High-temperature alloy blade additive manufacturing repair process for improving additive repair interface

Abstract

A high-temperature alloy blade additive manufacturing repairing technology for improving an additive repairing interface comprises the steps that firstly, a damaged part of a blade is milled and removed, heat treatment is conducted on the blade, and then a to-be-repaired area is polished and the surface is cleaned; then, the blade is moved to additive manufacturing equipment, additive repairing is carried out on the to-be-repaired area, and the blade is moved out when deposition is carried out to the set height; carrying out laser shock peening on the repaired part of the top surface; then the blade is dried, and the surface to be repaired is cleaned again; then the blade is moved to the additive manufacturing equipment to continue additive repairing, and deposition is repeated until the blade is higher than the surface of the base body; and finally, the repaired part material higher than the surface of the base body is removed through milling, the repaired surface is polished to be consistent with the base body, and repairing is completed. According to the method, laser shock peening is preset in the to-be-repaired area, so that effective regulation and control of the microstructure of the repaired interface of the high-temperature alloy blade are achieved, and improvement of the microstructure of the interface layer is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of additive repair of high-temperature alloy blades, and in particular to a high-temperature alloy blade additive manufacturing and repair process with improved additive repair interface. Background Art

[0002] High-temperature alloy blades are expensive to manufacture and have a long manufacturing cycle. They are prone to damage or failure because they usually work in harsh environments with high temperature, high pressure and strong corrosion. Blade damage such as cracks, wear and deformation will affect the safety and reliability of the engine or turbine. Therefore, to ensure the smooth operation of the equipment, the operating blades must be replaced once defects are determined. Due to the lack of effective high-performance repair processes, they cannot be used again, resulting in waste of resources and high replacement costs. Achieving high-performance repair of high-temperature alloy blades can extend their service life, reduce costs, save resources, and improve equipment utilization and operational efficiency.

[0003] Due to the limitations of traditional processes, the repair cost, repair quality and qualified rate of blades still cannot meet the actual application standards. The introduction of additive manufacturing provides an effective solution for defect repair and remanufacturing of defective parts. However, the current additive repair of high-temperature alloy blades still faces problems such as sudden changes in the microstructure of the repaired part, differences in microalloy elements between the repair material and the blade material, and uneven stress distribution inside the repaired part. In particular, the uneven distribution of microstructure and precipitated phases at the interface can easily lead to premature failure of parts due to uneven deformation and stress concentration in fatigue conditions. Therefore, it is urgent to develop a repair process that can achieve high-performance connection of the repair interface.

[0004] The patent application entitled "A composite repair method for aluminum alloy centrifugal impeller parts" (publication number CN118272805A) discloses that low-energy laser shock strengthening is performed on the welds, heat-affected zones and exhaust edges of the centrifugal impeller crack repair area where cracks are easily generated. The purpose is to improve the crack resistance and fatigue resistance of the aluminum alloy centrifugal impeller parts repair area, not to improve the connection strength of the repair interface. The patent application entitled "A high-strength aluminum alloy laser additive repair method based on multi-dimensional stress regulation" (publication number CN116809959A) discloses that the groove area to be repaired is first subjected to laser shock strengthening before the repair test begins. However, the purpose of the process is only to introduce residual compressive stress in softer alloy materials such as aluminum alloy to offset the thermal stress generated by subsequent deposition. The effective depth and stress value of laser shock strengthening to introduce residual tensile stress in high-strength high-temperature alloys are limited, and it cannot achieve similar effects as aluminum alloys. The patent application named "A method and device for preventing thermal deformation of metal parts during additive repair" (publication number CN114850510A) also intends to use pre-laser shock strengthening to achieve the purpose of introducing residual compressive stress, and then achieve the purpose of suppressing deformation by offsetting the residual tensile stress during the repair process. None of the above-mentioned prior arts involve the relevant process design and intention of controlling the microstructure and precipitation phase of the component interface through laser shock strengthening, and it is also impossible to improve the microstructure of the interface layer. At present, there is no relevant process design to achieve effective control of the microstructure and precipitation phase of the additive manufacturing repair interface. Summary of the invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide an additive manufacturing repair process for high-temperature alloy blades with improved additive repair interface, by pre-setting laser shock strengthening in the area to be repaired to achieve effective regulation of the microstructure of the high-temperature alloy blade repair interface and improve the microstructure of the interface layer.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A high temperature alloy blade additive manufacturing repair process for improving the additive repair interface comprises the following steps:

