CN108213832B - Repair method for realizing complex shape of flow channel in single crystal or directional crystal alloy blade - Google Patents

Abstract

The invention discloses a repair method for realizing the complex shape of a flow passage in a single crystal or directional crystal alloy blade, which comprises the following steps: step S100: judging and analyzing the failure and the defect of the blade before repairing; step S200: cutting off the failure or defect part of the blade, and polishing and cleaning the blade; step S300: mounting and fixing a pre-manufactured complex mold for ensuring high-precision complex shape of the flow channel structure in the blade in a cavity of the blade to be repaired, wherein the complex mold is a core mold of which the outer surface can form the flow channel of the inner cavity of the blade through solidification of subsequent blade material melts; step S400: preheating the part to be repaired to the melting point of the material which is more than 75 percent of the melting point of the material calculated in Kelvin, and realizing the epitaxial controlled growth of the repaired part of the blade by adopting a metal melt filling mode; step S500: and removing the profiling die after finishing metal cladding, and performing subsequent processing treatment on the blade. The repaired blade meets the use requirements of the single crystal or directional crystal blade, the service life of the blade is prolonged to the maximum extent, and the method has great theoretical and practical significance.

Description

A repair method for realizing the complex shape of the inner flow channel of a single crystal or oriented crystal alloy blade

technical field

The invention relates to the field of repairing aeronautical parts, and in particular relates to an epitaxial repairing method for realizing high-precision complex shape of the inner flow channel structure of a single crystal or oriented crystal alloy blade.

Background technique

As the "crown jewel" of modern industry, the technical level of aero-engines is an important symbol to measure a country's comprehensive scientific and technological level, industrial strength and comprehensive national strength. The development of modern aviation industry is closely related to the progress of aero-engine technology. The performance of aero-engines The indicators directly determine the performance of the aircraft. As an important component of aero-engines and ground gas turbines, the comprehensive performance of blades, such as the level of service temperature and the length of service life, seriously restricts the progress of aero-engine technology. At the same time, due to the extremely harsh working environment of aero-engines or ground gas turbines, the long-term operation of the blades in the environment of high temperature, high pressure and complex cyclic stress loads is prone to defects such as wear, corrosion, cracks, material loss, etc., but single crystal or oriented crystal blades The production is difficult and the cost is high, with the unit price of each piece reaching tens of thousands of dollars. The development of repair technology can restore or even partially exceed the original performance of the blade to prolong the service life of the blade, which can not only greatly reduce the maintenance cost of the aero-engine, but also greatly save the precious blade raw materials, which has significant economic and social benefits.

Commonly used alloy materials for blades, such as nickel-based superalloys, have a face-centered cubic crystal structure, which has the characteristics of epitaxial growth (that is, under certain conditions, the microstructure can continue to grow along the crystallographic direction of the matrix) during the repair process. Manufacturing and other processes provide technical prerequisites for repairing failed blades. During the repair of single crystal or oriented crystal blade, the microstructure grows epitaxially with the solidification of the molten pool, but when the single crystal or oriented crystal structure grows to a certain height, the equiaxed crystal structure is easy to appear and destroy the single crystal or oriented crystal structure. grow. Due to the lack of grain boundary strengthening elements in common nickel-based superalloy blade materials, once the grain boundary, especially the grain boundary perpendicular to the main stress axis of the blade, is formed, cracks can easily germinate and expand at the grain boundary under the action of stress, which seriously threatens the blade. service safety. Therefore, the key to the repair of single crystal or oriented crystal blades is how to accurately adjust the repair temperature field through process control, so as to realize the continuous epitaxial growth of single crystal or oriented crystal structure without causing defects such as cracks and equiaxed crystals.

Arc repair has a wide and important application in traditional parts repair. Using arc to repair single crystal or oriented crystal alloy blades, compared with laser, electron beam and other processes, the equipment is simple, the size limit of repair parts is small, and the overall repair cost is low, and the automatic repair of single crystal or oriented crystal blades can be realized through the arc additive manufacturing process. It has important application value.

