Friction stir connection method

Abstract

The invention discloses a stirring friction connection method which comprises the following steps: arranging a base plate below a gap between a first component and a second component, and forming a filling space between the base plate and the gap; adding an intermediate material layer at the bottom of the filler space, wherein the intermediate material layer comprises a zinc material layer; the deposition material is rotated and rubbed with at least one of the first component, the second component and the base plate for thermal plasticization, so that the thermal plasticized part of the deposition material is filled in the filler space, and the intermediate material layer is subjected to eutectic liquefaction; and the shaft shoulder moves along the track of the filling space. According to the invention, caulking connection between materials with a large-gap structure can be realized, and heat conduction heat is generated by utilizing the temperature of a solid-phase composite technology during thermal plasticizing of a deposition material of an aluminum alloy to induce eutectic liquefaction reaction; the root defects such as interface matching and holes generated at the root when the solid-phase composite technology is used for caulking and connecting the materials of the large-gap structure can be avoided.

Description

Technical Field

[0001] This invention relates to the field of material joining technology, and in particular to a friction stir joining method. Background Technology

[0002] Solid-state composite technology is an emerging non-melting metal additive manufacturing technology. This technology uses a non-consumable, hollow, rotating welding fixture, through which raw materials (such as metal rods) are continuously fed into the hollow area of ​​the fixture via a feeding device. The feed material rotates at high speed with the welding fixture, and dynamic friction and extrusion occur when the two (feed material and substrate) come into contact. Simultaneously, the feed material is heated and plasticized. Under the shearing force of the welding fixture and the forging force of the feeding device, the plasticized feed material is extruded and filled into the gap between the welding fixture head and the material to be deposited, forming a deposition layer. As the welding fixture moves, the deposition layer accumulates layer by layer, eventually forming the desired geometry.

[0003] Solid-state composite technology, as a solid-state additive manufacturing method, controls the process temperature between 70% and 90% of the solidus temperature of the raw materials. For aluminum alloys, the peak temperature is approximately 450°C to 550°C. This temperature characteristic has the following drawbacks when used for welding homogeneous or dissimilar materials such as aluminum / aluminum, aluminum / titanium, and aluminum / steel:

[0004] 1. The oxide film on the material surface is difficult to remove effectively. The dense oxide film on the surface of materials such as aluminum and titanium has a high melting point (Al2O3 about 1800℃, TiO2 about 1843℃) and is extremely stable. Aluminum alloys in a plastic state cannot effectively break or reduce the oxide film, resulting in the inability to form a strong metallurgical bond between the deposited material and the material to be welded, and low interface strength.

[0005] 2. Differences in thermophysical properties lead to process mismatch. Materials such as titanium and steel differ significantly from aluminum in terms of melting point, coefficient of thermal expansion, and thermal conductivity. This not only makes it difficult to meet the requirements of both materials being welded in terms of welding heat input, but also results in significant residual thermal stress at the interface of dissimilar materials due to uneven shrinkage during cooling, which can easily lead to cracking.

[0006] 3. The above problems are further amplified when joining materials with large gaps. When the gap width (3mm or more) is large, the fluidity of the ductile aluminum alloy is insufficient, making it difficult to completely fill the gap and establish an effective interface connection. Therefore, defects such as voids and incomplete bonding are easily generated at the root of the gap and at the interface between the deposited material and the material to be welded, making it difficult to achieve a reliable connection. Summary of the Invention

[0007] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a friction stir joining method, which can avoid root defects such as splicing and voids at the root of the gap when the solid-state composite technology is used to process large gap material components, thus facilitating a reliable connection.

