Method for rapid diffusion bonding of high-temperature titanium alloy through microwave sintering
Through microwave sintering technology and infrared temperature measurement monitoring in vacuum environment, the rapid and reliable diffusion connection of high-temperature titanium alloys is achieved, solving the problems of slow temperature rise and coarse grains in traditional methods, and significantly improving welding efficiency and yield. High quality welded joints were obtained.
Patent Information
- Application Number
- CN202411155691.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-22
- Publication Date
- 2024-12-13
AI Technical Summary
Traditional high-temperature titanium alloy diffusion connection technology has problems such as slow heating speed, low processing efficiency, uneven temperature distribution and unstable diffusion quality, which is difficult to meet the demand for fast and reliable connections in the aerospace field.
Using microwave sintering technology, rapid diffusion connection is achieved through microwave heating, and the coupling effect between microwave and material is used to achieve efficient heating and inhibit grain tissue growth, obtain ultra-fine grain structure, and combine vacuum environment and infrared temperature measurement system for real-time temperature Monitor to ensure welding uniformity and yield.
The rapid and reliable diffusion connection of high-temperature titanium alloys is achieved, which reduces the exposure time of the material at high temperatures, significantly improves the material microstructure, improves welding efficiency and yield, and solves the slow temperature rise rate and coarse grains in traditional methods. The problem is that high quality welded joints are obtained.
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Figure CN119115172A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of titanium alloy welding, and in particular to a method for rapidly diffusing and connecting high-temperature titanium alloys by microwave sintering. Background Art
[0002] High-temperature titanium alloys can still maintain high mechanical properties, creep resistance and oxidation resistance under high temperature environment. They are often used to produce compressor parts and blades near the combustion chamber of aircraft engines, and they occupy an important position in the field of aerospace. Diffusion bonding technology refers to a reliable connection technology in which atoms diffuse on the connection surface of the same or different metals and non-metallic materials under high temperature, high pressure, vacuum or protective gas environment. Diffusion bonding technology is often used for the connection of titanium alloys. Compared with traditional welding methods, diffusion bonding technology effectively avoids product quality defects caused by metal melting. With the development of lightweight in the field of aerospace, titanium alloy diffusion bonding technology has been fully developed. Traditional high-temperature titanium alloy diffusion bonding technology is often achieved by vacuum diffusion bonding and other methods, but there are problems such as slow heating speed, high required diffusion temperature, and long residence time of materials under high temperature conditions. Therefore, it is urgent to provide a method for rapid diffusion welding of high-temperature titanium alloys to solve the problems of long diffusion time, low processing efficiency, rapid heating but uneven temperature distribution, and unstable diffusion quality in traditional vacuum hot pressing diffusion welding. Summary of the invention
[0003] The object of the present invention is to provide a method which can realize reliable and rapid diffusion connection of high-temperature titanium alloy by utilizing the advantages of microwave sintering with high heating efficiency and automatic heating.
[0004] The present invention is achieved through the following technical solution: a method for rapidly diffusing and connecting high-temperature titanium alloys by microwave sintering, comprising the following steps: (1) Pre-treating the surfaces of high-temperature titanium alloy to be joined; (2) Completely overlap two pre-treated high-temperature titanium alloy specimens to form a test specimen; (3) Place the sample in a microwave sintering furnace and apply a pressure of 0.5 MPa to 1.5 MPa on the sample; (4) Using a microwave sintering furnace, under vacuum conditions, the sample is heated to a connection temperature of 970 °C by real-time monitoring of the sample temperature; (5) The high-temperature titanium alloy joint is kept at a connection temperature of 970 °C for 0.5 h to 1.5 h. After the connection temperature is maintained at 970 °C, the high-temperature titanium alloy joint is cooled to obtain a high-temperature titanium alloy diffusion connection joint.