[0008] 1) Milling is performed to remove the material of the damaged blade including the defective part to ensure that the defect features are completely removed; at the same time, the side wall of the pit formed by milling is processed to a certain inclination angle to ensure the feasibility of the subsequent laser shock peening process;

[0009] 2) heat treating the blade with defect features removed in step 1) to eliminate microstructural changes and work hardening caused by machining in the area to be repaired;

[0010] 3) Grinding the area to be repaired of the blade heat-treated in step 2) to ensure a smooth surface, and using acetone to clean surface stains;

[0011] 4) moving the blade polished in step 3) to the additive manufacturing equipment, performing additive repair on the area to be repaired, and removing the blade when the deposition reaches a height of 1-1.5 mm;

[0012] 5) Perform laser shock peening on the top surface of the repaired part to ensure that the depth of the laser shock peening affected layer is higher than the height of the deposited layer;

[0013] 6) Dry the blade after laser shock peening to remove surface moisture, and use acetone to clean the surface to be repaired after laser shock peening again;

[0014] 7) Move the blade to the additive manufacturing equipment to continue additive repair, repeat steps 4) to 6), and stop when the deposition is higher than the substrate surface;

[0015] 8) Use milling to remove the repair material that protrudes above the substrate surface, grind the repair surface to make its surface roughness consistent with the substrate, and the repair is completed.

[0016] In the step 1), the certain inclination angle is 30°-60°.

[0017] The heat treatment in step 2) is as follows: the heat treatment temperature is 700-1200° C., and the heat treatment time is 1-16 hours. The heat treatment temperature is adjusted and the number of heat treatments is increased according to the actual effect.

[0018] In the step 3), the polishing process uses a precision engraving machine with 200-2000 mesh sandpaper to gradually polish the surface of the pit until there is no obvious milling mark on the surface.

[0019] In the step 5), the laser shock peening is as follows: the laser shock energy is 4-10J, the spot diameter is 2mm, the overlap rate is 50%, a water layer is used as a constraint layer, and aluminum foil is pasted on the impact surface as an absorption layer. After the impact is completed, the surface aluminum foil is removed.

[0020] In step 6), the drying is performed in a dryer at a temperature of 300° C. for 6 hours.

[0021] The high-temperature alloy blade additive manufacturing repair process with improved additive repair interface is suitable for a powder bed melting process with a remelting depth of less than 1.5 mm and a laser powder feeding directed energy deposition process.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. After removing the internal defects of the blade by defect milling, the present invention eliminates the near-surface work hardening effect introduced by mechanical processing by heat treating the high-temperature alloy blade, thereby improving the depth and effect of the influence layer of subsequent laser shock strengthening.

[0024] 2. The present invention forms a large number of vacancies in the element transition zone of the interface layer by laser shock strengthening the area where element diffusion occurs near the interface layer. During the repair process, the element diffusion effect is improved due to the increase in the vacancy content at the repair interface, thereby promoting the homogenization of the interface microstructure.

[0025] 3. The present invention performs laser shock strengthening on the area where element diffusion occurs near the interface layer, and pre-inserts a large number of dislocations in the element transition zone of the interface layer. Under the continuous heat influence generated in the subsequent repair process, relying on the large number of nucleation points provided by the dislocations, a large number of dispersed and fine precipitates are generated in the element diffusion area of ​​the interface layer, thereby effectively suppressing the element segregation problem in the area near the interface layer, reducing the probability of forming coarse precipitates, and further improving the microstructure and mechanical properties of the interface layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The process flow chart of an embodiment of the present invention.

[0027] Figure 2 This is a microscopic picture of the substrate area and the repair area of ​​Example 1 of the present invention.

[0028] Figure 3 This is a microscopic picture of the substrate area and the repair area of ​​Example 2 of the present invention.

