Pre-embedded brazing flux aluminum alloy composite material and preparation method thereof
By depositing flux and Al-Si alloy layers on aluminum alloy substrates using friction extrusion additive manufacturing technology, the problems of low interfacial bonding strength and easy cracking of aluminum alloy pre-embedded flux composite materials are solved, and efficient and stable preparation of aluminum alloy composite materials is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHEJIANG GEELY HLDG GRP CO LTD
- Filing Date
- 2026-06-24
- Publication Date
- 2026-07-21
Smart Images
Figure CN122425396A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of aluminum alloy brazing plate technology, and in particular to a pre-embedded flux aluminum alloy composite material and its preparation method. Background Technology
[0002] In the field of aluminum alloy pre-embedded flux composite material preparation technology, in order to overcome the problems of flux waste and poor accessibility in traditional brazing processes, the industry has proposed the technology of "pre-embedded flux", which is to pre-composite the flux inside the brazing filler metal layer, so that the brazing filler metal has both film breaking and filling functions, thus eliminating the need for additional flux spraying during the brazing process.
[0003] Currently, related technologies typically employ powder metallurgy to prepare flux-containing functional layers, which are then rolled together with the core material. For example, flux powder is mixed with aluminum alloy powder and hot isostatically pressed or extruded to form a brazed layer ingot, which is then hot-rolled together with an aluminum alloy core material. However, because the functional layer has a powder metallurgy structure while the core material has a cast structure, the differences in composition and high-temperature rheological stress between the two are significant. This results in poor synergistic deformation during large deformation hot rolling, leading to poor bonding, microcracks, and even cracking at the interface between the functional layer and the core material. Especially when it is necessary to increase the flux content or roll to ultra-thin specifications, the ductility of the powder metallurgy ingot decreases sharply, further exacerbating the cracking risk and limiting the stable production of high flux-content composite materials. In addition, powder metallurgy methods involve multiple processes such as powder mixing, filling, pressing, and sintering, making the process relatively cumbersome and resulting in low production efficiency.
[0004] Therefore, how to achieve high interfacial bonding strength between the functional layer and the core material, improve the processability of the high flux functional layer, and simplify the preparation process to facilitate continuous production during the preparation of pre-embedded flux composite materials has become a technical problem that urgently needs to be solved in this field. Summary of the Invention
[0005] The purpose of this invention is to overcome the problems of easy cracking, low interfacial bonding strength, complex process, and discontinuity in the preparation of aluminum alloy pre-embedded flux composite materials using powder metallurgy methods. This invention provides a pre-embedded flux aluminum alloy composite material and its preparation method. This preparation method avoids the brittleness of powder metallurgy billets through solid-phase deposition, resulting in a high-density, fine-grained, and ductile deposited layer. The high temperature and pressure of friction extrusion additive manufacturing cause atomic diffusion and mechanical interlocking between the deposited layer and the substrate (or lower layer), resulting in high bonding strength. Furthermore, additive manufacturing allows for continuous deposition, achieving near 100% material utilization with no cutting waste.
[0006] To achieve the above objectives, the first aspect of the present invention provides a method for preparing a pre-embedded flux aluminum alloy composite material, comprising the following steps: S1. By friction extrusion additive manufacturing, a flux / Al-Si alloy layer containing flux and Al-Si alloy, and an Al-Si alloy surface layer are sequentially solid-phase deposited on an aluminum alloy substrate to obtain a composite board. S2. The aluminum alloy substrate in the composite plate is stacked on at least one surface of the aluminum alloy ingot, and then hot-rolled to obtain a pre-embedded flux aluminum alloy composite material.
[0007] In some embodiments, the flux / Al-Si alloy layer is formed by friction extrusion additive manufacturing of a first feed material, and the Al-Si alloy surface layer is formed by friction extrusion additive manufacturing of a second feed material; the first feed material comprises flux / Al-Si alloy wire formed by extruding a mixture of Al-Si alloy powder and flux powder, and the second feed material comprises Al-Si alloy wire.
[0008] In some of these embodiments, Al-Si alloy powder is mixed with flux powder and then extruded into wire at 100°C-200°C.
[0009] In some embodiments, the diameter of the Al-Si alloy wire is 3mm-8mm.
[0010] In some embodiments, the diameter of the flux / Al-Si alloy wire is 3mm-8mm.
[0011] In some embodiments, the weight ratio of the Al-Si alloy powder to the flux powder is (80-95):(5-20).
[0012] In some embodiments, the mass content of Si in the Al-Si alloy powder is 7%-12.5%.
[0013] In some embodiments, the flux comprises a potassium fluoroaluminate-based flux, which includes KAlF4 and K2AlF5.
[0014] In some embodiments, the mass content of Si in the Al-Si alloy wire is 7%-12.5%.
[0015] In some embodiments, the aluminum alloy substrate is made of 3-series aluminum alloys and / or 4-series aluminum alloys.
[0016] In some embodiments, the aluminum alloy ingot is made of 3-series aluminum alloys and / or 4-series aluminum alloys.
[0017] In some embodiments, the aluminum alloy substrate and the aluminum alloy ingot are made of the same material.
[0018] In some embodiments, the thickness ratio of the aluminum alloy substrate, the flux / Al-Si alloy layer, and the Al-Si alloy surface layer is (5-20):(1-3):(1-5).
[0019] In some embodiments, the thickness of the flux / Al-Si alloy layer and the Al-Si alloy surface layer accounts for 8%-15% of the total thickness of the aluminum alloy substrate, the flux / Al-Si alloy layer, the Al-Si alloy surface layer, and the aluminum alloy ingot.
[0020] In some embodiments, in step S1, the tool head of the triboelectric additive manufacturing moves in a serpentine path and creates a lateral overlap between adjacent deposition trajectories to deposit the flux / Al-Si alloy layer and / or the Al-Si alloy surface layer, wherein the overlap between adjacent deposition trajectories is 10%-20%.
[0021] In some embodiments, in step S1, the tool head of the friction extrusion additive manufacturing operates at a rotational speed of 500 rpm to 1500 rpm, and the applied axial pressure is 3 kN to 10 kN.
[0022] In some embodiments, in step S1, the deposition rate of the solid phase deposition is 100 mm / min to 400 mm / min.
[0023] In some of these embodiments, step S2, the hot rolling composite method includes: holding at 450℃-500℃ for 4h-6h followed by multiple hot rolling passes, with a final rolling temperature not lower than 300℃.
[0024] In some embodiments, the preparation method further includes hot rolling followed by cold rolling and annealing.
[0025] In some of these embodiments, the cold rolling conditions include a single-pass reduction of 20%-30%.
[0026] In some of these embodiments, the annealing conditions include: holding at 380°C for 2-4 hours.
[0027] The second aspect of the present invention provides a pre-embedded flux aluminum alloy composite material prepared by the preparation method of the pre-embedded flux aluminum alloy composite material described in the first aspect of the present invention.
[0028] Through the above technical solution, the method for preparing pre-embedded flux aluminum alloy composite material provided by the present invention has at least the following beneficial effects: (1) Simple process, high material utilization rate, and continuous production: direct additive manufacturing, no need for complex powder filling molds and sintering process; additive manufacturing is near net shape, material utilization rate is close to 100%, no cutting waste; the deposition process can be carried out continuously, suitable for mass production.
[0029] (2) High interface bonding strength, enabling gradient functional design: The high temperature and pressure during the friction extrusion additive manufacturing process cause atomic diffusion and mechanical interlocking between the deposited layer and the substrate (or lower layer), resulting in high bonding strength; by switching wires with different flux contents, a gradient distribution of flux content can be achieved in the thickness direction, optimizing brazing performance. Attached Figure Description
[0030] Figure 1 The diagram shown is a flowchart of the preparation process of a pre-embedded flux aluminum alloy composite material in one embodiment.
[0031] Figure 2 The diagram shown is a schematic of friction extrusion additive manufacturing in one embodiment.
[0032] Figure 3 The image shown is a metallographic photograph of the double-sided symmetrical pre-embedded flux aluminum alloy composite material in Example 1.
[0033] Explanation of reference numerals in the attached figures: 1. Al-Si alloy wire; 2. Al-Si alloy surface layer; 3. Flux / Al-Si alloy layer; 4. Deposited substrate; 5. Hollow non-consumable tool head. Detailed Implementation
[0034] The endpoints and any values of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of the various ranges, the endpoint values of the various ranges and individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.