[0008] According to an embodiment of the present invention, a friction stir joining method is used to fill the gap between a first component and a second component using a friction stir deposition apparatus. The friction stir deposition apparatus includes a shoulder and a deposit material. The shoulder is provided with a feeding channel. The deposit material is made of aluminum alloy or magnesium alloy and is disposed within the feeding channel. The method includes: placing a pad below the gap between the first component and the second component to form a filler space between the pad and the gap; adding an intermediate material layer at the bottom of the filler space, the intermediate material layer including a zinc layer; rotating the deposit material and frictionally thermoplasticizing it with at least one of the first component, the second component, and the pad, so that the thermoplasticized portion of the deposit material fills the filler space, and causing the intermediate material layer to undergo eutectic liquefaction; and moving the shoulder along the trajectory of the filler space.

[0009] According to the friction stir joining method of the present invention, the friction stir deposition method can achieve gap filling connection between materials with large gap structures, as well as direct connection of the same or dissimilar materials. Furthermore, by utilizing the heat generated and conducted during the thermoplasticization of the aluminum alloy deposit using solid-state composite technology, a eutectic liquefaction reaction is induced. Taking advantage of the material's tendency to flow from pressure to low-pressure regions during solid-state composite processing, root defects such as interface contact and voids can be avoided at the root when filling gaps between materials with large gap structures using solid-state composite technology. This improves the high-quality connection between the first and second components under large gap conditions, enhancing connection reliability. Moreover, the overall process is simple, low-cost, and allows for one-time forming connection of the first and second components, resulting in high connection efficiency.

[0010] In some embodiments of the present invention, the intermediate material layer further includes a magnesium material layer.

[0011] In some embodiments of the present invention, the intermediate material layer further includes a copper layer.

[0012] In some embodiments of the present invention, the copper layer, the magnesium layer, and the zinc layer are stacked from top to bottom.

[0013] In some embodiments of the present invention, the intermediate material layer further includes an aluminum material layer, which is located at the bottom of the intermediate material layer.

[0014] In some embodiments of the present invention, the intermediate material layer further includes at least one of a magnesium material layer, a copper material layer, and an aluminum material layer.

[0015] In some embodiments of the present invention, the copper layer, the magnesium layer, the aluminum layer and the zinc layer are single metal layers or alloy layers.

[0016] In some embodiments of the present invention, when the copper layer, the magnesium layer, the aluminum layer and the zinc layer are alloy layers, the alloy layer includes silicon.

[0017] In some embodiments of the present invention, the thickness of the copper layer, the magnesium layer, the zinc layer and the aluminum layer is 0.05mm to 1mm.

[0018] In some embodiments of the present invention, the pad is made of aluminum, magnesium, titanium, iron, or copper metal, or an alloy of aluminum, magnesium, titanium, iron, and copper.

[0019] In some embodiments of the present invention, the first component is a metal component made of aluminum, magnesium, titanium, iron, or copper, or an alloy component made of aluminum, magnesium, titanium, iron, or copper, and the second component is a metal component made of aluminum, magnesium, titanium, iron, or copper, or an alloy component made of aluminum, magnesium, titanium, iron, or copper.

[0020] In some embodiments of the present invention, the method further includes preheating the pad, the first component, and the second component before the step of rotating the deposit and tribothermally thermoplasticizing it with at least one of the first component, the second component, and the pad.

[0021] In some embodiments of the present invention, the method further includes: after adding an intermediate material layer at the bottom of the filling space, the intermediate material layer comprising a zinc material layer, the method further includes: providing a movable pressure-following mechanism on the intermediate material layer to press the intermediate material layer into the filling space.

[0022] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0023] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 A diagram showing the connection between a first component and a second component in a stir-friction deposition apparatus provided in some embodiments of the present invention; Figure 2 This is a schematic diagram showing the corner region of the filler space after the intermediate material layer eutectic liquefaction is provided in some embodiments of the present invention; Figure 3 A flowchart illustrating a friction stir bonding method provided in some embodiments of the present invention; Figure 4 This is a metallographic image of the first and second components after they are connected in the related technology. Figure 5 Metallographic image of the first component and the second component after being connected by the friction stir bonding method provided in the embodiment of the present invention.

