Method for repairing single crystal thin-walled component by laser cladding and laser cladding equipment

Abstract

The present disclosure relates to the technical field of laser cladding repair, and particularly relates to a laser cladding repair method for single-crystal thin-walled components and a laser cladding device. The repair method comprises determining each damaged part of a single-crystal thin-walled component to be repaired; obtaining state information of each damaged part respectively and obtaining a repair powder group corresponding to each damaged part respectively; the repair powder group comprises at least one repair powder, and the repair powder is a single-crystal alloy powder or a polycrystal alloy powder; the state information comprises a temperature field and a stress-strain distribution; laser cladding process parameters are determined, the process parameters comprise a laser power, a scanning speed and a powder feeding amount; a repair path of the single-crystal thin-walled component to be repaired is obtained; and laser cladding repair is performed on each damaged part. The method proposes a method for repairing single-crystal thin-walled components by using polycrystal alloy powder, thereby reducing the repair cost of the single-crystal thin-walled components.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of laser cladding repair, in particular, to a laser cladding repair method for single-crystal thin-walled components and a laser cladding device. BACKGROUND

[0002] In the related art, various methods for laser cladding repair of thin-walled single-crystal components are proposed. However, the nickel-based single-crystal thin-walled components have complex geometric structures, various failure forms, and contain a large amount of noble metal elements such as Re and Ta, so the direct replacement or repair processing by the method in the related art has a high cost.

[0003] It should be noted that the information disclosed in the above background section is only configured to strengthen the understanding of the background of the present disclosure, and therefore can include information that does not constitute prior art known to those of ordinary skill in the art. SUMMARY

[0004] The present disclosure aims to overcome the deficiencies of the prior art, and provides a laser cladding repair method for single-crystal thin-walled components and a laser cladding device. The method proposes a method for repairing single-crystal thin-walled components by using polycrystalline alloy powder, thereby reducing the repair cost of single-crystal thin-walled components. At the same time, the method uses a combination of simulation and experiment to quickly narrow the process screening range and shorten the repair cycle of single-crystal thin-walled components.

[0005] According to one aspect of the present disclosure, a laser cladding repair method for single-crystal thin-walled components is provided, comprising:

[0006] determining each damaged site of a single-crystal thin-walled component to be repaired;

[0007] obtaining state information of each damaged site, and based on the state information, obtaining a corresponding repair powder group for each damaged site; the repair powder group includes at least one repair powder, and the repair powder is a single-crystal alloy powder or a polycrystalline alloy powder; the state information includes a temperature field and a stress-strain distribution;

[0008] determining laser cladding process parameters based on each damaged site and the corresponding repair powder, the process parameters including laser power, scanning speed, and powder feeding amount;

[0009] obtaining a repair path of the single-crystal thin-walled component to be repaired; and based on the process parameters, the repair path, and the repair powder, performing laser cladding repair on each damaged site.

[0010] In one embodiment of the present disclosure, the process parameters further include a transverse magnetic field strength.

[0011] In an embodiment of the present disclosure, determining each damaged site of the single-crystal thin-walled component to be repaired comprises:

[0012] Adopting overall blade profile detection and non-destructive testing to determine each damaged site of the single-crystal thin-walled component to be repaired.

[0013] In an embodiment of the present disclosure, obtaining state information of each damaged site respectively comprises:

[0014] Obtaining a temperature field of each damaged site by conducting a fluid-thermal coupling analysis on the single-crystal thin-walled component to be repaired;

[0015] Obtaining a stress-strain distribution of each damaged site by conducting a strength analysis on the single-crystal thin-walled component to be repaired.

[0016] In an embodiment of the present disclosure, based on the state information, obtaining a repair powder group corresponding to each damaged site respectively comprises:

[0017] Based on the state information of each damaged site, in combination with the chemical composition and high-temperature mechanical properties of each polycrystalline alloy powder, the chemical composition and high-temperature mechanical properties of each single-crystal alloy powder, and the base material of the single-crystal thin-walled component to be repaired, judging the polycrystalline alloy powder and / or single-crystal alloy powder that can be used to repair each damaged site, thereby obtaining a repair powder group corresponding to each damaged site.

[0018] In an embodiment of the present disclosure, when the repair powder group includes at least one polycrystalline alloy powder, one of the polycrystalline alloy powders is used to repair the damaged site.

[0019] In an embodiment of the present disclosure, before laser cladding repair is performed on the damaged site, the damaged site is further pre-processed.