[0029] Figure 4 This is a microscopic picture of the substrate area and the repair area of ​​Example 3 of the present invention. DETAILED DESCRIPTION

[0030] The present invention is described in detail below in conjunction with the embodiments and drawings.

[0031] Example 1, reference Figure 1 , a high-temperature alloy blade additive manufacturing repair process with improved additive repair interface, GH3536 high-temperature alloy blade is selected, GH4169 high-temperature alloy powder is selected as the repair material, and e-book powder bed fusion is used as the additive repair process, which specifically includes the following steps:

[0032] 1) Milling is performed to remove the material of the damaged blade including the defective part to ensure that the defect features are completely removed; at the same time, the side wall of the pit formed by milling is processed to a certain inclination angle (45°) to ensure the feasibility of the subsequent laser shock peening process;

[0033] In this embodiment, industrial CT is used to detect the size and distribution of defects inside the blade, and the defects near the surface of the blade are completely removed by milling, and then expanded into a square pit with rounded corners, and the inclination angle of the pit side wall is processed to 45°;

[0034] 2) heat treating the blade with defect features removed in step 1) to eliminate microstructural changes and work hardening caused by machining in the area to be repaired;

[0035] The heat treatment in this embodiment is as follows: the heat treatment temperature is 1100°C and the heat treatment time is 1 hour;

[0036] 3) Grinding the area to be repaired of the heat-treated blade in step 2) to ensure a smooth surface, and using acetone to clean the surface stains and remove impurities such as residual cutting fluid on the surface;

[0037] In this embodiment, a precision engraving machine is used with 400-mesh and 1000-mesh sandpaper to grind the surface of the pit until there is no obvious milling mark on the surface;

[0038] 4) moving the blade polished in step 3) to the additive manufacturing equipment, performing additive repair on the area to be repaired, and removing the blade when the deposition reaches a height of 1-1.5 mm;

[0039] In this embodiment, the blade is moved into the forming chamber of the electron beam powder bed melting equipment, and the deposition process parameters are voltage 60kV, current 8mA, scanning speed 1000mm / s, spot diameter 250μm, ambient pressure 0.1Pa, and after ten layers are deposited (the total deposition height is 1mm at this time), the blade is removed to remove the residual metal powder on the surface;

[0040] 5) Perform laser shock peening on the top surface of the repaired part to ensure that the depth of the laser shock peening affected layer is higher than the height of the deposited layer;

[0041] The laser shock peening in this embodiment is as follows: the laser shock energy is 10J, the spot diameter is 2mm, the overlap rate is 50%, a water layer is used as a constraint layer, and an aluminum foil is pasted on the impact surface as an absorption layer. After the impact is completed, the surface aluminum foil is removed;

[0042] 6) Dry the blade after laser shock peening to remove surface moisture, and use acetone to clean the surface to be repaired after laser shock peening again;

[0043] In this embodiment, the surface of the blade after laser shock strengthening is cleaned again with acetone to remove residual adhesive, and then sent to a dryer for drying. The drying temperature is set to 120°C and the drying time is set to 1h.

[0044] 7) The dried blade is sent back into the electron beam powder bed melting forming chamber, and steps 4) to 6) are repeated to continue the additive repair until the repair height is 0.5 mm higher than the substrate surface;

[0045] 8) The excess part of the additive material that is higher than the surface of the blade substrate is eliminated by milling, and then the milled part is polished by a precision engraving machine to make it basically consistent with the surface roughness of the substrate, and the repair is completed.

[0046] The additive manufacturing equipment used in this embodiment is an electron beam powder bed melting equipment, but the specific implementation can select additive manufacturing processes such as laser selection melting equipment, laser powder feeding directional energy deposition equipment, etc. according to actual conditions.

[0047] In this embodiment, the laser shock peening process is performed after depositing ten layers. However, in specific implementation, the height of the repair layer during laser shock peening can be determined according to the actual element diffusion range and the depth of the affected layer of the laser shock peening process used.

[0048] This embodiment solves the problem of weak interface performance caused by interface microstructure differences, coarse precipitates, etc. during additive repair. Through laser shock strengthening of the repaired interface layer, uniform and controllable element diffusion near the interface layer is achieved, large-sized precipitates caused by element segregation are suppressed, and the microstructure differences between the matrix and the repaired part are weakened, thereby achieving high-performance repair of high-temperature alloy blade defects.

