Method for repairing creep damage of nickel-based superalloy for gas turbine blade

Abstract

The invention discloses a method for repairing creep damage of a nickel-based superalloy for a gas turbine blade, relates to the field of creep damage repairing, and is used for repairing a repaired part, the creep of the part to be repaired is before the end of a third creep stage, and the part to be repaired is the gas turbine blade made of the nickel-based superalloy Mar-M247. Comprising the following steps that S1, a to-be-repaired part is subjected to hot isostatic pressing treatment; s2, the to-be-repaired part subjected to hot isostatic pressing treatment is subjected to solution treatment; and S3, the to-be-repaired part subjected to solution treatment is sequentially subjected to high-temperature aging treatment and low-temperature aging treatment, and repairing of the creep damage of the to-be-repaired part is completed. Through hot isostatic pressing, solution treatment and two times of aging treatment, the damaged structure of the creep damaged alloy is recovered to a uniform cubic form, and the creep property is recovered to be close to or even beyond the original level.

Description

Technical Field

[0001] The invention relates to the field of creep damage repair, in particular to a method for repairing creep damage of a nickel-based high-temperature alloy for a gas turbine blade. Background Art

[0002] Gas turbines serve in harsh environments such as high temperature, alternating loads and corrosive atmospheres, and are prone to coating and substrate damage and failure. In order to ensure the reliability, economy and safety of the unit, regular inspection and maintenance of gas turbine blades must be carried out, and the repair of gas turbine blades is the focus of gas turbine maintenance. There is currently no effective repair method in China to increase the service life of components, reduce costs, and thus extend the life of gas turbines.

[0003] Creep damage is one of the main damages of gas turbine blades. Phase rafting, creep voids, carbide transformation and dislocation network formation significantly reduce the creep performance of the alloy, which in turn causes failure. In order to repair and extend the service life of damaged blades, appropriate repair methods are needed to repair the damaged structure and properties of the alloy material. The repair methods include hot isostatic pressing, solution treatment, aging treatment, etc. The selection of hot isostatic pressing process parameters is closely related to the degree of damage and type of the alloy. Improper temperature selection may produce a large amount of internal recrystallization while healing the holes. In 1977, hot isostatic pressing technology was used for the first time to repair the performance of turbine blades. After that, foreign research institutions have successively carried out repair research on more than 40 alloys such as IN700, IN738, U520, GTD444, ReneN5, CMSX-4, etc.

[0004] Domestic scholars have also conducted a lot of research on repair methods. For example, patent CN104878329A involves a repair process method for repairing creep damage of directionally solidified high-temperature alloy DZ125 for turbine blades. This method is aimed at creep damage of turbine blades made of DZ125 material; Chinese patent 110284087A (published on September 27, 2019) discloses a creep damage repair method for K403 alloy blades that produce obvious tissue degradation but no creep holes; patent CN202110107227 discloses "A method for repairing alloy creep damage", which is aimed at hot isostatic pressing and heat treatment repair of creep damage, mainly for third-generation high-temperature alloys; patent CN103643188A discloses "A K465 alloy turbine blade performance recovery heat treatment method", which is aimed at short-term creep The long-term performance of K465 alloy turbine blades in service (500h-600h) is restored, and the repaired alloy material is K465 turbine blades; Patent CN116423144A discloses "A recovery treatment process for heat-corrosion-resistant directional alloy turbine blades", which is applied to the engineering repair treatment of long-term service damage of directional high-temperature alloy DZ411 alloy turbine blades; Patent CN104878329A discloses "A recovery heat treatment method for repairing creep damage of DZ125 alloy", which is a recovery heat treatment method for repairing creep damage of directional solidification high-temperature alloy DZ125 for turbine blades; Patent CN115584455A discloses "A recovery heat treatment method for nickel-based single crystal high-temperature alloys", which is aimed at the second and third generation nickel-based single crystal high-temperature alloys with tissue damage before the second creep stage.

[0005] In summary, there is still little research on creep damage repair of gas turbine blades made of nickel-based high-temperature alloy Mar-M247 in the art. Summary of the invention

[0006] The purpose of the present invention is to provide a method for repairing creep damage of a nickel-based high-temperature alloy for gas turbine blades in response to the above-mentioned problems. Through hot isostatic pressing, solution treatment and two aging treatments, the damaged structure of the creep-damaged alloy is restored to a uniform cubic form, and the creep performance is restored to a level close to or even exceeding the original level.