[0035] In the field of pre-embedded flux aluminum alloy composite material preparation technology, in order to achieve the pre-composite of flux inside the solder layer, so that the solder itself has both film-breaking and filling functions, the commonly used method is to mix flux powder with aluminum alloy powder, and make powder metallurgy billets by hot isostatic pressing, etc., and then stack the billet as a functional layer with the core material ingot, and achieve the composite by hot rolling with large deformation at high temperature. Its basic working principle is to use the pressure and high temperature generated by hot rolling to cause deformation and diffusion at the interface between the functional layer billet and the core material, thereby forming a bond. However, the inventors of this invention have found that this method has the following technical problems: 1) Low interface bonding strength: The Al-Si alloy layer with pre-embedded flux (powder metallurgy billet) is directly hot rolled and composited with the ingot (melted billet). The differences in composition, microstructure (powder metallurgy structure and as-cast structure) and high-temperature rheological stress between the two are significant, resulting in poor synergistic deformation ability under large deformation of hot rolling, and poor bonding, microcracks or even cracks are easily generated at the composite interface. This problem is particularly pronounced when rolling to thinner dimensions (e.g., 0.1-2.0 mm). This limits its application in the preparation of high flux content (>10%) or ultra-thin composite materials. 2) Limited processing performance: To obtain rollable billets, the amount of flux added needs to be strictly controlled (e.g., controlled to 2%-4%). When the flux content needs to be increased (e.g., >10%) to meet specific brazing requirements, the ductility of the powder metallurgy billet decreases sharply, making it more prone to cracking when combined with ingots, and difficult to maintain stable production. 3) Cumbersome process steps and high cost: Multiple processes such as powder mixing, filling, pressing, and sintering are required, resulting in low production efficiency.
[0036] In view of this, after in-depth research, this invention proposes a method for preparing a flux-embedded aluminum alloy composite material using triboelectric additive manufacturing. By introducing triboelectric additive manufacturing, a solid-state processing technology, the feed material containing flux is directly deposited layer by layer on the core substrate in a thermoplastic state to construct a functional layer. This avoids the step of pre-fabricating brittle powder metallurgy billets and provides a composite billet with a metallurgically bonded interface and dense structure for subsequent rolling. In addition, the method also includes depositing a flux-free brazing alloy layer to form a laminated structure consisting of a flux-free brazing alloy surface layer and a brazing alloy composite intermediate layer containing flux. Then, the billet is laminated and hot-rolled with a homogeneous aluminum alloy ingot to obtain a flux-embedded aluminum alloy composite material with both high-strength interfacial bonding and excellent brazing processability.
[0037] In this invention, unless otherwise specified, "room temperature" refers to 20℃-25℃.
[0038] In a first aspect, the present invention provides a method for preparing a pre-embedded flux aluminum alloy composite material, comprising the following steps: S1. By friction extrusion additive manufacturing, a flux / Al-Si alloy layer containing flux and Al-Si alloy, and an Al-Si alloy surface layer are sequentially solid-phase deposited on an aluminum alloy substrate to obtain a composite board. S2. The aluminum alloy substrate in the composite plate is stacked on at least one surface of the aluminum alloy ingot, and then hot-rolled to obtain a pre-embedded flux aluminum alloy composite material.
[0039] In this invention, a solid-state friction extrusion additive manufacturing process is employed to deposit Al-Si alloy containing flux layer by layer onto an aluminum alloy substrate in a thermoplasticized state. The high temperature and pressure generated by friction achieve atomic diffusion and mechanical interlocking between the deposited layer and the substrate, resulting in a dense, fine-grained pre-embedded flux layer. Specifically, this preparation method uses pre-fabricated Al-Si alloy wire and Al-Si + flux mixed powder wire as feed materials, loaded into a tool head (e.g., a hollow non-consumable tool head). The high-speed rotating tool head generates heat through friction with the substrate (or the already deposited layer), causing the wire end to reach a thermoplasticized state. Under axial pressure, the thermoplasticized material is continuously extruded and deposited onto the substrate, achieving layer-by-layer additive manufacturing. The entire process is solid-state processing, and the material does not melt, thus avoiding the brittle defects of traditional powder metallurgy pre-embedded flux ingots, as well as the problems of poor synergistic deformation capacity, low interfacial bonding strength, and easy cracking at high flux content caused by significant differences in high-temperature rheological stress when hot-rolled with cast ingots. Subsequently, the composite plate is hot-rolled with aluminum alloy ingots. This process effectively prevents the generation of interface defects and achieves a significant reduction in thickness from millimeter-level slabs to sub-millimeter-level final composite materials while ensuring high interfacial bonding strength.
[0040] According to the present invention, "friction extrusion additive manufacturing" refers to a solid-phase additive manufacturing technology that utilizes the frictional heat between a rotating tool head and a substrate or pre-deposited layer to thermoplasticize the end of the feed material and continuously extrude and deposit it under axial pressure. Specifically, it can refer to specific processes such as friction additive manufacturing or friction extrusion additive manufacturing, the common characteristic of which is that the material does not melt during processing. For example, "solid-phase deposition" refers to a process in friction extrusion additive manufacturing where the feed material and the substrate material in contact with it remain in a solid state to complete plastic deformation and bonding, without macroscopic melting of the material throughout the process. This process differs from traditional fusion welding or thermal spraying processes involving liquid-phase solidification. Through solid-phase deposition, the decomposition and failure of flux due to high-temperature melting can be effectively avoided, while obtaining a dense deposition layer that is well-bonded to the substrate.
[0041] In some embodiments, the flux / Al-Si alloy layer containing flux and Al-Si alloy is formed by friction extrusion additive manufacturing of a first feed material, and the Al-Si alloy surface layer is formed by friction extrusion additive manufacturing of a second feed material; the first feed material includes flux / Al-Si alloy wire formed by extruding a mixture of Al-Si alloy powder and flux powder, and the second feed material includes Al-Si alloy wire.
[0042] In this invention, by employing two different feed materials—namely, wire formed by extruding a mixture of Al-Si alloy powder and flux powder as the first feed material, and Al-Si alloy wire as the second feed material—a flux / Al-Si alloy layer and an Al-Si alloy surface layer containing flux and Al-Si alloy can be independently constructed on an aluminum alloy substrate using a triboelectric additive manufacturing process. Specifically, this invention employs a dual-wire alternating deposition process: first, an Al-Si + flux mixed powder wire is used to deposit an Al-Si + flux composite material layer on the substrate; then, Al-Si alloy wire is used to deposit one or more Al-Si alloy layers on the previously deposited Al-Si + flux composite material layer, thereby forming a stacked structure consisting of a flux-free solder alloy surface layer and a flux / Al-Si alloy layer. By controlling the wire switching and the number of deposition layers, a gradient distribution of flux content or a multilayer composite structure can be achieved. This method not only achieves uniform pre-embedding of flux in the functional layer, avoiding performance fluctuations caused by uneven flux distribution or high-temperature melting in traditional powder metallurgy methods, but also further enhances the overall ductility of the deposited billet and its compatibility with subsequent rolling processes through solid-phase deposition of the Al-Si alloy surface. This simplifies the process while effectively ensuring the interfacial bonding strength between the functional layer and the core material in the final composite material, as well as the stability of brazing performance. Furthermore, in the initial stage of brazing, the melting of the Al-Si alloy surface provides a clean initial filler metal while protecting the internally embedded flux, preventing physical loss and chemical contamination. This makes the brazing process more controllable and significantly improves the weld ratio and post-weld surface quality.
[0043] In some embodiments, the Si content in the Al-Si alloy wire is 7%-12.5% by mass, for example, it can be 7%, 8%, 9%, 10%, 11%, 12%, 12.5%, or any combination of two of the above values. Controlling the Si content in the Al-Si alloy wire within the aforementioned range ensures that the wire has suitable plasticity and flow characteristics for friction extrusion additive manufacturing, and at the same time, it can melt synergistically with the flux / Al-Si alloy layer containing flux and Al-Si alloy during brazing to form a unified braze pool. The Al-Si alloy wire can be selected from, but is not limited to, the following commercial aluminum alloy grades: 4045 aluminum alloy (Al-10wt%Si), 4047 aluminum alloy (Al-12wt%Si), or 4343 aluminum alloy (Al-7.5wt%Si). Furthermore, the Al-Si alloy wire can be prepared by conventional extrusion or drawing processes from Al-Si alloy round ingots. Preferably, the diameter of the aforementioned Al-Si alloy wire is 3mm-8mm.