SUMMARY OF THE INVENTION

The invention proposes a repair method for realizing the complex shape of the inner flow channel of a single crystal or oriented crystal alloy blade. By prefabricating a special complex mold for blade repair and reasonably controlling the repair temperature field, supplemented by subsequent processing, it can ensure that the repair area has At the same time of the same single crystal or oriented crystal structure as the matrix, the high-precision complex of the flow channel structure in the single crystal or oriented crystal alloy blade is realized.

In order to achieve the above object, the present invention adopts the following technical solutions:

A repair method for realizing the complex shape of the inner flow channel of a single crystal or oriented crystal alloy blade, comprising the following steps:

Step S100: Judging and analyzing blade failures and defects before repairing;

Step S200: cutting out the failed or defective part of the blade and grinding and cleaning the blade;

Step S300: Install and fix the pre-manufactured complex mold for ensuring the high-precision complex of the flow channel structure in the blade in the cavity of the blade to be repaired;

Step S400 : implementing the controlled epitaxial growth of the repaired part of the blade by means of metal melt filling;

Step S500: After the metal cladding is completed, the complex mold is removed, and subsequent processing is performed on the blade to achieve blade repair.

Further, in step S300, the installation gap of the complex mold is less than 0.3 mm, and the positioning device is used for positioning at least one point on the outside.

Further, in step S400, after the growth size of the area to be repaired is not less than 1 mm and the growth part can be fixed to the replica mold, the locator is removed.

Further, when cutting the defective or defective part of the blade, the cutting line is at least 1.5 mm away from the defective or defective part.

Further, the blade to be repaired is preheated before repair, and the preheating temperature is not lower than 82% of the melting point of the blade material.

Further, in step S400, laser, electron beam, arc or flame is used as a heat source to heat the metal powder or wire, and the epitaxial direction-controlled growth of the repaired part of the blade is realized by filling the metal melt.

Further, the arc is used as the heat source to heat the metal powder or wire, and the epitaxial direction-controlled growth of the repaired part of the blade is realized by filling the metal melt; in the process of repairing the single crystal or oriented crystal alloy blade by the arc, the arc voltage, current, The material feeding speed and the blade movement speed are dynamically adjusted in real time according to the shape and size of the blade to be repaired. The real-time dynamic adjustment is to linearly adjust the material and heat supply according to the normal material equivalent thickness of the repaired local blade surface in the repair process to meet the needs of local material cladding. One of the following schemes is preferred, adjust the relative movement speed of the welding torch and the blade separately, or adjust the current and the feeding speed of the filling material in the same proportion, or adjust the current and the feeding speed of the material in the same proportion. Arc voltage over 20% range.

Further, the repairing process is carried out under the protective atmosphere of an inert gas, and the inert gas is selected from a single argon gas, helium gas, nitrogen gas or any two or a combination of the three thereof.

Further, after the blade is repaired, the dimensional accuracy is not less than 0.5mm, and the surface roughness Ra is not more than 30um.

Further, after the single crystal or oriented crystal blade is repaired and post-treated, there is no crack defect, the degree of deviation of the crystal orientation does not exceed 7°, and the rate of miscellaneous crystals does not exceed 6%.

Further, the open or compressed arc is used as a heat source to heat the metal powder or wire, and the epitaxial direction-controlled growth of the repaired part of the blade is realized by filling the metal melt.

Further, a plasma (or microbeam plasma) arc is used as a heat source to heat the metal powder or wire, and the epitaxial direction-controlled growth of the repaired part of the blade is realized by filling the metal melt.

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

The invention proposes an epitaxial repair method for realizing high-precision replica of the flow channel structure in a single crystal or oriented crystal blade. The controlled growth is supplemented by subsequent processing. While obtaining the same single crystal or oriented crystal structure of the repaired area and the matrix, the high-precision reconstruction of the inner flow channel structure during the blade repair process is realized, so that the repaired blade can meet the service requirements of the blade. The service life of the blade is extended on the basis of restoring or even partially exceeding the original performance of the blade.

