Tailor-welding repair method for guide vane of high-pressure turbine of aero-engine

Abstract

The invention discloses a tailor-welding repair method for a high-pressure turbine guide vane of an aero-engine, and relates to the technical field of aero-engine guide vane repair. The method comprises the following steps: S1, cutting a multi-linkage blade into a single-linkage blade; s2, cutting off the damaged part of the single-linkage blade, and treating the cutting surface; s3, splicing with the patch subjected to port pretreatment, and covering a splicing surface with an intermediate layer of solder; s4, vacuum brazing treatment is conducted, and aging heat treatment is conducted after brazing is completed; when vacuum brazing treatment is carried out, balancing weights are used for carrying out weight balancing and pressure applying on the spliced single-linkage blades; the middle layer solder is composed of Cr, Ni, W, B and Co; the purposes that the damaged guide blade is locally repaired, and overall replacement caused by local damage is avoided are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of repairing guide blades of aircraft engines, in particular to a method for repairing guide blades of high-pressure turbines of aircraft engines by welding. Background Art

[0002] Transient Liquid Phase Bonding (TLP) technology combines the advantages of solid-phase diffusion bonding and high-temperature brazing to obtain high-strength joints with the same structure as the parent material and no grain boundaries. The process is as follows: At the connection temperature, the intermediate layer alloy melts and fills the gap to form an intermediate liquid phase layer. The alloying elements in the intermediate liquid phase layer and the parent metal diffuse rapidly, dissolving a certain width of the parent material in a short time. The continuous diffusion of the alloying elements causes the composition change in the solid / liquid interface area, resulting in isothermal solidification of the liquid phase area, homogenization of the composition of the joint area, and finally obtaining a joint with the same composition and structure as the matrix.

[0003] Compared with traditional vacuum brazing, its process mainly differs in two aspects, one is the solder composition, and the other is the implementation process. In terms of solder composition, Chinese patent 201810770280.2 (published on August 14, 2020) discloses an intermediate powder and welding method for TLP diffusion welding, which is used for IC10 high-temperature alloy welding operations. The "Materials Guide" published in 2020, Volume 34, Issue 18, Pages 18131-18134, disclosed the transition liquid phase TLP diffusion welding of nickel-based amorphous foil KNi3A to IC9 single crystal high-temperature alloy, and studied the influence mechanism of welding parameters on the solidification dynamics of the joint. The above patents and papers are more focused on the research and innovation of TLP welding materials and welding parameters, but there is not much involvement in the industrial application level, especially in the exploration of batch application of parts repair in the field of aero-engine maintenance.

[0004] The guide vanes and other parts with complex internal hollow structures manufactured in modern aircraft engines have a complex manufacturing process and extremely high manufacturing costs. Guide vanes are usually prepared by integral casting, with 2, 3 or even more sections. In the harsh (high temperature, high pressure) service environment, cracks and ablation failures will appear in certain specific parts (such as: blade inlet and exhaust edges) after a period of time. They usually need to be replaced with new ones. Local failures cause the entire part to be scrapped, resulting in a large amount of property losses. It is of great practical significance to develop a new splicing repair method for guide vanes using the characteristics of the TLP process. Summary of the invention

[0005] The purpose of the present invention is to provide a method for welding and repairing a guide blade of a high-pressure turbine of an aircraft engine, so as to achieve local repair of the damaged guide blade and avoid the purpose of replacing the entire blade due to local damage.

[0006] In order to achieve the above object, the present invention adopts the following technical means: A method for repairing a high-pressure turbine guide blade of an aircraft engine by welding, comprising the following steps: S1. Cut the multi-joint blades into single-joint blades; S2. Cut off the damaged part of the single blade and process the cut surface; S3. Splice with the patch after port pre-processing and cover the intermediate layer of solder on the splicing surface; S4. Perform vacuum brazing, and perform aging heat treatment after brazing; During vacuum brazing, a counterweight is used to apply counterweight pressure to the spliced ​​single blades; The intermediate layer solder consists of Cr, Ni, W, B and Co.

