Laser cladding repairing method and laser cladding equipment for single-crystal thin-wall component

Abstract

The invention relates to the technical field of laser cladding repair, in particular to a laser cladding repair method for a single-crystal thin-wall component and laser cladding equipment. The repairing method comprises the following steps: determining each damaged part of the single crystal thin-wall component to be repaired; state information of all the damaged parts is obtained, and repairing powder sets corresponding to all the damaged parts are obtained; the repairing powder group comprises at least one kind of repairing powder, and the repairing powder is single-crystal alloy powder or polycrystal alloy powder; the state information comprises a temperature field and stress-strain distribution; determining laser cladding process parameters, wherein the process parameters comprise laser power, scanning speed and powder feeding amount; obtaining a repairing path of the single crystal thin-wall component to be repaired; and performing laser cladding repair on each damaged part. According to the method, the polycrystalline alloy powder is used for repairing the single-crystal thin-wall component, and the repairing cost of the single-crystal thin-wall component is reduced.

Description

Technical Field

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

[0002] In the related art, a variety of methods for laser cladding repair of thin-walled single crystal components have been proposed. However, nickel-based single crystal thin-walled components have complex geometric structures and various failure forms. Single crystal materials contain a large amount of precious metal elements such as Re and Ta. Direct replacement or repair using methods in the related art is costly.

[0003] It should be noted that the information disclosed in the above background technology section is only configured to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute prior art known to ordinary technicians in the field. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and to provide a laser cladding repair method and laser cladding equipment for single crystal thin-walled components. The method proposes a method for repairing single crystal thin-walled components using polycrystalline alloy powder, thereby reducing the repair cost of single crystal thin-walled components. At the same time, a combination of simulation and experiment is used 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 a single crystal thin-walled component is provided, comprising:

[0006] Determine the damaged parts of the single crystal thin-walled component to be repaired;

[0007] respectively obtaining state information of each damaged part, and based on the state information, respectively obtaining a repair powder group corresponding to each damaged part; 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] Based on each of the damaged parts and the corresponding repair powder, determining laser cladding process parameters, the process parameters including laser power, scanning speed and powder feeding amount;

[0009] A repair path of the single crystal thin-walled component to be repaired is obtained; and based on the process parameters, the repair path and the repair powder, laser cladding repair is performed on each of the damaged parts.

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

[0011] In one embodiment of the present disclosure, determining each damaged portion of the single crystal thin-walled component to be repaired includes:

[0012] The damaged parts of the single crystal thin-walled component to be repaired are determined by using overall blade profile detection and non-destructive detection.

[0013] In one embodiment of the present disclosure, respectively obtaining the status information of each damaged part includes:

[0014] By performing a fluid-heat coupling analysis on the single crystal thin-walled component to be repaired, the temperature field of each damaged part is obtained;

[0015] By performing strength analysis on the single crystal thin-walled component to be repaired, the stress-strain distribution of each damaged portion is obtained.

[0016] In one embodiment of the present disclosure, based on the state information, a repair powder group corresponding to each damaged part is obtained, including:

[0017] Based on the status information of each damaged part, 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 to be repaired, the polycrystalline alloy powder and / or single crystal alloy powder that can be used to repair each damaged part is determined, thereby obtaining a repair powder group corresponding to each damaged part.

[0018] In one 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 portion.

[0019] In one embodiment of the present disclosure, before the damaged part is repaired by laser cladding, the damaged part is also pre-treated;

[0020] The pre-processing comprises:

[0021] The failed part of the damaged part is removed to form a surface to be repaired, and the repaired surface is surface treated so that the roughness Ra of the repaired surface is between 3 and 10 μm.

[0022] In one 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 one embodiment of the present disclosure, based on each of the damaged parts and the corresponding repair powder, the laser cladding process parameters are determined, including:

[0024] Carry out multi-physics field single-pass laser cladding repair simulation, extract the temperature gradient in the solid-liquid interface area, and screen out the process parameter range that is conducive to the formation of single crystals on single crystal thin-walled components based on the transformation criterion of columnar crystals to equiaxed crystals during rapid solidification of nickel-based high-temperature alloys;

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

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

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

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

[0029] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings herein are incorporated into and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification are configured to explain the principles of the present disclosure. Obviously, the accompanying drawings described below are only some embodiments of the present disclosure, and for ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0031] Figure 1 This is a cross-sectional EBSD (electron backscatter diffraction technology) diagram of a single-pass laser cladding repair thin-wall process in one embodiment of the present disclosure (without magnetic field); wherein 500 μm is the scale bar.