[0020] The pre-processing comprises:

[0021] Removing the failure part at the damaged site to form a repair surface, and performing surface treatment on the repair surface to make the roughness Ra of the repair surface between 3-10 μm.

[0022] In an embodiment of the present disclosure, the single-crystal thin-walled component to be repaired is a nickel-based single-crystal thin-walled component.

[0023] In an embodiment of the present disclosure, based on each damaged site and its corresponding repair powder, determining laser cladding process parameters comprises:

[0024] A multi-physical field single-channel laser cladding repair simulation is carried out, a temperature gradient of a solid-liquid interface junction area is extracted, and a process parameter range beneficial to forming a single crystal on a single crystal thin-walled component is screened out based on a columnar crystal to equiaxed crystal transition criterion during rapid solidification of a nickel-based high-temperature alloy.

[0025] Based on the process parameter range, an orthogonal test method is used for process combination, a metallographic observation is performed on a cross section of a single-channel repair area, and specific laser cladding process parameters are determined according to the principles of no cracks, no voids, uniform dendrite growth, and consistent orientation with a substrate of the single crystal thin-walled component.

[0026] According to another aspect of the present disclosure, a laser cladding device is provided, having a laser cladding device body including a clamping module configured to clamp a workpiece to be cladded;

[0027] The laser cladding device further includes a driving member and two electromagnets, the two electromagnets being arranged on the driving member, and the driving member being configured to drive the two electromagnets to move closer to or farther away from each other;

[0028] The two electromagnets are distributed on both sides of the clamping module and provide a transverse magnetic field to a cladding area of the workpiece to be cladded.

[0029] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0030] The drawings herein are incorporated into the specification and form a part of the specification, show embodiments consistent with the present disclosure, and together with the specification, are configured to explain the principles of the present disclosure. Obviously, the drawings in the following description are only some embodiments of the present disclosure, and other drawings can be obtained from these drawings without creative labor for those skilled in the art.

[0031] Figure 1 In an embodiment of the present disclosure, a single-channel laser cladding repair thin-walled process cross-sectional EBSD (electron backscatter diffraction technology) diagram (without magnetic field) is shown, wherein 500 μm is a scale.

[0032] Figure 2 In an embodiment of the present disclosure, a single-channel laser cladding repair thin-walled process cross-sectional EBSD (electron backscatter diffraction technology) diagram (with magnetic field) is shown, wherein 500 μm is a scale.

[0033] Figure 3 In an embodiment of the present disclosure, a structural schematic diagram of a laser cladding device is shown.

[0034] Figure 4For an embodiment of the present disclosure, a schematic view of a blade structure.

[0035] BRIEF DESCRIPTION OF DRAWINGS

[0036] 1. Laser powder feeding module; 11. Laser head; 12. Powder feeding head; 2. Electromagnet; 3. Clamping module; 4. Driving member; 41. Guide rail; 42. Slide block; 5. Cooling module; 51. Cooling water tank; 52. Water pump; 53. Spraying head; 6. Support seat; 7. Damaged part; 8. Single crystal thin-walled component; 81. Blade back; 82. Blade leading edge; 83. Blade trailing edge; 84. Blade basin. DETAILED DESCRIPTION

[0037] Example embodiments now will be described more fully hereinafter with reference to the accompanying drawings. Example embodiments, may, however, be implemented in many different forms and should not be construed as limited to the implementations set forth herein; rather, these implementations are provided so that this disclosure will be thorough and complete, and will fully convey the scope of example embodiments to those skilled in the art. Like reference numerals refer to like elements throughout the description. Additionally, the drawings are merely schematic and are not drawn to scale.

[0038] While relative terms such as "upper," "lower," may be used in this specification to describe one component's relationship to another component of a figure, such terminology is configured to be merely for convenience in describing the example in the orientation as shown in the figures. It is understood that if the device of the figure were turned over so that what is described as "upper" is now "lower," the components would be described as such. When a structure is "on" another structure, it can mean that the structure is formed integrally with the other structure, or that the structure is "directly" on the other structure, or that the structure is "indirectly" on the other structure via another structure.

[0039] The terms "a," "an," "the," and "at least one" are used to mean one or more elements / components / etc.; the terms "comprises," "comprising," "includes," "including," and the like can mean the inclusion of an element / component / etc., without the exclusion of other elements / components / etc.