[0007] Furthermore, the intermediate layer solder is composed of Cr 21-23%, Ni 9-11%, W 7-9%, B2-4%, and the rest is Co.

[0008] Among them, the middle layer adopts Co-based solder. On the one hand, Co-based solder is used to reduce the brittle and hard phase formed during the brazing process, thereby avoiding the formation of a large amount of brittle and hard phases during the brazing process due to the addition of Cr, and the weld section is too brittle, which makes it difficult to adapt to the application environment of the guide blade after repair.

[0009] At the same time, the addition of Cr can not only increase the corrosion resistance of the solder, but also promote the interface diffusion between the entire intermediate layer solder and the cobalt-based high-temperature alloy, so that the solder and the cobalt-based high-temperature alloy have a stable interface structure.

[0010] Preferably, the intermediate layer solder is an amorphous thin strip, and the thickness of the intermediate layer solder is 0.02-0.05 mm.

[0011] Among them, the thickness of the solder has a great influence on the welding performance. If the thickness of the solder is too thick, micro cracks are likely to occur in the solder layer, thereby reducing the reliability of the solder layer. If the solder layer is too thin, problems such as cold solder joints and decreased interface bonding stability are likely to occur. Therefore, this application adopts an amorphous thin strip composed of Cr 21~23%, Ni 9~11%, W7~9%, B 2~4%, and the rest is Co, with a solder thickness of 0.02~0.05mm for brazing. It can be used in the welding repair of guide blades, and can take into account both welding reliability and use stability. After the solder is completed, it can meet the requirements of the guide blade use environment.

[0012] Furthermore, in step S1, the cutting of the multi-linked blades is performed by one of wire cutting, laser cutting or water jet cutting.

[0013] Furthermore, in step S2, the cutting surface is processed by milling, and the parallelism of the cutting surface is less than 0.03 mm. After the milling process, the thickness of the single-leaf blade is reduced to 1 / 2 of the original thickness.

[0014] Furthermore, after completing step S3, an intermediate layer solder positioning welding is performed before performing step S4, and the welding voltage is 200V.

[0015] Furthermore, in step S4, the brazing temperature of vacuum brazing is 1100-1300°C, and the brazing time is 20-30 hours.

[0016] By setting a specific temperature, voids in the solder layer can be avoided during the melting and flow of the solder.

[0017] Furthermore, in step S4, the aging temperature of the aging treatment is 800-900°C, and the time is 30-50 hours.

[0018] Aging treatment is used to avoid cracks inside the solder during the brazing process.

[0019] During use, the present invention has the following beneficial effects: The multi-unit (≥2) guide vanes are disassembled by cutting, the faulty parts are removed, and the qualified parts are reused, thereby increasing the parts utilization rate by more than 50%. The TLP diffusion connection method is used to obtain excellent joint performance. The counterweight pressure method is used to transfer the weld pressure required for TLP diffusion welding to the counterweight block, reducing the demand for brazing furnaces and complex tooling. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0021] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0023] Example 1 The guide vane of a certain type of engine is made of two joints and made of cobalt-based high-temperature alloy. The main components of the material are C: 0.4%~0.5%, Cr: 20%~25%, Ni: 8%~11%, W: 7%~10%, Co: balance. In view of the common blade cracks and ablation defects, the following welding repair process is used for repair.

[0024] The parts are cut by wire cutting, the cutting position is (center line + 1.0 mm), the cutting thickness width of the blade on the fault-free side is 1.0 mm, and the diameter of the wire cutting molybdenum wire is 0.3 mm.

[0025] The machining center is used to mill the line cutting surface. The machining requirements are parallel to the blade overlap end surface, and the parallelism is less than 0.03 mm. The width of the single blade after machining is 1 / 2 of the original blade. After milling, the single blades that need to be paired are combined, and the size is checked. The width of the spliced ​​blade is required to meet the requirements of the drawing.