Complex mold: The complex mold refers to the core mold whose outer surface can be solidified by the subsequent blade material melt to form the flow channel in the inner cavity of the blade. The alloy blade casting core manufacturing technology and process, the external shape size of which is consistent with the shape size of the inner cavity of the blade, is convenient to realize the high-precision reconstruction of the internal flow channel structure of the blade. Determine the cutting plan of the failed blade according to the specific situation of the blade failure. After cutting, place the replica mold in the inner cavity of the blade to be repaired and install and fix it. When the growth height of the area to be repaired is not less than 1mm, remove the replica mold fixing and positioning device, and the repair is completed. After that, the complex mold is removed for subsequent processing. The specific implementation process includes: using the existing core preparation technology for blade casting to prepare a complex mold suitable for blade repair before blade repair, analyzing the failure characteristics of the failed blade, and removing the failure parts of the blade (such as cracks, miscellaneous crystals, wear, corrosion, etc.). , drop block), the cut plane is perpendicular to the direction of the principal stress axis of the blade. During the cutting process, ensure that the shortest distance between the cut surface and the failure part along the principal stress axis of the blade is not less than 1.5mm. After the failure part is removed, the cut surface must be polished and cleaned (with sandpaper, the grades of sandpaper from low to high are 400, 600, 800, 1000, 1200, 1500, 2000, 2500, 3000, rinse with water after grinding, and then use Ultrasonic cleaning machine alcohol cleaning for more than 10 minutes, and finally dry the surface to be repaired with a hair dryer). Place the pre-manufactured complex mold in the inner cavity of the blade to be repaired. The pretreatment of the complex mold should not only ensure that the complex mold placement process is easy to implement, but also ensure that the complex mold is placed in the blade cavity and exposed. The size of the exposed part is within ±0.1mm, and the exposed size of the complex mold is too large or too small, which will seriously affect the dimensional accuracy of the repaired blade in the direction of the principal stress axis. At the same time, the interval between the inner wall of the blade and the surface of the complex mold should be controlled within 0.3mm to ensure the high-precision complex of the inner flow channel structure to the greatest extent. After the complex mold is placed inside the blade cavity, the complex mold is fixed from at least one place by a special locator to prevent the position of the complex mold from changing during the repair process. After the metal growth height in the area to be repaired is not less than 1mm enough to fix the complex mold, the locator is removed for subsequent repair. After the repair is completed, the complex mold is broken by vibration, so that the complex mold material is removed from the bottom of the blade, and then subsequent processing is performed.

Temperature field control: In the repair process, through precise control of the temperature field (including the size and direction of the temperature gradient) in the area to be repaired, growth conditions suitable for liquid metal single crystal or directional crystal of nickel-based alloys are created to meet the technical requirements of blade repair. The specific process includes: after the complex mold is installed and fixed in the inner cavity of the blade, the coil used for induction heating is placed and fixed around the blade repair interface. The shape of the induction heating coil is similar to the cross-sectional morphology of the blade, so as to maximize the Guaranteed heating efficiency and repair quality. The preheating temperature of the blade is not lower than 82% of the melting point of the material, and the growth rate of the liquid metal is reduced by the high preheating temperature of the substrate, and the epitaxial plane growth of the metal is realized to the greatest extent. During the blade repair process, the position of the induction coil used for metal heating of the base blade and the repaired area should be adjusted with the change of the position of the repair interface. Specifically, as the repair process proceeds, the distance between the interface to be repaired and the root of the blade increases. The induction coil should move upward synchronously, so that the moving speed of the coil is close to the upward moving speed of the repair interface, so as to ensure the heating effect and repair quality to the greatest extent.

Description of drawings

FIG. 1 is a flow chart of the method of the present invention.

Detailed ways

Specific embodiments of the present invention are given below in conjunction with the accompanying drawings, but the present invention is not limited to the following embodiments. The advantages and features of the present invention will become more apparent from the following description and claims. It should be noted that, the accompanying drawings are all in a very simplified form and use inaccurate ratios, and are only used for the purpose of assisting in explaining the embodiments of the present invention conveniently and clearly.

Please refer to FIG. 1 . FIG. 1 is a flow chart of a method for repairing an inner flow channel of a single crystal or oriented crystal alloy blade according to a preferred embodiment of the present invention.