[0040] With the continuous improvement of the performance of aero-engine and gas turbine, the structure wall thickness of hot end components such as nickel-based single crystal high-temperature alloy turbine blade is continuously reduced to improve the cooling efficiency. However, the single crystal thin wall component is often affected by fatigue, creep, thermal stress and other factors due to the severe service conditions, complex shape and high performance requirements, and often appears cracks, wear and corrosion and other problems. If the damaged single crystal thin wall component is directly replaced, the material will be wasted and the cost will be high. Therefore, developing efficient, high-precision, low-cost and high-quality repair and remanufacturing technology to restore the geometric shape, microstructure and mechanical properties of the damaged single crystal thin wall structure has important economic and engineering significance for realizing low-cost and high-quality operation of the engine.

[0041] The repair of the single crystal thin wall component is to remove the damage and repair the notch on the single crystal thin wall component according to the form and position of the damage of the single crystal thin wall component. The single crystal repair relies on the high temperature gradient and low solidification rate during directional solidification. The laser cladding repair technology adopts a high energy density laser heat source to quickly melt the alloy powder, so that it forms a good metallurgical bond with the base metal. The temperature gradient of the formed molten pool is high, which is suitable for the repair of the single crystal thin wall structure.

[0042] In the related art, a variety of methods for repairing single crystal thin wall components by laser cladding of single crystal alloy powder are proposed. However, the single crystal alloy powder contains a large amount of noble metal elements such as Re, Ta, etc. The method for repairing thin wall single crystal components by laser cladding of single crystal alloy powder will bring a large cost. If the direct replacement method is used, the cost is also high.

[0043] To solve the above problems, the present disclosure provides a laser cladding equipment, see Figure 3 The laser cladding equipment includes a laser cladding equipment body and a magnetic module.

[0044] In an example of the present disclosure, the laser cladding equipment body can adopt an existing laser cladding equipment. For example, the laser cladding equipment body has a support seat 6, a clamping module 3, a laser powder feeding module 1 and a cooling module 5. The clamping module 3 is arranged on the support seat 6, and the clamping module 3 is configured to clamp and fix the workpiece to be cladded. The specific structure of the clamping module 3 is not limited as long as it can meet the clamping function. The laser powder feeding module 1 has a laser head 11 and a powder feeding head 12. The laser head 11 emits laser, and the powder feeding head 12 transports the repair powder. The cooling module 5 includes a cooling water tank 51, a water pump 52 and a spraying head 53. The cooling water tank 51 is located below the clamping module 3. The water pump 52 transports the water in the cooling water tank 51 to the spraying head 53. During the laser cladding process, the spraying head 53 sprays cooling water on the workpiece to be cladded to cool it down. Then the cooling water tank 51 collects the cooling water for recycling. In the present disclosure, the workpiece to be cladded is the single crystal thin wall component 8 to be repaired.

[0045] In an embodiment of the present disclosure, the magnetic module comprises a driving member 4 and two electromagnets 2, wherein the driving member 4 is configured to drive the two electromagnets 2 to move towards or away from each other, the two electromagnets 2 are opposite in polarity on the side moving towards each other, and the two electromagnets 2 are located on the two sides of the clamping module 3. In this way, the two electromagnets 2 can be located on the two sides of the workpiece to be cladded, and can provide a transverse magnetic field for the damaged part 7 during laser cladding.

[0046] In an example of the present disclosure, the driving member 4 can comprise a motor, a double-headed screw, a guide rail 41, and two sliders 42, the two sliders 42 are arranged on the guide rail 41 and are distributed on the two sides of the clamping module 3, the two electromagnets 2 are arranged on the two sliders 42 respectively, the motor is arranged on the support seat 6, the output end of the motor is connected with one end of the double-headed screw, the other end of the double-headed screw passes through the two sliders 42, and the threads of the two ends of the double-headed screw are opposite in rotation direction. In this way, the motor can be used to drive the double-headed screw to rotate, so that the two electromagnets 2 move towards or away from each other. In another example, the driving member 4 can comprise two groups of sub-driving members 4, each group of sub-driving members 4 corresponds to one of the two electromagnets 2, and each sub-driving member 4 comprises a cylinder, a slider 42, and a guide rail 41. The slider 42 is arranged on the guide rail 41, and the electromagnet 2 is arranged on the slider 42. The power output end of the cylinder is connected with the slider 42. The cylinder is used to drive the electromagnet 2 to move, so as to realize the mutual approach or away of the two electromagnets 2. Of course, the driving member 4 can also be other structures not shown. The present disclosure does not limit the specific structure of the driving member 4.

[0047] In an embodiment of the present disclosure, the electromagnet 2 can be a permanent magnet. In this way, the magnetic field provided by the electromagnet 2 is more stable, and the service life is longer. Of course, in other examples, the electromagnet 2 can be other types of magnets.