[0044] According to the present invention, as long as the purpose of the present invention can be achieved, there is no particular limitation on the method of extruding the Al-Si alloy powder and the flux powder into wire. In some embodiments, the Al-Si alloy powder and the flux powder are mixed and extruded into wire at 100°C-200°C (for example, 100°C, 120°C, 130°C, 150°C, 160°C, 180°C or 200°C) (i.e., wire formed by extruding the Al-Si alloy powder and the flux powder). The extrusion can be carried out in any extruder in the art. Preferably, the diameter of the aforementioned flux / Al-Si alloy wire is 3mm-8mm.
[0045] In some embodiments, the weight ratio of Al-Si alloy powder to flux powder is (80-95):(5-20), for example, 80:20, 85:15, 90:10, or 95:5. Controlling the weight ratio of Al-Si alloy powder to flux powder within the aforementioned range ensures that the flux / Al-Si alloy layer has efficient film-breaking ability and sufficient solder supply. At the same time, it can also maintain the plastic deformation ability of the deposited layer, thereby giving the prepared pre-embedded flux aluminum alloy composite material excellent brazing performance.
[0046] In some embodiments, the Si mass content in the Al-Si alloy powder is 7%-12.5%, for example, it can be 7%, 8%, 9%, 10%, 11%, 12%, 12.5%, or any combination of two of the above values. Controlling the Si mass content in the Al-Si alloy powder within the aforementioned range enables the feed material to have a suitable thermoplasticization temperature and fluidity during the triboelectric additive manufacturing process, avoiding insufficient ductility of the deposited layer due to too low Si content or brittleness due to too high Si content. It also ensures that the flux / Al-Si alloy layer and the Al-Si alloy surface layer in the final composite material can provide sufficient eutectic liquid phase during subsequent brazing, thereby obtaining good wetting and spreading properties and reliable weld joints. The Al-Si alloy powder can be selected from, but is not limited to, the following commercial aluminum alloy grades: 4045 aluminum alloy (Al-10wt%Si), 4047 aluminum alloy (Al-12wt%Si), or 4343 aluminum alloy (Al-7.5wt%Si).
[0047] Furthermore, the Al-Si alloy powder and Al-Si alloy wire can be controlled to be homogeneous materials (i.e., both have the same silicon content, selected from the same range of 7%-12.5%). Homogeneous materials have similar thermoplasticization temperature windows and rheological behaviors during tribo-extruded additive manufacturing, ensuring that no additional compositional transition or process adjustment is required at the interlayer interface when depositing flux / Al-Si alloy layers containing flux and Al-Si alloy layers and Al-Si alloy surface layers sequentially, significantly improving the stability of the deposition process and the interlayer bonding strength. In addition, the homogeneous materials have consistent coefficients of thermal expansion and phase transformation behavior during subsequent hot rolling composite and brazing heating, effectively avoiding interfacial stress concentration or microcrack generation caused by compositional differences, further ensuring the overall mechanical properties of the composite material and the reliability of brazing.
[0048] According to the present invention, the particle sizes of the Al-Si alloy powder and the flux powder can be selected according to actual process requirements, mixing uniformity requirements, and the performance targets of the final product. As an example, the Dv of the flux powder... 50 The particle size is 10μm-50μm; as an example, the Dv of Al-Si alloy powder 50 The particle size is 20μm-60μm.
[0049] According to the present invention, as long as the purpose of the present invention can be achieved, any flux suitable for brazing aluminum alloys, capable of effectively removing the oxide film on the surface of aluminum alloys at brazing temperatures, promoting the spread and filling of the filler metal, and not undergoing harmful chemical reactions with the processed material during mixing with Al-Si alloy powder and subsequent processing. In some embodiments, the flux includes potassium fluoroaluminate-based fluxes. Potassium fluoroaluminate-based fluxes include KAlF4 (potassium tetrafluoroaluminate) and K2AlF5 (potassium pentafluoroaluminate). As an example, the flux is a KAlF4-K2AlF5 mixed powder with a KAlF4:K2AlF5 weight ratio of (1.8-5.7):1. Those skilled in the art know that the KAlF4-K2AlF5 mixed powder can be obtained through the eutectic transformation reaction of KF and AlF3.
[0050] In this invention, the conditions for manufacturing a flux / Al-Si alloy layer containing flux and Al-Si alloy by triboelectric additive manufacturing, and the conditions for manufacturing a solid-phase deposited Al-Si alloy surface layer by triboelectric additive manufacturing, can be the same or different, but are preferably the same. Using the same process conditions simplifies the process, leading to increased efficiency and reduced equipment costs.
[0051] In some embodiments, in step S1, the tool head of the triboelectric additive manufacturing process moves in a serpentine path, creating a lateral overlap between adjacent deposition trajectories to deposit a flux / Al-Si alloy layer and / or an Al-Si alloy surface layer. Here, "serpentine path" refers to the trajectory of the tool head moving in a continuous reciprocating manner during deposition. For example, it may include, but is not limited to, the tool head moving along the substrate surface in an "S"-shaped or zigzag pattern. Preferably, the overlap rate between adjacent deposition trajectories is controlled at 10%-20%, for example, 10%, 12%, 15%, 18%, or 20%. Here, "overlap rate" refers to the ratio of the width of the overlap between two adjacent deposition trajectories to the width of a single trajectory when using a serpentine path for triboelectric additive manufacturing deposition.
[0052] According to the present invention, the "tool head" used in friction extrusion additive manufacturing refers to a rotating component in a friction extrusion additive manufacturing apparatus used to generate heat through friction with a substrate or deposited layer and to extrude feed material. For example, it may include, but is not limited to, a hollow, non-consumable tool head whose rotation causes thermoplasticization of the feed material end. In some embodiments, in step S1, the tool head rotation speed in friction extrusion additive manufacturing is 500 rpm to 1500 rpm (e.g., 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm, 1000 rpm, 1200 rpm, or 1500 rpm), and the applied axial pressure is 3 kN to 10 kN (e.g., 3 kN, 4 kN, 5 kN, 6 kN, 7 kN, 8 kN, 9 kN, or 10 kN). Under the aforementioned conditions, the heat generated by the friction between the tool head and the substrate in controlled frictional extrusion additive manufacturing is sufficient to fully thermoplasticize the feed material, but not so high that it would cause the substrate to overheat or the material to melt. The axial pressure can ensure that the thermoplasticized material can be fully compacted and extruded from the tool head outlet to form a dense deposit layer.
[0053] In some embodiments, in step S1, the solid-phase deposition rate is 100 mm / min to 400 mm / min (e.g., 100 mm / min, 150 mm / min, 200 mm / min, 300 mm / min, or 400 mm / min). This deposition rate better matches the heat input and material supply rate, ensuring the uniformity and thickness consistency of the deposited layer.
[0054] According to the present invention, the aluminum alloy substrate is primarily a plate-shaped substrate used as a deposition starting point and structural support in friction extrusion additive manufacturing. It serves not only as the substrate for depositing flux / Al-Si alloy layers and Al-Si alloy surface layers, but also as a transition layer for bonding with the aluminum alloy ingot in the subsequent hot rolling composite step. The specific material of the aluminum alloy substrate is not particularly limited as long as the purpose of the present invention can be achieved. Generally, it is produced from a semi-continuous casting ingot as raw material, through complex processes such as homogenization annealing, hot rolling (heating and rolling the ingot), cold rolling, and heat treatment to obtain a rolled aluminum alloy plate. In some embodiments, the material of the aluminum alloy substrate includes 3-series aluminum alloys and / or 4-series aluminum alloys.
