Titanium alloy T-shaped structure stirring welding tool and welding method

Abstract

The application provides a titanium alloy T-shaped structure stirring welding tool and a welding method, the titanium alloy T-shaped structure comprises mutually perpendicular wings and a web, a space between one side of the web and the wings is recorded as a first area, a space between the other side of the web and the wings is recorded as a second area, the welding tool comprises a base, an inclined support and a stop welding head, the base has a supporting slope, one side of the wings away from the web abuts against the supporting slope, the inclined support is arranged in the first area and abuts against the wings and the web, the stop welding head is arranged in the second area and abuts against the wings and the web, and is used for stirring friction welding of a first welding position or a second welding position between the wings and the web; the application has the advantages of simple structure and easy implementation, can rigidly fix the T-shaped structure and support the back of the T-shaped structure, can effectively improve welding precision, guarantees the post-welding size of the T-shaped structure, simultaneously solves the problem of poor accessibility of the fillet weld of the T-shaped structure, and is also helpful to improve welding efficiency.

Description

Technical Field

[0001] This invention relates to the field of metal material welding technology, and in particular to a titanium alloy T-shaped structure stir welding fixture and welding method. Specifically, it refers to a high-efficiency and precision stir friction welding manufacturing method and special fixture for large T-shaped structures of powder metallurgy titanium alloys and carbon nanostructure reinforced titanium alloys. Background Technology

[0002] Titanium alloys, as an excellent lightweight and high-strength structural material, have been a preferred material in key fields such as marine engineering, high-end chemical engineering, and biomedicine since the mid-20th century due to their high specific strength, excellent corrosion resistance, good high-temperature performance, and outstanding biocompatibility. In particular, the application of titanium alloys is continuously improving in the main load-bearing structures of aircraft, pressure hulls, and key components of offshore platforms where ultimate performance and weight reduction are pursued.

[0003] With the ever-increasing demands of modern industry on material performance, traditional smelting and forging of titanium alloys is gradually facing bottlenecks in certain limiting performance indicators (such as strength, wear resistance, and high-temperature stability). Furthermore, the fabrication of large-size, complex structural parts suffers from low yield and high cost. To overcome these limitations, materials scientists have developed two promising advanced titanium alloy fabrication technologies: powder metallurgy titanium alloys and carbon nanostructure-reinforced titanium alloys. The former can achieve homogenization of the material's microstructure, enabling net or near-net-shape forming of complex-shaped parts. By introducing reinforcing phases (such as ceramic particles and intermetallic compounds) into the powder, it can prepare particle-reinforced titanium-based composite materials that are difficult to obtain using traditional methods, thereby significantly improving the material's strength, hardness, wear resistance, and high-temperature performance. The latter, by introducing carbon nanotubes, graphene, and other carbon nanomaterials as reinforcements into the titanium matrix through specific dispersion and composite processes, achieves a qualitative leap in strength, stiffness, fatigue performance, and thermal stability.

[0004] However, "materials are the foundation, manufacturing is the key." These high-performance titanium alloys face significant challenges in fabricating T-shaped structures: traditional forging or machining methods are difficult to form, have low material utilization, and are costly. Welding processes are typically used to prepare titanium alloy T-shaped structures, but traditional fusion welding methods (such as TIG, MIG, and laser welding) have the following inherent drawbacks when welding such materials:

[0005] 1. Insufficient joint strength. The fusion welding process produces a cast structure and a large heat-affected zone, making it difficult for the joint strength (especially fatigue strength) to reach the same level as the powder metallurgy base material / nano-reinforced base material.

[0006] 2. Prone to welding defects. Titanium alloys are highly reactive and easily react with oxygen, nitrogen, hydrogen, etc. in the air during fusion welding, producing defects such as porosity and inclusions, which significantly reduce the reliability of the joint and its service life.