[0048] The present disclosure also provides a laser cladding repair method for a single crystal thin-walled component, comprising:

[0049] S010, determining each damaged part 7 of the single crystal thin-walled component 8 to be repaired, wherein in this example, the number of damaged parts 7 is defined as N, and N is a positive integer greater than or equal to 1;

[0050] S020, obtaining the state information of the N damaged parts 7 respectively, and obtaining the repair powder group corresponding to the N damaged parts 7 based on the state information of the N damaged parts 7, wherein the repair powder group comprises at least one repair powder, and the repair powder is a single crystal alloy powder or a polycrystalline alloy powder; the state information comprises a temperature field and a stress-strain distribution;

[0051] S030, determining laser cladding process parameters based on the N damaged parts 7 of the single crystal thin-walled component 8 to be repaired and the repair powders corresponding to the N damaged parts 7, wherein the process parameters include laser power, scanning speed, powder feeding amount and transverse magnetic field strength;

[0052] S040, obtaining a repair path of the single crystal thin-walled component 8 to be repaired;

[0053] S050, repairing each damaged part based on the process parameters, the repair path and the repair powder.

[0054] In an embodiment of the present disclosure, the base material of the single crystal thin-walled component 8 to be repaired is a nickel-based material.

[0055] In an embodiment of the present disclosure, in step S010, the damaged parts 7 of the single crystal thin-walled component 8 to be repaired can be determined by means of overall blade profile detection, non-destructive testing, etc. In an example, the overall blade profile detection method can be used to detect the geometric shape of the single crystal thin-walled component 8 to be repaired as a whole, and the geometric shape parameters of the single crystal thin-walled component 8 to be repaired are compared with the geometric shape parameters of the standard single crystal thin-walled component corresponding to the single crystal thin-walled component 8. If the geometric shape parameters of the standard single crystal thin-walled component are the same as the geometric shape parameters of the single crystal thin-walled component 8 to be repaired, it indicates that the single crystal thin-walled component 8 to be repaired has no damage, no damaged parts 7, and no need for repair (of course, in general, the single crystal thin-walled component 8 is repaired after being damaged). If the geometric shape parameters of the standard single crystal thin-walled component are greater than the geometric shape parameters of the single crystal thin-walled component 8 to be repaired, it indicates that the single crystal thin-walled component 8 to be repaired has damage, and the damaged parts 7 are determined by the amount of reduction of the corresponding parameters. In an example, the ultrasonic testing (UT) method can be used to determine whether the single crystal thin-walled component 8 to be repaired has cracks, thereby determining the damaged parts 7. In other examples, the single crystal thin-walled component 8 to be repaired can also be detected by means of fluorescence detection, etc., as long as the damaged parts 7 of the single crystal thin-walled component 8 to be repaired can be determined.

[0056] In an embodiment of the present disclosure, in step S020, the state information of the N damaged parts 7 can be obtained by means of flow-thermal coupling analysis and strength analysis. It can be understood that the flow-thermal coupling analysis is carried out on the single crystal thin-walled component 8 to be repaired to obtain the temperature field of the damaged parts 7 of the single crystal thin-walled component 8 to be repaired, and the strength analysis is carried out according to the actual working condition of the single crystal thin-walled component 8 to be repaired to obtain the stress and strain distribution of the damaged parts 7 of the single crystal thin-walled component 8 to be repaired. Of course, the present disclosure does not limit the order of flow-thermal coupling analysis and strength analysis.

[0057] In one embodiment of the present disclosure, in step S020, based on the state information of the N damaged sites 7, the corresponding repair powder groups of the N damaged sites 7 are obtained respectively. Specifically, based on the state information of the N damaged sites 7, in combination with the chemical composition of the polycrystalline alloy powder and the high-temperature mechanical properties of the polycrystalline alloy powder, the chemical composition of the single-crystal alloy powder and the high-temperature mechanical properties of the single-crystal alloy powder, in combination with the matrix material of the single-crystal thin-walled component 8 to be repaired, and under the condition that the mechanical properties of the polycrystalline alloy powder for repairing the single-crystal thin-walled component 8 can meet the use requirements at the temperature of the actual working condition of the damaged site 7, it is determined which polycrystalline alloy powder or single-crystal alloy powder is used for repairing each damaged site 7, thereby obtaining the corresponding repair powder groups of the N damaged sites 7. For example, the polycrystalline alloy powder has the advantages of good plasticity, small probability of defects such as cracks during repair process, and larger crack-free process window for laser cladding repair compared with single-crystal alloy powder. For the parts under high temperature and susceptible to oxidation and corrosion in service conditions (referring to the working state of the equipment or system during actual operation, which reflects the performance and load condition of the equipment in actual use), polycrystalline alloy powder with good high-temperature resistance, oxidation resistance and corrosion resistance can be selected, such as DZ406 (nickel-based precipitation hardening directional solidification columnar crystal high-temperature alloy). Of course, other polycrystalline alloy powders can also be selected. For parts under high temperature (<1000℃), high stress level and large strain gradient in service conditions, especially in the case of complex structure and large curvature of the damaged site 7 of the single-crystal thin-walled component 8 to be repaired, polycrystalline alloy powder with different optimal service temperatures can be selected according to the actual temperature requirements, such as GH3625 (nickel-based high-temperature alloy), GH4169 (precipitation hardenable nickel-chromium alloy) and the like. For other parts under high temperature (≥1000℃) in service, single-crystal alloy powder with similar grade to the matrix material of the single-crystal thin-walled component 8 to be repaired can be used for repair.