[0032] Figure 2 This is a cross-sectional EBSD (electron backscatter diffraction technology) diagram (with magnetic field) of a single-pass laser cladding repair thin-wall process in one embodiment of the present disclosure; wherein 500 μm is the scale bar.

[0033] Figure 3 This is a schematic structural diagram of a laser cladding device in one embodiment of the present disclosure.

[0034] Figure 4This is a schematic diagram of the structure of a blade in one embodiment of the present disclosure.

[0035] Description of reference numerals:

[0036] 1. Laser powder feeding module; 11. Laser head; 12. Powder feeding head; 2. Electromagnet; 3. Clamping module; 4. Driving part; 41. Guide rail; 42. Slider; 5. Cooling module; 51. Cooling water tank; 52. Pump; 53. Spray 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 will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in a variety of forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that the present disclosure will be comprehensive and complete and fully convey the concepts of the example embodiments to those skilled in the art. The same reference numerals in the figures represent the same or similar structures, and thus their detailed description will be omitted. In addition, the drawings are only schematic illustrations of the present disclosure and are not necessarily drawn to scale.

[0038] Although relative terms such as "upper" and "lower" are used in this specification to describe the relative relationship of one component of the illustration to another component, these terms are configured in this specification for convenience only, such as according to the orientation of the examples described in the drawings. It is understood that if the device of the illustration is turned upside down, the component described as "upper" will become the component "lower". When a structure is "on" other structures, it may mean that the structure is formed integrally on the other structure, or that the structure is "directly" disposed on the other structure, or that the structure is "indirectly" disposed on the other structure through another structure.

[0039] The terms "a", "an", "the", "said" and "at least two" are used to indicate the presence of one or more elements / components / etc.; the terms "including" and "having" are used to express an open-ended inclusive meaning and mean that additional elements / components / etc. may be present in addition to the listed elements / components / etc.

[0040] As the performance of aircraft engines and gas turbines continues to improve, the wall thickness of hot-end components such as nickel-based single-crystal high-temperature alloy turbine blades is continuously reduced to improve cooling efficiency. However, due to harsh service conditions, complex shapes, and high performance requirements, single-crystal thin-walled components are affected by factors such as fatigue, creep, and thermal stress, and often suffer from problems such as cracks, wear, and corrosion. If the damaged single-crystal thin-walled components are directly replaced, materials will be wasted and the cost will be high. Therefore, the development of high-efficiency, high-precision, low-cost, and high-quality repair and remanufacturing technologies to restore the geometric shape, microstructure, and mechanical properties of damaged single-crystal thin-walled structures is of great economic and engineering significance for achieving low-cost and high-quality operation of engines.

[0041] The repair of single crystal thin-walled components is to repair the gaps on the single crystal thin-walled components after removing the damage according to the form and location of the damage of the single crystal thin-walled components. Single crystal repair relies on the high temperature gradient and low solidification rate during directional solidification. Laser cladding repair technology uses 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 formed molten pool has a high temperature gradient and is suitable for the repair of single crystal thin-walled structures.

[0042] In the related art, many methods of using single crystal alloy powder laser cladding to repair single crystal thin-walled components have been proposed. However, single crystal alloy powder contains a large amount of precious metal elements such as Re, Ta, etc. The method of using single crystal alloy powder laser cladding to repair thin-walled single crystal components will bring great costs. If direct replacement is adopted, the cost is also high.

[0043] In order to solve the above problems, the present invention provides a laser cladding device, see Figure 3 , the laser cladding equipment comprises a laser cladding equipment body and a magnetic module;

[0044] In one example of the present disclosure, the laser cladding equipment body can adopt the 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. Among them, 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 clad. 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 conveys the repair powder. The cooling module 5 includes a cooling water tank 51, a pump 52 and a spray head 53. The cooling water tank 51 is located below the clamping module 3. The pump 52 conveys the water in the cooling water tank 51 to the spray head 53. During the laser cladding process, the spray head 53 sprays cooling water on the workpiece to be clad to cool it down, and then the cooling water tank 51 collects the cooling water for recycling. In the present disclosure, the workpiece to be clad is a single crystal thin-walled component 8 to be repaired.