[0055] According to the present invention, an "aluminum alloy ingot" is a block billet formed by pouring molten aluminum alloy liquid into a mold and solidifying it. It is generally formed by pouring liquid aluminum or aluminum alloy into a mold and cooling and solidifying it. The main processes include vertical semi-continuous casting, horizontal continuous casting, etc. As long as the purpose of the present invention can be achieved, the specific material of the aluminum alloy ingot is not particularly limited. In some embodiments, the material of the aluminum alloy ingot includes 3-series aluminum alloys and / or 4-series aluminum alloys.
[0056] The above-mentioned 3-series aluminum alloys are Al-Mn series aluminum alloys, and their specific grades include, but are not limited to, at least one of 3003 aluminum alloy and 3003mod aluminum alloy (Mg content less than 0.3wt%); the above-mentioned 4-series aluminum alloys are Al-Si series aluminum alloys, and their specific grades include, but are not limited to, at least one of 4045 aluminum alloy, 4047 aluminum alloy and 4343 aluminum alloy.
[0057] In some embodiments, the aluminum alloy substrate and the aluminum alloy ingot are homogeneous materials. "Homogeneous materials" means that their composition and microstructure are identical. Because the aluminum alloy substrate and the aluminum alloy ingot are homogeneous materials, they have similar coefficients of thermal expansion and rheological stress characteristics at high temperatures. During the hot-rolling composite process, they can deform synergistically, effectively solving the problems of stress concentration and poor bonding at the composite interface caused by differences in material properties. This significantly improves the interfacial bonding strength between the ingot and the composite plate, avoids cracking and delamination during hot rolling, and ensures the overall mechanical properties of the final pre-embedded flux aluminum alloy composite material.
[0058] According to the present invention, the thickness of the flux / Al-Si alloy layer and the Al-Si alloy surface layer can be controlled by the deposition rate and deposition passes. In some embodiments, the thickness ratio of the aluminum alloy substrate, the flux / Al-Si alloy layer, and the Al-Si alloy surface layer is (5-20):(1-3):(1-5), for example, 10:2:4, 10:1:5, and 10:3:3. By controlling the relative thickness ratio of each functional layer in the composite material within the aforementioned range, the present invention enables the substrate to provide sufficient structural support. The flux-containing intermediate layer has a suitable thickness to avoid rolling cracking while ensuring the flux content provides excellent brazing performance. The surface Al-Si alloy layer, as a brazing filler material source, can fully melt and fill the weld during brazing. At the same time, each layer can deform in coordination during hot rolling composite process, avoiding interface stress concentration or uneven deformation caused by imbalance in layer thickness ratio. This effectively improves the overall brazing performance, interface bonding strength, and rolling forming quality of the composite material.
[0059] According to the present invention, the aluminum alloy substrate of the composite plate is stacked on at least one surface of the aluminum alloy ingot, which means that a single-sided composite or a double-sided composite method can be adopted. Single-sided composite means that the aluminum alloy substrate of a composite plate is stacked on one surface of an aluminum alloy ingot; double-sided composite means that the aluminum alloy substrates of two composite plates are respectively stacked on two opposite surfaces of an aluminum alloy ingot.
[0060] In some embodiments, based on the total thickness of the aluminum alloy substrate, the flux / Al-Si alloy layer, the Al-Si alloy surface layer, and the aluminum alloy ingot, the thickness percentage of the flux / Al-Si alloy layer and the Al-Si alloy surface layer is 8%-15%, for example, 8%, 9%, 10%, 11%, 12%, 13%, 14%, or 15%. This percentage ensures that the brazing functional layer has a sufficient volume fraction in the final product, allowing sufficient liquid brazing filler metal and active flux to be generated during brazing, fully filling the weld gap and forming a full rounded corner, thus meeting the requirements for reliable brazing connections.
[0061] In some embodiments, step S2 involves hot rolling followed by multiple passes of hot rolling after holding at 450℃-500℃ for 4-6 hours, with a final rolling temperature not lower than 300℃ (e.g., 300℃-380℃). Holding at 450-500℃ for 4-6 hours ensures the material uniformly reaches the required hot rolling temperature. Within this temperature range, the aluminum alloy exhibits good plasticity, facilitating deformation and promoting interfacial atomic diffusion. The requirement of a final rolling temperature not lower than 300℃ ensures the material retains a certain temperature after the final rolling pass, preventing severe work hardening or cracking due to excessively low temperatures.
[0062] In this invention, the aluminum alloy composite material with pre-embedded flux can be hot-rolled to an intermediate thickness according to the final required thickness. As an example, when it is necessary to roll to an intermediate thickness (e.g., 5mm-8mm), 5-9 passes of hot rolling can be performed, with the total reduction rate typically controlled between 80% and 95%. Those skilled in the art will understand that the specific selection of the number of passes needs to comprehensively consider the initial thickness of the product, the target intermediate thickness, the mill capacity, and the high-temperature deformation characteristics of the material, but is not limited to the above example.
[0063] After hot rolling composite, to obtain a thinner final product with higher surface quality and good plasticity, cold rolling and annealing can be performed as needed. That is, in some embodiments, the preparation method also includes cold rolling and annealing after hot rolling composite. Specifically, the hot-rolled composite plate is cooled to room temperature and then subjected to multiple cold rolling passes (e.g., 4-11 passes) to precisely roll the plate to the final finished thickness, for example, 0.3mm-2mm, with a single-pass reduction controlled at 20%-30%. After cold rolling, finished product annealing is performed according to product condition requirements, for example, holding at 380℃-400℃ for 2-4 hours, followed by air cooling or furnace cooling. Annealing can eliminate cold rolling work hardening, restore the plasticity of the material, and homogenize the microstructure, thereby obtaining a final product with good mechanical properties and brazing performance. Those skilled in the art will understand that the specific cold rolling passes and annealing parameters can be adjusted according to the target thickness, material condition, and equipment capabilities, and are not limited to the examples above.
[0064] As an example, the preparation flow chart of the pre-embedded flux aluminum alloy composite material is as follows: Figure 1 As shown, a schematic diagram of friction extrusion additive manufacturing is as follows. Figure 2 As shown.
[0065] The preparation of pre-embedded flux aluminum alloy composite material includes the following steps: Step 1: Wire Preparation Al-Si alloy wire 1: Al-(7wt%-12.5wt%)Si alloy wire with a diameter of 3-8mm is prepared by conventional extrusion or drawing processes.
[0066] Al-Si alloy / flux hybrid wire: Al-(7wt%-12.5wt%)Si alloy powder (Dv) 50 =20μm-60μm) and potassium fluoroaluminate flux powder (Dv) 50 =10μm-50μm) are mixed evenly at a weight ratio of (80-95):(5-20), and extruded into wires with a diameter of 3-8mm at 100℃-200℃ using an extruder.
[0067] Step 2: Substrate Preparation 3003 aluminum alloy rolled plate is used as the deposition substrate, with a thickness of 5mm-20mm. The surface is cleaned to remove oil and mechanically polished to remove the oxide film.
[0068] Step 3: First layer deposition (flux / Al-Si alloy layer 3) The Al-Si alloy / flux hybrid wire is loaded into the hollow non-consumable tool head 5 of the triboelectric additive manufacturing equipment. The equipment is started, and the tool head presses down to contact the substrate at a speed of 500rpm-1500rpm. Frictional heat generates thermoplasticity at the wire tip. Under an axial pressure of 3kN-10kN, the thermoplasticized material is continuously extruded and deposited on the substrate at a deposition rate of 100mm / min-400mm / min. The tool head moves in a serpentine path with an overlap rate of 10%-20% between adjacent trajectories, depositing a flux / Al-Si alloy layer 3 with a thickness of 1mm-3mm.
[0069] Step 4: Second layer deposition (Al-Si alloy surface layer 2) Replace the wire with Al-Si alloy wire 1, and deposit one or more Al-Si alloy surface layers 2 on the deposited flux / Al-Si alloy layer 3 in the same manner. The thickness of a single layer is 1mm-5mm, and the total thickness is determined according to the design requirements (the total thickness of flux / Al-Si alloy layer 3 and Al-Si alloy surface layer 2 accounts for 8%-15%). After deposition, a composite board including a 3003 aluminum alloy substrate, flux / Al-Si alloy layer 3, and Al-Si alloy surface layer 2 is obtained.
[0070] Step 5: Hot rolling composite Core material preparation: 3003 aluminum alloy ingot, surface milled flat.
[0071] Composite board: Surface milled flat.
