Die-casting aluminum alloy capable of being brazed as well as preparation method, manufacturing process and brazing process of die-casting aluminum alloy

Abstract

The invention relates to the technical field of aluminum alloy materials, and provides a brazed die-casting aluminum alloy and a preparation method, manufacturing and brazing process thereof, and the brazed die-casting aluminum alloy comprises the following components in percentage by mass: 1.0%-4.0% of Fe, 0.5%-2.5% of Cr, 0.3%-1.0% of Si, 0.05%-0.5% of V, 0.05%-0.5% of Mo, 0.05%-0.5% of W, 0.05%-0.5% of Y, 0.05%-0.5% of Ce, 0.05%-0.5% of Eu and the balance of Al. Wherein the total content of the three elements V, Mo and W is larger than or equal to 0.8%, the total content of the three elements Y, Ce and Eu is larger than or equal to 0.6%, the content of other inevitable single impurity elements is smaller than or equal to 0.03%, the total content of the impurity elements is smaller than or equal to 0.15%, and the balance is aluminum. By means of the elements, the alloy has excellent melt fluidity, heat resistance, good mechanical properties and the like, the die-casting formability and brazing adaptability can be balanced, a solution with low-cost die-casting and stable brazing is formed, and the core requirements of the new energy industry are met.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy materials technology, specifically to a brazable die-cast aluminum alloy and its preparation method, manufacturing process and brazing process. Background Technology

[0002] Brazing is a process that uses low-melting-point filler metals to achieve a strong connection between metal workpieces. It is widely used in the manufacture of aluminum alloy components, especially in the production of key components such as water-cooled radiators in new energy vehicles and energy storage fields. Currently, aluminum alloy brazing mostly uses 4000 series (Al-Si series) filler metals with a liquidus temperature below 620℃. It is required that the solidus temperature of the base material be higher than the liquidus temperature of the filler metal to ensure the stability of the base material morphology during brazing.

[0003] Currently, the aluminum alloys suitable for this brazing process are mainly 1000 and 3000 series. However, these require thick plates or forgings as raw materials and are machined, resulting in long production processes, high cutting losses, and high overall costs, making it difficult to meet the urgent need of the new energy industry for "efficiency improvement and cost reduction" in water-cooled radiators. In contrast, die casting is a preferred manufacturing method for aluminum alloy components due to its high forming efficiency and strong adaptability. However, existing die-cast aluminum alloys are generally not compatible with the brazing process, with the core issues concentrated in the solid-liquid phase temperature and elemental properties.

[0004] Traditional die-cast aluminum alloys are mostly Al-Si systems, whose solid-liquid phase temperatures are close to those of 4000 series brazing filler metals. During brazing, the base material is prone to melting or softening. Meanwhile, heat treatment-free processing is the mainstream development direction of die-casting technology. To improve the mechanical properties of the die-cast state (F state), Mg is usually added. However, while Mg achieves precipitation strengthening through solid solution strengthening and precipitation of the β” phase, it significantly lowers the solid-liquid phase temperature of the alloy. Moreover, it is prone to oxidation at brazing temperatures above 620℃, which hinders the flow and wetting of the filler metal. As a result, such alloys can only be brazed in a vacuum environment, which limits their applicability.

[0005] To address the brazing challenges of die-cast aluminum alloys, the industry has explored relevant technologies. However, existing solutions have not yet overcome the core contradictions, particularly regarding the crucial indicator of "solidspan temperature matching." For example, some solutions focusing on brazable die-cast aluminum alloys either suffer from insufficient liquid fluidity due to the use of Mn as the main alloying element, making them unsuitable for the molding requirements of complex water-cooled radiators, or excessive Si and Mg additions significantly lower the alloy's solidspan temperature, increasing the risk of brazing melting; or, due to the high content of Si, Mg, and Cu, the solidspan temperature is directly too low, leading to significant overheating issues during brazing. None of these solutions fundamentally balance the core requirements of "die-casting formability" and "brazing adaptability." In summary, existing technologies have consistently failed to provide an effective solution for both low-cost die casting and stable brazing. Summary of the Invention

[0006] In view of the above-mentioned shortcomings of the prior art, the present invention provides a brazable die-cast aluminum alloy, its preparation method, manufacturing and brazing process.

[0007] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, a brazable die-cast aluminum alloy is provided, comprising, by weight percentage: Fe: 1.0%~4.0%, Cr: 0.5%~2.5%, Si: 0.3%~1.0%, V: 0.05%~0.5%, Mo: 0.05%~0.5%, W: 0.05%~0.5%, Y: 0.05%~0.5%, Ce: 0.05%~0.5%, Eu: 0.05%~0.5%; The total content of V, Mo, and W is ≥0.8%, the total content of Y, Ce, and Eu is ≥0.6%, other unavoidable single impurity elements are ≤0.03%, the total amount of impurity elements is ≤0.15%, and the balance is aluminum.

[0008] In some embodiments, the composition, by mass percentage, includes: Fe: 1.5%–3.5%, Cr: 0.8%–2.2%, Si: 0.4%–0.8%, V: 0.08%–0.45%, Mo: 0.08%–0.45%, W: 0.08%–0.45%, Y: 0.08%–0.4%, Ce: 0.08%–0.4%, and Eu: 0.08%–0.4%. The total content of V, Mo, and W is ≥0.9%, the total content of Y, Ce, and Eu is ≥0.7%, other unavoidable single impurity elements are ≤0.03%, the total amount of impurity elements is ≤0.15%, and the balance is aluminum.