[0045] In one embodiment of the present disclosure, the magnetic module includes a driving member 4 and two electromagnets 2, wherein the driving member 4 is configured to drive the two electromagnets 2 to move closer to or farther from each other, the two electromagnets 2 have opposite polarities when they are closer to each other, and the two electromagnets 2 are located on both sides of the clamping module 3. In this way, the two electromagnets 2 can be located on both sides of the workpiece to be clad, and can provide a transverse magnetic field for the damaged part 7 during the laser cladding process.

[0046] In one example of the present disclosure, the driving member 4 may include 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 distributed on both sides of the clamping module 3, the two electromagnets 2 are respectively arranged on the two sliders 42, the motor is arranged on the support seat 6, the output end of the motor is connected to one end of the double-headed screw, the other end of the double-headed screw passes through the two sliders 42, and the thread rotation directions of the two ends of the double-headed screw are opposite, so that the double-headed screw can be driven by the motor to rotate, so that the two electromagnets 2 are close to or away from each other. In another example, the driving member 4 may include two groups of sub-driving members 4, the two groups of sub-driving members 4 correspond to the two electromagnets 2 one by one, the sub-driving member 4 includes a cylinder, a slider 42, and a guide rail 41, the slider 42 is arranged on the guide rail 41, the electromagnet 2 is arranged on the slider 42, the power output end of the cylinder is connected to the slider 42, and the electromagnet 2 is pushed to move by the cylinder, so as to achieve the two electromagnets 2 close to or away from each other. Of course, the driving member 4 may also be other structures not shown. The present disclosure does not limit the specific structure of the driving member 4.

[0047] In one embodiment of the present disclosure, the electromagnet 2 may be a permanent magnet, so that the magnetic field provided by the electromagnet 2 is more stable and has a longer service life. Of course, in other examples, the electromagnet 2 may 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 portion 7 of the single crystal thin-walled component 8 to be repaired, wherein in this example, the number of damaged portions 7 is defined as N, where N is a positive integer greater than or equal to 1;

[0050] S020, respectively obtaining status information of the N damaged parts 7, and based on the status information of the N damaged parts 7, respectively obtaining repair powder groups corresponding to the N damaged parts 7, wherein the repair powder groups include at least one repair powder, and the repair powder is a single crystal alloy powder or a polycrystalline alloy powder; the status information includes 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. Based on the process parameters, repair path and repair powder, each damaged part is repaired separately.

[0054] In one 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 one embodiment of the present disclosure, in step S010, the damaged part 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 one example, the overall blade profile detection method can be used to perform geometric shape detection on the single crystal thin-walled component 8 to be repaired as a whole, and the overall 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 means that the single crystal thin-walled component 8 to be repaired is not damaged, has no damaged part 7, and does not need to be repaired (of course, under normal circumstances, it is confirmed that the single crystal thin-walled component 8 is damaged before repair); 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 means that the single crystal thin-walled component 8 to be repaired is damaged, and the damaged part 7 is determined by the reduction in the corresponding parameters. In one example, an 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 portion 7. In other examples, fluorescent testing and other methods can also be used to detect the single crystal thin-walled component 8 to be repaired, as long as the damaged portion 7 of the single crystal thin-walled component 8 to be repaired can be determined.