[0072] Design of the thickness ratio between the composite plate and the ingot: The total thickness ratio of the single-sided brazed functional layers (flux / Al-Si alloy layer 3, Al-Si alloy surface layer) is required to be 8%-15%. After hot rolling composite, the deformation of the composite plate and the ingot is basically the same, and the original thickness ratio remains unchanged.
[0073] Single-sided composite: The 3003 aluminum alloy substrate of the composite plate is stacked with a 3003 aluminum alloy ingot.
[0074] Double-sided composite: Two composite plates are stacked on the top and bottom sides of a 3003 aluminum alloy ingot.
[0075] Heat the stacked billets to 450℃-500℃ and hold for 4-6 hours.
[0076] Multiple hot rolling passes are performed on a hot rolling mill, with a final rolling temperature greater than 300℃, and the thickness is 5mm-8mm.
[0077] Step Six: Cold Rolling and Finished Product Annealing Cool the hot-rolled plate to room temperature.
[0078] Multiple cold rolling passes are performed to achieve a final product thickness of 0.3mm-2.0mm, with a single pass reduction of 20%-30%.
[0079] Anneal the finished product at 380℃-400℃ for 2-4 hours.
[0080] The final pre-embedded flux aluminum alloy composite material is obtained.
[0081] In a second aspect, the present invention provides a pre-embedded flux aluminum alloy composite material prepared by the preparation method of the pre-embedded flux aluminum alloy composite material provided in the first aspect above.
[0082] In this invention, the Al-Si alloy surface layer and the flux / Al-Si alloy layer in the pre-embedded flux aluminum alloy composite material together serve as the brazing functional layer, and the aluminum alloy substrate and the aluminum alloy ingot together serve as the core material layer.
[0083] The pre-embedded flux aluminum alloy composite material of this invention is not prone to delamination or cracking when subjected to subsequent brazing thermal cycles or machining. At the same time, the pre-embedded flux is evenly distributed in the intermediate layer, which can effectively break the oxide film on the surface of the aluminum alloy during brazing heating, and work synergistically with the filler metal formed by the melting of the Al-Si alloy surface layer to fill the weld seam fully and densely, thereby ensuring the high reliability and airtightness of the brazed joint. In addition, the matching design of the composition and thickness of each layer of material makes the composite material have good overall mechanical properties (such as strength and plasticity).
[0084] The present invention will be described in detail below through embodiments.
[0085] In the following examples and comparative examples: The characteristics of the composite interface can be observed by metallographic photographs of aluminum alloy composite materials with pre-embedded flux.
[0086] The interfacial bonding strength of the final pre-embedded flux aluminum alloy composite material was tested using an electronic universal testing machine at a tensile speed of 5 mm / min.
[0087] The pre-embedded flux aluminum alloy composite material was heated from room temperature to a specified temperature and held at that temperature for a specified time to simulate CAB brazing. Its spread area was tested in accordance with GB / T 11364-2020.
[0088] Example 1 This embodiment provides a friction extrusion additive manufacturing method for double-sided pre-embedded flux aluminum alloy composite materials, the specific steps of which are as follows: (1) Wire preparation Al-Si alloy wire: 5mm diameter wire is made of 4045 aluminum alloy (Al-10wt%Si) through extrusion drawing process.
[0089] Al-Si alloy / flux hybrid wire: Al-10wt%S alloy powder (Dv) 50 =40μm) and potassium fluoroaluminate flux powder (KAlF4-K2AlF5 mixed powder, KAlF4 and K2AlF5 weight ratio is 6:1, Dv 50 =25μm) are mixed evenly at a weight ratio of 88:12 and extruded into wire with a diameter of 5mm at 150℃ using an extruder.
[0090] (2) Substrate preparation A 3003 aluminum alloy rolled plate with a thickness of 10mm was used as the deposition substrate 4. The surface was cleaned to remove oil and mechanically polished to remove the oxide film.
[0091] (3) First layer deposition (flux / Al-Si alloy layer) Al-Si alloy / flux hybrid wire was loaded into a hollow, non-consumable tool head of a triboelectric additive manufacturing apparatus. The tool head rotated at 800 rpm, the deposition rate was 250 mm / min, and the axial pressure was 6 kN. The tool head moved along a serpentine path on the deposition substrate 4, with an overlap rate of 20% between adjacent paths. Under the action of frictional heat and axial pressure, the wire tip was thermoplasticized and continuously extruded, depositing a flux / Al-Si alloy layer with a thickness controlled at 2 mm. After deposition, a composite containing a 3003 aluminum alloy substrate and a flux / Al-Si alloy layer was obtained.
[0092] (4) Second layer deposition (Al-Si alloy surface layer) The wire was replaced with an Al-Si alloy wire (5mm in diameter). Using the same equipment parameters (tool head speed 800 rpm, deposition speed 250 mm / min, axial pressure 6 kN; the tool head moves along a serpentine path on the deposition substrate, with an overlap rate of 20% between adjacent paths), an Al-Si alloy surface layer was deposited on top of the already deposited flux / Al-Si alloy layer. The deposition thickness was controlled at 4mm. After deposition, a composite board was obtained consisting of a 3003 aluminum alloy substrate (10mm), a flux / Al-Si alloy layer (2mm), and an Al-Si alloy surface layer (4mm), with a total thickness of 16mm.
[0093] (5) Hot-rolled composite (double-sided) Prepare two milled and smoothed composite plates and a 43mm thick 3003 aluminum alloy ingot. Stack the 3003 aluminum alloy substrate of the composite plate onto the top and bottom surfaces of the 3003 aluminum alloy ingot, with the Al-Si alloy surface layer of the composite plate facing outwards, to obtain the laminated billet. The total thickness of the single-sided brazed functional layer (Al-Si alloy surface layer and flux / Al-Si alloy layer) is 6mm, and the proportion of the single-sided brazed functional layer to the final product thickness is 6mm / 75mm × 100% = 8%. Heat the laminated billet to 480℃ and hold for 5 hours. Perform 7 passes of hot rolling on a hot rolling mill, with a total reduction of approximately 92%, a final rolled thickness of 6mm, and a final rolling temperature of 350℃.
[0094] (6) Cold rolling and annealing The hot-rolled plate was cooled to room temperature and then cold-rolled in 8 passes, with a reduction of 20%-25% per pass, resulting in a final rolled thickness of 0.8 mm. The finished product was then annealed: held at 390℃ for 3 hours and air-cooled.
[0095] (7) Product structure and performance A double-sided symmetrical pre-embedded flux aluminum alloy composite material with a total thickness of 0.8 mm was obtained. The single-sided brazing functional layer (Al-Si alloy surface layer + flux / Al-Si alloy layer) has a thickness of approximately 0.064 mm, accounting for 8% of the total thickness; of which the Al-Si alloy surface layer is approximately 0.043 mm and the flux / Al-Si alloy layer is approximately 0.021 mm; the core material layer (3003 aluminum alloy substrate + 3003 aluminum alloy ingot) has a thickness of approximately 0.672 mm, accounting for 84% of the total thickness.
[0096] Metallographic photographs of double-sided symmetrical pre-embedded flux aluminum alloy composite materials are shown below. Figure 3 As shown in the metallographic photographs, the composite interface is free of cracks and pores; the average interfacial bonding strength, as determined by the T-type peel test, is 48 N / mm²; the average spread area in simulated CAB brazing (600℃, 6 minutes) is 463 mm². 2 No visible flux residue was found on the surface after brazing.
[0097] Example 2 This embodiment provides a friction extrusion additive manufacturing method for single-sided pre-embedded flux aluminum alloy composite materials, the specific steps of which are as follows: (1) Wire preparation Al-Si alloy wire: 4047 alloy (Al-12wt%Si), wire with a diameter of 5mm is prepared by extrusion drawing process.
[0098] Al-Si alloy / flux hybrid wire: Al-12wt%Si alloy powder (Dv) 50 =30μm) and potassium fluoroaluminate flux powder (KAlF4-K2AlF5 mixed powder, KAlF4 and K2AlF5 weight ratio is 1.8:1, Dv 50 =25μm) are mixed evenly at a weight ratio of 85:15 and extruded into wire with a diameter of 5mm at 150℃ using an extruder.