[0009] Secondly, a method for preparing a brazable die-cast aluminum alloy is provided, comprising: Weigh the raw materials according to the formula requirements; The raw materials are subjected to multiple refining processes, and samples are taken for analysis until the element content is adjusted to the required content of the formula to obtain a refined melt. The refined melt is subjected to two-stage filtration and then cast. During the casting process, permanent magnet stirring is applied to the melt entering the mold. After solidification, a brazable die-cast aluminum alloy ingot is obtained. In some embodiments, the operating parameters for the multiple refining processes include: The first refining process uses high-purity argon gas to inject a remelting refining agent. The amount of the remelting refining agent is 0.1% to 0.5% of the total amount of material in the furnace. The refining time is 20 min to 40 min, and the refining temperature is 720℃ to 820℃. The second refining process uses high-purity argon gas to inject a remelting refining agent. The amount of the remelting refining agent is 0.1% to 0.3% of the total amount of material in the furnace. The refining time is 10 min to 30 min, and the refining temperature is 700℃ to 800℃.

[0010] In some embodiments, the operating parameters of the two-stage filtration process include: The first-stage filter plate has a mesh size of 60, and the second-stage filter plate has a mesh size of 80.

[0011] In some embodiments, the operating parameters of the permanent magnet stirrer include: a magnetic induction intensity of 2000 Gs to 6000 Gs and a magnet rotation speed of 200 r / min to 800 r / min.

[0012] Thirdly, a manufacturing and brazing process for brazable die-cast aluminum alloy parts is provided, including: A brazable die-cast aluminum alloy ingot is loaded into an aluminum melting furnace, heated and remelted while being stirred. The brazable die-cast aluminum alloy ingot is prepared by the method for preparing brazable die-cast aluminum alloy described in any of the above embodiments. After refining, it is kept at a certain temperature to obtain a die-cast melt. The die casting melt is transferred to a cold chamber die casting machine for die casting, and after cooling, a die casting part is obtained. The brazing connection surface of the die casting is milled and degreased. After completion, brazing solder is evenly applied to the brazing connection surface, and the part is fixed with a fixture and placed in a brazing furnace for brazing. After the workpiece is taken out of the furnace, it is cooled to room temperature to obtain the product.

[0013] In some embodiments, the operating parameters of the refining process include: The remelting agent is injected with high-purity argon gas. The amount of the remelting agent is 0.1% to 0.4% of the total amount of material in the furnace. The refining time is 10 min to 30 min and the refining temperature is 700℃ to 800℃.

[0014] In some embodiments, the die casting process is configured as high-pressure die casting, and the operating parameters include: The die-casting temperature is 680℃~780℃. During the die-casting process, the first-stage injection speed is 0.1m / s~0.6m / s, the second-stage injection speed is 0.4m / s~1.8m / s, the third-stage injection speed is 2.5m / s~10m / s, the die-casting pressure is 50MPa~150MPa, and the holding pressure is 20s~40s.

[0015] In some embodiments, the working parameters of the brazing process include: a brazing temperature of 600℃~630℃ and a brazing holding time of 2min~14min.

[0016] Compared with the prior art, the beneficial effect of the present invention is that the Al-Fe-Cr ternary alloy system will undergo a ternary eutectic reaction (L→α-Al+Al) at 655℃~658℃. 13 Fe⁴⁺θ imparts excellent melt fluidity to the alloy, making it perfectly suited for die casting processes; its reaction temperature is also higher than the commonly used brazing temperature (≤620℃), thus ensuring stable brazing of the alloy. V, Mo, and W can respectively form intermediate phases with Al, such as Al₂O₃. 21 V2, Al3Mo, and Al3W are added to improve the heat resistance of the alloy. Simultaneously, Si reacts with Cr and Fe to form α-Al(Cr,Fe)Si2 intermetallic compounds, transforming the originally brittle compounds in the alloy into spherical or blocky shapes and refining them, effectively strengthening the matrix. This eliminates the need for high Mg content to ensure mechanical strength, thus avoiding the drawbacks of Mg oxidation hindering solder wetting and lowering the solidus temperature, overcoming the limitations of vacuum brazing. Rare earth elements Y, Ce, and Eu form complex intermetallic compounds with Cr and Fe, altering their preferred growth pattern and transforming them from lath and lanceolate to equiaxed and blocky morphologies. Furthermore, because the intermediate phase containing rare earth elements precipitates first during solidification, it can become a precursor for α-Al and Al2O3 intermetallic compounds. 13 Fe4+ intermediate phase nucleates complex intermetallic compounds, thereby increasing its nucleation rate and reducing the size of these intermetallic compounds. This invention integrates these characteristics, balancing die-casting formability and brazing adaptability to form a low-cost die-casting and stable brazing solution, meeting the core needs of the new energy industry. Attached Figure Description

[0017] Figure 1 This is a metallographic schematic diagram of the brazable die-cast aluminum alloy ingot provided by the present invention; Figure 2 This is a SEM image of the brazable die-cast aluminum alloy die-casting part provided by the present invention; Figure 3 This is a schematic diagram of the DSC analysis results of the brazable die-cast aluminum alloy provided by the present invention; Figure 4 This is a schematic diagram of the DSC analysis results for 3003 aluminum alloy. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. The described embodiments are some, but not all, of the embodiments of the present invention.