[0007] 3. Deformation control is difficult. The high heat input during fusion welding causes large welding stress and deformation. For large and precision T-shaped structures, the dimensional accuracy after welding is difficult to meet design requirements, requiring complex straightening treatment, which increases manufacturing costs and time.

[0008] 4. Challenges in weld leg treatment. Some T-shaped structure designs require reinforcement of the weld legs. Traditional methods require additional welding or assembly of reinforcing parts, which is complex and can easily introduce new stress concentration sources.

[0009] Friction stir welding (FSW), as a solid-state joining technology, offers advantages such as low welding temperature, minimal deformation, no smoke or dust, a fine-grained forged joint structure free from fusion welding defects like porosity, cracks, and lack of fusion, and excellent joint mechanical properties, providing a potential solution to the aforementioned problems. However, directly applying conventional FSW to fillet welds in T-shaped structures faces challenges such as poor accessibility, high requirements for back support, and complex tooling, especially for large components, making it difficult to achieve efficient and high-precision welding. Summary of the Invention

[0010] In view of this, the present invention aims to propose a stirring welding fixture and welding method for titanium alloy T-shaped structures, so as to solve the problems of complex fixture structure and low welding accuracy in the existing technology when welding powder metallurgy titanium alloy T-shaped structures and carbon nanostructure reinforced titanium alloy T-shaped structures.

[0011] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0012] A titanium alloy T-shaped structure stir welding fixture, wherein the titanium alloy T-shaped structure includes mutually perpendicular flanges and webs, the space between one side of the web and the flange is designated as a first region, and the space between the other side of the web and the flange is designated as a second region. The welding fixture includes a base, an inclined support, and a stop welding head. The base has a supporting inclined surface, the side of the flange away from the web abuts against the supporting inclined surface, the inclined support is disposed in the first region and abuts against the flange and the web, and the stop welding head is disposed in the second region and abuts against the flange and the web, for performing stir friction welding on the first welding position or the second welding position between the flange and the web.

[0013] Furthermore, both the base and the inclined support are triangular prisms with a right-angled triangular cross-section.

[0014] Furthermore, the welding fixture includes a first side clamping device and a second side clamping device. The first side clamping device is located on the side of the base away from the titanium alloy T-shaped structure and abuts against the base and the wing plate. The second side clamping device is located on the side of the inclined support away from the titanium alloy T-shaped structure and abuts against the inclined support, the wing plate, and the web plate.

[0015] Furthermore, the welding fixture includes a first pressure plate and a second pressure plate. The first pressure plate is connected to a first side clamping device. The top end of the wing plate is located between the first pressure plate and the first side clamping device and abuts against the first pressure plate and the first side clamping device. The second pressure plate is connected to a second side clamping device. The top end of the web plate is located between the second pressure plate and the second side clamping device and abuts against the second pressure plate and the second side clamping device.

[0016] Furthermore, the stop welding head includes a stationary shoulder and a stirring pin. The stirring pin is rotatable relative to the stationary shoulder for performing friction stir welding. The stop welding head abuts against the wing plate and the web plate through the stationary shoulder.

[0017] Furthermore, a reinforcing material is provided at the first or second welding position, wherein the reinforcing material is at least one of titanium alloy strip, titanium alloy foil, or titanium alloy powder, which is the same material as the titanium alloy T-shaped structure.

[0018] A method for stir welding a titanium alloy T-shaped structure, using a stir welding fixture for the titanium alloy T-shaped structure; the method includes: S1, cleaning the areas to be welded of the flange and web; S2, clamping and fixing the flange and web using the welding fixture, so that the flange and web are assembled into a T-shaped structure; S3, using a stop welding head to abut against the flange and web, and performing stir friction welding on the first or second welding position between the flange and web; S4, adjusting the area where the tilting support and the stop welding head are located, or rotating the entire T-shaped structure 180°, re-clamping and fixing the flange and web using the welding fixture, and performing stir friction welding on the unwelded one of the first and second welding positions using the stop welding head, to obtain the titanium alloy T-shaped structure.

