Electron beam brazing repair method for replacing blade cover plate

Abstract

This invention discloses an electron beam brazing repair method for replacing blade cover plates, comprising the following steps: placing a new cover plate between two oppositely arranged blade top walls, positioning the new cover plate on two oppositely arranged shoulder wall protrusions and an airflow baffle between the two shoulder wall protrusions, with the receiving groove on the new cover plate corresponding to the airflow baffle on the blade; inserting a first adhesive brazing filler metal into the receiving groove, and covering the first adhesive brazing filler metal with a first amorphous thin strip brazing filler metal; arranging a second adhesive brazing filler metal at the corner where the new cover plate connects to the shoulder wall protrusion, and covering the second adhesive brazing filler metal with a second amorphous thin strip brazing filler metal; heating and melting the first adhesive brazing filler metal and the first amorphous thin strip brazing filler metal to weld the new cover plate to the airflow baffle, and heating and melting the second adhesive brazing filler metal and the second amorphous thin strip brazing filler metal to weld the new cover plate to the shoulder wall protrusion. The amount of brazing filler metal can be precisely controlled, brazing filler metal is less prone to splashing, and the requirements for pre-welding treatment of the surface of the workpiece are not high.

Description

Technical Field

[0001] This invention relates to the field of brazing repair technology, and specifically to an electron beam brazing repair method for replacing blade cover plates. Background Technology

[0002] With the increasing scale of aero-engines and gas turbines, the higher service intensity of blades, and the significant increase in the number of damaged blades, blade repair and reuse are particularly important for reducing the operation and maintenance costs of engines and gas turbines. During the service life of blades, serious service defects such as cracking and burn-out of the blade tip cover weld are prone to occur, requiring replacement of the cover and re-welding. Blade welding repair technologies mainly include fusion welding, powder metallurgy, and brazing-diffusion welding repair technologies. Among them, fusion welding technology is mainly used to repair cobalt-based and nickel-based superalloy blades with good weldability, but the residual stress after welding severely restricts the service performance of the repaired blades; powder metallurgy repair technology is mainly for large gap cracks; brazing-diffusion welding technology has unique advantages such as avoiding the generation of crystallization cracks, no large deformation and residual stress during overall heating, and the ability to repair multiple cracks simultaneously, making it more flexible and economical for blade repair.

[0003] However, conventional vacuum brazing technology has prominent problems such as high requirements for the surface treatment of the parts to be brazed, low precision in controlling the amount of brazing filler metal, and turbulent flow of brazing filler metal, which leads to an increase in welding defects in blade cover plates.

[0004] Given the shortcomings of conventional vacuum brazing technology, it is necessary to design a new repair method for replacing blade covers. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is that in conventional vacuum brazing technology, there are prominent problems such as high requirements for the surface treatment of the parts to be brazed, low precision in the control of the amount of brazing filler metal, and turbulent flow of brazing filler metal, which lead to an increase in welding defects of the blade cover plate. Thus, an electron beam brazing repair method for replacing the blade cover plate is provided.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0007] An electron beam brazing repair method for replacing blade cover plates includes the following steps:

[0008] S1. Place the new cover plate between two oppositely arranged blade top walls, so that the new cover plate is placed on the two oppositely arranged shoulder wall protrusions and the airflow baffle between the two shoulder wall protrusions, and make the receiving groove on the new cover plate correspond to the airflow baffle.

[0009] S2. Insert the first adhesive solder into the receiving groove, and cover the first adhesive solder with a first amorphous thin strip solder.

[0010] S3. Arrange a second adhesive solder at the corner where the new cover plate connects to the shoulder wall boss, and cover the second adhesive solder with a second amorphous thin strip solder.

[0011] S4. The first adhesive solder and the first amorphous thin strip solder are heated and melted by a vacuum electron beam to weld the new cover plate to the airflow baffle. The second adhesive solder and the second amorphous thin strip solder are heated and melted by a vacuum electron beam to weld the new cover plate to the shoulder boss.