[0019] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0020] This invention provides a brazable die-cast aluminum alloy comprising, by mass percentage: Fe: 1.0%–4.0%, Cr: 0.5%–2.5%, Si: 0.3%–1.0%, V: 0.05%–0.5%, Mo: 0.05%–0.5%, W: 0.05%–0.5%, Y: 0.05%–0.5%, Ce: 0.05%–0.5%, Eu: 0.05%–0.5%; wherein the total content of V, Mo, and W is ≥0.8%, the total content of Y, Ce, and Eu is ≥0.6%, other unavoidable single impurity elements are ≤0.03%, the total amount of impurity elements is ≤0.15%, and the balance is aluminum.

[0021] Specifically, the selection of the specific content of each component shall be based on actual production needs and is not limited here.

[0022] Furthermore, the brazable die-cast aluminum alloy comprises, by mass percentage: Fe: 1.5%–3.5%, Cr: 0.8%–2.2%, Si: 0.4%–0.8%, V: 0.08%–0.45%, Mo: 0.08%–0.45%, W: 0.08%–0.45%, Y: 0.08%–0.4%, Ce: 0.08%–0.4%, Eu: 0.08%–0.4%; wherein the total content of V, Mo, and W is ≥0.9%, the total content of Y, Ce, and Eu is ≥0.7%, other unavoidable single impurity elements are ≤0.03%, the total amount of impurity elements is ≤0.15%, and the balance is aluminum.

[0023] The functions of each element are as follows: Main alloying elements Fe and Cr: Theoretically, in the Al-Fe-Cr ternary alloy system, thermodynamic analysis shows that the alloy will undergo a ternary eutectic reaction in the temperature range of 655℃ to 658℃. The standard reaction formula can be expressed as: L→α-Al+Al 13 Fe4+θ, where L represents the liquid phase, α-Al is an aluminum-based solid solution, and Al 13Fe4 is an intermetallic compound of iron and aluminum, while the θ phase is a ternary intermediate phase containing Cr. This ternary eutectic reaction has a dual positive effect on the alloy's properties: On the one hand, the reaction enables the alloy to obtain excellent melt flowability and filling capacity within a suitable range close to the eutectic temperature—the low viscosity characteristics during the liquid-to-multi-solid phase transition in the eutectic reaction effectively improve the filling effect of the alloy melt on the die-casting mold cavity, thus meeting the core requirements of die-casting process for the formability of aluminum alloys; on the other hand, the eutectic reaction temperature of this system, 655℃~658℃, is significantly higher than the temperature of the commonly used high-temperature brazing process for aluminum alloys (usually ≤620℃). This temperature difference ensures that the alloy base material will not melt or overheat due to reaching the eutectic temperature during brazing, providing a key thermodynamic guarantee for the stable brazing of the alloy.

[0024] Transition metal elements V, Mo, and W, which improve heat resistance: all three are transition metals, and their elemental forms all have relatively high melting points. Theoretically, in aluminum alloy systems, these three elements can form intermediate phases with Al, such as Al... 21 V2, Al3Mo, and Al3W, these three intermediate phases, have high melting points, meaning they exhibit high thermal stability. They can remain stable at high temperatures for extended periods without transforming into other phases or softening, which is one aspect of their thermal stability. Furthermore, V, Mo, and W have extremely low diffusion coefficients in aluminum alloys. Once formed, the size of these intermediate phases does not change significantly even at high temperatures, which is another aspect of their thermal stability. In actual alloy systems, V, Mo, and W form more complex intermetallic compounds in aluminum alloys, exhibiting extremely high thermal stability. Moreover, by controlling process parameters during casting and solidification, these intermetallic compounds can be uniformly and diffusely distributed in relatively small sizes within the alloy. During high-temperature brazing, they act as a skeletal support, ensuring the alloy possesses high high-temperature strength.

[0025] The modifying elements Si and rare earth elements Y, Ce, and Eu: In the Al-Fe-Cr ternary alloy system, Si can induce the formation of α-Al(Cr,Fe)Si2 type intermetallic compounds through interfacial reactions with Cr and Fe. This reaction can not only alter the primary Fe and Cr-based intermetallic compounds in the alloy (such as Al...) 13The growth habits of Fe4 and θ phases can transform the brittle needle-like and plate-like morphology into more stable spherical or blocky forms. Furthermore, the size of the compounds can be significantly refined, allowing for dispersed distribution within the aluminum matrix, thus effectively modifying the alloy. This modification effect, regulated by Si, further enhances the overall performance of the alloy—the spherical and blocky α-Al(Cr,Fe)Si2 compounds reduce stress concentration, while the refined and dispersed distribution simultaneously strengthens the matrix, providing structural support for the alloy to achieve both die-casting formability and mechanical properties.

[0026] The three rare earth elements Y, Ce, and Eu: θ and Al, without metamorphism. 13 The Fe4 mesophase tends to form coarse lamellar or acicular morphologies, characterized by small thickness dimensions but large width and length dimensions. At the phase interface with the α-Al matrix, it easily leads to stress concentration and crack initiation, thus exerting a severing effect on the α-Al matrix. This significantly reduces the alloy's strength and service safety at room temperature. However, by incorporating appropriate amounts of Y, Ce, and Eu, in aluminum alloy systems, rare earth elements Y, Ce, and Eu tend to form complex intermetallic compounds with Cr and Fe, altering their preferred growth pattern and transforming them from lamellar and acicular morphologies to equiaxed and blocky morphologies. Furthermore, because the mesophase containing rare earth elements precipitates first during solidification, it can become a precursor for θ and Al... 13 Fe4 intermediate phases form nuclei of complex intermetallic compounds, thereby increasing their nucleation rate and reducing the size of these intermetallic compounds.

