Method for preparing high-purity GH4169 disc through laser strengthening

Abstract

The invention provides a method for preparing a high-purity GH4169 disc through laser strengthening. According to the method, laser strengthening is carried out on the GH4169 alloy disc with the surface covered with a conductive adhesive tape. Wherein the power density of laser strengthening is 106-109W / cm < 2 >, and the pulse duration is 20-50ns, so that the smooth proceeding of the alloy surface strengthening process is guaranteed, and the consistency of the process and the performance of parts is improved. Compared with a GH4169 alloy disc prepared through a traditional shot peening strengthening process, the fatigue performance of the GH4169 alloy disc subjected to laser strengthening is improved by 35%.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of GH4169 alloy disc surface laser strengthening for aero-engines and gas turbines, and particularly relates to a method for preparing high-purity GH4169 disc by laser strengthening. BACKGROUND

[0002] GH4169 alloy has excellent comprehensive performance such as high strength, oxidation resistance, good hot working and welding performance, and is a main material in the main material system of high-temperature alloy for aero-engines in China. The service condition of GH4169 disc parts in aero-engines is very harsh, the working temperature is high, and the stress is large, among which, low-cycle fatigue caused by cyclic stress is the most prominent, and is considered as an important factor affecting the service life of disc parts. Studies have shown that the service life of disc parts is mainly related to the surface integrity of the parts. If high surface roughness and surface tensile stress layer are generated in the machining process of the parts, the service life of the GH4169 disc parts will be adversely affected. At present, it is generally believed in the technical field that shot peening strengthening technology is an effective means to improve the surface integrity and fatigue performance of the parts. This method uses high-speed shot to impact the surface of the workpiece, so that the surface layer of the part produces elastic and plastic deformation, and presents work-hardened microstructure and residual compressive stress distribution, thereby improving the fatigue strength, fretting fatigue resistance and damage tolerance of the alloy, which plays an important role in preventing disc failure caused by fatigue, improving the service life of the disc and ensuring the reliable use of the disc. Studies have shown that the surface strengthening process can effectively improve the surface roughness of the high-temperature alloy parts, eliminate tool marks and significantly improve the fatigue life of the disc parts. At present, shot peening is the main process method applied in the surface integrity manufacturing technology of GH4169 disc parts of aero-engines.

[0003] In recent years, laser strengthening, as a new surface strengthening technology for metal parts, is similar to the conventional shot peening process, which enhances the fatigue resistance of metal parts by introducing beneficial residual compressive stress on the metal surface. However, the application of laser strengthening process to aero-engine parts is still in the exploratory research stage, and there is no relevant report on the preparation of GH4169 alloy disc. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a method for preparing high-purity GH4169 disc by laser strengthening. This method helps to improve the quality level of GH4169 alloy disc and meet the demand for high reliability and long service life of parts.

[0005] To achieve this purpose, the present application adopts the following technical solutions:

[0006] The present application provides a method for preparing GH4169 disc by laser strengthening, comprising the following steps:

[0007] The GH4169 alloy disc part with the conductive adhesive tape on the surface is subjected to laser strengthening, and the GH4169 alloy disc part is obtained.

[0008] The power density of the laser strengthening is 10 6 ~ 10 9 W / cm 2 , and the pulse duration is 20~50 ns.

[0009] Preferably, the power density of the laser strengthening is 10 6 ~ 10 8 W / cm 2 , and the pulse duration is 35~50 ns.

[0010] Preferably, during the laser strengthening, the laser impact head is radially moved to the rim part of the GH4169 alloy disc part, and after reaching the boundary of the rim part, the laser impact head is circumferentially moved by 3~4 mm, and then the above steps are repeated to complete the laser strengthening of the set region.

[0011] Preferably, the thickness of the conductive adhesive tape is 0.5~1.0 mm.

[0012] Preferably, the surface of the conductive adhesive tape has a water flow layer.

[0013] Preferably, the thickness of the water flow layer is 3~6 mm.

[0014] Preferably, the GH4169 alloy disc part is obtained by melting the GH4169 alloy and disc forging.