[0012] Furthermore, in step S4, when heating the first adhesive solder and the first amorphous thin strip solder, and / or when heating the second adhesive solder and the second amorphous thin strip solder, the first electron beam is used to scan and heat to complete one melting and welding to form a weld, and then the second electron beam is used for a second supplementary slow cooling heating along a repeating path, and the power of the first electron beam is greater than the power of the second electron beam.

[0013] Furthermore, in step S4, the new cover plate is first welded to the airflow baffle, and then the new cover plate is welded to the shoulder wall protrusion.

[0014] Furthermore, prior to step S4, the method further includes spot welding the new cover plate to the shoulder wall protrusion and spot welding the new cover plate to the airflow baffle.

[0015] Furthermore, prior to step S1, the following steps are also included:

[0016] S12. Draw the center line of the airflow baffle and extend the center line of the airflow baffle to the shoulder wall protrusion to form the main marking line;

[0017] S13. Pre-assemble the new cover plate onto the corresponding position on the blade, and form a secondary marking line on the new cover plate, and connect the two ends of the secondary marking line to the main marking line, and make the horizontal projections of the secondary marking line and the main marking line lie on the same straight line.

[0018] S14. Remove the new cover plate and open the receiving groove at the position of the secondary marking line on the new cover plate.

[0019] Furthermore, in step S1, the receiving groove does not penetrate the new cover plate.

[0020] Furthermore, the following steps are included before step S12:

[0021] S11. Clean the new cover plate.

[0022] Furthermore, in step S12, the centerline of the airflow baffle extends to the blade tip wall.

[0023] Furthermore, prior to step S1, the following steps are also included:

[0024] S10. Remove the welding marks from the original cover plate on the blade, and form a surface to be welded on the shoulder wall protrusion and the airflow baffle.

[0025] Furthermore, in step S10, the welding marks are removed by mechanical grinding, sandpaper polishing, sandblasting, or ultrasonic cleaning with acetone.

[0026] The technical solution of this invention has the following advantages:

[0027] 1. This invention provides an electron beam brazing repair method for replacing blade cover plates. The new cover plate has a receiving groove corresponding to an airflow baffle. A first adhesive brazing filler metal is placed inside the receiving groove, and a first amorphous thin-film brazing filler metal is placed over the first adhesive brazing filler metal. A second adhesive brazing filler metal is placed at the corner where the new cover plate connects to the shoulder wall boss, and a second amorphous thin-film brazing filler metal is placed over the second adhesive brazing filler metal. Because both the adhesive brazing filler metal and the amorphous thin-film brazing filler metal have good flexibility, appropriate sizes of adhesive brazing filler metal and amorphous thin-film brazing filler metal can be selected and arranged according to the gap of the brazed joint. Therefore, brazing filler metal waste and turbulence problems during the brazing process can be reduced. Furthermore… Because the adhesive solder is covered with an amorphous thin strip solder, the spatter of powdered solder on the adhesive solder can be reduced during the brazing process. Furthermore, since vacuum electron beam heating is used, the heat is concentrated, which can quickly melt the solder and weld it nearby. Compared with ordinary vacuum brazing, which requires slow heating of the solder and capillary action to make the solder flow to the area to be welded, vacuum electron beam brazing technology has less demanding requirements for the pre-welding surface treatment of the workpiece, which can reduce the difficulty of the pre-welding surface treatment. Therefore, even when the operating space for pre-welding is limited, the pre-welding requirements can be met more easily.

[0028] 2. The present invention provides an electron beam brazing repair method for replacing blade cover plates, wherein the receiving groove does not penetrate the new cover plate, so that the receiving groove can serve as both a welding bevel and a sufficient amount of brazing filler metal, thereby ensuring the welding quality between the new cover plate and the airflow baffle.

[0029] 3. The present invention provides an electron beam brazing repair method for replacing blade cover plates. Before heating and welding, the new cover plate is spot welded to the shoulder wall protrusion and the new cover plate is spot welded to the airflow baffle. This can prevent the new cover plate from shifting during the welding process and reduce the risk of deformation of the new cover plate.