[0027] The brazable die-cast aluminum alloy of the present invention is micro-alloyed by rationally optimizing alloying elements and adding appropriate amounts of rare earth elements, so that the material has a high solid-liquid phase temperature, which can meet both the requirements of die casting formability and the requirements of high-temperature brazing of aluminum alloys, thus broadening the application range of die casting technology and the parts produced therefrom.

[0028] This invention provides a method for preparing a brazable die-cast aluminum alloy, comprising the following steps: S110, weigh the raw materials according to the formula requirements.

[0029] Specifically, the raw materials are weighed according to their main components: aluminum ingots, aluminum-iron master alloys, aluminum-chromium master alloys, metallic silicon, aluminum-vanadium master alloys, aluminum-molybdenum master alloys, aluminum-tungsten master alloys, aluminum-yttrium master alloys, aluminum-cerium master alloys, and aluminum-europium master alloys.

[0030] S120 involves refining the raw materials multiple times, taking samples for analysis until the element content is adjusted to the required content in the formula, and obtaining a refined melt.

[0031] The specific steps are as follows: (1) Aluminum ingots, aluminum-iron master alloys, aluminum-chromium master alloys, metallic silicon, aluminum-vanadium master alloys, aluminum-molybdenum master alloys, and aluminum-tungsten master alloys are loaded into a melting and holding furnace and heated and held at a temperature of 760℃~860℃. Mechanical stirring is applied to the melt to make the alloy elements uniform.

[0032] (2) The first refining process is carried out, followed by settling and slag removal; the first refining process uses high-purity argon gas to blow remelting refining agent, the amount of remelting refining agent is 0.1% to 0.5% of the total amount of material in the furnace, the refining time is 20 min to 40 min, and the refining temperature is 720℃ to 820℃.

[0033] (3) Add aluminum yttrium master alloy, aluminum cerium master alloy and aluminum europium master alloy and heat-hold melt at 700℃~800℃. During this period, mechanical stirring is applied to the melt. Then a small amount of sample is taken from the high temperature melt for chemical composition analysis. If there is a deviation in composition, the composition is adjusted and the sample is taken again for analysis until all elements reach the expected index. (4) Perform a second refining process, then let it stand and remove the slag. After refining, take a sample for analysis again. If the composition is still within the expected range, proceed to the next process. If the composition deviates, adjust the composition until all elements reach the expected range before proceeding to the next process. The second refining process uses high-purity argon gas to blow remelting refining agent. The amount of remelting refining agent is 0.1% to 0.3% of the total amount of material in the furnace. The refining time is 10 min to 30 min and the refining temperature is 700℃ to 800℃.

[0034] Furthermore, the total time for the two refining processes is 30 to 60 minutes.

[0035] S130 involves a two-stage filtration process for the refined melt, followed by casting. During casting, a permanent magnet is applied to the melt entering the mold, and after solidification, a brazable die-cast aluminum alloy ingot is obtained.

[0036] Specifically, the refined melt is released from the bottom of the furnace into the runner. The melt in the runner first undergoes a two-stage filtration process before entering the automatic ingot casting machine for casting. The alloy melt entering the mold is then subjected to permanent magnet stirring. After solidification, a brazable die-cast aluminum alloy ingot is obtained.

[0037] The operating parameters for the dual-stage filtration process include: the first-stage filter plate is 60 mesh, and the second-stage filter plate is 80 mesh.

[0038] The casting temperature is 660℃~760℃.

[0039] The operating parameters of the permanent magnet stirrer include: magnetic induction intensity of 2000Gs~6000Gs and magnet rotation speed of 200r / min~800r / min.

[0040] It is worth noting that the brazable die-cast aluminum alloy ingot of the present invention undergoes permanent magnetic stirring during the solidification process of the melt. This enhances the heat and mass transfer processes within the melt during solidification, reduces the temperature and concentration gradients within the undried melt, and ensures uniform composition. Furthermore, the applied external permanent magnetic stirring can effectively refine various intermetallic compounds that precipitate out during crystallization.

[0041] refer to Figure 1 As can be seen from the metallographic diagram of the brazable die-cast aluminum alloy ingot prepared according to this method and the formula of the present invention, the intermetallic compounds in the alloy are spherical and blocky dispersed, without brittle needle-like phases, which can reduce stress concentration and improve the mechanical properties of the die-cast state; the phase size is fine and the distribution is uniform, which not only ensures that the melt fluidity is suitable for die casting, but also supports stable brazing, perfectly matching the core requirements of both.

[0042] This invention provides a manufacturing process and brazing process for a brazable die-cast aluminum alloy die-casting part, comprising the following steps: Step 1: The brazable die-cast aluminum alloy ingot is placed into the aluminum melting furnace, heated and remelted while being stirred. The brazable die-cast aluminum alloy ingot is prepared by the above method for preparing brazable die-cast aluminum alloy. After refining, it is kept at a certain temperature to obtain the die-cast melt.

[0043] Specifically, the brazable die-cast aluminum alloy ingot is loaded into an aluminum melting furnace, heated and remelted, stirred, and then the alloy melt is refined. After standing, the slag is removed, and the melt is kept at a certain temperature range.