The invention provides a repair method for realizing the complex shape of the inner flow channel of a single crystal or oriented crystal alloy blade, comprising the following steps:

Step S100: before repairing, judging and analyzing blade failures and defects;

Step S200: cutting out the failed or defective part of the blade and grinding and cleaning the blade;

Step S300: Install and fix the pre-manufactured complex mold for ensuring the high-precision complex shape of the inner flow channel structure of the blade in the cavity of the blade to be repaired. The shape and size are consistent, the installation gap between the surface of the complex mold and the inner wall of the blade to be repaired is less than 0.3mm, and at least one point on the outside is positioned with a locator;

Step S400 : preheating the to-be-repaired part to more than 75% of the melting point of the material in Kelvin, and using metal melt filling to realize the epitaxial direction-controlled growth of the blade repaired part;

Step S500: After the metal cladding is completed, the complex mold is removed, and subsequent processing is performed on the blade.

According to a preferred embodiment of the present invention, the cutting line is at least 1.5mm away from the failed or defective part when cutting the blade failure or defect, so as to ensure that the tissue affected during the blade failure or defect is completely removed.

According to a preferred embodiment of the present invention, the blade to be repaired must be preheated before repairing, and the preheating temperature is not lower than 82% of the melting point of the material.

According to a preferred embodiment of the present invention, laser, electron beam, arc, and flame are used as heat sources to heat metal powder or wire, and the epitaxial direction-controlled growth of the repaired part of the blade is realized by filling with metal melt.

According to a preferred embodiment of the present invention, the open or compressed arc is used as the heat source to heat the metal powder or wire, and the epitaxially controlled growth of the repaired part of the blade is realized by filling the metal melt.

According to a preferred embodiment of the present invention, a plasma (or microbeam plasma) arc is used as a heat source to heat the metal powder or wire, and the epitaxial direction-controlled growth of the repaired part of the blade is realized by filling the metal melt.

According to a preferred embodiment of the present invention, the repairing process is performed under a protective atmosphere of an inert gas, and the inert gas is selected from a single argon gas, helium gas, nitrogen gas, or any two or a combination of the three thereof.

According to a preferred embodiment of the present invention, after the blade is repaired by subsequent processing, the dimensional accuracy is not less than 0.5mm, and the surface roughness Ra is not more than 30um.

According to the preferred embodiment of the present invention, the single crystal or oriented crystal blade is repaired and post-processed without crack defects, the service performance of the epitaxial growth zone is restored to the greatest extent or even partially exceeds the original performance of the blade, the crystal orientation deviation does not exceed 7°, the miscellaneous crystal rate does not exceed 6%.

In summary, the present invention proposes a repair method for realizing the complex shape of the inner flow channel of a single crystal or oriented crystal alloy blade. The repair temperature field is reasonably controlled by the thermal control device, supplemented by subsequent processing, to obtain the same single crystal or oriented crystal structure of the repair area and the matrix, and at the same time to achieve the high-precision complex of the inner flow channel structure during the blade repair process. , so that the repaired blade meets the service requirements of the blade, and the service life of the blade is extended on the basis of restoring or even partially exceeding the original performance of the blade.

The preferred embodiment of the present invention is exemplified as follows:

1. Using the repair method mentioned in the present invention, the single crystal nickel-based alloy aero-engine blade was successfully repaired. In the process of repairing the blade, the cutting line is more than 1.5mm away from the failed part when cutting the failed part, the preheating temperature is not lower than 82% of the melting point of the material, and the argon used in the repairing process is high-purity argon. After the repair, the blade has no crack defects, the dimensional accuracy is less than 0.5mm, and the surface roughness Ra is not more than 30um. The miscellaneous crystal rate does not exceed 6%, and the crystal orientation deviation does not exceed 7°. The repaired blade sample meets the service requirements.

2. Using the repair method mentioned in the present invention, the directional crystal nickel-based alloy aero-engine blade is successfully repaired. In the process of repairing the blade, the cutting line is more than 1.5mm away from the failed part when cutting the failed part, the preheating temperature is not lower than 82% of the melting point of the material, and the argon used in the repairing process is high-purity argon. After the repair, the blade has no crack defects, the dimensional accuracy is less than 0.5mm, and the surface roughness Ra is not more than 30um. The miscellaneous crystal rate does not exceed 6%, and the crystal orientation deviation does not exceed 7°. The repaired blade sample meets the service requirements.