[0058] In one example of the present disclosure, if the repair powder group contains only one repair powder, the repair powder is directly used for laser cladding repair. If the repair powder group contains at least two repair powders, and at least one of them is a polycrystalline alloy powder, one of the polycrystalline alloy powders is selected for laser cladding repair.

[0059] In an embodiment of the present disclosure, in step S030, based on the N damaged sites 7 of the single-crystal thin-walled component 8 to be repaired and the repair powders (single-crystal alloy powder or polycrystal alloy powder) corresponding to the N damaged sites 7, a single-pass repair test is carried out (in the test, the ratio of the laser spot diameter to the wall thickness of the damaged site 7 is 2-4:1, the laser power ranges from 150 to 500 W, the scanning speed is 120-500 mm / min, the powder feeding speed is 0.5-3 g / min, and the transverse magnetic field strength is 0-0.2 T). Specifically, first, a multi-physical field single-pass laser cladding repair simulation is carried out by using the Comsol finite element software, the temperature gradient of the solid-liquid interface junction area (paste area) is extracted, and the process parameter range conducive to single-crystal formation is preliminarily screened out by using the CET criterion for the rapid solidification of nickel-based superalloys proposed by Hunt J D et al., and then based on the process parameter range, an orthogonal test method is adopted to combine the processes, the cross section of the single-pass repair is observed by metallography, and the appropriate laser cladding process parameters are screened out according to the principles of no cracks, no voids, uniform dendrite growth, and the same orientation as the substrate. In the present disclosure, it is first proposed to use polycrystal alloy powder to repair single-crystal thin-walled components, thereby reducing the cost.

[0060] In an embodiment of the present disclosure, in step S040, the repair path of the single-crystal thin-walled component 8 to be repaired is obtained. In an example, the center points of each cross section of the single-crystal thin-walled component 8 to be repaired along the thickness direction are obtained at a Qmm interval, the center lines are obtained by connecting the center points, and the center lines are the laser path center lines of the laser cladding. In this step, based on the center line of the laser path, the laser cladding repair path is obtained. In an example, Qmm can be 0.2 mm, or 0.5 mm, or 0.8 mm, etc., and can be set according to requirements.

[0061] In an embodiment of the present disclosure, before the laser cladding repair of the damaged part 7, the damaged part 7 is also pre-processed. Specifically, the failed part at the damaged part 7 is removed to form a surface to be repaired, and the surface to be repaired is surface treated to make the roughness Ra of the surface to be repaired between 3-10 μm. In an example, the diamond grinding head, pneumatic grinding, etc. can be used to remove the failed part at the damaged part 7 to form the surface to be repaired, and then 600# and 800# are used in sequence to control the roughness Ra of the surface to be repaired to be between 3-10 μm (which can ensure good bonding of the repaired interface, and at the same time avoid the roughness being too low to affect the cladding effect in the laser cladding process), and then cleaned and dried. In an example, anhydrous ethanol can be used for cleaning and a hair dryer can be used for quick drying. In other examples, other ways can also be used for cleaning and drying. In an example, 600# and 800# are used in sequence for grinding, and the roughness can be 3 μm, 5 μm, 9 μm, 10 μm, etc. Of course, in other examples, other ways can also be used for grinding, and the surface to be repaired can also be other roughness not shown.

[0062] In an embodiment of the present disclosure, in step S050, the laser cladding repair of the single crystal thin-walled member to be repaired 8 is carried out in an inert gas environment. Specifically, the single crystal thin-walled member to be repaired 8 is clamped on the clamping module 3 of the laser cladding device, and a certain amount of inert gas with a certain concentration is pre-charged, and the laser cladding repair of the single crystal thin-walled member to be repaired 8 is completed under the protection of the inert gas. In this example, the inert gas can be pre-charged for 30 minutes to meet the requirements of laser cladding.

