Aluminum alloy and processing technology of aluminum alloy profile

Abstract

The application provides an aluminum alloy, which comprises the following components in percentage by mass: Zn 4.0-5.0%, Mg 1.2-1.8%, Cu 0.1-0.3%, Zr 0.08-0.12%, Ti 0.02-0.06%, Fe less than or equal to 0.25%, and the balance of Al. The alloy elements containing Zn 4.0-5.0%, Mg 1.2-1.8%, Cu 0.1-0.3%, Zr 0.08-0.12%, Ti 0.02-0.06% and Fe less than or equal to 0.25% are added into a smelting furnace together with pure aluminum, smelted at 700-750 DEG C to form a melt, refined by blowing in inert gas or adding a refining agent, and the gas and inclusions are removed. The application utilizes the shearing force generated by the different rotating speeds of the upper and lower rollers of a differential rolling mill to break the coarse structure, refine the grains, and increase the dislocation density. The aluminum alloy is rolled at 480-500 DEG C to reduce the deformation resistance, promote dynamic recrystallization, maintain the processing performance, and further enhance the performance by 60-70% of the total deformation. After rolling, the aluminum alloy is subjected to multi-directional forging, the strain direction is changed multiple times, the grains are broken, the structure is homogenized, and anisotropy is eliminated, so that the comprehensive performance and application range of the aluminum alloy profile are improved. The problem that the structure cannot be refined and the dislocation density cannot be increased during the rolling process is solved.

Description

Technical Field

[0001] This invention belongs to the field of metal manufacturing, specifically a processing technology for aluminum alloys and aluminum alloy profiles. Background Technology

[0002] Aluminum alloy profiles are aluminum-based alloy materials processed into specific geometric shapes. Due to their lightweight, high strength, and corrosion resistance, they are widely used in aerospace, automotive, construction, and many other fields. Traditional aluminum alloy profile processing technologies often employ methods such as simultaneous rolling. During the rolling process, the as-cast microstructure is difficult to effectively break down, resulting in coarse grains and an uneven microstructure. This leads to poor overall performance and significant anisotropy in the profiles, limiting their application in some demanding performance fields.

[0003] In the prior art document (CN102634705B), by heating medium and high strength aluminum alloys to 490℃, extruding them under specific mold temperatures and extrusion speeds, and using water mist or air cooling quenching methods, the dependence on special equipment for quenching treatment in traditional processes has been solved to some extent, and aluminum alloy profiles with high tensile strength and complex cross-sections can be produced.

[0004] However, this method has shortcomings in improving the uniformity and anisotropy of the microstructure of aluminum alloy profiles. It does not effectively control the microstructure refinement and dislocation density increase during the rolling process. It cannot break up coarse microstructure, refine grains, and increase dislocation density like the shearing force generated by the different speeds of the upper and lower rolls of a differential rolling mill. It also does not homogenize the microstructure and eliminate anisotropy by changing the strain direction multiple times through multi-directional forging. This limits the comprehensive performance and application range of the profiles. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a processing technology for aluminum alloys and aluminum alloy profiles, which solves the problems mentioned in the background art.

[0006] An aluminum alloy comprises, by mass percentage: Zn 4.0-5.0%, Mg 1.2-1.8%, Cu 0.1-0.3%, Zr 0.08-0.12%, Ti 0.02-0.06%, Fe ≤ 0.25%, with the balance being Al;

[0007] The above-mentioned aluminum alloy processing technology includes the following steps:

[0008] S1 Melting and Casting: Alloying elements containing 4.0-5.0% Zn, 1.2-1.8% Mg, 0.1-0.3% Cu, 0.08-0.12% Zr, 0.02-0.06% Ti, and ≤0.25% Fe are added to a melting furnace along with pure aluminum and melted at 700-750℃ to form a melt. Inert gas is introduced or a refining agent is added to refine the melt, removing gases and inclusions. The melt is then transferred to casting equipment and cast into ingots or billets using a semi-continuous or continuous casting method at a cooling rate of 5-15℃ / s.

[0009] High-temperature asynchronous rolling S2: A differential speed rolling mill is used, with the upper roll speed at 20-25 rpm and the lower roll speed at 25-30 rpm, and the lower roll speed ratio at 1:1.0-1.2. The rolling temperature is 480-500℃, the total deformation is 60-70%, and multi-directional forging is performed immediately after rolling, with strain path changes ≥3 times and single deformation of 10-15%.

[0010] Gradient aging treatment S3: The first stage uses a solution treatment at 475℃×1h followed by water quenching to room temperature. The second stage uses a two-stage aging process of 120℃×8h+180℃×2h with a heating rate ≤5℃ / min.

[0011] Hot-press electromagnetic bending S4: The mold is preheated to 300-350℃, the bending rate is 1.0-1.2m / min, and an axial pressure of 80-100MPa and an alternating magnetic field of 0.8-1.2T are applied simultaneously. The magnetic field frequency is dynamically adjusted according to f=8×σ, where σ is the real-time compressive stress.