[0049] The beneficial effects of this embodiment are: Figure 2 High-energy LSP can effectively eliminate defects such as solidification cracks in the interface area, while achieving grain refinement and effectively improving the bonding strength at the interface. The heat treatment process can eliminate the component segregation near the interface (matrix area and repair area) to a certain extent, optimize the microstructure of the repair area, and improve the material mechanical properties of the repair area. At the same time, due to the simplified heat treatment process, the time for blade repair can be effectively shortened.

[0050] Example 2: The difference from Example 1 is that: in step 1), the inclination angle is 30°; in step 2), the heat treatment is performed at a temperature of 1100°C and a time of 1 hour, and a two-stage heat treatment is performed at a temperature of 700°C and a time of 16 hours; in step 5), the laser shock strengthening is performed at a laser shock energy of 7J, a spot diameter of 2mm, and an overlap rate of 50%.

[0051] The beneficial effects of this embodiment are: Figure 3By reducing the LSP laser energy and optimizing the heat treatment steps, the potential influence of the residual compressive stress introduced by LSP on the interface in some areas can be eliminated. At the same time, the optimized heat treatment process can compensate for the weakening of the microstructure optimization effect caused by the weakening of laser energy in the LSP process. On the basis of Example 1, the microstructure of the repair interface (repair area and matrix area) is further homogenized, and the weakening and anisotropy of the mechanical properties caused by component segregation and microstructure inhomogeneity are reduced.

[0052] Example 3: The difference from Example 1 is that: in step 1), the inclination angle is 60°; in step 2), the heat treatment is performed at a temperature of 1200°C and a time of 1 hour, followed by a second heat treatment at a temperature of 980°C and a time of 1 hour, followed by a third heat treatment at a temperature of 700°C and a time of 16 hours; in step 5), the laser shock strengthening is performed at a laser shock energy of 4J, a spot diameter of 2mm and an overlap rate of 50%.

[0053] The beneficial effects of this embodiment are: Figure 4 By introducing the three-stage heat treatment, the microstructure at the interface (repair area and matrix area) can be further optimized compared with Example 1 and Example 2, and effective regulation of the precipitated phase can be achieved. The strengthening of the heat treatment effect can further increase the adjustment space of the LSP process. By continuing to reduce the laser energy of the LSP process, the negative impact on the stress state at the interface can be completely eliminated while achieving the goal of improving the microstructure and closing defects, thereby achieving the optimization of the microstructure at the interface and the strengthening of mechanical properties.

Claims

1. A high-temperature alloy blade additive manufacturing repair process with improved additive repair interface, characterized in that: The following steps are involved: 1) Milling is performed to remove the material of the damaged blade including the defective part to ensure that the defect features are completely removed; at the same time, the side wall of the pit formed by milling is processed to a certain inclination angle to ensure the feasibility of the subsequent laser shock peening process; 2) heat treating the blade with defect features removed in step 1) to eliminate microstructural changes and work hardening caused by machining in the area to be repaired; 3) Grinding the area to be repaired of the blade heat-treated in step 2) to ensure a smooth surface, and using acetone to clean surface stains; 4) moving the blade polished in step 3) to the additive manufacturing equipment, performing additive repair on the area to be repaired, and removing the blade when the deposition reaches a height of 1-1.5 mm; 5) Perform laser shock peening on the top surface of the repaired part to ensure that the depth of the laser shock peening affected layer is higher than the height of the deposited layer; 6) Dry the blade after laser shock peening to remove surface moisture, and use acetone to clean the surface to be repaired after laser shock peening again; 7) Move the blade to the additive manufacturing equipment to continue additive repair, repeat steps 4) to 6), and stop when the deposition is higher than the substrate surface; 8) Use milling to remove the repair material that protrudes above the substrate surface, grind the repair surface to make its surface roughness consistent with the substrate, and the repair is completed.