[0030] 4. The present invention provides an electron beam brazing repair method for replacing blade cover plates, which uses vacuum electron beam heating. When heating the first adhesive brazing filler metal and the first amorphous thin strip brazing filler metal, and / or when heating the second adhesive brazing filler metal and the second amorphous thin strip brazing filler metal, the first electron beam is used to scan and heat to complete one melting welding to form a weld. Then, the second electron beam is used to perform a second supplementary slow cooling heating through a repeating path. The power of the first electron beam is greater than the power of the second electron beam to promote the full release of thermal stress in the weld and avoid the occurrence of welding cracks.

[0031] 5. The electron beam brazing repair method for replacing blade cover plates provided by the present invention further includes the following steps: drawing the center line of the airflow baffle and extending the center line of the airflow baffle to the shoulder wall protrusion to form a main marking line; pre-assembling the new cover plate to the corresponding position on the blade, drawing a secondary marking line on the new cover plate, connecting the two ends of the secondary marking line to the main marking line, and making the horizontal projections of the secondary marking line and the main marking line lie on the same straight line; removing the new cover plate and opening a receiving groove at the position of the secondary marking line on the new cover plate. In this way, by aligning the main marking line and the secondary marking line, the receiving groove of the new cover plate can correspond to the center line of the airflow baffle, thereby improving the welding balance and firmness of the new cover plate and the airflow baffle. Attached Figure Description

[0032] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram showing the fit between the new cover plate and the blade top wall and shoulder wall bosses in this invention;

[0034] Figure 2 This is a schematic diagram showing the cooperation between the new cover plate and the blade top wall, shoulder wall protrusion, and airflow baffle in this invention;

[0035] Figure 3 This is a schematic flowchart of an electron beam brazing repair method for replacing blade cover plates according to the present invention.

[0036] Explanation of reference numerals in the attached figures:

[0037] 1. New cover plate; 2. Blade top wall; 3. Shoulder wall boss; 4. Airflow baffle; 5. First adhesive strip brazing filler metal; 6. First amorphous thin strip brazing filler metal; 7. Second adhesive strip brazing filler metal; 8. Second amorphous thin strip brazing filler metal; 9. Marking line. Detailed Implementation

[0038] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0040] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0041] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0042] Example

[0043] like Figures 1 to 3 As shown, this embodiment provides an electron beam brazing repair method for replacing blade cover plates. It employs vacuum electron beam brazing, using a high-energy-density, easily controllable electron beam as the energy source to locally heat and melt the brazing filler metal along a specific path, achieving welding between the new cover plate and the corresponding part of the blade. The method includes the following steps:

[0044] S1. Assemble the new cover plate 1, placing the new cover plate 1 with the opening of the receiving groove between the two oppositely arranged blade top walls 2, and placing the new cover plate 1 on the oppositely arranged shoulder wall protrusions 3 and the airflow baffle 4 between the two shoulder wall protrusions 3, and making the receiving groove correspond to the airflow baffle 4 on the blade. Preferably, the receiving groove is aligned with the center line of the airflow baffle 4. In this way, the welding area on both sides of the center line of the airflow baffle 4 and the new cover plate 1 will be more balanced and the welding will be stronger.

[0045] S2. The first adhesive solder 5 is placed in the receiving groove, and the first amorphous thin strip solder 6 is covered on the outside of the first adhesive solder 5. In this embodiment, since the first adhesive solder 5 and the first amorphous thin strip solder 6 have good flexibility, the appropriate size of the first adhesive solder 5 and the first amorphous thin strip solder 6 can be selected and laid according to the gap of the brazing joint (here, the gap of the brazing joint is the receiving groove). In other words, the amount of solder used can be controlled more precisely according to the gap of the brazing joint, so as to reduce solder waste and turbulence during the brazing process. In addition, since the first amorphous thin strip solder 6 is covered on the outside of the first adhesive solder 5, the splashing of powder solder on the first adhesive solder 5 during the brazing process can be reduced.