[0015] Preferably, the melting is performed by vacuum induction melting, protective atmosphere electroslag remelting and vacuum consumable remelting in sequence.

[0016] Preferably, the GH4169 alloy after the melting has a sulfur content lower than 5 ppm and an oxygen content lower than 50 ppm.

[0017] Preferably, the surface roughness of the GH4169 alloy disc part is not more than 1.6 μm.

[0018] Preferably, the surface hardness of the GH4169 alloy disc part after the laser strengthening is higher than 530 HBW, and the fatigue resistance is higher than 1.67*10 5 cycles.

[0019] Compared with the prior art, the present application has the following beneficial effects:

[0020] The present application combines the characteristics of the current laser strengthening process, and designs a method for surface strengthening of a GH4169 alloy disc part. The method is to perform laser strengthening on the GH4169 alloy disc part with the conductive adhesive tape on the surface. The power density of the laser strengthening is 106 ~ 10 9 W / cm 2 The pulse duration is 20-50 ns, which ensures smooth progress of the alloy surface strengthening process and improves consistency of the process and the performance of the parts. Compared with the GH4169 alloy disc parts prepared by the traditional shot peening strengthening process, the surface hardness of the GH4169 alloy disc parts after laser strengthening can be increased by 20%, and the fatigue performance can be increased by 35%. DETAILED DESCRIPTION

[0021] The technical solutions of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0022] In view of the problems of low surface hardness and short fatigue life of high-purity GH4169 alloy disc parts used in the fields of aerospace and gas turbines, the present application provides a method for preparing high-purity GH4169 disc parts (also referred to as GH4169 alloy turbine disc parts) by laser strengthening, comprising the following steps:

[0023] The GH4169 alloy disc part with conductive adhesive tape on the surface is subjected to laser strengthening, and the GH4169 alloy disc part is obtained.

[0024] According to the present application, a GH4169 alloy disc part is first provided.

[0025] In the present application, the GH4169 alloy is first subjected to pure smelting and disc forging to obtain a GH4169 alloy disc part.

[0026] In some embodiments of the present application, vacuum induction melting + protective atmosphere electroslag remelting + vacuum consumable remelting process is preferably used for smelting to prepare high-purity GH4169 alloy bars with chemical compositions meeting the standard requirements. In the smelted GH4169 alloy, the content of harmful element sulfur (S) is required to be lower than 5 ppm, and the content of gaseous element oxygen (O) is required to be lower than 50 ppm.

[0027] In some embodiments of the present application, hydraulic press forging is preferably used to prepare GH4169 alloy disc forgings with mechanical properties, high and low magnification structures meeting the standard requirements.

[0028] After the above smelting and forging are completed, the GH4169 alloy disc forgings are preferably subjected to processing.

[0029] In some embodiments of the present application, the finished GH4169 alloy disc forging is preferably subjected to rough machining, semi-finishing machining and finishing machining to prepare a turbine disc part, and the surface roughness of the disc part is not more than 1.6 μm. After rough machining of the disc part, water immersion ultrasonic nondestructive testing is performed, and the sensitivity reaches Φ

[0030] 0.4 mm, and no metallurgical defects are required.

[0031] Then, laser strengthening is performed according to the present application.

[0032] In some embodiments of the present application, the area requiring laser strengthening is marked in advance on the rim portion of the GH4169 alloy disc part, and a layer of conductive cloth adhesive tape is uniformly pasted on the area requiring laser strengthening, and the thickness of the adhesive tape is about 0.5-1.0 mm, such as 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm or 1.0 mm; the conductive adhesive tape serves as an energy absorption layer for laser strengthening.

[0033] In some preferred embodiments of the present application, the GH4169 alloy disc part with the conductive adhesive tape pasted thereon is placed under the laser head of the laser shock peening device. The surface of the conductive adhesive tape is kept as a flowing water layer with a thickness of about 3-6 mm, such as 3 mm, 4 mm, 5 mm or 6 mm, as a constraint layer, and the flowing water layer functions to carry away the heat generated during the laser strengthening of the surface of the disc part, so as to avoid overheating or overburning of the disc part and cause metallurgical defects.