[0026] Prepare the middle layer solder, solder state amorphous thin strip, thickness 0.03 mm, composition Cr: 22%, Ni: 10%, W: 8%, B: 3%, Co: balance. Use scissors to cut the amorphous thin strip to ensure that the thin strip can fully cover the surface to be welded.

[0027] The middle layer of solder is spot welded and fixed on the prepared single-joint blade using a storage energy spot welder. The spot welding parameters are: voltage 200V, electrode pressure, manual.

[0028] Place the two blades to be welded on the fixed fixture in order, check and confirm that the positions are aligned, and then place a counterweight block on top of the blades. The material of the counterweight block is GH3044 and weighs 2Kg.

[0029] Vacuum brazing treatment, system: brazing temperature 1200℃, brazing time 24h.

[0030] After brazing, the parts are subjected to aging heat treatment, with the aging temperature at 850°C and the time at 32h.

[0031] Quality inspection, using fluorescent and ultrasonic flaw detection methods to check the brazed joints, confirming that there are no crack defects in the welded parts, no incomplete defects inside the weld, and after welding, the total length of the blade is checked to meet the requirements of the drawing.

[0032] Example 2 The guide vane of a certain type of engine is made of two joints and made of cobalt-based high-temperature alloy. The main components of the material are C: 0.4%~0.5%, Cr: 20%~25%, Ni: 8%~11%, W: 7%~10%, Co: balance. In view of the common blade cracks and ablation defects, the following welding repair process is used for repair.

[0033] The parts are cut by wire cutting, the cutting position is (center line + 1.0 mm), the cutting thickness width of the blade on the fault-free side is 1.0 mm, and the diameter of the wire cutting molybdenum wire is 0.3 mm.

[0034] The machining center is used to mill the line cutting surface. The machining requirements are parallel to the blade overlap end surface, and the parallelism is less than 0.03 mm. The width of the single blade after machining is 1 / 2 of the original blade. After milling, the single blades that need to be paired are combined, and the size is checked. The width of the spliced ​​blade is required to meet the requirements of the drawing.

[0035] Prepare the middle layer solder, solder state amorphous thin strip, thickness 0.02 mm, composition Cr: 21%, Ni: 9%, W: 7%, B: 2%, Co: balance. Use scissors to cut the amorphous thin strip to ensure that the thin strip can fully cover the surface to be welded.

[0036] The middle layer of solder is spot welded and fixed on the prepared single-joint blade using a storage energy spot welder. The spot welding parameters are: voltage 200V, electrode pressure, manual.

[0037] Place the two blades to be welded on the fixed fixture in order, check and confirm that the positions are aligned, and then place a counterweight block on top of the blades. The material of the counterweight block is GH3044 and weighs 2Kg.

[0038] Vacuum brazing treatment, system: brazing temperature 1100℃, brazing time 20h.

[0039] After brazing, the parts are subjected to aging heat treatment, with the aging temperature at 800°C and the time at 30h.

[0040] Quality inspection, using fluorescent and ultrasonic flaw detection methods to check the brazed joints, confirming that there are no crack defects in the welded parts, no incomplete defects inside the weld, and after welding, the total length of the blade is checked to meet the requirements of the drawing.

[0041] Example 3 The guide vane of a certain type of engine is made of two joints and made of cobalt-based high-temperature alloy. The main components of the material are C: 0.4%~0.5%, Cr: 20%~25%, Ni: 8%~11%, W: 7%~10%, Co: balance. In view of the common blade cracks and ablation defects, the following welding repair process is used for repair.

[0042] The parts are cut by wire cutting, the cutting position is (center line + 1.0 mm), the cutting thickness width of the blade on the fault-free side is 1.0 mm, and the diameter of the wire cutting molybdenum wire is 0.3 mm.

[0043] The machining center is used to mill the line cutting surface. The machining requirements are parallel to the blade overlap end surface, and the parallelism is less than 0.03 mm. The width of the single blade after machining is 1 / 2 of the original blade. After milling, the single blades that need to be paired are combined, and the size is checked. The width of the spliced ​​blade is required to meet the requirements of the drawing.