[0005] The working principle of this technical solution is that microwave sintering uses microwave heating to sinter materials, which is different from traditional heating methods. The absorption of microwaves by materials is achieved by coupling with microwave electric fields or magnetic fields to convert microwave energy into thermal energy. Traditional heating relies on the heating body to transfer heat energy to the heated object through convection, conduction or radiation to make it reach a certain temperature. The heat is transferred from the outside to the inside. The traditional heating method has a long sintering time and high energy consumption. Microwave sintering has the characteristics of fast heating speed, high energy utilization rate, fast heating efficiency, safety, hygiene and pollution-free, and can improve the uniformity and yield of products. For large parts, when vacuum hot pressing and other methods are used for heating, the traditional heating method is not enough to make large parts heat evenly, affecting their performance, while microwave sintering uses a heating method that generates heat by coupling fine structures to make large parts heat evenly. In addition, compared with conventional sintering, the rapid heating advantage of microwave sintering can effectively inhibit the growth of grain structure, obtain ultrafine grain structure materials, and significantly improve the microstructure of materials. Therefore, the present invention uses a microwave sintering method to perform rapid diffusion welding on high-temperature titanium alloys to avoid problems and shortcomings such as slow heating rate and low processing efficiency during the diffusion process, and coarse grains caused by the plate staying at high temperature for too long. Reliable and rapid diffusion connection of high-temperature titanium alloys is achieved with higher heating efficiency (heating rate of 100°C / min) and automatic heating.
[0006] In order to better implement the method of the present invention, further, in the step (1), the process of pre-treating the surfaces of the high-temperature titanium alloy to be connected is to perform mechanical processing and polishing on the surfaces of the high-temperature titanium alloy to be connected, then ultrasonically clean them with alcohol, and finally dry them.
[0007] In order to better implement the method of the present invention, further, in the step (3), pressure is applied to the top of the sample by placing a heavy object above the sample, and a material that does not absorb microwaves is used to separate the sample and the heavy object.
[0008] In order to better implement the method of the present invention, further, the placed heavy object is SiC.
[0009] In order to better implement the method of the present invention, further, the material separating the sample and the weight is Al2O3 brick.
[0010] In order to better implement the method of the present invention, further, in the step (4), the vacuum condition is a vacuum degree of 10 -3 ~10 -4 Pa high vacuum environment.
[0011] In order to better implement the method of the present invention, further, the method of real-time detection of the sample temperature in step (4) is to use an infrared temperature measurement system, aim the infrared temperature measurement system at the sample, and obtain the real-time temperature of the sample in a non-contact manner.
[0012] In order to better implement the method of the present invention, further, the temperature measurement range of the infrared temperature measurement system is 300~1800℃, and the system accuracy reading is ±0.1%.
[0013] To better implement the method of the present invention, further, in the step (4), the heating rate of the heated sample is 100 °C / min.
[0014] In order to better implement the method of the present invention, further, in the step (5), the high temperature titanium alloy joint is placed in a vacuum degree of 10 -3 ~10 -4 Pa high vacuum environment.