[0034] Then, the laser strengthening device is started according to the present application, and the power density setting parameter of the laser device is 10 6 ~10 9 W / cm 2 , such as 10 6 W / cm 2 , 10 7 W / cm 2 , 10 8 W / cm 2 , 10 6 W / cm 2 , etc., preferably 10 6 ~10 8 W / cm 2 ; the pulse duration is 20-50 ns, such as 20 ns, 25 ns, 30 ns, 35 ns, 40 ns, 45 ns or 50 ns, etc., preferably 35-50 ns, and within the preferred range, the surface strengthening of all the areas requiring strengthening can be completed.

[0035] During laser strengthening, the laser impact head moves radially along the rim of the GH4169 alloy wheel. Upon reaching the boundary, it moves circumferentially, a distance of 3-4 mm. This strengthening operation (radial-circumferential movement) is then repeated to better improve the material's fatigue properties. This process is repeated until all areas of the disk surface requiring strengthening are laser-strengthened. Measurements show that the amplitude range of the laser-strengthened shock wave on the turbine disk surface is 10. 3 ~10 4 Pa causes minute plastic deformation on the rim surface, resulting in a dislocation entanglement structure in the microstructure. This structure is particularly helpful in improving the surface hardness and fatigue performance of GH4169 alloy discs.

[0036] Tests showed that the GH4169 alloy discs prepared according to the above method had a surface hardness of over 530 HBW and a fatigue resistance of 1.67 × 10⁻⁶. 5 More than one cycle. Compared with GH4169 alloy discs prepared by traditional shot peening, the surface hardness of laser-strengthened GH4169 alloy discs is increased by 20%, and the fatigue performance is improved by 35%.

[0037] Finally, after the laser strengthening of the GH4169 alloy disc surface is completed, the black conductive tape is removed, and the residual adhesive on the surface is wiped clean before it can be placed in the product warehouse for use.

[0038] In summary, the present invention provides a more specific implementation scheme, which is as follows:

[0039] (1) Pure smelting of GH4169 alloy. High-purity GH4169 alloy bars with chemical composition meeting the standard requirements are prepared by vacuum induction melting + protective atmosphere electroslag remelting + vacuum consumable remelting process. Among them, the chemical composition of the GH4169 alloy after smelting is required to have a sulfur (S) content of less than 5 ppm and an oxygen (O) content of less than 50 ppm.

[0040] (2) Disc forging. GH4169 alloy disc forgings with mechanical properties and microstructure meeting standard requirements at both high and low magnification were produced by hydraulic forging.

[0041] (3) Machining and Preparing Turbine Disk Parts. The forged GH4169 alloy disk forgings are rough-machined, semi-finished, and finished to prepare the disk parts. The surface roughness of the disk parts does not exceed 1.6μm. Among them, after rough machining, the disk parts are subjected to water immersion ultrasonic non-destructive testing with a sensitivity reaching 0.4mm for flat-bottomed holes, and are required to be free of metallurgical defects;

[0042] (4) Mark the reinforcement area. Mark the area requiring laser reinforcement on the rim of the GH4169 alloy disc;

[0043] (5) Part surface treatment. The area of the GH4169 alloy disc part that needs to be laser strengthened is uniformly pasted with a layer of conductive cloth tape, and the thickness of the tape is about 0.5-1.0 mm;

[0044] (6) Process preparation. The GH4169 alloy disc part pasted with the conductive tape is placed under the laser head of the laser shock strengthening equipment, and a layer of flowing water layer with a thickness of about 3-6 mm is kept on the surface of the conductive tape as a constraint layer;

[0045] (7) Laser strengthening. The laser strengthening equipment is started, and the power density of the laser equipment is set to 10 6 ~10 9 W / cm 2 , and the pulse duration is 20-50 ns. The laser impact head is moved radially along the GH4169 alloy rim part, and when the boundary is reached, it is moved circumferentially. The moving distance is 3-4 mm, and then the above strengthening operation is repeated;

[0046] (8) Disc part inspection. After the surface laser strengthening of the GH4169 alloy disc part is completed, the black conductive tape is removed, the remaining adhesive on the surface is scrubbed clean, and the disc part is placed in the product warehouse for standby.