[0044] The remelting and heat preservation temperature is 700℃~800℃.

[0045] The refining process parameters include: using high-purity argon gas to inject remelting refining agent, with the amount of remelting refining agent being 0.1% to 0.4% of the total material in the furnace, the refining time being 10 min to 30 min, and the refining temperature being 700℃ to 800℃.

[0046] Step 2: Transfer the die casting melt to a cold chamber die casting machine for die casting, and obtain the die casting after cooling.

[0047] Specifically, a robotic arm is used to transfer the molten alloy to a cold chamber die casting machine for die casting. The die casting process is set to high-pressure die casting, and the operating parameters include: The die-casting temperature is 680℃~780℃. During the die-casting process, the first-stage injection speed is 0.1m / s~0.6m / s, the second-stage injection speed is 0.4m / s~1.8m / s, the third-stage injection speed is 2.5m / s~10m / s, the die-casting pressure is 50MPa~150MPa, and the holding pressure is 20s~40s.

[0048] Step 3: Mill and degrease the brazing joint surface of the die casting. After completion, apply brazing solder evenly to the brazing joint surface, fix it with a fixture, and place it in the brazing furnace for brazing. After the workpiece is removed from the furnace, it is cooled to room temperature to obtain the product.

[0049] Specifically, the brazing joint surfaces of die-cast parts manufactured from different molds are milled and degreased. Brazing solder is then evenly applied to the brazing joint surfaces, and the parts are fixed with fixtures before brazing. The working parameters for brazing include: brazing temperature of 600℃~630℃ and brazing holding time of 2min~14min.

[0050] It is worth noting that the aluminum alloy material involved in this invention can not only be brazed in the die-cast state, but also has good room temperature mechanical properties and excellent thermal conductivity, making it very suitable for the production of water-cooled radiator components used in industries such as new energy vehicles and energy storage, thereby achieving efficiency improvement and cost reduction.

[0051] refer to Figure 2 This is a SEM image of the brazable die-cast aluminum alloy die-casting part provided by the present invention. As can be seen, the 10,000x SEM image shows that the alloy phase exhibits a refined and regular morphology, with no acicular or brittle phases and a uniform distribution. This structure not only improves melt fluidity, adapting to the efficient molding of complex die-cast parts, but also strengthens the properties of the die-cast matrix, preventing phase coarsening and deterioration during brazing, perfectly supporting the dual performance requirements of die casting and brazing. Simultaneously, the alloy phase and aluminum matrix interface are tightly bonded with no obvious gaps, reducing the risk of interface cracking under stress and improving mechanical property stability. The good uniformity of phase size and the absence of obvious compositional segregation indicate precise compositional control during the die-casting process, which is beneficial for consistent performance in mass production. The material is free of microcracks, porosity, and other defects, exhibiting high density, which also ensures effective filling of the brazing filler metal during brazing, further enhancing joint strength.

[0052] Example 1 A brazable die-cast aluminum alloy comprising, by mass percentage: Fe: 2.8%, Cr: 1.6%, Si: 0.6%, V: 0.29%, Mo: 0.41%, W: 0.37%, Y: 0.32%, Ce: 0.26%, Eu: 0.14%, Si ≤ 0.15%, other unavoidable single impurity elements ≤ 0.03%, total impurity elements ≤ 0.15%, and the balance being aluminum.

[0053] A method for preparing a brazable die-cast aluminum alloy, comprising: Weighing and material preparation; Aluminum ingots, aluminum-iron master alloys, aluminum-chromium master alloys, metallic silicon, aluminum-vanadium master alloys, aluminum-molybdenum master alloys, and aluminum-tungsten master alloys are loaded into a melting and holding furnace, heated to 840℃, and mechanically stirred during the process to ensure uniform composition. The first refining process was carried out at 780℃, with the amount of remelting refining agent being 0.4% of the total material volume, and the refining time being 30 minutes. After the process was completed, the material was allowed to stand and the slag was removed. Add aluminum yttrium master alloy, aluminum cerium master alloy, and aluminum europium master alloy at 780℃ and keep warm. Then, mechanically stir to make the composition uniform. After sampling and testing to ensure compliance, proceed to the next process. The second refining process is carried out at 760℃, with the amount of remelting refining agent being 0.2% of the total material and the refining time being 15 minutes. After the process is completed, the material is allowed to stand, the slag is removed, and samples are taken for testing. Once the samples meet the standards, the refined melt is obtained and proceeds to the next process. The refined melt is released from the bottom of the furnace into the flow channel. The melt in the flow channel first passes through a double-stage filtration process of 60 mesh and 80 mesh, and then flows into the casting mold through an automatic ingot casting machine. The melt is subjected to the stirring action of a permanent magnet with a magnetic induction intensity of 5000 Gs and a magnet rotation speed of 700 rpm in the mold. After gradually solidifying, a brazable die-cast aluminum alloy ingot is obtained.