[0046] S3. Arrange the second adhesive solder 7 at the corner where the new cover plate 1 connects to the shoulder wall boss 3, and cover the second adhesive solder 7 with the second amorphous thin strip solder 8. In this embodiment, since both the second adhesive solder 7 and the second amorphous thin strip solder 8 have good flexibility, the appropriate size of the second adhesive solder 7 and the second amorphous thin strip solder 8 can be selected and arranged according to the gap of the brazing joint (here, the gap of the brazing joint is the difference in thickness direction at the corner formed by the shoulder wall boss 3 and the new cover plate 1). In other words, the amount of solder used can be more precisely controlled according to the gap of the brazing joint, thus reducing solder waste and turbulence during the brazing process. In addition, since the second adhesive solder 7 is covered with the second amorphous thin strip solder 8, the splashing of powder solder on the second adhesive solder 7 during the brazing process can be reduced.

[0047] S4. The new cover plate 1 is welded to the airflow baffle 4 by melting the first adhesive solder 5 and the first amorphous thin strip solder 6 using a vacuum electron beam. The new cover plate 1 is then welded to the shoulder wall boss 3 by melting the second adhesive solder 7 and the second amorphous thin strip solder 8 using a vacuum electron beam. In this embodiment, the receiving groove on the new cover plate 1 is welded to the airflow baffle 4 first, followed by the welding of the new cover plate 1 to the shoulder wall boss 3. Furthermore, the principle of welding longer sections first and then shorter sections is consistently adhered to. This reduces the risk of deformation or warping of the new cover plate 1 and improves the welding quality. Specifically, when heating the first adhesive solder 5 and the first amorphous thin strip solder 6, a high-power first electron beam is first used to complete a melting weld to form a weld. Then, a lower-power second electron beam is used for a secondary, supplementary, slow-cooling heating process along a repeating path. This promotes the full release of thermal stress in the weld and prevents welding cracks between the new cover plate 1 and the airflow baffle 4. Furthermore, the high-energy first electron beam can both melt the first adhesive solder 5 and the first amorphous thin strip solder 6 and penetrate the bottom of the receiving tank. Similarly, when heating the second adhesive solder 7 and the second amorphous thin strip solder 8, a high-power first electron beam is first used to complete a melting weld to form a weld. Then, a lower-power second electron beam is used for a secondary, supplementary, slow-cooling heating process along a repeating path. This promotes the full release of thermal stress in the weld and prevents welding cracks between the new cover plate 1 and the shoulder boss 3. In this embodiment, the power of the first electron beam is 80kW-100kW, and the power of the second electron beam is 40kW-60kW. Of course, the specific power values ​​can be adjusted according to actual needs, and no specific limitation is made here.

[0048] S5. Welding Quality Assessment. Welding quality assessment includes the evaluation of the appearance quality of the solder joint and the evaluation of its internal quality. The evaluation of the appearance quality of the solder joint mainly assesses the wettability of the solder joint, the surface condition of the solder joint, the condition of the base metal, and the condition of the solder near the solder joint.

[0049] S6. Repair welding for defects. If there are defects on the surface of the weld joint, repair welding is required. After repair welding, the welding quality must be reassessed. Repair welding should not be performed more than twice.

[0050] In addition, in this embodiment, the following steps are included before step S1:

[0051] S10. Remove the welding marks of the original cover plate on the blade by means of mechanical grinding, sandpaper polishing, sandblasting or acetone ultrasonic cleaning, and form a surface to be welded on the shoulder wall boss 3 and the airflow baffle 4.

[0052] S11. Clean the new cover plate 1;

[0053] S12. Draw the center line of the airflow baffle 4 and extend the center line of the airflow baffle to the shoulder wall protrusion 3 and the blade top wall 2 to form the main marking line.

[0054] S13. Pre-assemble the new cover plate 1 to the corresponding position on the blade, and draw a secondary marking line on the new cover plate 1, and connect the two ends of the secondary marking line to the main marking line, and make the horizontal projection of the secondary marking line and the main marking line lie on the same straight line; the main marking line and the secondary marking line are connected together to form the marking line 9;

[0055] S14. Remove the new cover plate 1 and create the aforementioned receiving groove at the secondary marking line position on the new cover plate 1. Specifically, cut the receiving groove with a width of 0.8mm-1.2mm and a depth of 0.6mm-1.0mm using wire cutting. The receiving groove does not penetrate the bottom of the new cover plate 1 to facilitate the placement of the first adhesive solder 5 within the receiving groove. The receiving groove serves both as a filling groove for the solder and as a bevel for vacuum electron beam welding, ensuring the welding quality between the new cover plate 1 and the airflow baffle 4.