[0047] The above method provided by the application is simple and convenient, easy to implement, and can significantly improve the surface strength of the GH4169 alloy disc part, improve the low-cycle fatigue performance, prolong the service life of the disc part, meet the use requirements of the aero-engine and the ground gas turbine, and has obvious innovation, practicality and broad application prospect

[0048] In order to further illustrate the application, the following examples are used for detailed description. The experimental raw materials used in the following examples of the application are all general commercially available products.

[0049] Example 1

[0050] (1) GH4169 alloy pure smelting: a high-purity GH4169 alloy bar with chemical composition meeting the standard requirements is prepared by vacuum induction melting + protective atmosphere electroslag + vacuum consumable remelting process, wherein the harmful element sulfur (S) content in the smelted GH4169 alloy chemical composition is 2 ppm, and the gas element oxygen (O) content is 15 ppm;

[0051] (2) Disc forging: a GH4169 alloy disc forging part with required mechanical properties, high and low magnification structures is prepared by hydraulic machine forging;

[0052] (3) Machining to prepare turbine disk parts: the forged GH4169 alloy disk forgings are subjected to rough machining, semi-finishing machining and finishing machining to prepare turbine disk parts, and the surface roughness of the disk parts reaches 1.6 μm. After rough machining of the disk parts, water immersion ultrasonic nondestructive testing is performed, and the sensitivity reaches Φ0.4 mm flat bottom hole, and no metallurgical defects are required;

[0053] (4) Marking the strengthening area: the area to be laser strengthened is marked on the rim portion of the GH4169 alloy disk;

[0054] (5) Part surface treatment: the area to be laser strengthened on the rim portion of the GH4169 alloy disk is uniformly pasted with a layer of conductive cloth adhesive tape (the conductive cloth adhesive tape structure includes a conductive layer (base material), a conductive filler and an adhesive system. The conductive layer is conductive cloth, the conductive filler is carbon black, and the adhesive is polyurethane / epoxy resin), and the thickness of the adhesive tape is about 0.5 mm. The adhesive tape serves as an energy absorption layer for laser strengthening;

[0055] (6) Process preparation: the GH4169 alloy disk with the pasted conductive adhesive tape is placed under the laser head of the laser shock strengthening equipment, and a flowing water layer with a thickness of about 3 mm is maintained on the surface of the conductive adhesive tape as a restraining layer. The flowing water layer functions to carry away the heat generated during the laser strengthening process of the disk surface, thereby avoiding overheating or overburning of the disk and causing metallurgical defects;

[0056] (7) Laser strengthening: the laser strengthening equipment is started, and the power density of the laser equipment is set to 10 6 W / cm 2 , and the pulse duration is 20 ns. The laser impact head moves radially along the rim portion of the GH4169 alloy, and when it reaches the boundary, it moves circumferentially. The circumferential movement distance is 3 mm, and then the above strengthening operation is repeated. After completing the strengthening of all the required areas, the operation is ended. It is measured that the amplitude of the laser shock wave generated on the surface of the turbine disk part ranges from 10 3 Pa. After the laser strengthening of the surface of the GH4169 alloy disk is completed, the black conductive adhesive tape is removed, the remaining adhesive on the surface is scrubbed clean, and the disk is placed in the product warehouse for standby.