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

[0057] In one embodiment of the present disclosure, in step S020, based on the status information of the N damaged parts 7, the repair powder groups corresponding to the N damaged parts 7 are obtained respectively. Specifically, based on the status information of the N damaged parts 7, combined 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, and combined with the base material of the single crystal thin-walled component 8 to be repaired, and under the condition that the mechanical properties of the single crystal thin-walled component 8 repaired by the polycrystalline alloy powder at the temperature of the actual working condition of the damaged part 7 can meet the use requirements, it is determined which polycrystalline alloy powder or single crystal alloy powder is used to repair each damaged part 7, so as to obtain the repair powder groups corresponding to the N damaged parts 7. For example, taking advantage of the good plasticity of polycrystalline alloy powder, the low probability of defects such as cracks during the repair process, and the larger crack-free process window of laser cladding repair compared to single crystal alloy powder, for parts that are extremely high in temperature and susceptible to oxidation corrosion under service conditions (referring to the working state during the actual operation of the equipment or system, which reflects the performance and load conditions of the equipment in actual use), polycrystalline alloy powders with good high temperature resistance, oxidation resistance, and corrosion resistance can be selected, such as DZ406 (nickel-based precipitation hardening directionally solidified columnar high temperature alloy). Of course, other polycrystalline alloys can also be selected. Gold powder; for parts with high temperature (<1000℃), high stress level and large strain gradient under service conditions, especially when the damaged part 7 of the single crystal thin-walled component 8 to be repaired has a complex structure and a large curvature, polycrystalline alloy powders 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), etc.; for other parts with higher service temperatures (≥1000℃), single crystal alloy powders with a grade similar to that of the matrix material of the single crystal thin-walled component 8 to be repaired can be used for repair.

[0058] In an 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 one embodiment of the present disclosure, in step S030, a single-channel repair test is carried out based on the N damaged parts 7 of the single crystal thin-walled component 8 to be repaired and the repair powders (single crystal alloy powder or polycrystalline alloy powder) corresponding to the N damaged parts 7 (in this test, the ratio of the laser spot diameter to the wall thickness of the damaged part 7 is 2 to 4:1, the laser power range is 150 to 500 W, the scanning speed is 120 to 500 mm / min, the powder feeding speed is 0.5 to 3 g / min, and the transverse magnetic field strength is 0 to 0.2 T). Specifically, Comsol finite element software was first used to carry out multi-physics field single-pass laser cladding repair simulation, and the temperature gradient of the solid-liquid interface junction area (mushy area) was extracted. The columnar crystal (single crystal) to equiaxed crystal transformation (CET) criterion proposed by Hunt JD et al. during the rapid solidification of nickel-based high-temperature alloys was used to preliminarily screen out the process parameter range that is conducive to the formation of single crystals. Then, based on the process parameter range, the orthogonal test method was used to combine the processes, and the cross section of the single-pass repair was cut for metallographic observation. According to the principle of no cracks, no voids, uniform dendrite growth, and orientation consistent with the matrix, the appropriate laser cladding process parameters were selected. In this disclosure, it is first proposed to use polycrystalline alloy powder to repair single crystal thin-walled components, which reduces costs.

[0060] In one embodiment of the present disclosure, in step S040, a repair path of the single crystal thin-walled component 8 to be repaired is obtained. In one example, with a spacing of Qmm, the center point of each cross section of the single crystal thin-walled component 8 to be repaired along the thickness direction is obtained, and each center point is connected to obtain a center line, which is the center line of the laser path of laser cladding. In this step, based on the center line of the laser path, a laser cladding repair path is obtained. In one example, Qmm can be 0.2mm, or 0.5mm, or 0.8mm, etc., and can be set according to needs.

[0061] In one embodiment of the present disclosure, before the damaged part 7 is repaired by laser cladding, the damaged part 7 is also pretreated. 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 so that the roughness Ra of the surface to be repaired is between 3 and 10 μm. In one example, a diamond grinding head, pneumatic grinding, etc. can be used to remove the failed part at the damaged part 7 to form a surface to be repaired, and 600# and 800# are used for grinding in sequence to control the roughness Ra of the surface to be repaired between 3 and 10 μm (within this range, a good combination of the interface after repair can be guaranteed, while avoiding the low roughness causing the laser reflection during the laser cladding process to affect the cladding effect), and then cleaning and drying are performed. In one example, anhydrous ethanol can be used for cleaning and quick drying with a hair dryer. In other examples, other methods can also be used for cleaning and drying. In one example, 600# and 800# are used for grinding in sequence, and the roughness can be 3μm, 5μm, 9μm, 10μm, and so on. Of course, in other examples, other methods may be used for grinding, and the surface to be repaired may also have other roughness not shown.