[0054] A manufacturing and brazing process for a brazable die-cast aluminum alloy part includes the following steps: The brazable die-cast aluminum alloy ingot is loaded into the aluminum melting furnace, heated to 780°C, remelted, and stirred evenly. The material is refined at 760℃, with the amount of remelting refining agent being 0.2% of the total material volume. The refining time is 20 minutes. After the refining is completed, the material is allowed to stand and the slag is removed to obtain the die-casting melt. Die casting was started at 720℃. The first injection speed was 0.2m / s, the second injection speed was 1.1m / s, and the third injection speed was 4.5m / s. The die casting pressure was 120MPa, and the pressure was held for 30 seconds to obtain the die casting. The connecting surfaces of the workpieces to be brazed are milled, degreased, and then brazing filler is applied to the connecting surfaces. The workpieces are then assembled, and after the fixture is installed, they are placed in the brazing furnace for brazing. The actual temperature of the brazing working area of ​​the brazing furnace is 620℃. After holding at this temperature for 10 minutes, the workpieces are removed from the furnace and cooled to complete the brazing process and obtain the desired product.

[0055] Example 2 A brazable die-cast aluminum alloy comprising, by mass percentage: Fe: 3.0%, Cr: 1.2%, Si: 0.53%, V: 0.18%, Mo: 0.42%, W: 0.36%, Y: 0.25%, Ce: 0.34%, Eu: 0.12%, other unavoidable single impurity elements ≤0.03%, total impurity elements ≤0.15%, and the balance being aluminum.

[0056] A method for preparing a brazable die-cast aluminum alloy, comprising: Weighing and material preparation; Aluminum ingots, aluminum-iron master alloys, aluminum-chromium master alloys, metallic silicon, aluminum-vanadium master alloys, aluminum-molybdenum master alloys, and aluminum-tungsten master alloys are loaded into a melting and holding furnace, heated to 820°C, and mechanically stirred during the process to ensure uniform composition. The first refining process was carried out at 760℃, with the amount of remelting refining agent being 0.3% of the total material volume, and the refining time being 30 minutes. After the process was completed, the material was allowed to stand and the slag was removed. Add aluminum yttrium master alloy, aluminum cerium master alloy, and aluminum europium master alloy at 760℃ and keep warm. Then, mechanically stir to make the composition uniform. After sampling and testing to ensure compliance, proceed to the next process. The second refining process is carried out at 740℃, with the amount of remelting refining agent being 0.3% of the total material and the refining time being 20 minutes. After the process is completed, the material is allowed to stand, the slag is removed, and samples are taken for testing. Once the samples meet the standards, the refined melt is obtained and proceeds to the next process. The refined melt is released from the bottom of the furnace into the flow channel. The melt in the flow channel first passes through a double-stage filtration process of 60 mesh and 80 mesh, and then flows into the casting mold through an automatic ingot casting machine. The melt is subjected to the stirring action of a permanent magnet with a magnetic induction intensity of 5500 Gs and a magnet rotation speed of 600 rpm in the mold. After gradually solidifying, a brazable die-cast aluminum alloy ingot is obtained.

[0057] A manufacturing and brazing process for a brazable die-cast aluminum alloy part includes the following steps: The brazable die-cast aluminum alloy ingot is loaded into the aluminum melting furnace, heated to 760°C, remelted, and stirred evenly. The material is refined at 750℃, with the amount of remelting refining agent being 0.3% of the total material volume. The refining time is 20 minutes. After the refining is completed, the material is allowed to stand and the slag is removed to obtain the die-casting melt. Die casting was started at 720℃. The first injection speed was 0.3m / s, the second injection speed was 1.6m / s, and the third injection speed was 6.5m / s. The die casting pressure was 100MPa, and the pressure was held for 20 seconds to obtain the die casting. The connecting surfaces of the workpieces to be brazed are milled, degreased, and then brazing filler is applied to the connecting surfaces. The workpieces are then assembled, and after the fixture is installed, they are placed in the brazing furnace for brazing. The actual temperature of the brazing working area of ​​the brazing furnace is 620℃. After holding at this temperature for 10 minutes, the workpieces are removed from the furnace and cooled to complete the brazing process and obtain the desired product.

[0058] Example 3 A brazable die-cast aluminum alloy comprising, by mass percentage: Fe: 3.2%, Cr: 2.0%, Si: 0.76%, V: 0.42%, Mo: 0.37%, W: 0.33%, Y: 0.36%, Ce: 0.30%, Eu: 0.25%, other unavoidable individual impurity elements ≤0.03%, total impurity elements ≤0.15%, and the balance being aluminum.

[0059] A method for preparing a brazable die-cast aluminum alloy, comprising: Weighing and material preparation; Aluminum ingots, aluminum-iron master alloys, aluminum-chromium master alloys, metallic silicon, aluminum-vanadium master alloys, aluminum-molybdenum master alloys, and aluminum-tungsten master alloys are loaded into a melting and holding furnace, heated to 850°C, and mechanically stirred during the process to ensure uniform composition. The first refining process was carried out at 800℃, with the amount of remelting refining agent being 0.4% of the total material volume, and the refining time being 30 minutes. After the process was completed, the material was allowed to stand and the slag was removed. Add aluminum yttrium master alloy, aluminum cerium master alloy, and aluminum europium master alloy at 800℃ and keep warm. Then, mechanically stir to make the composition uniform. After sampling and testing to ensure compliance, proceed to the next process. The second refining process is carried out at 760℃, with the amount of remelting refining agent being 0.3% of the total material and the refining time being 20 minutes. After the process is completed, the material is allowed to stand, the slag is removed, and samples are taken for testing. Once the samples meet the standards, the refined melt is obtained and proceeds to the next process. The refined melt is released from the bottom of the furnace into the flow channel. The melt in the flow channel first passes through a double-stage filtration process of 60 mesh and 80 mesh, and then flows into the casting mold through an automatic ingot casting machine. The melt is subjected to the stirring action of a permanent magnet with a magnetic induction intensity of 4000 Gs and a magnet rotation speed of 600 rpm in the mold. After gradually solidifying, a brazable die-cast aluminum alloy ingot is obtained.