[0007] The technical solution adopted by the present invention is as follows: a method for repairing creep damage of a nickel-based high-temperature alloy for a gas turbine blade, wherein the creep of the part to be repaired is before the end of the third creep stage, and the part to be repaired is a gas turbine blade made of the nickel-based high-temperature alloy Mar-M247, comprising the following steps: S1: subjecting the repaired part to hot isostatic pressing; S2: subjecting the repaired part to solid solution treatment after hot isostatic pressing treatment; S3: performing high temperature aging treatment and low temperature aging treatment on the repaired part after the solution treatment in sequence to complete the repair of the creep damage of the repaired part.

[0008] Furthermore, in step S1, the temperature of the hot isostatic pressing treatment is 1000-1260°C, the pressure is 100-150 MPa, the insulation time is 1-8 hours, and air cooling is performed after the insulation is completed.

[0009] Furthermore, in step S1, hot isostatic pressing equipment is used to perform hot isostatic pressing treatment.

[0010] Furthermore, in step S2, the temperature of the solution treatment is 1160-1260°C, the holding time is 1-8h, and air cooling is performed after the holding is completed.

[0011] Furthermore, in step S3, the temperature of the high temperature aging treatment is 1020-1140°C, and the temperature is kept for 1-10 hours, and air cooling is performed after the temperature is kept.

[0012] Furthermore, in step S3, the temperature of the low-temperature aging treatment is 800-960°C, and the insulation is 8-26 hours, followed by air cooling.

[0013] Furthermore, solution treatment, high temperature aging treatment and low temperature aging treatment are performed in a vacuum environment.

[0014] Furthermore, vacuum heat treatment equipment is used to carry out solution treatment, high temperature aging treatment and low temperature aging treatment.

[0015] Furthermore, the vacuum degree of the vacuum environment is 10 -2 Pa-10 -4 Pa.

[0016] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: The method disclosed in the present invention can effectively repair the creep damaged structure and performance of the gas turbine blade made of nickel-based high-temperature alloy Mar-M247, and the performance after repair can eliminate creep cavities and restore The cubic morphology of the phase particles eliminates the residual eutectic and makes the structure homogenous, so that the repair heat treatment performance is close to or even exceeds the original level; this method is simple and reliable, low-cost, suitable for industrial production, and has broad application prospects in the repair of autonomous combustion engine blades. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 It is the original organization of Mar-M247; Figure 2 Creep damaged tissue and creep holes; Figure 3 The microstructure, creep void morphology and size after repair; Figure 4 For creep curve comparison. DETAILED DESCRIPTION

[0018] like Figure 1 As shown, a method for repairing creep damage of a nickel-based high-temperature alloy for a gas turbine blade is provided. The part to be repaired is a gas turbine blade made of the nickel-based high-temperature alloy Mar-M247, and the creep of the part to be repaired is before the end of the third creep stage.

[0019] The method is used to perform a repair experiment on the repaired part. Before the repair, the repaired part needs to be prepared; specifically, Figure 1 As shown in the figure, the original structure of the nickel-based high-temperature alloy Mar-M247 material was observed, and the nickel-based high-temperature alloy Mar-M247 material was processed into a test rod with a diameter of 6 mm and a length of 30 mm; the test rod was subjected to a creep test at 900°C and 250MPa, and the test rod creeped; according to the creep curve, an interrupted creep test was carried out before the test rod creeped to the end of the third creep stage, and the strain at the interruption should be between 0.8% and 1.4%, as shown in the figure. Figure 2 As shown, the tissue damage and creep holes existing after the creep damage that occurs before the end of the third creep stage of the test rod are obtained, that is, the part to be repaired used in the repair experiment.

[0020] Repairing the repaired part includes the following steps: S1: Use hot isostatic pressing equipment to perform hot isostatic pressing on the repaired parts; the temperature of hot isostatic pressing is 1000-1260℃, the pressure is 100-150MPa, the insulation time is 1-8h, and air cooling is performed after the insulation is completed; the creep voids and microcracks inside the material are effectively eliminated through hot isostatic pressing.

[0021] S2: Use vacuum heat treatment equipment (such as vacuum furnace) to perform solid solution treatment on the repaired parts after hot isostatic pressing in a vacuum environment. The vacuum degree of the vacuum environment is 10 -2 Pa-10 -4 Pa, the solution treatment temperature is 1160-1260℃, the holding time is 1-8h, and air cooling is performed after the holding period. The solution treatment effectively eliminates the creep damage in the organization. phase, and the residual eutectic structure and carbides dissolve back into the γ phase to form a γ single-phase structure. After air cooling, a large number of dispersed micro- Phase particles.