[0015] Compared with the prior art, the present invention has the following advantages and beneficial effects: (1) The present invention utilizes a microwave sintering furnace to quickly obtain high-quality high-temperature titanium alloy diffusion bonding joints with a higher heating efficiency (heating rate of 100 ℃ / min). Since microwave sintering has a fast heating rate and a short heating time (less than 10 minutes), it reduces the exposure time of the high-temperature titanium alloy base material to high temperatures. Long-term exposure of the base material to high temperatures will promote the continuous growth of grains and increase the grain size of the base material, thereby affecting the structure and mechanical properties of the base material. At the same time, microwave sintering utilizes the special waveband of microwaves to couple with the basic fine structure of the material to generate heat, which has the advantages of inhibiting the growth of grain structure, facilitating the acquisition of ultrafine grain structure materials, and significantly improving the microstructure of the material; (2) The present invention uses an infrared temperature measurement system to directly measure the temperature of the sample in the microwave sintering furnace, and obtains the real-time temperature of the sample. Compared with the temperature measurement in the vacuum diffusion furnace using a thermocouple, the real-time temperature of the sample is more accurate; (3) The present invention can significantly improve welding efficiency while obtaining high-quality welded joints, ensure the uniformity and yield of the diffusion process, and provide a new method for reliable and rapid diffusion welding of high-temperature titanium alloys; (4) The present invention provides a welding method for rapidly diffusion-bonding high-temperature titanium alloys by microwave sintering. The method can achieve a heating rate of up to 100 °C / min when achieving diffusion bonding of high-temperature titanium alloys. The method has high processing efficiency and solves the problems of slow heating rate and long heating time of conventional vacuum hot pressing furnaces, and deterioration of the structure of high-temperature titanium alloys caused by long exposure time to high temperatures. The high-temperature titanium alloy diffusion joint obtained by the method has the advantages of stable diffusion quality, fine grain structure of the joint, and high yield rate, and is suitable for wide promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments with reference to the following drawings: Figure 1 The microstructure diagram of the Ti60 / Ti60 diffusion bonding interface in the present invention obtained by scanning electron microscopy; Figure 2 It is the line distribution diagram of the main elements in the interface area of the Ti60 / Ti60 diffusion bonding joint in the present invention; Figure 3 It is an X-ray flaw detection image of the Ti60 / Ti60 titanium alloy diffusion bonded joint in the present invention; Figure 4 is a backscattered electron diffraction pattern of the Ti60 / Ti60 diffusion joint interface region obtained by microwave sintering in the present invention; Figure 5 This is a backscattered electron diffraction pattern of the Ti60 / Ti60 diffusion joint interface region obtained by vacuum hot pressing in the present invention. DETAILED DESCRIPTION
[0017] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.
[0018] In order to make the purpose, process conditions and advantages of the present invention more clearly understood, the present invention is further described in detail in conjunction with the following embodiments, but the embodiments of the present invention are not limited thereto. Without departing from the above-mentioned technical ideas of the present invention, various substitutions and changes are made according to the common technical knowledge and customary means in the field, which should all be included in the scope of the present invention. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.
[0019] The high-temperature titanium alloy involved in the embodiment of the present invention is Ti60 provided by Baoji Titanium Co., Ltd. Ti60 titanium alloy is a near-α-type high-temperature titanium alloy of Ti-Al-Sn-Zr-Mo-Nb-Ta-Si series multi-component composite strengthening. The alloy uses high alloying, micro-alloying and composite strengthening methods. On the basis of Ti-Al-Sn-Zr, a certain amount of Ta, Nb and Mo, three isomorphous high-melting-point stabilizing elements, are added at the same time. Through the proper matching and cooperation between these three elements and α-stabilizing elements such as Al, Sn and Zr, the alloy becomes a multi-component composite strengthening heat-resistant titanium alloy that combines fine grain strengthening, solid solution strengthening and second phase (α2 and silicide) dispersion strengthening. It has excellent comprehensive properties, which makes it have a good match of high thermal strength, oxidation resistance and satisfactory thermal stability at working temperature. The size of the Ti60 welding test piece involved in the embodiment of the present invention is 50 mm * 50 mm * 1 mm, of which the 50 mm * 50 mm size area is the area to be welded.