[0024] Figure label: 11. First component; 12. Second component; 101. Gap; 20. Stirred friction deposition apparatus; 201. Shaft shoulder; 2011. Feeding channel; 202. Deposited material; 30. Pad; 40. Intermediate material layer; 401. Zinc material layer; 402. Magnesium material layer; 403. Copper material layer; 404. Aluminum material layer. Detailed Implementation

[0025] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0026] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, features defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0027] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0028] Friction stir deposition (FSD) is an emerging and important solid-phase additive manufacturing technology. In FSD, a non-consumable, hollow, rotating jig is used, and a feedstock (such as a metal rod) is delivered via a feeding device. The jig and feedstock rotate synchronously at high speed. Upon contact with the substrate, dynamic contact friction and extrusion occur, causing the feedstock to rapidly heat up and plasticize. Under the shear force of the jig and the forging force of the feeding device, the plasticized feedstock is extruded and fills the gap between the jig head and the substrate, forming a deposition layer. As the jig head moves, the deposition layer accumulates layer by layer, eventually forming the desired geometry.

[0029] The following is for reference. Figures 1-3 This describes a friction stir bonding method according to an embodiment of the present invention.

[0030] According to an embodiment of the present invention, a friction stir bonding method is used to perform a filler bonding between a first component 11 and a second component 12 using a friction stir deposition apparatus 20. For example... Figure 1 As shown, the friction stir deposition apparatus 20 includes a shoulder 201 and a deposit 202. The shoulder 201 has a feeding channel 2011. The deposit 202 is made of aluminum alloy or magnesium alloy and is disposed within the feeding channel 2011. The shoulder 201 is at least part of the structure of the welding fixture described above. The deposit 202 is configured to rotate at high speed within the feeding channel 2011, and the deposit 202 can move axially relative to the shoulder 201 under axial pressure. The axial pressure on the deposit 202 can be a normal pressure along the axial direction or a frictional thrust along the side of the deposit 202. The deposit 202 mentioned herein can be, but is not limited to, rods, wires, powders, or granular materials.

[0031] Other components and operations of the agitation and friction deposition apparatus 20 of this invention are known to those skilled in the art and will not be described in detail here.

[0032] like Figures 1 to 3 As shown, the friction stir bonding method of this invention includes: Step 1: A pad 30 is placed below the gap 101 between the first component 11 and the second component 12, forming a filler space between the pad 30 and the gap 101. The first component 11 and the second component 12 can be, but are not limited to, flat plates, curved plates, or other similar materials. Optionally, the materials of the first component 11 and the second component 12 can be the same or different. The material of the pad 30 can be the same as or different from that of the first component 11 and the second component 12. The first component 11 and the second component 12 can also be the same as or different from the material of the deposit 202. For example, the first component 11 and the second component 12 can be made of aluminum alloy. When the materials of the first component 11 and / or the second component 12 are the same as those of the deposit 202, they can be the same grade of aluminum alloy or different grades of aluminum alloy.

[0033] Step 2: Add an intermediate material layer 40 to the bottom of the filling space. The intermediate material layer 40 includes a zinc material layer 401.

[0034] Step 3: Rotate the deposit 202 and rub it against at least one of the first component 11, the second component 12 and the pad 30 to thermoplasticize it, so that the thermoplasticized portion of the deposit 202 fills the filler space and causes the intermediate material layer 40 to undergo eutectic liquefaction.

[0035] Step 4: Move the shoulder 201 along the trajectory of the packing space.