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

[0063] In one embodiment of the present disclosure, after step S050, step S060 is also included, laser cladding post-processing to restore the geometric shape of the repaired single crystal thin-walled component 8 to the geometric shape of the standard single crystal thin-walled component, and then carry out relevant machining and surface treatment on its surface to make its surface meet the corresponding precision requirements.

[0064] In an implementation manner of the present disclosure, step S040 only needs to be performed before step S050, and the specific time sequence is not limited.

[0065] Since single crystal thin-walled components have complex shapes and large curvatures, their repair is prone to produce microcracks. In the present disclosure, for certain areas where the temperature resistance requirements are not high, low-cost polycrystalline alloy powders can be considered for repair. On the one hand, polycrystalline alloy powder repair is not prone to produce microcracks, and can achieve better organizational and performance recovery; on the other hand, a larger repair process window can be achieved; in addition, polycrystalline alloy powders contain fewer precious elements, which can improve the economy of single crystal thin-walled component repair.

[0066] In general, the present disclosure proposes a method of using polycrystalline alloy powder to repair single-crystal thin-walled components 8, which can reduce costs and achieve low-cost repair of single-crystal thin-walled components 8; and the present disclosure uses a combination of simulation and experiment to quickly narrow the process screening range and shorten the thin-walled component repair cycle. Not only that, the present disclosure also proposes a solution to use a transverse magnetic field to assist in the use of polycrystalline alloy powder laser cladding to repair complex single-crystal thin-walled components. The magnetic field and the selected well-shaped polycrystalline alloy powder enable the method proposed in the present disclosure to effectively expand the crack-free process window for repairing thin-walled structures compared to existing single-crystal repair processes. In addition, magnetic field-assisted laser cladding repair is a new technology that improves and overcomes the defects of laser cladding repair technology in related technologies by introducing a magnetic field as a new energy field. The magnetic field affects the flow and heat transfer of the molten pool through the thermal damping effect and thermal battery effect of the metal fluid in the molten pool during the laser cladding repair process, thereby reducing the number of pores and cracks in the cladding layer, improving the density of the cladding layer, and improving the hardness and corrosion resistance. At the same time, by slowing down the Marangoni flow inside the molten pool, the epitaxial growth of dendrites in the cladding repair layer is promoted, which facilitates the formation of single crystal structure and improves the performance of the powder after repair.

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

[0068] See also Figure 4 A nickel-based single crystal thin-walled component (nickel-based single crystal thin-walled blade) has cracks, blade tip wear and other faults due to fatigue, creep, thermal stress, mechanical wear and other factors. The method disclosed in the present invention is used to perform laser cladding repair on the nickel-based single crystal thin-walled component (nickel-based single crystal thin-walled blade), including the following steps:

[0069] S010, the overall blade shape detection method is used to carry out the geometric shape detection of the nickel-based single crystal thin-walled component 8 to be repaired, and the geometric model is compared with 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 is shortened by about 0.4 mm. Ultrasonic detection is used to find that the blade basin of the nickel-based single crystal thin-walled component 8 to be repaired has cracks, and two damaged parts 7 are marked;

[0070] S020, performing heat-flow coupling analysis and strength analysis on the nickel-based single crystal thin-walled component 8 to be repaired, and obtaining the temperature field and stress-strain distribution of the two damaged parts 7 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 matrix material of the nickel-based single crystal thin-walled component 8 to be repaired, and the condition that the mechanical properties of the single crystal repaired by the polycrystalline alloy powder under the actual working temperature of the damaged part 7 can meet the use requirements, it is judged that the cracks in the blade basin 84 area (between the blade trailing edge 83 and the blade leading edge 82) can be repaired with GH4169 powder, and the blade back 81 area and the blade trailing edge 83 can be repaired with DD5 (second-generation nickel-based single crystal high-temperature alloy) alloy powder consistent with the blade powder;

[0071] S030, carry out 8 single-pass repair tests on the single-crystal thin-walled components to be repaired, including 8 single-pass repair tests on the single-crystal thin-walled components to be repaired with single-crystal alloy powders, and 8 single-pass repair tests on the single-crystal thin-walled components to be repaired with polycrystalline alloy powders;

[0072] First, the process parameters need to be established. According to the thickest part of the damaged part 7, a 1.5mm×15mm×15mm substrate is cut for a single-pass repair test. The laser power range of the single-pass 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 strength is 0-0.2T.