[0060] A manufacturing and brazing process for a brazable die-cast aluminum alloy part includes the following steps: The brazable die-cast aluminum alloy ingot is loaded into the aluminum melting furnace, heated to 760°C, remelted, and stirred evenly. The material is refined at 740℃, with the amount of remelting refining agent being 0.3% of the total material volume. The refining time is 20 minutes. After refining, the material is allowed to stand and the slag is removed to obtain the die-casting melt. Die casting was started at 730℃. The first injection speed was 0.4 m / s, the second injection speed was 1.8 m / s, and the third injection speed was 8.0 m / s. The die casting pressure was 150 MPa, and the pressure was held for 40 seconds to obtain the die casting. The connecting surfaces of the workpieces to be brazed are milled, degreased, and then brazing filler is applied to the connecting surfaces. The workpieces are then assembled, and after the fixtures are installed, they are placed in the brazing furnace for brazing. The actual temperature of the brazing working area in the brazing furnace is 620℃. After holding at this temperature for 12 minutes, the workpieces are removed from the furnace and cooled to complete the brazing process and obtain the desired product.

[0061] Comparative Example 1 Die-cast parts are made from ADC12 aluminum alloy using a die-casting process. The main components of ADC12 are: Si: 10.8%, Mg: 0.19%, Cu: 1.8%, Zn: 0.5%, Fe: 1.0%, Mn: 0.6%, other unavoidable single impurity elements ≤0.03%, total impurity elements ≤0.15%, balance is aluminum.

[0062] Comparative Example 2 Workpieces of the same dimensions as die-cast parts are machined from 3003 aluminum alloy thick plates. The main components of 3003 are: Mn: 1.18%, Fe: 0.62%, Si: 0.48%, other unavoidable single impurity elements ≤0.03%, total impurity elements ≤0.15%, balance is aluminum.

[0063] Performance testing The brazable die-cast aluminum alloy ingots (base materials) prepared in Examples 1 to 3 above, the ADC12 aluminum alloy die casting of Comparative Example 1, and the 3003 aluminum alloy machined part of Comparative Example 2 were tested as follows: 1. Mechanical property testing According to GB / T 228.1-2010 "Metallic materials, tensile testing—Part 1: Room temperature test method", samples of the brazable die-cast aluminum alloy ingots (base materials) prepared in Examples 1 to 3 were taken for room temperature mechanical property testing. Samples of the ADC12 aluminum alloy die-casting part of Comparative Example 1 and the 3003 aluminum alloy machined part of Comparative Example 2 were also taken for room temperature mechanical property testing. The yield strength, tensile strength, and elongation after fracture of the samples were examined. The results are shown in Table 1.

[0064] Table 1. Results of room temperature mechanical properties test 2. Brazing performance test The brazable die-cast aluminum alloy ingots (base materials) prepared in Examples 1 to 3, the ADC12 aluminum alloy die-casting part of Comparative Example 1, and the 3003 aluminum alloy machined part of Comparative Example 2 were machined and then subjected to high-temperature brazing tests using 4000 series brazing filler metal. The tests investigated whether deformation or softening occurred after the high-temperature brazing process. Sampling was conducted according to GB / T 11363-2008 "Test Method for Strength of Brazed Joints," and the mechanical properties of the welds of intact samples after brazing were tested. The results are shown in Table 2.

[0065] Table 2. Test results of brazing process and mechanical properties of brazed joints After brazing, the workpieces of Examples 1 to 3 and Comparative Example 2 showed no significant deformation, while Comparative Example 1 (ADC12) exhibited severe deformation and partial melting, indicating its inability to adapt to the target high-temperature brazing process. Joint performance tests showed that the tensile strength of the welds in the examples (143 MPa to 168 MPa) was higher than that of 3003 aluminum alloy (136 MPa), and the elongation after fracture (10.9% to 14.2%) was also close to that of 3003 aluminum alloy (18.9%). Subsequent shear strength tests further verified this, showing that the shear strength of the brazed joints in the examples reached 85 to 92 MPa, higher than the 72 MPa of 3003 aluminum alloy. Therefore, the brazing compatibility of the embodiments of this invention is comparable to that of 3003 aluminum alloy, and the joint tensile strength and shear strength are both superior, with overall mechanical properties more in line with actual application requirements.

[0066] Combination Figure 3 , 4 DSC analysis results show that the melting peak of the alloy of this invention (647.6℃) and that of 3003 aluminum alloy (659.8℃) are both significantly higher than the liquidus temperature of 4000 series brazing filler metal (≤620℃), thus meeting the thermodynamic requirements for brazing. Furthermore, the alloy of this invention can be directly die-cast, replacing the machining method of 3003 aluminum alloy, significantly reducing costs and improving efficiency. Simultaneously, considering the formability and performance stability demonstrated by metallographic and SEM structures, the alloy of this invention, after high-pressure casting, not only solves the prominent problem of traditional die-cast aluminum alloys being unable to undergo high-temperature brazing, but also achieves both "efficient die casting" and "stable brazing," making it more suitable for the cost reduction and efficiency improvement needs of mass production of new energy components.