[0019] Furthermore, the method includes: before performing friction stir welding, providing a reinforcing material at the first welding position or the second welding position, wherein the reinforcing material is at least one of titanium alloy strip, titanium alloy foil, or titanium alloy powder, which is the same material as the titanium alloy T-structure.

[0020] Furthermore, the method includes: cooling the titanium alloy T-structure obtained in step S4, then cleaning the weld, and performing visual inspection and non-destructive testing on the weld.

[0021] Compared with existing technologies, the titanium alloy T-shaped structure stirring welding fixture and welding method described in this invention have the following advantages:

[0022] This invention discloses a titanium alloy T-shaped structure stir welding fixture and welding method. The fixture uses a base, inclined support, and a stop-weld head to simultaneously stop and limit the titanium alloy T-shaped structure, and then performs friction welding via the stop-weld head. Besides the simple structure and ease of implementation of the welding fixture, firstly, it provides rigid fixation and back support for the T-shaped structure, effectively improving welding accuracy. Combined with the low heat input characteristics of friction stir welding, it reduces welding stress and deformation of the T-shaped structure, effectively improving the post-weld dimensional accuracy and reducing or even eliminating post-weld straightening procedures. Secondly, the inclined support of the welding fixture allows for the adjustment of difficult-to-weld oblique welding positions (i.e., fillet welds) between the flanges and webs into easily weldable areas. Regarding the welding orientation (such as vertical or horizontal), this invention solves the problem of poor accessibility of conventional friction stir welding equipment when applied to fillet welds of T-shaped structures. Thirdly, after welding one welding position, the application allows for adaptive adjustments to the area containing the tilting support and the stop welding head (correspondingly, the remaining accessories of the welding fixture, further described below), or, by keeping the welding fixture position unchanged and rotating the entire T-shaped structure 180°, welding can be performed on another welding position. This enables the welding fixture to be suitable for symmetrical welding of both sides of the T-shaped structure, ensuring the overall performance and stress balance of the T-shaped structure. It also eliminates the need to replace another set of welding fixtures, thus improving welding efficiency and reducing the cost of welding-related tools.

[0023] Furthermore, based on the aforementioned welding fixture, this application utilizes friction stir welding, a solid-state joining technology, which features low heat input and a narrow heat-affected zone, effectively avoiding common casting defects and porosity problems found in fusion welding. The joint microstructure of the titanium alloy T-structure is a fine-grained forging structure, exhibiting excellent mechanical properties, particularly fatigue performance significantly superior to fusion-welded joints, facilitating equal strength matching with high-performance titanium alloy base materials. Simultaneously, the friction stir welding process is smokeless, produces no arc light or spatter, requires no shielding gas (or operates under simple shielding), and provides a friendly working environment. It offers high welding speed and a high degree of automation, making it suitable for the efficient mass production of large T-structures. Attached Figure Description

[0024] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0025] Figure 1 This is a schematic diagram of the structure of a titanium alloy T-shaped stir welding fixture during the welding process according to an embodiment of the present invention;

[0026] Figure 2This is a schematic diagram of a titanium alloy T-shaped structure stirring welding fixture according to an embodiment of the present invention (the base and inclined support are hidden).

[0027] Figure 3 This is an X-ray film of the titanium alloy T-shaped structure at the T-shaped welded joint as described in the embodiment of the present invention.

[0028] Explanation of reference numerals in the attached figures:

[0029] 1. Base; 101. Supporting inclined surface; 2. Inclined support; 3. First side clamping device; 4. Second side clamping device; 5. Wing plate; 6. Web plate; 7. First pressure plate; 8. Second pressure plate; 9. Stop welding head; 10. Table surface; 11. First welding position; 12. Second welding position. Detailed Implementation

[0030] The inventive concepts of this application will be described below using terminology commonly used by those skilled in the art to communicate the essence of their work to others skilled in the art. However, these inventive concepts may be embodied in many different forms and should not be construed as limited to the embodiments described herein.

