce a mass ratio. Also, for example, the brazing temperature and time may be increased to promote B diffusion into the substrate. The mass ratio between the non-molten alloy powder and the molten alloy powder can be adjusted, and the mass ratio of the molten alloy powder can be reduced by changing the shape of the repaired part (such as a narrow crack or a relatively wide groove), It can be carried out as appropriate according to the chemical composition of the base material to be repaired.

  Here, the manufacturing method of the brazing repair material of 2nd Embodiment which concerns on this invention is demonstrated.

  The molten alloy powder is produced by the same method as the method for producing the brazing material alloy of the first embodiment described above. The non-molten alloy powder is produced by melting a material having a chemical composition that constitutes the non-molten alloy powder to obtain a powder by an atomizing method. Then, the molten alloy powder and the non-molten alloy powder are mixed at a predetermined mixing ratio to produce a brazing repair material. The brazing repair material may be formed into a paste by adding a binder to a mixture obtained by mixing the molten alloy powder and the non-molten alloy powder.

  Further, a material having a chemical composition constituting the non-molten alloy may be melted, cast into a plate shape or a rod shape, and processed into a foil shape or a line shape. When the non-molten alloy is formed in a foil shape, for example, the brazed repair material may be configured by alternately laminating the molten alloy processed in the foil shape.

  Next, a method for brazing and repairing defects generated in the base material using the above-described brazing repair material will be described. FIG. 1 is a block diagram for explaining a process of brazing and repairing a defect generated in a base material by using the brazing repair material according to the second embodiment of the present invention.

  First, the surface of the base material, which is a gas turbine component such as a stationary blade that has been decomposed from the gas turbine and has defects such as cracks and thinning, is cleaned by, for example, blasting to remove deposits and oxide layers. (Step S10).

  Subsequently, the presence / absence, position, and shape of the defect are examined by nondestructive inspection such as ultrasonic flaw detection test and X-ray flaw detection test (step S11), the surface of the repaired part is suspended (step S12), and hydrogen cleaning is performed. Then, the oxide layer (oxide film) on the bonding surface is removed (step S13). If necessary, the brazed surface of the repaired part is cleaned with acetone or the like.

  Subsequently, for example, when the crack is penetrating, a process such as sealing welding is performed to prevent the brazing repair material from dripping from the repaired part (step S14).

  Steps S10 to S14 described above are preprocessing steps.

  Subsequently, a brazing repair material flow-preventing enclosure is formed around the repaired portion (step S15), and the repaired portion is filled with the brazing repair material produced by the manufacturing method described above (step S16).

  Here, the brazing repair material has a small apparent viscosity and easily flows. Therefore, in order to prevent the flow and movement of the brazing repair material, it is effective to keep the processing surface of the repaired part close to the horizontal state. In addition, as a measure to prevent the flow of the repair material, use a mixed powder that has been made pasty by adding a binder to the brazing repair material (mixed powder), or heat-resistant tape around the repaired part. Enclosed with can be adopted.

  Subsequently, the base material filled with the brazing repair material is placed in a vacuum furnace, and the temperature at which the tensile strength of the base material to be brazed is reduced by 10% with respect to the tensile strength at room temperature (the highest strength maintenance). Brazing is performed by heating to a temperature equal to or lower than the temperature Tm) and higher than the solidus temperature of the molten alloy powder (step S17). At this time, the molten alloy powder is melted and spreads over the entire repaired portion together with the non-molten alloy powder. For example, as described above, when a base material made of FSX414 is used, the maximum strength maintenance temperature Tm is 1210 ° C., which shortens the heating time, reduces the burden on the heating furnace, or is exposed to the brazing temperature. From the viewpoint of reducing the influence on the substrate, the heating temperature during brazing is more preferably 1100 ° C. or lower.

  Here, when there are a plurality of parts to be repaired and the processes in steps S16 and S17 described above cannot be performed at the same time, the processes in steps S16 and S17 are repeated for the other repaired parts. As mentioned above, the solidus temperature of the molten alloy after brazing is higher than the solidus temperature of the molten alloy before brazing, so that it was already brazed when repairing other defects. The repair material will not melt and flow out.

  Subsequently, a finishing process including a non-destructive inspection of a brazed repaired part, an additional repair of a partially defective part, and a cooling hole repairing process by an ultrasonic flaw detection test or an X-ray flaw detection test is performed (step S18). In addition, when a partial repair defect location exists, the process of step S16 and step S17 is performed with respect to the location.