[0099] (2) Substrate preparation 3003 aluminum alloy rolled plate with a thickness of 10mm was used as the deposition substrate. The surface was cleaned to remove oil and mechanically polished to remove the oxide film.
[0100] (3) First layer deposition (flux / Al-Si alloy layer) Al-Si alloy / flux hybrid wire is loaded into a hollow, non-consumable tool head of a triboelectric additive manufacturing apparatus. The tool head rotates at 800 rpm, the deposition rate is 250 mm / min, and the axial pressure is 6 kN. The tool head moves along a serpentine path on the deposition substrate, with an overlap rate of 15% between adjacent paths. Under the action of frictional heat and axial pressure, the wire tip is thermoplasticized and continuously extruded, depositing a flux / Al-Si alloy layer with a thickness controlled at 1 mm. After deposition, a composite containing a 3003 aluminum alloy substrate and the flux / Al-Si alloy layer is obtained.
[0101] (4) Second layer deposition (Al-Si alloy surface layer) The wire was replaced with an Al-Si alloy wire (5mm diameter). Using the same equipment parameters (tool head speed 800 rpm, deposition speed 250 mm / min, axial pressure 6 kN; tool head moves along a serpentine path on the deposition substrate, with an overlap rate of 15% between adjacent paths), an Al-Si alloy surface layer was deposited on top of the already deposited flux / Al-Si alloy layer. The deposition thickness was controlled at 5mm. After deposition, a composite board was obtained consisting of a 3003 aluminum alloy substrate (10mm), a flux / Al-Si alloy layer (1mm), and an Al-Si alloy surface layer (5mm), with a total thickness of 16mm.
[0102] (5) Single-sided hot-rolled composite Prepare a composite plate with a milled and smooth surface and a 34mm thick 3003 aluminum alloy ingot. Stack the 3003 aluminum alloy substrate of the composite plate onto the 3003 aluminum alloy ingot, with the Al-Si alloy surface layer of the composite plate facing outwards, to obtain the laminated billet. The total thickness of the single-sided brazed functional layer (Al-Si alloy surface layer and flux / Al-Si alloy layer) is 6mm, and the proportion of the single-sided brazed functional layer to the final product thickness is 6mm / (34+16)mm×100%=12%. Heat the laminated billet to 470℃ and hold for 6 hours. Perform 7 passes of hot rolling on a hot rolling mill, with a total reduction of approximately 86%, a final rolled thickness of 7mm, and a final rolling temperature of 320℃.
[0103] (6) Cold rolling and annealing The hot-rolled plate was cooled to room temperature and then cold-rolled in 7 passes, with a reduction of 20%-25% per pass, resulting in a final rolled thickness of 1.2 mm. The finished product was then annealed: held at 380℃ for 4 hours and then air-cooled.
[0104] (7) Product structure and performance A single-sided pre-embedded flux aluminum alloy composite material with a total thickness of 1.2 mm was obtained. The single-sided brazing functional layer (Al-Si alloy surface layer + flux / Al-Si alloy layer) has a thickness of approximately 0.144 mm, accounting for 12% of the total thickness; of which the Al-Si alloy surface layer is approximately 0.12 mm and the flux / Al-Si alloy layer is approximately 0.024 mm; the core material layer (3003 aluminum alloy substrate + 3003 aluminum alloy ingot) has a thickness of approximately 1.056 mm, accounting for 88% of the total thickness.
[0105] The composite interface showed no cracks or pores; the interfacial bonding strength, as measured by the T-type peel test, averaged 50 N / mm; and the average spread area in simulated CAB brazing (600℃ × 5 min) was 518 mm². 2 No visible flux residue was found on the surface after brazing.
[0106] Example 3 This embodiment provides a friction extrusion additive manufacturing method for thin-gauge double-sided pre-embedded flux aluminum alloy composite materials, the specific steps of which are as follows: (1) Wire preparation Al-Si alloy wire: 4343 alloy (Al-7.5wt%Si), wire with a diameter of 5mm is prepared by extrusion drawing process.
[0107] Al-Si alloy / flux hybrid wire: Al-7.5wt%Si alloy powder (Dv) 50 =40μm) and potassium fluoroaluminate flux powder (KAlF4-K2AlF5 mixed powder, KAlF4 and K2AlF5 weight ratio is 4:1, Dv 50 =25μm) are mixed evenly at a weight ratio of 91:9 and extruded into wire with a diameter of 5mm at 150℃ using an extruder.
[0108] (2) Substrate preparation 3003 aluminum alloy rolled plate with a thickness of 10mm was used as the deposition substrate. The surface was cleaned to remove oil and mechanically polished to remove the oxide film.
[0109] (3) First layer deposition (flux / Al-Si alloy layer) Al-Si alloy / flux hybrid wire is loaded into a hollow, non-consumable tool head of a triboelectric additive manufacturing apparatus. The tool head rotates at 1000 rpm, the deposition rate is 300 mm / min, and the axial pressure is 6 kN. The tool head moves along a serpentine path on the deposition substrate, with an overlap of 10% between adjacent paths. Under the action of frictional heat and axial pressure, the wire tip is thermoplasticized and continuously extruded, depositing a flux / Al-Si alloy layer with a thickness controlled at 3 mm. After deposition, a composite containing a 3003 aluminum alloy substrate and the flux / Al-Si alloy layer is obtained.
[0110] (4) Second layer deposition (Al-Si alloy surface layer) The wire was replaced with Al-Si alloy wire (5mm diameter). Using the same equipment parameters (tool head speed 1000rpm, deposition speed 300mm / min, axial pressure 6kN; tool head moves along a serpentine path on the deposition substrate, with an overlap rate of 10% between adjacent paths), an Al-Si alloy surface layer was deposited on top of the already deposited flux / Al-Si alloy layer. The deposition thickness was controlled at 3mm. After deposition, a composite board was obtained consisting of a 3003 aluminum alloy substrate (10mm), a flux / Al-Si alloy layer (3mm), and an Al-Si alloy surface layer (3mm), with a total thickness of 16mm.
[0111] (5) Hot-rolled composite (double-sided) Prepare two milled and smoothed composite plates and a 28mm thick 3003 aluminum alloy ingot. Stack the 3003 aluminum alloy substrate of the composite plate onto the top and bottom surfaces of the 3003 aluminum alloy ingot, with the Al-Si alloy surface layer of the composite plate facing outwards, to obtain the laminated billet. The total thickness of the single-sided brazed functional layer (Al-Si alloy surface layer and flux / Al-Si alloy layer) is 6mm, and the proportion of the single-sided brazed functional layer to the final product thickness is 6mm / 60mm × 100% = 10%. Heat the laminated billet to 500℃ and hold for 4 hours. Perform 6 passes of hot rolling on a hot rolling mill, with a total reduction of approximately 91.67%, a final rolled thickness of 5mm, and a final rolling temperature of 300℃.
[0112] (6) Cold rolling and annealing The hot-rolled plate was cooled to room temperature and then cold-rolled in 7 passes, with a reduction of 25%-30% per pass, resulting in a final rolled thickness of 0.5 mm. The finished product was then annealed: held at 400℃ for 2 hours and then air-cooled.
[0113] (7) Product structure and performance A double-sided symmetrical pre-embedded flux aluminum alloy composite material with a total thickness of 0.5 mm was obtained. The single-sided brazing functional layer (Al-Si alloy surface layer + flux / Al-Si alloy layer) has a thickness of about 0.05 mm, accounting for 10% of the total thickness, of which the Al-Si alloy surface layer is about 0.025 mm and the flux / Al-Si alloy layer is about 0.025 mm. The core material layer (3003 aluminum alloy substrate + 3003 aluminum alloy ingot) has a thickness of about 0.4 mm, accounting for 80% of the total thickness.
[0114] The composite interface showed no cracks or pores, and the interfacial bonding strength averaged 44 N / mm in a T-type peel test. Simulated CAB brazing (600℃×5min) resulted in a full weld with an average spread area of 492 mm², and no visible flux residue was observed on the surface after brazing.
[0115] Example 4 The method of Example 1 is followed, except that the thickness of the deposited substrate is 4 mm; the deposition thickness of the flux / Al-Si alloy layer is controlled at 5 mm; the deposition thickness of the Al-Si alloy surface layer is controlled at 7 mm; and a composite board comprising a 3003 aluminum alloy substrate (4 mm), a flux / Al-Si alloy layer (5 mm), and an Al-Si alloy surface layer (7 mm) is obtained.