2. The process according to claim 1, characterized in that In the step 1), the certain inclination angle is 30°-60°.

3. The process according to claim 1, characterized in that The heat treatment in step 2) is as follows: the heat treatment temperature is 700-1200° C., and the heat treatment time is 1-16 hours. The heat treatment temperature is adjusted and the number of heat treatments is increased according to the actual effect.

4. The process according to claim 1, characterized in that In the step 3), the polishing process uses a precision engraving machine with 200-2000 mesh sandpaper to gradually polish the surface of the pit until there is no obvious milling mark on the surface.

5. The process according to claim 1, characterized in that In the step 5), the laser shock peening is as follows: the laser shock energy is 4-10J, the spot diameter is 2mm, the overlap rate is 50%, a water layer is used as a constraint layer, and aluminum foil is pasted on the impact surface as an absorption layer. After the impact is completed, the surface aluminum foil is removed.

6. The process according to claim 1, characterized in that In step 6), the drying is performed in a dryer at a temperature of 300° C. for 6 hours.

7. The process according to claim 1, characterized in that The high-temperature alloy blade additive manufacturing repair process with improved additive repair interface is suitable for a powder bed melting process with a remelting depth of less than 1.5 mm and a laser powder feeding directed energy deposition process.

8. The process according to any one of claims 1 to 7, characterized in that A high-temperature alloy blade additive manufacturing repair process for improving the additive repair interface, using GH3536 high-temperature alloy blades, using GH4169 high-temperature alloy powder as the repair material, and using electronic book powder bed melting as the additive repair process, specifically including the following steps: 1) Milling is performed to remove the material of the damaged blade including the defective part to ensure that the defect features are completely removed; at the same time, the side wall of the pit formed by milling is processed to a 45° inclination angle to ensure the feasibility of the subsequent laser shock peening process; Industrial CT was used to detect the size and distribution of defects inside the blades, and the near-surface defects of the blades were completely removed by milling, and then expanded into square pits with rounded corners. At the same time, the inclination angle of the pit sidewalls was processed to 45°. 2) heat treating the blade with defect features removed in step 1) to eliminate microstructural changes and work hardening caused by machining in the area to be repaired; The heat treatment is as follows: the heat treatment temperature is 1100°C and the heat treatment time is 1 hour; 3) Grinding the area to be repaired of the heat-treated blade in step 2) to ensure a smooth surface, and using acetone to clean the surface stains and remove impurities such as residual cutting fluid on the surface; Use a precision engraving machine with 400-mesh and 1000-mesh sandpaper to grind the surface of the pit until there are no obvious milling marks on the surface; 4) moving the blade polished in step 3) to the additive manufacturing equipment, performing additive repair on the area to be repaired, and removing the blade when the deposition reaches a height of 1-1.5 mm; The blade was moved into the forming chamber of the electron beam powder bed melting equipment. The deposition process parameters were voltage 60 kV, current 8 mA, scanning speed 1000 mm / s, spot diameter 250 μm, and ambient pressure 0.1 Pa. After ten layers were deposited, the blade was removed. At this time, the total deposition height was 1 mm, and the residual metal powder on the surface was removed. 5) Perform laser shock peening on the top surface of the repaired part to ensure that the depth of the laser shock peening affected layer is higher than the height of the deposited layer; Laser shock peening is as follows: laser shock energy is 10J, spot diameter is 2mm, overlap rate is 50%, water layer is used as constraint layer, aluminum foil is pasted on the impact surface as absorption layer, and the surface aluminum foil is removed after the impact is completed; 6) Dry the blade after laser shock peening to remove surface moisture, and use acetone to clean the surface to be repaired after laser shock peening again; The surface of the blade after laser shock strengthening was cleaned again with acetone to remove the residual adhesive, and then sent to the dryer for drying. The drying temperature was set to 120℃ and the drying time was set to 1h. 7) The dried blade is sent back into the electron beam powder bed melting forming chamber, and steps 4) to 6) are repeated to continue the additive repair until the repair height is 0.5 mm higher than the substrate surface; 8) The excess part of the additive material that is higher than the surface of the blade substrate is eliminated by milling, and then the milled part is polished by a precision engraving machine to make it consistent with the surface roughness of the substrate, and the repair is completed.

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