  Heat treatment of solution treatment and aging heat treatment is performed on the repaired portion that has undergone finishing treatment (step S19). Here, since the solidus temperature of the molten alloy after brazing is higher than the solution heat treatment temperature, the brazed brazing repair material does not melt and flow out during the solution heat treatment. For example, when a base material made of FSX414 is used, since the solution heat treatment temperature of FSX414 is 1150 to 1180 ° C, at least the solidus temperature of the molten alloy after brazing is 1150 ° C (solution solution of FSX414) When the heat treatment temperature is 1150 ° C., it is set to a temperature exceeding, and preferably set to a temperature exceeding the maximum strength maintenance temperature Tm. The aging heat treatment temperature is set lower than the solution heat treatment temperature, so that the brazed repair material that has been brazed does not melt and flow out.

  The base material is brazed and repaired by the above-described process. In the above-described brazing repair method, an example is shown in which the brazing repair material using the mixture of the molten alloy powder and the non-molten alloy powder according to the second embodiment of the present invention is used. As the brazing repair material, the brazing alloy according to the first embodiment of the present invention can be used alone.

  Further, the gas turbine parts are not limited to the stationary blades, and include a combustor liner, a transition piece, a moving blade, and the like, and the brazing repair similar to the above can be applied to these gas turbine parts.

  Furthermore, although the repair of cracks and thinning that occurred in gas turbine parts has been described here, the brazing repair method described above should be applied not only to repairing cracks and thinning, but also to joining gas turbine parts. You can also.

  According to the brazing repair material and brazing repair method of the second embodiment described above, the solidus temperature of the molten alloy after brazing is made higher than the solidus temperature of the molten alloy before brazing. Therefore, after repairing some of the defects on the substrate, when repairing other defects, it is possible to prevent the brazing repair material that has already been brazed from melting and flowing out. In addition, since the solidus temperature of the molten alloy after brazing is higher than the solution heat treatment temperature of the base material to be brazed, the solution heat treatment is performed without melting and flowing out the brazed brazing repair material. It can be carried out.

  Hereinafter, in the alloy for brazing material according to the first embodiment of the present invention (the molten alloy of the brazing repair material according to the second embodiment), the B concentration is reduced by half by diffusion, and the solid phase after brazing The fact that the line temperature becomes higher than the solidus temperature before brazing will be described with reference to examples.

(Evaluation of solidus temperature)
Table 2 shows the chemical compositions of Sample 1 to Sample 21 used for the evaluation of the solidus temperature. Samples 1 to 15 are alloys in the chemical composition range of the embodiment of the present invention, and Samples 16 to 21 are alloys whose chemical composition is not in the chemical composition range of the embodiment of the present invention. Yes, it is a comparative example. Further, the alloy in the chemical composition range of the embodiment of the present invention used here contains C as an inevitable impurity.

  In the evaluation of the solidus temperature, materials for constituting the chemical compositions of Sample 1 to Sample 21 shown in Table 2 were melted in a melting furnace, respectively, and alloys of Sample 1 to Sample 21 were produced. In addition, in order to evaluate the solidus temperature of the brazing alloy after brazing in which the B concentration has been reduced by half, only the B of the chemical composition has a half content in the alloys of Sample 1 to Sample 21. A sample was prepared.

  These samples were subjected to differential scanning calorimetry (DSC) to measure the solidus temperature. Table 3 shows the measurement results of the solidus temperature. Table 3 shows the solidus temperature Tb before brazing, which is the solidus temperature of the brazing alloy before brazing, and the solidus temperature of the brazing alloy after brazing, in which the B concentration is halved by diffusion. The post-brazing solidus temperature Ta and the rise in solidus temperature (Ta-Tb) are shown.

  Further, as the judgment criteria shown in Table 3, regarding the solidus temperature Tb before brazing, 1210 ° C. or lower is “◯”, 1100 ° C. or lower is “◎”, and the temperature exceeding 1210 ° C. is “×”. It was. Regarding the solidus temperature Ta after brazing, a value exceeding 1150 ° C. was indicated as “◯”, a value exceeding 1210 ° C. was indicated as “◎”, and a temperature below 1150 ° C. was indicated as “x”. Here, “◯” and “◎” belong to the solidus temperature range of the embodiment of the present invention, and “◎” belong to a more preferable temperature range. On the other hand, “x” does not belong to the solidus temperature range of the embodiment of the present invention.