[0056] After the main and secondary marking lines are drawn, and the receiving groove is processed, the receiving groove on the new cover plate 1 can be aligned with the center line of the airflow baffle 4 by aligning the main and secondary marking lines, thereby improving the welding balance and firmness of the new cover plate 1 and the airflow baffle 4.

[0057] In addition, before step S4, the following steps are included: spot welding the new cover plate 1 to the shoulder wall protrusion 3 and spot welding the new cover plate 1 to the airflow baffle 4. First, identify the easily deformable or warped areas on the new cover plate 1 where it overlaps with the shoulder wall protrusion 3, and the easily deformable or warped areas on the new cover plate 1 where it overlaps with the airflow baffle 4. Then, use a high-energy spot welding machine to set several spot welding nodes at these easily deformable or warped areas to ensure that the new cover plate 1 does not shift or deform during the welding process.

[0058] In this embodiment, amorphous thin-strip brazing filler metal is chosen for winding because it offers significant advantages over conventional brittle powder, wire, sheet, paste, and rod-shaped brazing filler metals, resulting in higher weld quality. Specifically, the advantages of amorphous thin-strip brazing filler metal compared to conventional brittle powder, wire, sheet, and rod-shaped brazing filler metals are as follows:

[0059] 1) The weld structure and composition are uniform. The brazing filler metal is rapidly cooled from the liquid state to form a solid brazing filler metal. The composition of the solid brazing filler metal maintains the uniformity of the liquid brazing filler metal. There are no grains or eutectic phases precipitated, and the melting is relatively uniform.

[0060] 2) The brazing filler metal is pure, the joint quality is high, and the preparation of the brazing filler metal does not require forging, rolling, drawing, or other processes. The brazing filler metal has low impurity content and high purity.

[0061] 3) The brazing filler metal has good flexibility and is easy to use. It can be well accommodated in small gaps, reducing waste. In addition, it has strong compositional adjustability, allowing for easy adjustment of the master alloy composition to obtain amorphous brazing filler metals with different compositions.

[0062] 4) The brazing filler metal has good wettability and fluidity, and melts and spreads almost simultaneously and uniformly during the heating process;

[0063] 5) Thinner brazing filler metal strips are thinner, allowing for smaller weld seams;

[0064] 6) The heat resistance temperature of the brazed joint does not decrease, and the brazing reaction layer will not remelt at lower temperatures.

[0065] The advantage of the adhesive-bonded brazing filler metal selected in this embodiment is that copper-based, nickel-based, and other high-temperature alloy brazing filler metals contain elements such as Si and B, which makes them very brittle and difficult to roll into wires or strips. They are generally supplied in powder or paste form, which severely restricts their application range. In contrast, adhesive-bonded brazing filler metal is a flexible strip-shaped brazing filler metal with certain viscosity. It has the advantages of simple operation and controllable brazing area. As long as a suitable binder is selected, high-temperature alloy brazing filler metal powder can be prepared into adhesive-bonded brazing filler metal, overcoming the problem of the narrow application range caused by the high brittleness of high-temperature alloy brazing filler metal and the difficulty in rolling it into wires or strips.

[0066] In addition, the electron beam brazing repair method for replacing blade cover plates provided in this embodiment has the following advantages:

[0067] 1) Compared with traditional vacuum brazing, the welding equipment in this embodiment is smaller in size, which can improve the ease of use. In addition, the welding repair time is shorter, and there is no need to heat the entire blade during welding repair. Therefore, the impact on the quality of the blade in non-welded areas can be reduced. Since only specific areas need to be heated to achieve local repair, the energy consumption is lower.