[0031] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0032] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0033] To address the problems of complex tooling and low welding accuracy in existing technologies for welding powder metallurgy titanium alloy T-structures and carbon nanostructure-reinforced titanium alloy T-structures, this embodiment proposes a stir welding fixture for titanium alloy T-structures, as shown in the attached figure. Figure 1-2 As shown, the titanium alloy T-shaped structure includes mutually perpendicular flanges 5 and webs 6. The space between one side of the web 6 and the flange 5 is designated as the first region, and the space between the other side of the web 6 and the flange 5 is designated as the second region. The welding fixture includes a base 1, an inclined support 2, and a stop welding head 9. The base 1 has a supporting inclined surface 101. The side of the flange 5 away from the web 6 abuts against the supporting inclined surface 101. The inclined support 2 is located in the first region and abuts against the flange 5 and the web 6. The stop welding head 9 is located in the second region and abuts against the flange 5 and the web 6. It is used to perform friction stir welding on the first welding position 11 or the second welding position 12 between the flange 5 and the web 6.

[0034] Among them, wing plate 5 and web plate 6 are conventional names for the various plates in T-shaped structures and I-shaped structures in the prior art. For ease of understanding, wing plate 5 is the flat plate (i.e., horizontal plate) in T-shaped structure, and web plate 6 is the vertical plate (i.e., vertical plate) in T-shaped structure.

[0035] This application uses a base 1, an inclined support 2, and a stop welding head 9 to simultaneously stop and limit the titanium alloy T-shaped structure, and performs friction welding through the stop welding head 9. Besides the simple structure and ease of implementation of the welding fixture, firstly, it forms a rigid fixation and back support for the T-shaped structure, effectively improving welding accuracy. Combined with the low heat input characteristics of friction stir welding, it reduces welding stress and deformation of the T-shaped structure, effectively improving the post-weld dimensional accuracy of the T-shaped structure and reducing or even eliminating post-weld straightening procedures. Secondly, through the inclined support form of the welding fixture, this application can adjust the difficult-to-weld oblique welding position (i.e., fillet weld) between the flange 5 and the web 6 to an easily weldable position (such as vertical or horizontal), solving the problems of conventional friction stir welding. The first aspect addresses the issue of poor accessibility of the welding equipment when applied to fillet welds of T-shaped structures. The second aspect is that after welding one welding position, the area containing the tilting support 2 and the stop welding head 9 (correspondingly, the remaining accessories of the welding fixture, further described below, are also adaptively adjusted). Alternatively, by keeping the welding fixture position unchanged and rotating the entire T-shaped structure 180°, welding can be performed on another welding position. This allows the welding fixture to be suitable for symmetrical welding of both sides of the T-shaped structure, ensuring the overall performance and stress balance of the T-shaped structure. It also eliminates the need to replace another set of welding fixtures, thus improving welding efficiency and reducing the cost of welding-related tools. Of course, the preferred approach is to keep the welding fixture position unchanged and rotate the entire T-shaped structure 180°.

[0036] It should be noted that, since this application is suitable for double-sided symmetrical welding of T-shaped structures, the first welding position 11 can be a welding position in the first region or a welding position in the second region, and the second welding position 12 can be a welding position in the second region or a welding position in the first region. This application does not impose any specific restrictions.

[0037] Furthermore, based on the aforementioned welding fixture, this application utilizes friction stir welding, a solid-state joining technology, which features low heat input and a narrow heat-affected zone, effectively avoiding common casting defects and porosity problems found in fusion welding. The joint microstructure of the titanium alloy T-structure is a fine-grained forging structure, exhibiting excellent mechanical properties, particularly fatigue performance significantly superior to fusion-welded joints, facilitating equal strength matching with high-performance titanium alloy base materials. Simultaneously, the friction stir welding process is smokeless, produces no arc light or spatter, requires no shielding gas (or operates under simple shielding), and provides a friendly working environment. It offers high welding speed and a high degree of automation, making it suitable for the efficient mass production of large T-structures.