[0063] In an embodiment of the present disclosure, after step S050, step S060 of laser cladding post-processing is further included, which restores the geometry of the repaired single crystal thin-walled member to be repaired 8 to the geometry of the standard single crystal thin-walled member, and then carries out related machining and surface treatment on the surface thereof to make the surface meet the corresponding accuracy requirements.

[0064] In an embodiment of the present disclosure, step S040 can be performed before step S050, and the specific time sequence is not limited.

[0065] Since the single crystal thin-walled member has a complex shape and large curvature, its repair is prone to micro-cracks. In the present disclosure, for some areas with low temperature resistance requirements, low-cost polycrystalline alloy powder can be considered for repair. On the one hand, polycrystalline alloy powder repair is not prone to micro-cracks, and better organization and performance recovery can be achieved; on the other hand, a larger repair process window can be achieved; in addition, polycrystalline alloy powder contains less noble elements, which can improve the economic efficiency of single crystal thin-walled member repair.

[0066] In general, the disclosure proposes a method for repairing a single crystal thin-walled component 8 using polycrystalline alloy powder, which can reduce costs and achieve low-cost repair of single crystal thin-walled components 8; and the disclosure uses a combination of simulation and experiment to quickly narrow the process screening range and shorten the thin-walled component repair cycle. Moreover, the disclosure proposes a scheme for repairing complex single crystal thin-walled components using polycrystalline alloy powder laser cladding assisted by a transverse magnetic field. The magnetic field and the selected good shaping polycrystalline alloy powder enable the method proposed in the disclosure to effectively expand the crack-free process window for repairing thin-walled structures compared to existing single crystal repair processes. Furthermore, magnetic field-assisted laser cladding repair is a new technology that introduces a magnetic field as a new energy field to improve and overcome the defects of laser cladding repair technology in related technologies. The thermal damping effect and thermal cell effect of the magnetic field on the molten pool metal fluid during the laser cladding repair process affect the molten pool flow and heat transfer, thereby reducing the number of pores and cracks in the cladding layer, improving the cladding layer density, improving the hardness and corrosion resistance, and at the same time, slowing down the Marangoni flow inside the molten pool, promoting the epitaxial growth of dendrites in the cladding repair layer, facilitating the formation of single crystal structure, and thus improving the performance of the repaired powder.

[0067] Based on the above method, the disclosure provides the following embodiments:

[0068] Referring to Figure 4 A certain nickel-based single crystal thin-walled component (nickel-based single crystal thin-walled blade) has cracks, tip wear, and other failures due to factors such as fatigue, creep, thermal stress, mechanical wear, etc. The method in the disclosure is used to repair the nickel-based single crystal thin-walled component (nickel-based single crystal thin-walled blade), which includes the following steps:

[0069] S010, the overall geometry of the nickel-based single crystal thin-walled component 8 to be repaired is detected in an overall blade shape detection manner, and compared with the geometric model of the standard nickel-based single crystal thin-walled component. It is found that the tip of the nickel-based single crystal thin-walled component 8 to be repaired has a wear of about 0.4 mm. Ultrasonic detection finds that cracks appear in the blade basin of the nickel-based single crystal thin-walled component 8 to be repaired, and the two damaged parts 7 are marked;

[0070] S020, the thermal-fluid coupling analysis and strength analysis are performed on the nickel-based single crystal thin-walled component 8 to be repaired, and the temperature field and stress-strain distribution of the two damaged parts 7 are obtained respectively. Based on the temperature field and stress-strain distribution of the two damaged parts 7, combined with the chemical composition of the polycrystalline alloy powder and the high-temperature mechanical properties of the polycrystalline alloy powder, combined with the chemical composition of the single crystal alloy powder and the high-temperature mechanical properties of the single crystal alloy powder, combined with the base material of the nickel-based single crystal thin-walled component 8 to be repaired, and under the condition that the polycrystalline alloy powder repair single crystal mechanical properties can meet the use requirements under the actual working condition temperature of the damaged part 7, it is judged that the crack in the blade basin 84 area (between the blade trailing edge 83 and the blade leading edge 82) can be repaired by GH4169 powder, and the blade back 81 area and the blade trailing edge 83 use DD5 (second generation nickel-based single crystal high-temperature alloy) alloy powder consistent with the blade powder;