[0116] The total thickness of the single-sided brazing functional layer (Al-Si alloy surface layer and flux / Al-Si alloy layer) is 12mm, and the proportion of the single-sided brazing functional layer to the final product thickness is 12mm / 75mm×100%=16%.
[0117] The rest is the same as in Example 1, and a double-sided symmetrical pre-embedded flux aluminum alloy composite material is prepared.
[0118] Product structure and performance A double-sided symmetrical pre-embedded flux aluminum alloy composite material with a total thickness of 0.8 mm was obtained. The single-sided brazing functional layer (Al-Si alloy surface layer + flux / Al-Si alloy layer) has a thickness of approximately 0.128 mm, accounting for 16% of the total thickness; of which the Al-Si alloy surface layer is approximately 0.075 mm and the flux / Al-Si alloy layer is approximately 0.053 mm; the core material layer (3003 aluminum alloy substrate + 3003 aluminum alloy ingot) has a thickness of approximately 0.544 mm, accounting for 68% of the total thickness.
[0119] The interfacial bonding strength, as measured by the T-type peel test, averaged 24 N / mm; the average spread area in simulated CAB brazing (600℃ × 6 min) was 480 mm². 2 No visible flux residue was found on the surface after brazing.
[0120] Example 5 The method of Example 1 is followed, except that the thickness of the deposited substrate is 8 mm; the deposition thickness of the flux / Al-Si alloy layer is controlled at 6 mm; the deposition thickness of the Al-Si alloy surface layer is controlled at 2 mm; and a composite board comprising a 3003 aluminum alloy substrate (8 mm), a flux / Al-Si alloy layer (6 mm), and an Al-Si alloy surface layer (2 mm) is obtained.
[0121] The total thickness of the single-sided brazing functional layer (Al-Si alloy surface layer and flux / Al-Si alloy layer) is 8mm, and the proportion of the single-sided brazing functional layer to the final product thickness is 8mm / 75mm×100%=10.67%.
[0122] The rest is the same as in Example 1, and a double-sided symmetrical pre-embedded flux aluminum alloy composite material is prepared.
[0123] Product structure and performance A double-sided symmetrical pre-embedded flux aluminum alloy composite material with a total thickness of 0.8 mm was obtained. The single-sided brazing functional layer (Al-Si alloy surface layer + flux / Al-Si alloy layer) has a thickness of approximately 0.085 mm, accounting for 10.67% of the total thickness; of which the Al-Si alloy surface layer is approximately 0.021 mm and the flux / Al-Si alloy layer is approximately 0.064 mm; the core material layer (3003 aluminum alloy substrate + 3003 aluminum alloy ingot) has a thickness of approximately 0.63 mm, accounting for 78.66% of the total thickness.
[0124] The interfacial bonding strength, as measured by the T-type peel test, averaged 28 N / mm; the average spread area in simulated CAB brazing (600℃ × 6 min) was 450 mm². 2 No visible flux residue was found on the surface after brazing.
[0125] Example 6 The method of Example 1 is followed, except that the thickness of the deposited substrate is 25 mm, resulting in a composite plate comprising a 3003 aluminum alloy substrate (25 mm), a flux / Al-Si alloy layer (2 mm), and an Al-Si alloy surface layer (4 mm). The thickness of the 3003 aluminum alloy ingot is 13 mm.
[0126] The rest is the same as in Example 1, and a double-sided symmetrical pre-embedded flux aluminum alloy composite material is prepared.
[0127] Product structure and performance A double-sided symmetrical pre-embedded flux aluminum alloy composite material with a total thickness of 0.8 mm was obtained. The single-sided brazing functional layer (Al-Si alloy surface layer + flux / Al-Si alloy layer) has a thickness of approximately 0.064 mm, accounting for 8% of the total thickness; of which the Al-Si alloy surface layer is approximately 0.043 mm and the flux / Al-Si alloy layer is approximately 0.021 mm; the core material layer (3003 aluminum alloy substrate + 3003 aluminum alloy ingot) has a thickness of approximately 0.672 mm, accounting for 84% of the total thickness.
[0128] The interfacial bonding strength, as measured by the T-type peel test, averaged 32 N / mm; the average spread area in simulated CAB brazing (600℃ × 6 min) was 470 mm². 2 No visible flux residue was found on the surface after brazing.
[0129] Comparative Example 1 This comparative example provides a friction extrusion additive manufacturing method for single-sided pre-embedded flux aluminum alloy composite materials, the specific steps of which are as follows: (1) Wire preparation Al-Si alloy wire: Same as in Example 2.
[0130] Al-Si alloy / flux hybrid wire: Same as Example 2.
[0131] (2) Substrate preparation Prepare a 44mm thick 3003 aluminum alloy ingot that has been milled flat as a deposition substrate.
[0132] (3) First layer deposition (flux / Al-Si alloy layer) Referring to Example 1, a composite comprising a 3003 aluminum alloy substrate and a flux / Al-Si alloy layer was obtained.
[0133] (4) Second layer deposition (Al-Si alloy surface layer) Referring to Example 1, a composite board comprising a 3003 aluminum alloy substrate (44mm), a flux / Al-Si alloy layer (1mm), and an Al-Si alloy surface layer (5mm) was obtained, with a total thickness of 50mm.
[0134] (5) Single-sided hot rolling The composite plate was heated to 470℃ and held for 6 hours. It was then hot-rolled for 7 passes on a hot rolling mill, with a total reduction of approximately 86%, a final rolling thickness of 7 mm, and a final rolling temperature of 320℃.
[0135] (6) Cold rolling and annealing Refer to Example 1.
[0136] (7) Product structure and performance A single-sided pre-embedded flux aluminum alloy composite material with a total thickness of 1.2 mm was obtained. The single-sided brazing functional layer (Al-Si alloy surface layer + flux / Al-Si alloy layer) has a thickness of approximately 0.144 mm, accounting for 12% of the total thickness; of which the Al-Si alloy surface layer is approximately 0.12 mm and the flux / Al-Si alloy layer is approximately 0.024 mm; the core material layer (3003 aluminum alloy ingot) has a thickness of approximately 1.056 mm, accounting for 88% of the total thickness.
[0137] The interfacial bonding strength, as measured by the T-type peel test, averaged 18 N / mm; the average spread area in simulated CAB brazing (600℃ × 6 min) was 180 mm². 2 After brazing, visible flux residue is visible on the surface.
[0138] Comparative Example 2 This comparative example provides a friction extrusion additive manufacturing method for double-sided pre-embedded flux aluminum alloy composite materials, the specific steps of which are as follows: (1) Wire preparation Al-Si alloy / flux hybrid wire: Same as Example 1.
[0139] (2) Substrate preparation Same as Example 1.
[0140] (3) Deposition of flux / Al-Si alloy layer Al-Si alloy / flux hybrid wire is loaded into a hollow, non-consumable tool head of a triboelectric additive manufacturing (TEM) machine. The tool head rotates at 800 rpm, the deposition rate is 250 mm / min, and the axial pressure is 6 kN. The tool head moves along a serpentine path on the deposition substrate, with an overlap of 20% between adjacent paths. Under the action of frictional heat and axial pressure, the wire tip is thermoplasticized and continuously extruded, depositing a flux / Al-Si alloy layer with a thickness controlled at 6 mm. After deposition, a composite board containing a 3003 aluminum alloy substrate and a flux / Al-Si alloy layer is obtained, with a total thickness of 16 mm.
[0141] (5) Hot-rolled composite (double-sided) Prepare two composite plates with milled surfaces and a 43mm thick 3003 aluminum alloy ingot. Stack the 3003 aluminum alloy substrate of the composite plate onto the top and bottom surfaces of the 3003 aluminum alloy ingot, with the flux / Al-Si alloy layer of the composite plate facing outwards, to obtain a laminated billet. The total thickness of the single-sided brazed functional layer (flux / Al-Si alloy layer) is 6mm, and the proportion of the single-sided brazed functional layer to the final product thickness is 6mm / 75mm × 100% = 8%. Hot-roll the laminated billet according to the method in Example 1.