  As shown in Table 3, in all of Samples 1 to 15, the pre-brazing solidus temperature Tb is 1210 ° C. or lower, and the post-brazing solidus temperature Ta exceeds 1150 ° C. Among these, Sample 1, Sample 2, and Sample 6 have a solidus temperature Tb before brazing of 1100 ° C. or lower, and a solidus temperature Ta after brazing exceeds 1210 ° C. That is, Sample 1, Sample 2, and Sample 6 can be brazed at a relatively low temperature, and the solidus temperature becomes high after brazing. Therefore, for example, by setting the brazing temperature to a temperature exceeding 1100 ° C. and not more than 1210 ° C., it has been found that it has excellent characteristics that it does not melt even when exposed to the brazing temperature. It was.

  On the other hand, all of the samples 16 to 18 have a low post-brazing solidus temperature Ta and lower than 1150 ° C. Moreover, all of the samples 19 to 21 have a high pre-brazing solidus temperature Tb, which exceeds 1210 ° C.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention.

Claims (14)

  A brazing alloy characterized by containing, by mass%, Cr: 15-30, B: 0.2-5, the balance being Ni and inevitable impurities.   The brazing alloy according to claim 1, further comprising 7% by mass or less of Si.   The brazing alloy according to claim 1 or 2, further comprising less than 15% by mass of Co.   4. The unavoidable impurity, wherein at least Fe is suppressed to 5% by mass or less, Mn is suppressed to 1% by mass or less, and C is suppressed to 0.3% by mass or less. Alloy for brazing filler metal.   5. The solidus temperature of the brazing alloy after brazing is higher than the solidus temperature of the brazing alloy before brazing. 6. Alloy for brazing material.   The brazing alloy according to any one of claims 1 to 5, wherein a solidus temperature of the brazing alloy after brazing is higher than a solution heat treatment temperature of a base material to be brazed. .   The brazing alloy according to any one of claims 1 to 6, wherein a solidus temperature of the brazing alloy after brazing is higher than 1150 ° C.   The brazing alloy according to any one of claims 1 to 7, wherein the B concentration after brazing is 50% or less of the B concentration before brazing due to diffusion.   The solidus temperature of the brazing alloy before brazing is not more than the temperature at which the tensile strength of the base material to be brazed is reduced by 10% with respect to the tensile strength at normal temperature. Item 9. An alloy for brazing filler metal according to any one of Items 1 to 8.   10. The brazing alloy according to claim 1, wherein a solidus temperature of the brazing alloy before brazing is 1210 ° C. or lower. Surface treatment of substrate of defective gas turbine parts, nondestructive inspection of defective part, surface of repaired part is suspended, surface oxide layer is removed, brazing repair material is prevented from dripping from repaired part A step of performing a pretreatment including:
Forming a flow-preventing enclosure of brazing repair material around the portion to be repaired;
A brazing repair material comprising a mixture of a non-molten alloy powder that does not melt when brazed and a molten alloy powder that is melted when brazed and is made of a brazing alloy according to any one of claims 1 to 10. Filling the repaired part;
The step of brazing by heating to a temperature lower than the temperature at which the tensile strength of the base material to be brazed is reduced by 10% with respect to the tensile strength at normal temperature and higher than the solidus temperature of the molten alloy powder When,
A process of non-destructive inspection of brazed repair locations, additional repair of partially defective locations, and finishing processing including cooling hole repair processing;
A brazing repair method comprising: performing a solution treatment and an aging heat treatment on a repaired portion that has undergone a finishing treatment.   Whether the chemical composition other than B in the non-molten alloy powder is the same as the chemical composition of the molten alloy powder, and the B content in the non-molten alloy powder is smaller than the B content in the molten alloy powder The brazing repair method according to claim 11, wherein the repairing method is zero.   The brazing repair method according to claim 11 or 12, wherein the non-molten alloy powder is made of the same material as the base material.   The brazing repair according to any one of claims 11 to 13, wherein the temperature when the tensile strength of the base material to be brazed is reduced by 10% with respect to the tensile strength at room temperature is 1210 ° C. Method.

Images