[0038] Both the base 1 and the inclined support 2 are triangular prisms with right-angled triangular cross-sections, allowing the inclined support form of the welding fixture to be fully adapted to the T-shaped structure. This provides "full contact" back support for the T-shaped structure, effectively preventing deformation at the joint and allowing the fillet weld between the wing plate 5 and the web plate 6 to be directly adjusted to a vertical or horizontal position for easy welding. Preferably, the cross-sections of the base 1 and the inclined support 2 are both isosceles right-angled triangles; that is, the inclination angle of the supporting inclined surface 101 and the inclination angle of the inclined surface provided by the inclined support 2 are both 45°.

[0039] The welding fixture includes a first side clamping device 3 and a second side clamping device 4. The first side clamping device 3 is located on the side of the base 1 away from the titanium alloy T-shaped structure and abuts against the base 1 and the wing plate 5. The second side clamping device 4 is located on the side of the inclined support 2 away from the titanium alloy T-shaped structure and abuts against the inclined support 2, the wing plate 5, and the web plate 6. The two side clamping devices help to further improve the rigid fixing effect of the welding fixture on the T-shaped structure, at least in the horizontal direction, preventing displacement or deformation between the wing plate 5 and the web plate 6 under welding pressure. The first side clamping device 3 and the second side clamping device 4 can be fixedly connected to the table 10. Alternatively, the base 1 can also be fixedly connected to the table 10, which can be the table surface of the welding equipment or the ground.

[0040] It should be noted that the first side clamping device 3 and the second side clamping device 4 are not essential components. In certain specific situations, materials can be sourced locally, such as fixing the base 1 to the tabletop 10 and using a wall as the second side clamping device 4.

[0041] Furthermore, based on the first side clamping device 3 and the second side clamping device 4, the welding fixture includes a first pressure plate 7 and a second pressure plate 8. The first pressure plate 7 is connected to the first side clamping device 3, and the top end of the wing plate 5 is located between the first pressure plate 7 and the first side clamping device 3, abutting against both the first pressure plate 7 and the first side clamping device 3. The second pressure plate 8 is connected to the second side clamping device 4, and the top end of the web plate 6 is located between the second pressure plate 8 and the second side clamping device 4, abutting against both the second pressure plate 8 and the second side clamping device 4. By further adding two pressure plates, the rigid fixing effect of the welding fixture on the T-shaped structure can be further improved, at least in the vertical direction, preventing displacement or deformation between the wing plate 5 and the web plate 6 under welding pressure. The first pressure plate 7 and the first side clamping device 3 are detachably connected, and the second pressure plate 8 and the second side clamping device 4 are also detachably connected, for example, by fasteners, so that the position of related components can be adjusted after welding at one welding position.

[0042] Correspondingly, by combining the base 1, the inclined support 2, the two side clamping devices, the two pressure plates, and the stop welding head 9, a rigid fixation and back support for the entire T-shaped structure can be formed, which can effectively improve the welding accuracy and ensure the post-weld dimensions of the T-shaped structure.

[0043] The stop-weld head 9 includes a stationary shoulder and a stirring pin (not shown). The stirring pin is rotatable relative to the stationary shoulder for friction stir welding. The stop-weld head 9 abuts against the flange 5 and the web 6 via the stationary shoulder. Existing technologies can be used for the friction stir welding generated by the stirring pin, as well as related principles and equipment, and these will not be elaborated upon here. The focus of this application in describing the stop-weld head 9 is primarily on the structure of its abutment against the flange 5 and the web 6.