[0036] In the above connection method, the deposit 202 can be thermoplasticized by friction with any of the first component 11, the second component 12, and the pad 30, and then filled into the gap 101 between the first component 11 and the second component 12. The thermoplasticized deposit 202 contacts the pad 30 downwards and fills the filler space in its current position under pressure. Then, the shoulder 201 carries the deposit 202 along the trajectory of the filler space, completing the filling of the filler space and finally achieving the connection between the first component 11 and the second component 12. Because the first component 11 and the second component 12 are connected by friction stirring deposition, the thermoplasticized filler can more fully metallurgically bond with the first component 11 and the second component 12, thereby achieving the connection of a wider gap 101. For example, the above method can achieve the filling connection of two components with a gap width of 3 mm or more.

[0037] When connecting the first component 11 and the second component 12 by stirring friction, the friction process between the deposit 202 and the first component 11, the second component 12 and the pad 30 can be analyzed in two cases: with an inlet plate and without an inlet plate.

[0038] When there is an inlet plate, if the width of the deposit 202 is less than the width of the gap 101, the deposit 202 first rubs against the inlet plate on the outside to achieve thermoplasticization, and then enters the gap 101. Subsequently, the deposit 202 mainly achieves thermoplasticization by stirring and rubbing against the pad 30 to generate heat. If the width of the deposit 202 is greater than the width of the gap 101, the deposit 202 first rubs against the inlet plate on the outside to achieve thermoplasticization, and then the deposit 202 achieves thermoplasticization by stirring and rubbing against the first component 11 and the second component 12 to generate heat. The thermoplasticized deposit flows into the gap 101 and will rub slightly against the pad 30, and diffuse between the pad 30 and the pad 30.

[0039] When no plate is introduced, if the width of the deposit 202 is less than the width of the gap 101, the deposit 202 enters the gap 101, and subsequently, the deposit 202 and the pad 30 are stirred and rubbed to generate heat to achieve thermoplasticization. If the width of the deposit 202 is greater than the width of the gap 101, the deposit 202 and the first component 11 and the second component 12 are stirred and rubbed to generate heat to achieve thermoplasticization. The thermoplasticized deposit flows into the gap 101 and will rub slightly against the pad 30, and diffuse between them.

[0040] It should be noted that the aforementioned introduction plate refers to the plate that undergoes stirring and frictional thermoplasticization with the deposit material 202. Its function is to thermoplasticize the deposit material 202 before it enters the gap 101, so as to ensure that the deposit material 202 can be fully thermoplasticized in the gap 101 and to ensure the quality of the filling.

[0041] During the process of friction stirring to connect the first component 11 and the second component 12, the thermoplasticized portion of the deposit 202 fills the filler space. Due to the insufficient fluidity of the plastic aluminum and the difference in the physical properties of the materials, the corner areas on both sides of the bottom of the filler space between the first component 11 and the second component 12 are prone to forming cavity areas, which in turn produce root defects such as joints and holes. This results in unreliable connection in the corner areas on both sides of the bottom of the filler space, thus affecting the overall connection reliability of the first component 11 and the second component 12.

[0042] In the friction stir joining method of the present invention, the deposit 202 is made of aluminum alloy or magnesium alloy. During the process of joining the first component 11 and the second component 12 by friction stir additive manufacturing, the temperature of the deposit 202 undergoing frictional thermoplasticization will enter the range of 340 degrees Celsius to 550 degrees Celsius. For ease of understanding, the following explanation will take aluminum alloy as an example. During the frictional thermoplasticization process of the deposit 202, when the temperature reaches 382 degrees Celsius, the aluminum alloy and zinc material layer 401 can undergo eutectic liquefaction to form a liquid phase. It can be understood that during the friction stir joining process, as the temperature gradually increases, the intermediate material layer 40 undergoes partial eutectic liquefaction. Since the liquid phase is more easily deformed than the plastic solid, a local low-pressure zone is formed in the liquefaction zone. At the same time, under the combined action of axial high pressure and radial rotational force, the upper deposit 202 has a tendency to flow to the lower pressure zone, that is, to fill the liquefaction zone. This flow path encourages the liquefied phase to flow towards a lower pressure region, i.e., to fill the initially formed cavity (the corner regions on both sides of the bottom of the filler space). This, in turn, allows the intermediate material layer 40, after liquefaction, to fill this cavity region (see...). Figure 2 And, it forms a good metallurgical bond with the first component 11 and the thermoplasticized deposit 202 and the second component 12 and the thermoplasticized deposit 202, which helps to eliminate defects caused by root non-bonding, enhance the interface bonding strength, and achieve a high-quality connection between the two components under large gap conditions.