[0073] Firstly, Comsol finite element software was used to carry out multi-physics field single-pass laser cladding repair simulation to extract the temperature gradient of the solid-liquid interface (mushy area). In this example, the temperature gradient is 4×10 6 ~6×10 6 K×m -1 , the columnar crystal (single crystal) to equiaxed crystal transformation (CET) criterion proposed by Hunt JD et al. during rapid solidification of nickel-based high-temperature alloys was used to preliminarily screen out the process parameter range that is conducive to the formation of single crystals. Then, based on the initial range of process parameters, the orthogonal test method was used to combine the processes, and the metallographic observation was carried out on the cross section cut out of the single-pass repair. The appropriate process parameters were selected according to the principles of no cracks, no voids, uniform dendrite growth, and orientation consistent with the matrix. Due to the weakening of the Marangoni flow at the solid-liquid interface of the molten pool under the assistance of the magnetic field, the dendrites maintained a trend of continuous growth. Based on the preliminary optimization of the process parameters, the dendrite orientation analysis with and without a transverse magnetic field was carried out, such as Figure 1 and Figure 2The cross-sectional EBSD images of single-pass laser cladding with and without magnetic field under the same process show that the single crystal grows well with the assistance of magnetic field, the impurity crystals are reduced, and the repair effect is good. The process parameters include laser power of 300W, scanning speed of 480mm / min, powder feeding rate of 0.59g / min, and transverse magnetic field strength of 0.2T. The process for DD5 powder repairing the substrate is similar. The process parameters for obtaining better repair include laser power of 400W, scanning speed of 240mm / min, powder feeding rate of 1.57g / min, and transverse magnetic field strength of 0.2T.

[0074] S040. Model and slice the nickel-based single crystal thin-walled component 8 to be repaired as a whole, and plan the laser cladding repair path. With a spacing of 0.2 mm, the thickness of each section thin wall varies within the range of 0.2 to 1.5 mm, and then draw the center line of each height thickness profile, which is the center line of the laser path, and then obtain the repair path;

[0075] S045. Based on different damaged parts 7, diamond grinding heads, pneumatic grinding, etc. are used to grind the cracks to produce a smooth groove of about 135°. In addition, the surfaces of other parts of the blade tip (blade trailing edge 83, blade leading edge 82, blade basin 84, blade back 81) are processed. First, pneumatic grinding is used to remove carbon deposits, oxides, etc. caused by long-term work, and then 600# and 800# are used to grind the entire blade tip in turn to control its roughness Ra=3~10μm, and then it is cleaned with anhydrous ethanol and quickly dried with a hair dryer. 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 3μm, 5μm, 9μm, 10μm, etc., of course, it can also be other roughness not shown. Based on the nickel-based matrix powder DD5, nickel-based polycrystalline GH4169 was selected as the repair powder. The GH4169 alloy powder used was prepared by vacuum gas atomization method, and the powder particle size was 50-150 μm. Before the test, the high-temperature alloy powder was first dried and cooled in a vacuum drying oven;

[0076] S050. Carry out laser cladding repair of nickel-based single crystal thin-walled components in an inert gas environment.

[0077] For the blade top (blade leading edge 82, blade back 81 and blade trailing edge 83), each layer is repaired in three parts according to the repair path. DD5 alloy powder is used to repair the blade back 81 and blade trailing edge 83. The path is ABC. The process is laser power 400W, scanning speed 240mm / min, powder feeding rate 1.57g / min, transverse magnetic field 0.2T. During the movement, the spot diameter is adjusted according to different wall thicknesses. The thickness of the blade trailing edge 83 part BC is 0.2-1.5mm, and the spot diameter is 0.8mm at 0.2 to 0.6mm. The rest of the blade top uses a spot diameter of 1.5mm. GH4169 is used to repair the blade basin 84 area CA. The process parameters are laser power 300W, scanning speed 480mm / min, powder feeding rate 0.59g / min, and transverse magnetic field 0.2T. Repeat the path AB, BC, CA three times, and the blade top is extended to the required height.