[0142] (6) Cold rolling and annealing Refer to Example 1.
[0143] (7) Product structure and performance A double-sided symmetrical pre-embedded flux aluminum alloy composite material with a total thickness of 0.8 mm was obtained. The single-sided brazing functional layer (flux / Al-Si alloy layer) is about 0.064 mm thick, accounting for 8% of the total thickness; the core material layer (3003 aluminum alloy substrate + 3003 aluminum alloy ingot) is about 0.672 mm thick, accounting for 84% of the total thickness.
[0144] The interfacial bonding strength, as measured by the T-type peel test, averaged 13 N / mm; the average spread area in simulated CAB brazing (600℃ × 6 min) was 120 mm². 2 After brazing, a large amount of flux residue remains on the surface.
[0145] Comparative Example 3 This comparative example provides a double-sided symmetrical pre-embedded flux aluminum alloy composite material, including the following steps: (1) Preparation of pre-embedded flux billet Al-10.0wt%Si alloy powder (Dv) 50 =40μm, oxygen content 250ppm) and potassium fluoroaluminate flux powder (KAlF4-K2AlF5 mixed powder, KAlF4:K2AlF5 weight ratio is 5.7:1, Dv 50=25μm) were mixed uniformly at a weight ratio of 88:12. A V-type powder mixer was used at a speed of 5 r / min for 4 hours. The uniformly mixed powder was loaded into a stainless steel sleeve, sealed, and then placed in a hot isostatic press to obtain a hot isostatic ingot. The pressing process parameters were: vacuum to 2 Pa, temperature 470℃, pressure 120 MPa, and holding time for 4 hours. After pressing, the hot isostatic ingot was machined (milled) to remove the stainless steel sleeve. The thickness after milling was 6 mm, resulting in a flux-embedded ingot.
[0146] (2) Hot-rolled composite The aforementioned flux-embedded billets were stacked on both sides of a 63mm thick 3003 aluminum alloy ingot, resulting in a stacked billet with a total thickness of 75mm (of which the single-sided flux-embedded billet is 6mm thick, accounting for 8% of the total thickness). After heating to 480℃ and holding for 5 hours, it underwent 7 passes of hot rolling with a total reduction of approximately 92%, aiming for a final rolled thickness of approximately 6mm. However, during the hot rolling process, macroscopic cracks appeared at multiple points at the interface between the billet and the core material, and cracks also formed inside the billet. Therefore, subsequent steps were not performed.
[0147] Comparative Example 4 This comparative example provides a double-sided symmetrical pre-embedded flux aluminum alloy composite material, including the following steps: (1) Preparation of pre-embedded flux billet Al-10.0wt%Si alloy powder (Dv) 50 =40μm, oxygen content 250ppm) and potassium fluoroaluminate flux powder (KAlF4-K2AlF5 mixed powder, KAlF4:K2AlF5 weight ratio is 5.7:1, Dv 50 =25μm) were mixed uniformly at a weight ratio of 96:4. A V-type powder mixer was used at a speed of 5 r / min for 4 hours. The uniformly mixed powder was placed into a stainless steel sleeve, sealed, and then placed in a hot isostatic press to obtain a hot isostatic ingot. The pressing process parameters were: vacuum to 2 Pa, temperature 470℃, pressure 120 MPa, and holding time for 4 hours. After pressing, the hot isostatic ingot was machined (milled) to remove the stainless steel sleeve. The thickness after milling was 6 mm, resulting in a flux-embedded ingot.
[0148] (2) Hot-rolled composite The above-mentioned flux-embedded billet is stacked on the upper and lower sides of a 63mm thick 3003 aluminum alloy ingot to obtain a stacked billet with a total thickness of 75mm (of which the thickness of the single-sided pre-embedded flux billet is 6mm, accounting for 8% of the total thickness). After being heated to 480℃ and held for 5 hours, it is hot rolled in 7 passes with a total reduction rate of about 92% and a target final rolled thickness of about 6mm.
[0149] (3) Cold rolling and annealing The hot-rolled plate was cooled to room temperature and then cold-rolled in 8 passes with a reduction of 20%-25% per pass, resulting in a final rolled thickness of 0.8 mm. The finished product was then annealed: held at 390℃ for 3 hours and air-cooled to obtain a double-sided symmetrical aluminum alloy composite material with embedded flux.
[0150] (4) Product performance Simulated CAB brazing (600℃×5min), average spread area 76mm. 2 Furthermore, a small amount of flux residue remains on the surface after brazing.
[0151] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.
Claims
1. A method for preparing a pre-embedded flux aluminum alloy composite material, characterized in that, Includes the following steps: S1. By friction extrusion additive manufacturing, a flux / Al-Si alloy layer containing flux and Al-Si alloy, and an Al-Si alloy surface layer are sequentially solid-phase deposited on an aluminum alloy substrate to obtain a composite board. S2. The aluminum alloy substrate in the composite plate is stacked on at least one surface of the aluminum alloy ingot, and then hot-rolled to obtain a pre-embedded flux aluminum alloy composite material.
2. The preparation method according to claim 1, characterized in that, The flux / Al-Si alloy layer is formed by friction extrusion additive manufacturing of a first feed material, and the Al-Si alloy surface layer is formed by friction extrusion additive manufacturing of a second feed material; the first feed material includes flux / Al-Si alloy wire formed by extruding a mixture of Al-Si alloy powder and flux powder, and the second feed material includes Al-Si alloy wire.
3. The preparation method according to claim 2, characterized in that, Al-Si alloy powder is mixed with flux powder and then extruded into wire at 100℃-200℃. And / or, the diameter of the Al-Si alloy wire is 3mm-8mm; And / or, the diameter of the flux / Al-Si alloy wire is 3mm-8mm.
4. The preparation method according to claim 2, characterized in that, The weight ratio of the Al-Si alloy powder to the flux powder is (80-95):(5-20); And / or, the mass content of Si in the Al-Si alloy powder is 7%-12.5%; And / or, the flux includes potassium fluoroaluminate-based flux, which includes KAlF4 and K2AlF5; And / or, the mass content of Si in the Al-Si alloy wire is 7%-12.5%.
5. The preparation method according to claim 1, characterized in that, The aluminum alloy substrate is made of 3-series aluminum alloy and / or 4-series aluminum alloy. And / or, the material of the aluminum alloy ingot includes 3-series aluminum alloys and / or 4-series aluminum alloys; And / or, the aluminum alloy substrate and the aluminum alloy ingot are made of the same material.
6. The preparation method according to claim 1, characterized in that, The thickness ratio of the aluminum alloy substrate, the flux / Al-Si alloy layer, and the Al-Si alloy surface layer is (5-20):(1-3):(1-5). And / or, based on the total thickness of the aluminum alloy substrate, the flux / Al-Si alloy layer, the Al-Si alloy surface layer and the aluminum alloy ingot, the thickness ratio of the flux / Al-Si alloy layer and the Al-Si alloy surface layer is 8%-15%.
7. The preparation method according to claim 1, characterized in that, In step S1, the tool head of the triboelectric additive manufacturing moves in a serpentine path and creates a lateral overlap between adjacent deposition trajectories to deposit the flux / Al-Si alloy layer and / or the Al-Si alloy surface layer, wherein the overlap rate between adjacent deposition trajectories is 10%-20%. And / or, in step S1, the tool head of the friction extrusion additive manufacturing process rotates at a speed of 500 rpm to 1500 rpm and applies an axial pressure of 3 kN to 10 kN. And / or, in step S1, the deposition rate of the solid phase deposition is 100 mm / min-400 mm / min.
8. The preparation method according to any one of claims 1-7, characterized in that, In step S2, the hot rolling composite method includes: holding at 450℃-500℃ for 4h-6h and then performing multiple hot rolling passes, with the final rolling temperature not lower than 300℃. And / or, the preparation method further includes hot rolling followed by cold rolling and annealing.
9. The preparation method according to claim 8, characterized in that, The conditions for cold rolling include: a single-pass reduction of 20%-30%; And / or, the annealing conditions include: holding at 380℃-400℃ for 2h-4h.
10. A pre-embedded flux aluminum alloy composite material, characterized in that, It is prepared by the method for preparing the pre-embedded flux aluminum alloy composite material according to any one of claims 1-9.