[0067] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; 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; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0068] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are only for the convenience of describing this 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 this invention. In addition, the terms "first," "second," "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0069] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0070] In this invention, unless otherwise expressly specified and limited, "above or below" a first feature may include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on" the first feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the first feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0071] Although the description of the invention has been given in conjunction with the specific embodiments described above, it will be apparent to those skilled in the art that many substitutions, modifications, and variations can be made based on the foregoing. Therefore, all such substitutions, modifications, and variations are included within the spirit and scope of the appended claims.

Claims

1. A brazable die-cast aluminum alloy, characterized in that, In terms of mass percentage, it includes: Fe: 1.0%~4.0%, Cr: 0.5%~2.5%, Si: 0.3%~1.0%, V: 0.05%~0.5%, Mo: 0.05%~0.5%, W: 0.05%~0.5%, Y: 0.05%~0.5%, Ce: 0.05%~0.5%, Eu: 0.05%~0.5%; The total content of V, Mo, and W is ≥0.8%, the total content of Y, Ce, and Eu is ≥0.6%, other unavoidable single impurity elements are ≤0.03%, the total amount of impurity elements is ≤0.15%, and the balance is aluminum.

2. The brazable die-cast aluminum alloy according to claim 1, characterized in that, The components, expressed as a percentage by mass, are: Fe: 1.5%–3.5%, Cr: 0.8%–2.2%, Si: 0.4%–0.8%, V: 0.08%–0.45%, Mo: 0.08%–0.45%, W: 0.08%–0.45%, Y: 0.08%–0.4%, Ce: 0.08%–0.4%, and Eu: 0.08%–0.4%. The total content of V, Mo, and W is ≥0.9%, the total content of Y, Ce, and Eu is ≥0.7%, other unavoidable single impurity elements are ≤0.03%, the total amount of impurity elements is ≤0.15%, and the balance is aluminum.

3. A method for preparing a brazable die-cast aluminum alloy, characterized in that, include: Weigh the raw materials according to the formula requirements; The raw materials are subjected to multiple refining processes, and samples are taken for analysis until the element content is adjusted to the required content of the formula to obtain a refined melt. The refined melt is subjected to two-stage filtration and then cast. During the casting process, permanent magnet stirring is applied to the melt entering the mold. After solidification, a brazable die-cast aluminum alloy ingot is obtained.

4. The method for preparing a brazable die-cast aluminum alloy according to claim 3, characterized in that, The working parameters for the multiple refining processes include: The first refining process uses high-purity argon gas to inject a remelting refining agent. The amount of the remelting refining agent is 0.1% to 0.5% of the total amount of material in the furnace. The refining time is 20 min to 40 min, and the refining temperature is 720℃ to 820℃. The second refining process uses high-purity argon gas to inject a remelting refining agent. The amount of the remelting refining agent is 0.1% to 0.3% of the total amount of material in the furnace. The refining time is 10 min to 30 min, and the refining temperature is 700℃ to 800℃.

5. The method for preparing a brazable die-cast aluminum alloy according to claim 3, characterized in that, The operating parameters of the two-stage filtration process include: The first-stage filter plate has a mesh size of 60, and the second-stage filter plate has a mesh size of 80.

6. The method for preparing a brazable die-cast aluminum alloy according to claim 3, characterized in that, The operating parameters of the permanent magnet stirrer include: magnetic induction intensity of 2000Gs~6000Gs and magnet rotation speed of 200r / min~800r / min.

7. A manufacturing process and brazing process for a brazable die-cast aluminum alloy die-casting part, characterized in that, include: A brazable die-cast aluminum alloy ingot is loaded into an aluminum melting furnace, heated and remelted while being stirred. The brazable die-cast aluminum alloy ingot is prepared by the method for preparing brazable die-cast aluminum alloy according to any one of claims 3 to 6. After refining, it is kept at a certain temperature to obtain a die-cast melt. The die casting melt is transferred to a cold chamber die casting machine for die casting, and after cooling, a die casting part is obtained. The brazing connection surface of the die casting is milled and degreased. After completion, brazing solder is evenly applied to the brazing connection surface, and the part is fixed with a fixture and placed in a brazing furnace for brazing. After the workpiece is taken out of the furnace, it is cooled to room temperature to obtain the product.

8. The manufacturing and brazing process of a brazable die-cast aluminum alloy die-casting part according to claim 7, characterized in that, The operating parameters for the refining process include: The remelting agent is injected with high-purity argon gas. The amount of the remelting agent is 0.1% to 0.4% of the total amount of material in the furnace. The refining time is 10 min to 30 min and the refining temperature is 700℃ to 800℃.

9. The manufacturing and brazing process of a brazable die-cast aluminum alloy die-casting part according to claim 7, characterized in that, The die-casting process is configured as high-pressure die-casting, and the operating parameters include: The die-casting temperature is 680℃~780℃. During the die-casting process, the first-stage injection speed is 0.1m / s~0.6m / s, the second-stage injection speed is 0.4m / s~1.8m / s, the third-stage injection speed is 2.5m / s~10m / s, the die-casting pressure is 50MPa~150MPa, and the holding pressure is 20s~40s.

10. The manufacturing and brazing process of a brazable die-cast aluminum alloy die-casting part according to claim 7, characterized in that, The working parameters for the brazing process include: brazing temperature of 600℃~630℃ and brazing holding time of 2min~14min.

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