[0020] Embodiment 1: This embodiment provides a method for rapid diffusion bonding of high-temperature titanium alloys using microwave sintering, comprising the following steps: Step 1: Use sandpaper to polish the surface of the Ti60 test piece to ensure that the surface of the Ti60 test piece is flat and smooth. Use the same polishing process for the Ti60 test piece to ensure the uniformity of the sample surface quality; Step 2: Place the ground Ti60 test piece in alcohol for ultrasonic cleaning to ensure that there are no impurities or contamination at the welding point, and then dry and store it; Step 3: Completely overlap the two treated Ti60 titanium alloy test pieces to obtain a Ti60 / Ti60 sample; Step 4: Place the Ti60 / Ti60 sample in a microwave sintering furnace, and use high-pressure gas to blow away impurities in the furnace; apply a weight pressure of 1 MPa on the sample, the weight is SiC, and the sample and the weight are separated by a piece of Al2O3 brick, aim the infrared temperature measurement system at the Ti60 / Ti60 sample to obtain the real-time temperature of the Ti60 / Ti60 sample, and close the furnace door; during the microwave sintering process, both the sample and the weight SiC have the ability to absorb microwaves, and direct contact between the two is prone to mutual reaction and even bonding. Al2O3 bricks are ceramics that hardly absorb microwaves. In order to avoid direct contact between the sample and the weight SiC, a piece of Al2O3 brick that hardly absorbs microwaves is added between the sample and the weight SiC to isolate the sample and the weight SiC to prevent the sample and the weight SiC from reacting with each other under high temperature and high pressure environment; Step 5: Evacuate the furnace body. When the vacuum degree of the furnace body reaches 10 -3 ~10 -4After being placed under high vacuum conditions of 100°C / min, the sample is automatically heated according to the set program. The temperature is raised to 970°C at a rate of 100°C / min. During the heating process, the infrared temperature measurement system is aimed at the sample to monitor the real-time temperature of the sample in real time. The infrared temperature measurement system is placed between the inner wall of the microwave sintering furnace and the built-in insulation box of the microwave sintering furnace. The sample is placed in the insulation box. A through hole is opened on the insulation box. The infrared temperature measurement system can directly aim at the sample through the through hole on the insulation box to measure the real-time temperature of the sample. The temperature measurement range of the infrared temperature measurement system used is 300~1800°C, and the system accuracy reading is ±0.1%; Step 6: After keeping the temperature at 970 °C for 1 h, the sample was cooled to room temperature to obtain a Ti60 / Ti60 high-temperature titanium alloy diffusion bonded joint. During the whole process, the test piece was kept in a vacuum of 10 -3 ~10 -4 Pa high vacuum state.
[0021] Embodiment 2: Based on the above embodiment, this embodiment uses X-ray to detect the quality of the Ti60 / Ti60 titanium alloy diffusion joint obtained by diffusion welding. After the X-ray detection is completed, the Ti60 / Ti60 titanium alloy diffusion joint is cut using an electric spark wire cutting machine to prepare a metallographic sample. The metallographic sample is then ground and polished to remove the cutting marks on the surface, and then the sample is degreased with acetone, and the sample is placed in alcohol and placed in an ultrasonic cleaning machine for cleaning to remove impurities on the surface of the sample, and then dried. The organization and morphology of the weld of the Ti60 / Ti60 titanium alloy diffusion joint are observed and analyzed.
[0022] The results are as follows Figure 1 , Figure 2 , Figure 3 shown.
[0023] Figure 1 The microstructure of the Ti60 / Ti60 diffusion bonding interface was obtained by scanning electron microscopy. Figure 1 It can be seen that there are almost no unwelded holes in the weld.
[0024] Figure 2 The main element line distribution diagram of Ti60 / Ti60 diffusion bonded joint (interface area) is shown in Figure 2. Figure 2 It can be seen that the content of each element changes steadily from one piece of Ti60 titanium alloy to another, with little fluctuation at the weld interface.
[0025] Figure 3This is the X-ray flaw detection image of Ti60 / Ti60 titanium alloy diffusion bonded joint. Figure 3 It can be seen that almost no defects were found. In summary, it is feasible to use microwave sintering to quickly achieve diffusion bonding between Ti60 / Ti60 high-temperature titanium alloys.
[0026] Embodiment 3: In this embodiment, a backscattered electron diffraction test was performed on the metallographic sample of Ti60 / Ti60 diffusion bonded joint obtained by microwave sintering and the metallographic sample obtained by vacuum hot pressing under the same connection temperature and holding time conditions, and the difference in sample grains under the two preparation methods was compared and analyzed.