[0068] 2) The pre-welding processing space between the shoulder wall boss 3 of the blade and the new cover plate 1 is limited. If conventional vacuum brazing is used, the high requirements for pre-welding cleaning of the components make cleaning difficult. However, vacuum electron beam heating can quickly melt the brazing filler metal and weld it nearby due to the concentrated heat. Compared with ordinary vacuum brazing, which requires slow heating of the brazing filler metal and capillary action to spread the brazing filler metal to the area to be welded, vacuum electron beam brazing technology has lower requirements for pre-welding processing of the surface of the parts to be brazed, which can reduce the difficulty of pre-welding processing of the surface of the parts to be welded. Therefore, even when the pre-welding processing operation space is limited, the pre-welding processing requirements can be met more easily.

[0069] 3) The short high-temperature dwell time can greatly reduce the erosion of the base material by the brazing filler metal. In addition, the input energy is controllable and the energy input path can be edited arbitrarily.

[0070] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An electron beam brazing repair method for replacing blade cover plates, characterized in that, Includes the following steps: S1. Place the new cover plate between two oppositely arranged blade top walls, so that the new cover plate is placed on the two oppositely arranged shoulder wall protrusions and the airflow baffle between the two shoulder wall protrusions, and make the receiving groove on the new cover plate correspond to the airflow baffle, and the receiving groove does not penetrate the new cover plate. S2. Insert the first adhesive solder into the receiving groove, and cover the first adhesive solder with a first amorphous thin strip solder. S3. Arrange a second adhesive solder at the corner where the new cover plate connects to the shoulder wall boss, and cover the second adhesive solder with a second amorphous thin strip solder. S4. The first adhesive solder and the first amorphous thin strip solder are heated and melted by a vacuum electron beam to weld the new cover plate to the airflow baffle. The first adhesive solder, the first amorphous thin strip solder and the bottom of the receiving groove are melted by the vacuum electron beam to weld the new cover plate to the airflow baffle. The new cover plate is welded to the shoulder boss by heating and melting the second adhesive strip solder and the second amorphous thin strip solder.

2. The electron beam brazing repair method for replacing blade cover plates according to claim 1, characterized in that, In step S4, when heating the first adhesive solder and the first amorphous thin strip solder, and / or when heating the second adhesive solder and the second amorphous thin strip solder, the first electron beam is used to scan and heat to complete one melting and welding to form a weld, and then the second electron beam is used to perform a second supplementary slow cooling heating along a repeating path, and the power of the first electron beam is greater than the power of the second electron beam.

3. The electron beam brazing repair method for replacing blade cover plates according to claim 1, characterized in that, In step S4, the new cover plate is first welded to the airflow baffle, and then the new cover plate is welded to the shoulder wall protrusion.

4. The electron beam brazing repair method for replacing blade cover plates according to claim 1, characterized in that, Before step S4, the process also includes spot welding the new cover plate to the shoulder wall protrusion and spot welding the new cover plate to the airflow baffle.

5. A method for electron beam brazing repair of a blade cover plate according to any one of claims 1-4, characterized in that, Before step S1, the following steps are also included: S12. Draw the center line of the airflow baffle and extend the center line of the airflow baffle to the shoulder wall protrusion to form the main marking line; S13. Pre-assemble the new cover plate onto the corresponding position on the blade, and form a secondary marking line on the new cover plate, and connect the two ends of the secondary marking line to the main marking line, and make the horizontal projections of the secondary marking line and the main marking line lie on the same straight line; S14. Remove the new cover plate and open the receiving groove at the position of the secondary marking line on the new cover plate.

6. The electron beam brazing repair method for replacing blade cover plates according to claim 5, characterized in that, The following steps are included before step S12: S11. Clean the new cover plate.

7. The electron beam brazing repair method for replacing blade cover plates according to claim 5, characterized in that, In step S12, the centerline of the airflow baffle also extends to the blade tip wall.

8. A method for electron beam brazing repair of a blade cover plate according to any one of claims 1-4, characterized in that, Before step S1, the following steps are also included: S10. Remove the welding marks from the original cover plate on the blade, and form a surface to be welded on the shoulder wall protrusion and the airflow baffle.

9. The electron beam brazing repair method for replacing blade cover plates according to claim 8, characterized in that, In step S10, the welding marks are removed by mechanical grinding, sandpaper polishing, sandblasting, or ultrasonic cleaning with acetone.

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