[0044] To simultaneously achieve structural connection and weld leg reinforcement during a single welding process at the welding position, a reinforcing material is provided at the first welding position 11 or the second welding position 12 before friction stir welding. The reinforcing material is at least one of the following: titanium alloy strip, titanium alloy foil, or titanium alloy powder, all made of the same material as the titanium alloy T-structure. This allows for simultaneous structural connection and weld leg reinforcement during friction stir welding of a single welding position, achieving metallurgical bonding between the reinforcing material and the base material. This avoids the need for subsequent additional welding or assembly of reinforcing components, simplifying the welding process and preventing the creation of new stress concentration sources.

[0045] Based on the aforementioned welding fixture, this application further proposes a stir welding method for titanium alloy T-shaped structures, comprising:

[0046] S1. Clean the areas to be welded on the wing plate 5 and web plate 6 to remove oil and oxide film;

[0047] S2. The wing plate 5 and the web plate 6 are clamped and fixed by the welding fixture, so that the wing plate 5 and the web plate 6 are assembled into a T-shaped structure, and the wing plate 5 and the web plate 6 are tightly fitted without gaps.

[0048] As for the assembly between the welding fixture and the flange 5 and the web 6, it can be set up and assembled according to the structural content introduced above. The method here will not repeat the structural content.

[0049] S3. The stop welding head 9 abuts against the wing plate 5 and the web plate 6, and performs stir friction welding on the first welding position 11 or the second welding position 12 between the wing plate 5 and the web plate 6.

[0050] Before friction stir welding, a reinforcing material is provided at the first welding position 11 or the second welding position 12. The reinforcing material is at least one of titanium alloy strip, titanium alloy foil, or titanium alloy powder, which is the same material as the titanium alloy T-shaped structure. Specifically, when the wing plate 5 and the web plate 6 are assembled into a T-shaped structure in step S2, the reinforcing material is provided at the first welding position 11 or the second welding position 12 to be welded.

[0051] Meanwhile, the specific process parameters of friction stir welding (such as stirring pin rotation speed, welding speed, etc.) can adopt the existing friction stir welding process, which will not be elaborated here. During the friction stir welding process, the frictional heat and plastic flow of the stirring pin cause the material in the weld area to plasticize and mix, and form a dense weld under the constraint of the stationary shoulder. At the same time, if a reinforcing material is placed at the welding position, the reinforcing material will be drawn into the plasticized zone, realizing the filling and strengthening of the weld leg shape.

[0052] S4. For the area where the tilting support 2 and the stop welding head 9 are located, or, the entire T-shaped structure is rotated 180°, and the wing plate 5 and the web plate 6 are clamped and fixed again by the welding fixture. The stop welding head 9 performs friction stir welding on one of the unwelded positions 11 and 12 to obtain the titanium alloy T-shaped structure.

[0053] It should be noted that in step S4, when the tilting support 2 and the stop welding head 9 are located, or when the T-shaped structure is rotated 180° as a whole, it is necessary to first disassemble some parts of the welding fixture (such as the first pressure plate 7 and the second pressure plate 8), adjust the position of the corresponding parts, and then re-clamp and fix the wing plate 5 and the web plate 6 through the welding fixture.

[0054] In addition, to ensure welding quality, the method includes: cooling the titanium alloy T-structure obtained in step S4, then cleaning the weld, and performing visual inspection and non-destructive testing on the weld. Specifically, after completing the entire welding operation in step S4, it is essential to first remove part of the welding fixture (such as the first pressure plate 7 and the second pressure plate 8) and take out the titanium alloy T-structure; allow the titanium alloy T-structure to cool naturally or under controlled cooling, clean the weld, and remove burrs and other imperfections; the visual inspection of the weld can be performed by the operator, and non-destructive testing can be conducted using conventional methods such as X-ray inspection and ultrasonic testing.

[0055] To verify the effectiveness of the present invention, the following embodiments are provided to further illustrate the present invention, but the scope of protection of the present invention is not limited to the following embodiments.