[0043] According to the friction stir joining method of the present invention, the friction stir deposition method can achieve gap filling connection between materials with large gap structures, as well as direct connection of the same or dissimilar materials. Furthermore, by utilizing the heat generated and conducted during the thermoplasticization of the aluminum alloy deposit 202 using solid-state composite technology, a eutectic liquefaction reaction is induced. Taking advantage of the material's tendency to flow from pressure to low-pressure regions during solid-state composite processing, root defects such as interface contact and voids can be avoided at the root during gap filling connection of materials with large gap structures using solid-state composite technology. This improves the high-quality connection between the first component 11 and the second component 12 under large gap conditions, enhancing connection reliability. Moreover, the overall process is simple, low-cost, and can achieve one-time forming connection of the first component 11 and the second component 12, resulting in high connection efficiency.

[0044] In some embodiments of the present invention, such as Figure 1 As shown, the intermediate material layer 40 also includes a magnesium material layer 402.

[0045] It is understandable that the magnesium layer 402 can undergo a eutectic liquefaction reaction with the zinc layer 401 at a temperature of 340 degrees Celsius, and the magnesium layer 402 can also undergo a eutectic liquefaction reaction with the aluminum alloy at a temperature of 437 degrees Celsius to 450 degrees Celsius. It can be seen that during the process of thermoplastic filling of the filler space by the deposit 202, magnesium and zinc can undergo eutectic liquefaction first, followed by aluminum and zinc, and then aluminum and magnesium. The whole process can realize multi-level eutectic liquefaction reaction in multiple temperature zones, which can expand the temperature range and reaction time of the liquefied phase, improve the interfacial metallurgical reaction effect, further improve root defects such as joints and voids, and improve the connection reliability of the first component 11 and the second component 12.

[0046] In some embodiments of the present invention, such as Figure 1 As shown, the intermediate material layer 40 also includes a copper material layer 403.

[0047] The copper layer 403 can undergo a eutectic liquefaction reaction with the zinc layer 401 at 425 degrees Celsius, and with the magnesium layer 402 at 485 degrees Celsius, as well as with aluminum at 548 degrees Celsius. In other words, this technical solution can further increase the temperature range and the number of eutectic liquefaction reactions, thereby further expanding the temperature range and reaction time of the liquefied phase, improving the interfacial metallurgical reaction effect, and mitigating root defects such as joints and voids.

[0048] In some embodiments of the present invention, the copper layer 403, magnesium layer 402, and zinc layer 401 are stacked from top to bottom. Since the zinc layer 401 undergoes a lower eutectic liquefaction reaction, it liquefies first, followed by the magnesium layer 402, and finally the copper layer 403. Therefore, with the above arrangement, the zinc layer 401, being at the bottom, can achieve the eutectic liquefaction reaction first and fill the root position in the corner area, thus helping to solve the root defect problem. It should be noted that the above is only a preferred embodiment of the present invention; the stacking order of the copper layer 403, magnesium layer 402, and zinc layer 401 is not limited to this, and they can also be stacked from top to bottom in other orders, which will not be described in detail here.

[0049] In some embodiments of the present invention, such as Figure 1 As shown, the intermediate material layer 40 also includes an aluminum layer 404, which is located at the bottom of the intermediate material layer 40. Since the copper layer 403, magnesium layer 402, and zinc layer 401 can all undergo a eutectic liquefaction reaction with aluminum within a certain temperature range, by setting the intermediate material layer 40 to also include an aluminum layer 404, more aluminum can participate in the eutectic liquefaction reaction, making the eutectic liquefaction reaction of the intermediate material layer 40 more complete.