[0057] Example 2

[0058] (1) Pure melting of GH4169 alloy: a high-purity GH4169 alloy rod with chemical composition meeting the standard requirements is prepared by vacuum induction melting + protective atmosphere electroslag + vacuum consumable remelting process, wherein the content of harmful element sulfur (S) in the chemical composition of the melted GH4169 alloy is 2 ppm, and the content of gaseous element oxygen (O) is 20 ppm;

[0059] (2) Disk forging: using hydraulic machine to forge GH4169 alloy disk forgings with mechanical properties, high and low magnification structures meeting the standard requirements;

[0060] (3) Machining turbine disk parts: the forged GH4169 alloy disk forgings are machined to prepare turbine disk parts through rough machining, semi-finishing and finishing, and the surface roughness of the disk parts reaches 1.6 μm. After the rough machining of the disk parts, water immersion ultrasonic nondestructive testing is performed, and the sensitivity reaches Φ0.4 mm of flat bottom hole, and no metallurgical defects are required;

[0061] (4) Calibration of the strengthening area: the area needing laser strengthening is marked on the rim of the GH4169 alloy disk;

[0062] (5) Part surface treatment: the area needing laser strengthening on the rim of the GH4169 alloy disk is uniformly pasted with a layer of conductive cloth adhesive tape, and the thickness of the adhesive tape is about 0.8 mm. The adhesive tape serves as an energy absorption layer for laser strengthening;

[0063] (6) Process preparation: the GH4169 alloy disk pasted with the conductive adhesive tape is placed under the laser head of the laser shock strengthening equipment, wherein a flowing water layer with a thickness of about 5 mm is maintained on the surface of the conductive adhesive tape as a constraint layer. The flowing water layer functions to take away the heat generated during the laser strengthening of the disk surface, so as to avoid overheating or overburning of the disk, thereby causing metallurgical defects;

[0064] (7) Laser strengthening: the laser strengthening equipment is started, and the power density of the laser equipment is set to 10 8 W / cm 2 , and the pulse duration is 50 ns. The laser impact head moves radially along the rim of the GH4169 alloy, and when the boundary is reached, the circumferential movement is performed. The moving distance is 4 mm, and then the above strengthening operation is repeated. After the laser strengthening of the surface of the GH4169 alloy disk is completed, the black conductive adhesive tape is removed, the residual adhesive on the surface is cleaned, and the disk is placed in the product warehouse for standby.

[0065] The above description of the disclosed embodiments enables those skilled in the art to carry out or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing high-purity GH4169 disc by laser strengthening, characterized in that, The method comprises the following steps: A GH4169 alloy disc part with a conductive adhesive tape on the surface is subjected to laser strengthening, and the GH4169 alloy disc part is obtained; The power density of the laser strengthening is 10 6 ~ 10 9 W / cm 2 , and the pulse duration is 20~50 ns.

2. The method of claim 1, wherein, The power density of the laser strengthening is 10 6 ~ 10 8 W / cm 2 , and the pulse duration is 35~50 ns.

3. The method according to claim 1 or 2, characterized in that, In the process of laser strengthening, a laser impact head moves radially to the flange part of the GH4169 alloy disc part, and then moves circumferentially after reaching the boundary of the flange part, and the moving distance is 3-4 mm, and then the above steps are repeated to complete laser strengthening of the set region.

4. The method according to any one of claims 1 to 3, characterized in that, The thickness of the conductive adhesive tape is 0.5-1.0 mm.

5. The method according to any one of claims 1 to 4, characterized in that, The surface of the conductive adhesive tape has a water flow layer.

6. The method of claim 5, wherein, The thickness of the water flow layer is 3-6 mm.

7. The method according to any one of claims 1 to 6, characterized in that, The GH4169 alloy disc part is obtained by melting GH4169 alloy, disc forging, etc.

8. The method of claim 7, wherein, The melting is performed by vacuum induction melting, protective atmosphere electroslag remelting and vacuum consumable remelting in sequence. The sulfur content of the GH4169 alloy after melting is lower than 5 ppm, and the oxygen content is lower than 50 ppm.

9. The method according to any one of claims 1 to 8, characterized in that, The surface roughness of the GH4169 alloy disc part is not more than 1.6 μm.

10. The method according to any one of claims 1 to 9, characterized in that, The surface hardness of the laser-strengthened GH4169 alloy disc part is above 530 HBW, and the fatigue resistance is above 1.67 x 10 5 cycles.