[0056] Example 1

[0057] The workpiece to be welded is a large ship titanium alloy profile with a T-shaped structure. The material is carbon nanotube reinforced powder metallurgy titanium alloy. The web plate 6 is 800mm high, the wing plate 5 is 400mm wide, and both are 12mm thick.

[0058] The cross-sections of the base 1 and the inclined support 2 are both isosceles right triangles to accommodate the 90° fillet weld of the T-shaped structure and to ensure that the fillet weld to be welded is vertically upward.

[0059] refer to Figure 1 Securely install the base 1 on the workbench of the welding machine and install the first side clamping device 3 and the second side clamping device 4; then clean the areas to be welded of the wing plate 5 and the web plate 6, and install the wing plate 5, the web plate 6 and the inclined support 2 so that the wing plate 5 and the web plate 6 cooperate to form a T-shaped structure, and continue to install the first pressure plate 7 and the second pressure plate 8 to achieve rigid fixation of the T-shaped structure.

[0060] After assembly, taking the first welding position 11 facing upwards as an example, a stop welding head 9 with a matching diameter is selected, the stirring needle speed is set to 800 rpm, and the welding speed is 150 mm / min. The welding equipment is started, the stop welding head 9 moves downwards, its stationary shoulder abuts and presses against the wing plate 5 and the web plate 6, the stirring needle is inserted into the root of the first welding position 11, and welding is performed at a uniform speed along the weld length direction to complete the welding of the first welding position 11.

[0061] Remove the first pressure plate 7 and the second pressure plate 8, rotate the T-shaped structure 180° using a crane, and then reinstall the first pressure plate 7 and the second pressure plate 8 to achieve rigid fixation of the T-shaped structure. At this time, the second welding position 12 faces upward, and the same welding parameters as the first welding position 11 are used to complete the welding of the second welding position 12.

[0062] After welding, remove the first pressure plate 7 and the second pressure plate 8. After natural cooling, remove the T-shaped structure, clean the welds, and perform X-ray and ultrasonic testing. The X-ray film is attached. Figure 3 As shown, the weld has no internal defects and is well formed. Key dimensions were measured, and the deformation was controlled within the design requirements (less than 1 mm / m).

[0063] Example 2

[0064] Similar to Example 1, the difference is that it is a titanium alloy T-shaped structure with weld reinforcement. That is, based on Example 1, the requirement for weld reinforcement is added.

[0065] Specifically, during the rigid assembly of the T-shaped structure, a titanium alloy foil strip with a width of 5mm and a thickness of 1mm, made of the same material as the titanium alloy T-shaped structure, is used as a reinforcing material and placed at the welding position to be welded.

[0066] During the welding process, the reinforcing material is pressed firmly against the root of the weld position, and the same welding operation as in Example 1 is performed. During welding, the stirring of the stirring needle and the plastic flow of the material fully entrain the pre-placed reinforcing material into the plasticized zone, achieving metallurgical bonding with the base material. The final weld not only achieves structural connection but also forms a smoothly transitioning reinforced zone at the weld foot, achieving simultaneous reinforcement of shape and performance.

[0067] Post-weld macroscopic metallographic examination of the reinforcing weld leg showed good fusion between the reinforcing material and the base material, with no interface defects. Tensile testing of the joint (conducted according to GB / T2651-2023) showed fracture at the base material, meeting the strength requirement.

[0068] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A titanium alloy T-shaped structure stir welding fixture, wherein the titanium alloy T-shaped structure includes mutually perpendicular flanges (5) and webs (6), wherein the space between one side of the web (6) and the flange (5) is designated as a first region, and the space between the other side of the web (6) and the flange (5) is designated as a second region, characterized in that, The welding fixture includes a base (1), an inclined support (2), and a stop welding head (9). The base (1) has a supporting inclined surface (101). The side of the wing plate (5) away from the web plate (6) abuts against the supporting inclined surface (101). The inclined support (2) is set in a first region and abuts against the wing plate (5) and the web plate (6). The stop welding head (9) is set in a second region and abuts against the wing plate (5) and the web plate (6). It is used to perform friction stir welding on the first welding position (11) or the second welding position (12) between the wing plate (5) and the web plate (6).