[0022] S3: Use vacuum heat treatment equipment (such as vacuum furnace) to perform high temperature aging treatment on the repaired parts after solution treatment in a vacuum environment. The vacuum degree of the vacuum environment is 10 -2Pa-10 -4 Pa, the temperature of high temperature aging treatment is 1020-1140℃, insulation for 1-10h, air cooling after insulation; The particle size of the phase continues to increase and The phases are adjusted into a regular cubic shape, and carbides begin to precipitate and grow within the grains and at the grain boundaries; Then, vacuum heat treatment equipment (such as a vacuum furnace) is used to perform low-temperature aging treatment on the repaired parts after high-temperature aging treatment in a vacuum environment. The vacuum degree of the vacuum environment is 10 -2 Pa-10 -4 Pa, low temperature aging treatment temperature is 800-960℃, insulation for 8-26h, air cooling after insulation; low temperature aging treatment can use fine Phase particles and carbides precipitate more fully.

[0023] After low-temperature aging treatment, the creep damage of the repaired part is repaired.

[0024] Specifically, the repair method is used to repair the above-mentioned repaired part. When the creep of the repaired part is at the end of the third creep stage, the following embodiment is proposed for the specific parameter setting of the repair experiment, as shown in Table 1.

[0025] Table 1 Examples of repair experiments

[0026] In the creep test, the test rod made of the nickel-based high-temperature alloy Mar-M247 material was subjected to creep test, that is, interruption and fracture tests were performed respectively, and the interruption point time was 60% of the fracture time. Figure 4 Therefore, combining Table 1 and Figure 4 It can be seen that after the repaired part is repaired, the creep rupture time is significantly prolonged, that is, the creep performance is restored to a level close to or even exceeding the original level.

[0027] Take the repaired test rod in Example 3 for tissue observation. Figure 3 The microstructure and morphology and size of creep voids are shown in Figure 2. Figure 2 , Figure 2 The rafting has been obvious Creep-damaged tissue can be repaired and the obviously degraded tissue can be dissolved back into the collective In the phase, a uniform cubic morphology is re-precipitated during the subsequent aging process; at the same time, the creep holes formed under the action of hot isostatic pressing are reclosed; the recovery heat treatment can basically eliminate the typical damage holes and rafted structure caused by creep, and the mechanical properties are restored to be higher than that of the bulk.

[0028] In summary, the method disclosed in this embodiment can effectively repair the creep damaged structure and performance of the gas turbine blade made of nickel-based high-temperature alloy Mar-M247. The performance after repair can eliminate creep voids and restore The cubic morphology of the phase particles eliminates the residual eutectic and makes the structure homogenous, so that the repair heat treatment performance is close to or even exceeds the original level; this method is simple and reliable, low-cost, suitable for industrial production, and has broad application prospects in the repair of autonomous combustion engine blades.

[0029] The present invention is not limited to the above-mentioned specific embodiments, but extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

Claims

1. A method for repairing creep damage of nickel-based high-temperature alloy for gas turbine blades, characterized in that: The part to be repaired is a gas turbine blade made of nickel-based high-temperature alloy Mar-M247. The creep of the part to be repaired is before the end of the third creep stage. The following steps are included: S1: subjecting the repaired part to hot isostatic pressing; S2: subjecting the repaired part to solid solution treatment after hot isostatic pressing treatment; S3: performing high temperature aging treatment and low temperature aging treatment on the repaired part after the solution treatment in sequence to complete the repair of the creep damage of the repaired part.

2. The repair method according to claim 1, characterized in that: In step S1, the temperature of the hot isostatic pressing treatment is 1000-1260°C, the pressure is 100-150 MPa, the insulation time is 1-8 hours, and air cooling is performed after the insulation is completed.

3. The repair method according to any one of claims 1-2, characterized in that: In step S1, a hot isostatic pressing process is performed using a hot isostatic pressing device.

4. The repair method according to claim 1, characterized in that: In step S2, the temperature of the solution treatment is 1160-1260°C, the holding time is 1-8h, and air cooling is performed after the holding is completed.

5. The repair method according to claim 1, characterized in that: In step S3, the temperature of high temperature aging treatment is 1020-1140°C, and the temperature is kept for 1-10 hours, and then air-cooled after the temperature is kept.

6. The repair method according to claim 1, characterized in that: In step S3, the temperature of low-temperature aging treatment is 800-960°C, and the temperature is kept for 8-26 hours, and then air-cooled after the temperature is finished.

7. The repair method according to any one of claims 1, 4-6, characterized in that: Solution treatment, high temperature aging treatment and low temperature aging treatment are carried out in a vacuum environment.

8. The repair method according to claim 7, characterized in that: Vacuum heat treatment equipment is used for solution treatment, high temperature aging treatment and low temperature aging treatment.

9. The repair method according to claim 7, characterized in that: The vacuum degree of the vacuum environment is 10 -2 Pa-10 -4 Pa.

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