[0078] S060. Use a CNC machine tool to restore the geometric shape of the repaired single crystal thin-walled component 8 to the geometric shape of a standard single crystal thin-walled component, and then perform relevant machining and surface treatment on its surface to meet the corresponding accuracy 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 results. Additionally or alternatively, some steps may be omitted, multiple steps may be combined into one step, and / or one step may be decomposed into multiple steps, etc.

[0080] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the invention disclosed herein. This application is intended to cover any modification, use or adaptation of the present disclosure, which follows the general principles of the present disclosure and includes common knowledge or customary techniques in the art that are not disclosed in the present disclosure. The specification and examples are intended to be 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 a single crystal thin-walled component, characterized in that: include: Determining various damaged locations (7) of a single crystal thin-walled component (8) to be repaired; respectively obtaining status information of each damaged part (7), and based on the status information, respectively obtaining a repair powder group corresponding to each damaged part (7); 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 status information comprises a temperature field and a stress-strain distribution; Based on each of the damaged parts (7) and the corresponding repair powder, determining laser cladding process parameters, the process parameters including laser power, scanning speed and powder feeding amount; A repair path of the single crystal thin-walled component (8) to be repaired is obtained, and based on the process parameters, the repair path and the repair powder, laser cladding repair is performed on each of the damaged parts (7).

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

3. The laser cladding repair method for a single crystal thin-walled component according to claim 1 or 2, characterized in that: Determining each damaged portion (7) of the single crystal thin-walled component (8) to be repaired includes: The damaged parts (7) of the single crystal thin-walled component (8) to be repaired are determined by using overall blade profile detection and non-destructive detection.

4. The laser cladding repair method for single crystal thin-walled components according to claim 3, characterized in that: The state information of each damaged part (7) is obtained respectively, including: By performing a fluid-heat coupling analysis on the single crystal thin-walled component (8) to be repaired, the temperature field of each damaged part (7) is obtained; By performing strength analysis on the single crystal thin-walled component (8) to be repaired, the stress-strain distribution of each damaged portion (7) is obtained.

5. The laser cladding repair method for single crystal thin-walled components according to claim 4, characterized in that: Based on the state information, a repair powder group corresponding to each damaged part (7) is obtained respectively, including: Based on the status 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, the polycrystalline alloy powder and / or single crystal alloy powder that can be used to repair each damaged part (7) is determined, thereby obtaining a repair powder group corresponding to each damaged part (7).

6. The laser cladding repair method for a single crystal thin-walled component according to claim 5, 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).

7. The laser cladding repair method for a single crystal thin-walled component according to claim 6, characterized in that: Before the damaged part (7) is repaired by laser cladding, the method further includes pre-treating the damaged part (7); The pre-processing comprises: The failed part at the damaged part (7) is removed to form a surface to be repaired, and the repaired surface is subjected to surface treatment so that the roughness Ra of the repaired surface is between 3 and 10 μm.

8. The laser cladding repair method for a single crystal thin-walled component according to claim 7, characterized in that: The single crystal thin-walled component (8) to be repaired is a nickel-based single crystal thin-walled component (8).

9. The laser cladding repair method for a single crystal thin-walled component according to claim 8, characterized in that: Based on each of the damaged parts (7) and the corresponding repair powder, the laser cladding process parameters are determined, including: Conduct multi-physics field single-pass laser cladding repair simulation, extract the temperature gradient in the solid-liquid interface region, and select the process parameter range that is conducive to forming single crystals on single crystal thin-walled components (8) based on the transformation criterion of columnar crystals to equiaxed crystals during rapid solidification of nickel-based high-temperature alloys; Based on the process parameter range, an orthogonal test method is used to perform process combination, a cross section of a single-pass repair area is cut to perform metallographic observation, and 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).

10. A laser cladding device, characterized in that: A laser cladding equipment body is provided, wherein the laser cladding equipment body comprises a clamping module (3), wherein the clamping module (3) is configured to clamp a workpiece to be clad; The laser cladding equipment further comprises a driving member (4) and two electromagnets (2), wherein the two electromagnets (2) are arranged on the driving member (4), and the driving member (4) is configured to drive the two electromagnets (2) to move closer to or farther from each other; The two electromagnets (2) are distributed on both sides of the clamping module (3) to provide a transverse magnetic field to the to-be-clad area of ​​the workpiece to be clad.

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