[0050] In some embodiments of the present invention, the intermediate material layer 40 further includes at least one of a magnesium material layer 402, a copper material layer 403, and an aluminum material layer 404. It is understood that the intermediate material layer 40 may also include a zinc material layer 401 and a copper material layer 403, or a zinc material layer 401 and an aluminum material layer 404, or a zinc material layer 401, a magnesium material layer 402, and an aluminum material layer 404, etc., which will not be elaborated further here.

[0051] In some embodiments of the present invention, the copper layer 403, magnesium layer 402, aluminum layer 404, and zinc layer 401 are single-metal layers or alloy layers. That is, the copper layer 403 can be a pure copper layer or a copper alloy layer. The magnesium layer 402 can be a pure magnesium layer or a magnesium alloy layer. The aluminum layer 404 can be a pure aluminum layer or an aluminum alloy layer. The zinc layer 401 can be a pure zinc layer or a zinc alloy layer.

[0052] In some embodiments of the present invention, when the copper layer 403, magnesium layer 402, aluminum layer 404, and zinc layer 401 are alloy layers, the alloy layers include silicon. Increasing the silicon content improves the fluidity of each layer during eutectic liquefaction, allowing it to better fill the corner areas of the filler space and thus better address root defect problems.

[0053] In some embodiments of the present invention, the thicknesses of the copper layer 403, the magnesium layer 402, the zinc layer 401, and the aluminum layer 404 are 0.05 mm to 1 mm.

[0054] It is understood that the thicknesses of the copper layer 403, magnesium layer 402, zinc layer 401, and aluminum layer 404 can be equal or unequal. Specifically, the thicknesses of the copper layer 403, magnesium layer 402, zinc layer 401, and aluminum layer 404 can be, but are not limited to, 0.05mm, 0.1mm, 0.15mm, 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, 0.95mm, 1mm, etc.

[0055] In the above technical solution, by setting the thickness of the copper layer 403, magnesium layer 402, zinc layer 401 and aluminum layer 404 within the above range, the amount of copper layer 403, magnesium layer 402, zinc layer 401 and aluminum layer 404 can be controlled, thereby ensuring the filling effect of the corner area of ​​the filler space, that is, ensuring the improvement effect of root defects.

[0056] In some embodiments of the present invention, the pad 30 is made of aluminum, magnesium, titanium, iron, or copper metal, or is made of an alloy of aluminum, magnesium, titanium, iron, and copper.

[0057] In some embodiments of the present invention, the first component 11 is made of aluminum, magnesium, titanium, iron, or copper metal, or an alloy of aluminum, magnesium, titanium, iron, and copper; the second component 12 is made of aluminum, magnesium, titanium, iron, or copper metal, or an alloy of aluminum, magnesium, titanium, iron, and copper.

[0058] In some embodiments of the present invention, prior to the step of rotating the deposit 202 and frictionally thermoplasticizing it with at least one of the first component 11, the second component 12 and the pad 30, the friction stir bonding method of the present invention further includes: preheating the pad 30, the first component 11 and the second component 12.

[0059] It is understandable that by preheating the pad 30, the first component 11 and the second component 12, the initial temperature before the friction stir connection operation can be increased, thereby improving the fluidity of the filler material.

[0060] In some embodiments of the present invention, after the step of adding an intermediate material layer 40 at the bottom of the filling space, the intermediate material layer 40 including a zinc material layer 401, the friction stir connection method of the present invention further includes: setting a movable pressure-following mechanism on the intermediate material layer 40 to press the intermediate material layer 40 into the filling space.