[0027] The results are as follows Figure 4 , Figure 5 shown.
[0028] Figure 4 This is the backscattered electron diffraction pattern of the Ti60 / Ti60 diffusion joint (interface area) obtained by microwave sintering. Figure 5 This is the backscattered electron diffraction pattern of the Ti60 / Ti60 diffusion joint (interface area) obtained by vacuum hot pressing. Figure 4 and Figure 5 It can be seen that the grains of Ti60 high-temperature titanium alloy sintered by microwave sintering are finer than those sintered by vacuum hot pressing, which indicates that the exposure time of the base material to high temperature is short and microwave heating has the advantage of achieving fine grain structure of Ti60 high-temperature titanium alloy diffusion bonding joints.
[0029] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.
Claims
1. A method for rapid diffusion bonding of high temperature titanium alloys using microwave sintering, characterized in that: The following steps are involved: (1) Pre-treating the surfaces of high-temperature titanium alloy to be joined; (2) Completely overlap two pre-treated high-temperature titanium alloy specimens to form a test specimen; (3) Place the sample in a microwave sintering furnace and apply a pressure of 0.5 MPa to 1.5 MPa on the sample; (4) Using a microwave sintering furnace, under vacuum conditions, the sample is heated to a connection temperature of 970 °C by real-time monitoring of the sample temperature; (5) The high-temperature titanium alloy joint is kept at a connection temperature of 970 °C for 0.5 h to 1.5 h. After the connection temperature is maintained at 970 °C, the high-temperature titanium alloy joint is cooled to obtain a high-temperature titanium alloy diffusion connection joint.
2. The method for rapid diffusion bonding of high temperature titanium alloys by microwave sintering according to claim 1, characterized in that: In the step (1), the process of pre-treating the surfaces of the high-temperature titanium alloy to be connected is to perform mechanical processing and grinding on the surfaces of the high-temperature titanium alloy to be connected, then ultrasonically clean them with alcohol, and finally dry them.
3. A method for rapid diffusion bonding of high temperature titanium alloys by microwave sintering according to claim 1 or 2, characterized in that: In the step (3), pressure is applied to the top of the sample by placing a heavy object on the sample, and a material that does not absorb microwaves is used to separate the sample and the heavy object.
4. The method for rapid diffusion bonding of high temperature titanium alloys by microwave sintering according to claim 3, characterized in that: The placed heavy object is SiC.
5. The method for rapid diffusion bonding of high temperature titanium alloys by microwave sintering according to claim 3, characterized in that: The material separating the sample and the weight is Al2O3 brick.
6. A method for rapid diffusion bonding of high temperature titanium alloys by microwave sintering according to claim 1 or 2, characterized in that: In the step (4), the vacuum condition is a vacuum degree of 10 -3 ~10 -4 Pa high vacuum environment.
7. A method for rapid diffusion bonding of high temperature titanium alloys by microwave sintering according to claim 1 or 2, characterized in that: The method of real-time detection of the sample temperature in step (4) is to use an infrared temperature measurement system, aim the infrared temperature measurement system at the sample, and obtain the real-time temperature of the sample in a non-contact manner.
8. The method for rapid diffusion bonding of high temperature titanium alloys by microwave sintering according to claim 7, characterized in that: The temperature measurement range of the infrared temperature measurement system is 300~1800℃, and the system accuracy reading is ±0.1%.
9. A method for rapid diffusion bonding of high temperature titanium alloys by microwave sintering according to claim 1 or 2, characterized in that: In the step (4), the heating rate of the heated sample is 100°C / min.
10. A method for rapid diffusion bonding of high temperature titanium alloys by microwave sintering according to claim 1 or 2, characterized in that: In the step (5), the high temperature titanium alloy joint is placed in a vacuum degree of 10 -3 ~10 -4 Pa high vacuum environment.