2. The titanium alloy T-shaped structure stir welding fixture according to claim 1, characterized in that, The base (1) and the inclined support (2) are both triangular prisms with a right-angled triangle cross-section.

3. The titanium alloy T-shaped structure stirring welding fixture according to claim 1, characterized in that, The welding fixture includes a first side clamping device (3) and a second side clamping device (4). The first side clamping device (3) is located on the side of the base (1) away from the titanium alloy T-shaped structure and abuts against the base (1) and the wing plate (5). The second side clamping device (4) is located on the side of the inclined support (2) away from the titanium alloy T-shaped structure and abuts against the inclined support (2), the wing plate (5), and the web plate (6).

4. The titanium alloy T-shaped structure stirring welding fixture according to claim 3, characterized in that, The welding fixture includes a first pressure plate (7) and a second pressure plate (8). The first pressure plate (7) is connected to a first side clamping device (3). The top of the wing plate (5) is located between the first pressure plate (7) and the first side clamping device (3) and abuts against the first pressure plate (7) and the first side clamping device (3). The second pressure plate (8) is connected to a second side clamping device (4). The top of the web plate (6) is located between the second pressure plate (8) and the second side clamping device (4) and abuts against the second pressure plate (8) and the second side clamping device (4).

5. The titanium alloy T-shaped structure stirring welding fixture according to claim 1, characterized in that, The stop welding head (9) includes a stationary shoulder and a stirring pin. The stirring pin can rotate relative to the stationary shoulder for friction stirring welding. The stop welding head (9) abuts against the wing plate (5) and the web plate (6) through the stationary shoulder.

6. The titanium alloy T-shaped structure stirring welding fixture according to claim 1, characterized in that, The first welding position (11) or the second welding position (12) is provided with a reinforcing material, which is at least one of titanium alloy strip, titanium alloy foil, and titanium alloy powder, which are the same material as the titanium alloy T-shaped structure.

7. A method for stirring welding a titanium alloy T-shaped structure, characterized in that, The method is used for a titanium alloy T-shaped structure stir welding fixture as described in any one of claims 1-6; the method includes: S1. Clean the areas to be welded on the wing plate (5) and the web plate (6); S2. The wing plate (5) and the web plate (6) are clamped and fixed by the welding fixture, so that the wing plate (5) and the web plate (6) are assembled into a T-shaped structure. S3. The stop welding head (9) abuts against the wing plate (5) and the web plate (6), and performs stir friction welding on the first welding position (11) or the second welding position (12) between the wing plate (5) and the web plate (6). S4. For the area where the tilting support (2) and the stop welding head (9) are located, or, rotate the T-shaped structure as a whole by 180°, and clamp and fix the wing plate (5) and the web plate (6) again through the welding fixture. The stop welding head (9) performs stir friction welding on one of the unwelded positions in the first welding position (11) and the second welding position (12) to obtain the titanium alloy T-shaped structure.

8. The method for stirring welding a titanium alloy T-shaped structure according to claim 7, characterized in that, The method includes: before performing friction stir welding, a reinforcing material is provided at the first welding position (11) or the second welding position (12), wherein the reinforcing material is at least one of titanium alloy strip, titanium alloy foil, and titanium alloy powder, which are the same material as the titanium alloy T-structure.

9. The method for stirring welding a titanium alloy T-shaped structure according to claim 7, characterized in that, The method includes: cooling the titanium alloy T-structure obtained in step S4, then cleaning the weld, and performing visual inspection and non-destructive testing on the weld.

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