3. Using the repair method mentioned in the present invention, the single crystal cobalt-based alloy aero-engine blade is successfully repaired. In the process of repairing the blade, the cutting line is more than 1.5mm away from the failed part when cutting the failed part, the preheating temperature is not lower than 82% of the melting point of the material, and the argon used in the repairing process is high-purity argon. After the repair, the blade has no crack defects, the dimensional accuracy is less than 0.5mm, and the surface roughness Ra is not more than 30um. The miscellaneous crystal rate does not exceed 6%, and the crystal orientation deviation does not exceed 7°. The repaired blade sample meets the service requirements.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Those skilled in the art to which the present invention pertains can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be determined according to the claims.

Claims (4)

1. a repair method for realizing single crystal or directional crystal alloy blade inner flow channel complex, it is characterized in that: comprise the following steps: Step S100: Judging and analyzing blade failures and defects before repairing; Step S200: cutting out the failed or defective part of the blade and grinding and cleaning the blade; Step S300: Install and fix the pre-manufactured complex mold for ensuring the high-precision complex shape of the flow channel structure in the blade in the cavity of the blade to be repaired. The complex mold means that the outer surface can be solidified by the subsequent blade material melt. The core mold that forms the flow channel of the inner cavity of the blade; Step S400: After the complex mold is installed and fixed in the inner cavity of the blade, the coil for induction heating is placed and fixed around the blade repair interface. The shape of the induction heating coil is similar to the cross-sectional morphology of the blade; Heat to the point where the melting point of the material is more than 75% of Kelvin, and use the method of metal melt filling to realize the epitaxial direction-controlled growth of the repaired part of the blade; Step S500: After the metal cladding is completed, the complex mold is removed, and subsequent processing is performed on the blade to achieve blade repair; In step S300, the complex mold is inserted into the opening of the inner flow channel of the blade to be repaired, and the complex mold is installed and fixed by contacting the insertion part of the complex mold with the inner flow channel of the repaired blade, and the installation gap of the complex mold is less than 0.3 mm. At least one point on the outside is positioned with a locator to achieve stable fixation of the complex mold in the opening area of the blade to be repaired; In step S400, after the growth size of the area to be repaired is not less than 1 mm and the growth part can be fixed to the replica mold, the locator is removed; In step S400, the metal powder or wire is heated by using a laser, an electron beam, an arc or a flame as a heat source, and the epitaxial direction-controlled growth of the repaired part of the blade is realized by filling the metal melt; After the blade is repaired, the dimensional accuracy is not less than 0.5mm, and the surface roughness Ra is not more than 30um; After the single crystal or oriented crystal blade is repaired and post-treated, there is no crack defect, the degree of deviation of the crystal orientation does not exceed 7°, and the rate of miscellaneous crystals does not exceed 6%. 2 . The repair method for realizing the complex shape of the inner flow channel of a single crystal or oriented crystal alloy blade according to claim 1 , wherein the cutting line is at least 1.5 mm away from the failed or defective part when cutting the defective or defective part of the blade. 3 . 3. The repair method for realizing the complex shape of the inner flow channel of a single crystal or oriented crystal alloy blade according to claim 1, characterized in that: adopting an electric arc as a heat source to heat metal powder or wire, and filling it with metal melt. Epitaxial direction-controlled growth of the repaired part of the blade; in the process of repairing the single crystal or oriented crystal alloy blade by the arc, the arc voltage, current, feeding speed of the filling material, and blade movement speed are dynamically adjusted in real time according to the shape and size of the blade to be repaired; the Real-time dynamic adjustment is to linearly adjust the material and heat supply according to the normal material equivalent thickness of the repaired local blade surface during the repair process to meet the needs of local material cladding. One of the following schemes is adopted: adjust the welding torch and blade separately The relative moving speed, or adjust the current and the feeding speed of the filling material in the same proportion, or adjust the current and the feeding speed of the material in the same proportion, supplemented by adjusting the arc voltage within the range of no more than 20% in the same direction. 4. The repair method for realizing the complex shape of the inner flow channel of a single crystal or oriented crystal alloy blade according to claim 1, wherein the repair process is carried out under the protective atmosphere of an inert gas, and the inert gas is selected from a single argon gas, helium gas , nitrogen, or a combination of any two or three of them.

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