[0044] Prepare the middle layer solder, solder state amorphous thin strip, thickness 0.05 mm, composition Cr: 23%, Ni: 11%, W: 9%, B: 4%, Co: balance. Use scissors to cut the amorphous thin strip to ensure that the thin strip can fully cover the surface to be welded.

[0045] The middle layer of solder is spot welded and fixed on the prepared single-joint blade using a storage energy spot welder. The spot welding parameters are: voltage 200V, electrode pressure, manual.

[0046] Place the two blades to be welded on the fixed fixture in order, check and confirm that the positions are aligned, and then place a counterweight block on top of the blades. The material of the counterweight block is GH3044 and weighs 2Kg.

[0047] Vacuum brazing treatment, system: brazing temperature 1300℃, brazing time 30h.

[0048] After brazing, the parts are subjected to aging heat treatment, with the aging temperature at 900°C and the time at 50h.

[0049] Quality inspection, using fluorescent and ultrasonic flaw detection methods to check the brazed joints, found slight cracks in the welded parts, no incomplete brazing defects inside the weld, and post-weld dimensional inspection showed that the total length of the blade met the requirements of the drawing.

[0050] Comparative Example 1 In this comparative example, Fe is added to the intermediate layer solder, and the added content does not exceed 10%. The other conditions are the same as those in Example 1.

[0051] The welds in this comparative example were inspected for quality and subjected to mechanical tests, and it was found that the mechanical properties of the welds were reduced to varying degrees. Since Fe and Cr may undergo intergranular corrosion under the conditions involved in this application, the mechanical properties of the weld joints are reduced.

[0052] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for repairing the high-pressure turbine guide blades of an aircraft engine by welding, characterized in that: The following steps are involved: S1. Cut the multi-joint blades into single-joint blades; S2. Cut off the damaged part of the single blade and process the cut surface; S3. Splice with the patch after port pre-processing and cover the intermediate layer of solder on the splicing surface; S4. Perform vacuum brazing, and perform aging heat treatment after brazing; During vacuum brazing, a counterweight is used to apply counterweight pressure to the spliced ​​single blades; The intermediate layer solder consists of Cr, Ni, W, B and Co.

2. The method for repairing a high-pressure turbine guide blade of an aircraft engine by welding according to claim 1, characterized in that: The intermediate layer solder is composed of Cr 21-23%, Ni 9-11%, W 7-9%, B 2-4%, and the rest is Co.

3. A method for repairing a high-pressure turbine guide blade of an aircraft engine by tailor-welding according to claim 1 or 2, characterized in that: The intermediate layer solder is an amorphous thin strip, and the thickness of the intermediate layer solder is 0.02-0.05 mm.

4. The method for repairing a high-pressure turbine guide blade of an aircraft engine by welding according to claim 1, characterized in that: In step S1, the multi-blade is cut by one of wire cutting, laser cutting or water jet cutting.

5. The method for repairing a high-pressure turbine guide blade of an aircraft engine by welding according to claim 1, characterized in that: In step S2, the cutting surface is processed by milling, and the parallelism of the cutting surface is less than 0.03 mm. After the milling process, the thickness of the single-leaf blade is reduced to 1 / 2 of the original thickness.

6. The method for repairing a high-pressure turbine guide blade of an aircraft engine by welding according to claim 1, characterized in that: After completing step S3, before proceeding to step S4, intermediate layer solder positioning welding is also provided, and the welding voltage is 200V.

7. A method for repairing a high-pressure turbine guide blade of an aircraft engine by tailor welding according to claim 1 or 6, characterized in that: In step S4, the brazing temperature of vacuum brazing is 1100-1300° C., and the brazing time is 20-30 hours.

8. A method for repairing a high-pressure turbine guide blade of an aircraft engine by tailor welding according to claim 1 or 7, characterized in that: In step S4, the aging temperature of the aging treatment is 800-900°C and the time is 30-50 hours.