[0061] The pressure-following mechanism can refer to a mechanism or device such as a roller or shaft, wherein the length of the roller or shaft is equal to the width of the filling space. For example, the pressure-following mechanism can refer to a roller that can move synchronously and along the same trajectory as the shoulder 201.

[0062] In the above technical solution, the intermediate material layer 40 is pressed into the filling space by the pressure mechanism. This ensures that the intermediate material layer 40 can be pressed into the corner area on both sides of the filling space, which is beneficial to fully fill the cavity formed in the corner area when the intermediate material layer 40 undergoes eutectic liquefaction reaction, thereby improving the effect of root defect improvement; at the same time, it can prevent the intermediate material layer 40 from being rolled up during stirring and friction.

[0063] The following is combined with Figures 1 to 3 This describes a specific embodiment of the friction stir connection method of the present invention.

[0064] The friction stir joining method uses a friction stir deposition apparatus 20 to fill the gap between the first component 11 and the second component 12. The friction stir deposition apparatus 20 includes a shoulder 201 and a deposit 202. The shoulder 201 has a feeding channel 2011, and the deposit 202 is an aluminum alloy rod disposed within the feeding channel 2011. The deposit 202 is configured to rotate at high speed within the feeding channel 2011, and the deposit 202 can move axially relative to the shoulder 201 under axial pressure. The axial pressure on the deposit 202 can be a normal force along the axial direction or a frictional thrust along the side of the deposit 202.

[0065] Step S1: A pad 30 is placed below the gap 101 between the first component 11 and the second component 12, forming a filler space between the pad 30 and the gap 101. The first component 11 is made of aluminum, and the second component 12 is made of titanium. The width of the deposit 202 is smaller than the width of the gap 101.

[0066] Step S2: Add an intermediate material layer 40 to the bottom of the filling space. The intermediate material layer 40 includes a zinc material layer 401, a magnesium material layer 402, a copper material layer 403, and an aluminum material layer 404. The copper material layer 403, magnesium material layer 402, zinc material layer 401, and aluminum material layer 404 are all in foil form and are stacked from top to bottom.

[0067] Step S3: A movable pressure-following mechanism is set on the intermediate material layer 40 to press the intermediate material layer 40 into the filling space.

[0068] Step S4: Preheat the pad 30, the first component 11, and the second component 12.

[0069] Step S5: First, rotate the deposit 202 and rub it against the introduction plate to achieve plastic softening. Then, move the deposit 202 into the filling space. After the deposit 202 comes into contact with the intermediate material layer 40, continue to drop it and stir and rub against the pad 30 to fill the filling space with the thermoplasticized part of the deposit 202 and to cause the intermediate material layer 40 to undergo eutectic liquefaction.

[0070] Step S6: Move the shoulder 201 along the trajectory of the packing space, and move the pressing mechanism synchronously with the shoulder 201 along the same trajectory.

[0071] In the above scheme, the heat carried by the deposit 202 during the friction stir additive manufacturing process is continuously conducted, causing the copper, magnesium, zinc, and aluminum foils to heat up. When the temperature enters the range of 340°C to 548°C, a series of metal eutectic liquefaction reactions occur between the foils and between them and the aluminum deposit material, mainly including: Mg + Zn L(340°C), Al+Zn L(382°C), Al+Mg L (437~450°C), Cu+Zn L (425°C), Cu+Mg L(485°C), Al+Cu L(548°C), where "L" refers to the liquid phase after eutectic liquefaction.

[0072] As the temperature gradually increases, partial eutectic liquefaction occurs in the bottom foil. Since liquids are more easily deformed than plastic solids, a localized low-pressure zone forms in the liquefaction area. Simultaneously, under the combined action of axial high pressure and radial rotational force, the upper aluminum deposit tends to flow towards the lower pressure region, i.e., fill the liquefaction zone. This flow path promotes the flow of the liquefied phase towards the lower pressure region, i.e., filling the initially formed cavity, thereby effectively eliminating root unbonded defects, enhancing interfacial bonding strength, and achieving high-quality connections in aluminum-titanium components under large gap conditions.