[0071] S030, single-channel repair test of the single crystal thin-walled component 8 to be repaired is carried out, including single-channel repair test of the single crystal alloy powder repair single crystal thin-walled component 8 to be repaired, and single-channel repair test of the polycrystalline alloy powder repair single crystal thin-walled component 8 to be repaired;

[0072] Firstly, the process parameters need to be established, and the substrate of 1.5mm×15mm×15mm is cut according to the thickest part of the damaged part 7 for single-channel repair test, wherein the laser power range of the single-channel repair test is 150-500W, the scanning speed is 120-500mm / min, the powder feeding speed is 0.5-3g / min, and the transverse magnetic field intensity is 0-0.2T;

[0073] Firstly, the multi-physical field single-channel laser cladding repair simulation is carried out by using Comsol finite element software, and the temperature gradient of the solid-liquid interface junction area (paste area) is extracted. In this example, the temperature gradient is 4×10 6 -6×10 6 K×m -1 , the process parameter range beneficial to single crystal formation is preliminarily screened out by using the CET criterion of nickel-based high-temperature alloy rapid solidification proposed by Hunt JD et al. Then, the orthogonal test method is adopted based on the initial range of the process parameters, and the metallographic observation is carried out on the cross section of the single-channel repair. According to the principles of no crack, no gap, uniform dendrite growth and the same orientation as the substrate, the appropriate process parameters are screened out. Because the Marangoni flow at the solid-liquid interface of the molten pool is weakened under the assistance of the magnetic field, the dendrites tend to continue to grow. Based on the preliminary optimization of the process parameters, the dendrite orientation analysis under the magnetic field and without the magnetic field is carried out, such as Figure 1 and Figure 2For the cross-section EBSD images of single-channel laser cladding with and without magnetic field under the same process, it can be seen that the single crystal growth is good under the assistance of magnetic field, the mixed crystal is reduced, and the repair effect is better. The process parameters include laser power of 300 W, scanning speed of 480 mm / min, powder feeding rate of 0.59 g / min, and transverse magnetic field strength of 0.2 T. For the process of repairing the DD5 powder base, similar to the above process, the better repair process parameters include laser power of 400 W, scanning speed of 240 mm / min, powder feeding rate of 1.57 g / min, and transverse magnetic field strength of 0.2 T;

[0074] S040, model and slice the whole nickel-based single crystal thin-walled component 8 to be repaired, and plan the laser cladding repair path. According to the interval of 0.2 mm, the thickness of each cross-section thin-walled component is obtained in the range of 0.2-1.5 mm, and then the center line of each height thickness profile is drawn. The center line is the laser path center line, and then the repair path is obtained;

[0075] S045, based on different damaged parts 7, use diamond grinding head, pneumatic grinding and other methods to grind the cracks to produce a smooth groove of about 135°. In addition, the surfaces of other parts of the blade tip (blade tail edge 83, blade leading edge 82, blade basin 84, and blade back 81) are treated. First, use pneumatic grinding to remove carbon, oxides and other substances generated by long-term work. Then, use 600# and 800# to grind the entire blade tip, control the roughness Ra to be 3-10 μm, and then use anhydrous ethanol for cleaning and a hair dryer for quick drying. Of course, in other examples, the smooth groove can also be other angles less than 150°, for example, it can be 120°, 145°, 115°, etc. For example, the roughness Ra can be 3 μm, 5 μm, 9 μm, 10 μm, etc. Of course, it can also be other roughnesses not shown. Based on the nickel-based base powder DD5, nickel-based polycrystalline GH4169 is selected as the repair powder. The GH4169 alloy powder is prepared by vacuum gas atomization method, and the powder particle size is 50-150 μm. Before the test, first dry and cool the high-temperature alloy powder in the vacuum drying box;

[0076] S050, carry out nickel-based single crystal thin-walled component laser cladding repair in an inert gas environment.

[0077] For the tip (the leading edge 82, the trailing edge 81 and the trailing edge 83 of the blade), each layer is divided into three parts to carry out repair, the DD5 alloy powder is used to repair the trailing edge 81 and the trailing edge 83 of the blade, the path is A-B-C, the process is laser power 400W, scanning speed 240mm / min, powder feeding rate 1.57g / min, transverse magnetic field 0.2T, in the moving process, the spot diameter is adjusted according to different wall thickness, wherein the thickness of the trailing edge 83 part B-C is 0.2-1.5mm, wherein 0.2-0.6mm adopts spot diameter 0.8mm, the rest of the tip adopts spot diameter 1.5mm; the GH4169 is used to repair the area C-A of the blade basin 84, the process parameters are laser power 300W, scanning speed 480mm / min, powder feeding rate 0.59g / min, transverse magnetic field 0.2T. Repeat the path A-B, B-C, C-A three times, and the tip is lengthened to the required height.

[0078] S060, the numerical control machining tool is used to restore the geometric shape of the repaired single crystal thin-walled component 8 to the standard single crystal thin-walled component geometric shape, and then the surface is machined and treated to meet the corresponding precision requirements.

[0079] In addition, although the steps of the method in the present disclosure are described in a specific order in the drawings, this does not require or imply that the steps must be performed in this specific order, or that all the steps shown must be performed to achieve the desired result. In addition or alternatively, some steps can be omitted, a plurality of steps can be combined into one step, and / or one step can be divided into a plurality of steps, etc.

[0080] Other embodiments of the present disclosure will be readily apparent to those skilled in the art upon considering the specification and practicing the application disclosed herein. The present application is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include known equivalents or customarily used terms in the art to which the present disclosure pertains. The specification and examples are to be regarded as exemplary only, and the true scope and spirit of the present disclosure are indicated by the appended claims.

Claims

1. A laser cladding repair method for single-crystal thin-walled components, characterized in that, include: Identify each damaged part (7) of the single crystal thin-walled component (8) to be repaired; use overall blade profile detection and non-destructive testing to identify each damaged part (7) of the single crystal thin-walled component (8) to be repaired; The state information of each damaged part (7) is obtained; the temperature field of each damaged part (7) is obtained by performing thermal coupling analysis on the single crystal thin-walled component (8) to be repaired; the stress and strain distribution of each damaged part (7) is obtained by performing strength analysis on the single crystal thin-walled component (8) to be repaired. Based on the state information, repair powder groups corresponding to each damaged part (7) are obtained respectively; based on the state information of each damaged part (7), combined with the chemical composition and high-temperature mechanical properties of each polycrystalline alloy powder, the chemical composition and high-temperature mechanical properties of each single-crystal alloy powder, and the matrix material of the single-crystal thin-walled component (8) to be repaired, it is determined that polycrystalline alloy powder and / or single-crystal alloy powder can be used to repair each damaged part (7), thereby obtaining repair powder groups corresponding to each damaged part (7); the repair powder group includes at least one repair powder, which is a single-crystal alloy powder or a polycrystalline alloy powder; the state information includes temperature field and stress-strain distribution; Based on each of the damaged parts (7) and the corresponding repair powder, the laser cladding process parameters are determined, including laser power, scanning speed and powder feeding amount; The repair path of the single-crystal thin-walled component (8) to be repaired is obtained, and laser cladding repair is performed on each of the damaged parts (7) based on the process parameters, the repair path and the repair powder.

2. The laser cladding repair method for single-crystal thin-walled components according to claim 1, characterized in that, The process parameters also include the transverse magnetic field strength.

3. The laser cladding repair method for single-crystal thin-walled components according to claim 1, characterized in that, When the repair powder group includes at least one polycrystalline alloy powder, one of the polycrystalline alloy powders is used to repair the damaged part (7).

4. The laser cladding repair method for single-crystal thin-walled components according to claim 3, characterized in that, Before performing laser cladding repair on the damaged area (7), a pretreatment of the damaged area (7) is also included; The preprocessing includes: Remove the failed part at the damaged part (7) to form a surface to be repaired, and perform surface treatment on the repaired surface so that the roughness Ra of the repaired surface is between 3 and 10 μm.

5. The laser cladding repair method for single-crystal thin-walled components according to claim 4, characterized in that, The single-crystal thin-walled component (8) to be repaired is a nickel-based single-crystal thin-walled component.

6. The laser cladding repair method for single-crystal thin-walled components according to claim 5, characterized in that, Based on each of the damaged areas (7) and their corresponding repair powders, the laser cladding process parameters are determined, including: Multi-physics field single-channel laser cladding repair simulation was carried out to extract the temperature gradient of the solid-liquid interface region. Based on the transformation criterion of columnar crystal to equiaxed crystal during rapid solidification of nickel-based high-temperature alloys, the range of process parameters that are conducive to forming single crystals on single-crystal thin-walled components (8) was selected. Based on the range of process parameters, the process combination is carried out by orthogonal experiment method. Metallographic observation is performed on the cross section of the single-pass repair area. The specific laser cladding process parameters are determined based on the principle of no cracks, no voids, uniform dendrite growth, and orientation consistent with the matrix of the single crystal thin-walled component (8).

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