[0073] refer to Figure 4 and Figure 5 , Figure 4 The image shows a metallographic image of the first and second components connected in the related technology. It can be seen that there is a shaded area between the second component (titanium) and the filled part formed by the thermoplasticization of the deposit (aluminum), which means that root defects are generated. Figure 5 The metallographic image shows the first component 11 (aluminum) and the second component 12 (titanium) after being connected by the friction stir bonding method provided in the embodiment of the present invention. It can be seen from the figure that the bonding part between the second component 12 (titanium) and the filling part formed by the thermoplasticization of the deposit 202 (aluminum) remains consistent and no root defects are generated.

[0074] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0075] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A friction stir welding method characterized by, The method fills the gap between the first component and the second component by using a friction stir deposition device, the friction stir deposition device comprises a shoulder and a deposition material, the shoulder is provided with a feeding channel, the deposition material is made of aluminum alloy or magnesium alloy, and is arranged in the feeding channel, and the method comprises the following steps: A backing plate is arranged below the gap between the first component and the second component, so that a filling space is formed between the backing plate and the gap; An intermediate material layer is added at the bottom of the filling space, and the intermediate material layer comprises a zinc material layer; The deposition material is rotated and frictionally thermoplastics at least one of the first component, the second component and the backing plate, so that the thermoplastics part of the deposition material is filled in the filling space, and the intermediate material layer is eutectic liquefaction phenomenon; The shoulder moves along the trajectory of the filling space.

2. The friction stir welding method according to claim 1, characterized by The intermediate material layer further comprises a magnesium material layer.

3. The friction stir welding method according to claim 2, characterized by The intermediate material layer further comprises a copper material layer.

4. The friction stir welding method according to claim 3, characterized by The copper material layer, the magnesium material layer and the zinc material layer are arranged from top to bottom.

5. The friction stir welding method according to claim 3, wherein The intermediate material layer further comprises an aluminum material layer, which is at the bottom of the intermediate material layer.

6. The friction stir welding method according to claim 1, wherein The intermediate material layer further comprises at least one of a magnesium material layer, a copper material layer and an aluminum material layer.

7. The friction stir welding method according to claim 5, wherein The copper material layer, the magnesium material layer, the zinc material layer and the aluminum material layer are single metal material layers or alloy material layers.

8. The friction stir welding method according to claim 7, wherein When the copper material layer, the magnesium material layer, the zinc material layer and the aluminum material layer are alloy material layers, the alloy material layer comprises a silicon material.

9. The friction stir welding method according to any one of claims 5, 7, 8, characterized by, The thickness of the copper material layer, the magnesium material layer, the zinc material layer and the aluminum material layer is 0.05mm-1mm.

10. The friction stir welding method according to any one of claims 1 to 8, characterized by The backing plate is one of aluminum, magnesium, titanium, iron, copper metal material, or one of aluminum, magnesium, titanium, iron, copper alloy material.

11. The friction stir welding method according to any one of claims 1 to 8, characterized by The first component is one of aluminum, magnesium, titanium, iron, copper metal material, or one of aluminum, magnesium, titanium, iron, copper alloy material, and the second component is one of aluminum, magnesium, titanium, iron, copper metal material, or one of aluminum, magnesium, titanium, iron, copper alloy material.

12. The friction stir welding method according to any one of claims 1 to 8, characterized by Before the step of rotating the deposition material and frictionally thermoplastics at least one of the first component, the second component and the backing plate, the method further comprises preheating the backing plate, the first component and the second component.

13. The friction stir welding method according to any one of claims 1 to 8, characterized by After the step of adding the intermediate material layer comprising a zinc material layer at the bottom of the filling space, the method further comprises arranging a movable pressure mechanism on the intermediate material layer to compact the intermediate material layer in the filling space.

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