[0012] Surface treatment S5: Anodizing, electrophoretic coating or powder coating are performed on the shaped profile.

[0013] Preferably, the core temperature of the rolled sheet is fed back in real time by infrared thermometry, and the roll speed is dynamically adjusted to keep the temperature fluctuation ≤ ±5℃.

[0014] Preferably, the bent portion undergoes localized micro-arc oxidation treatment, wherein the micro-arc oxidation treatment uses an electrolyte containing... 25g / L + 15g / L SiC nanoparticles, voltage 500V, time 6-8min.

[0015] Preferably, in the second stage of the gradient aging treatment S3, the heating rate from 120℃ to 180℃ is 3-5℃ / min, and a pulsed magnetic field with a frequency of 50Hz and a magnetic field strength of 0.5-0.8T is applied during the heating process.

[0016] Preferably, in the multiple forging processes of the high-temperature asynchronous rolling S2, the strain path changes 4-6 times, the deformation amount per forging is controlled at 12-15%, and the included angle between two adjacent forging directions is 90°±5°.

[0017] Preferably, the material is in a dynamic recrystallization temperature window during the bending process, and the product of the bending rate and the axial pressure does not exceed 80% of the material's yield strength. In S3, the mold preheating temperature and the alternating magnetic field strength satisfy B = 0.003 × T + 0.2, where B is the magnetic field strength / T and T is the mold preheating temperature / °C.

[0018] Preferably, the flow rate of the inert gas during the refining process is controlled at 5-10 m³ / h, and the refining time is 15-25 min.

[0019] Preferably, the rolling force applied to the workpiece during the rolling process is 1000-1500kN, and an emulsion is used for cooling and lubrication during the rolling process, with the emulsion concentration controlled at 3%-5%.

[0020] Preferably, the product model and batch identification information are engraved on the surface of the profile, with a laser engraving power of 10-20W and an engraving speed of 50-100mm / s.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. In use, this invention utilizes the different rotational speeds of the upper and lower rolls of a differential speed rolling mill to generate shearing forces, breaking down coarse microstructures, refining grains, and increasing dislocation density. Rolling at 480-500℃ reduces deformation resistance, promotes dynamic recrystallization, maintains processing performance, and further enhances performance with 60-70% total deformation. Post-rolling multi-directional forging repeatedly changes the strain direction, breaking down grains, homogenizing the microstructure, eliminating anisotropy, and improving the overall performance and application range of aluminum alloy profiles.

[0023] 2. In use, this invention involves a 475℃×1h solution treatment to form a supersaturated solid solution, which is then retained in a water-quenched state. A two-stage aging process of 120℃×8h + 180℃×2h is then applied. The low-temperature process generates the GP zone, enhancing strength, while the high-temperature process transforms the GP zone, synergistically balancing strength and toughness. Furthermore, a heating rate of ≤5℃ / min ensures uniform precipitation of the strengthening phase, avoiding internal stress. Compared to traditional aging methods, this invention improves the overall mechanical properties and service performance of the profile.

[0024] 3. In use, the invention features 300-350℃ mold preheating, 1.0-1.2m / min bending rate to ensure uniform plastic flow, 80-100MPa axial pressure to suppress defects and improve molding quality, and 0.8-1.2T alternating magnetic field to adjust the frequency according to real-time compressive stress to reduce deformation resistance, refine grains, improve microstructure and properties, enhance fatigue resistance and corrosion resistance, and meet the molding requirements of complex structural parts. Attached Figure Description

[0025] Figure 1 This is a bar chart comparing the salt spray corrosion resistance time of the present invention;

[0026] Figure 2 This is a bar chart comparing the shear strength of this invention;

[0027] Figure 3 This is a bar chart comparing the minimum bending radius of the present invention;

[0028] Figure 4 This is a schematic diagram of the overall process flow of the present invention;

[0029] Figure 5 This is a schematic diagram illustrating a specific embodiment of the present invention. Detailed Implementation

[0030] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0031] An aluminum alloy comprises, by mass percentage: Zn 4.0-5.0%, Mg 1.2-1.8%, Cu 0.1-0.3%, Zr 0.08-0.12%, Ti 0.02-0.06%, Fe ≤ 0.25%, with the balance being Al;

[0032] In the above-mentioned aluminum alloy composition system, zinc (Zn) is the main strengthening element. Through solid solution strengthening and the formation of strengthening phases during aging, it significantly improves the strength of the alloy. Magnesium (Mg) works synergistically with zinc to form Mg-Zn strengthening phases, which not only enhance the strength of the alloy but also improve its plasticity and toughness. The addition of copper (Cu) can further improve the age hardening effect of the alloy and enhance its heat resistance. Zirconium (Zr) and titanium (Ti) are mainly used to refine the grains. By forming dispersed compounds, they inhibit grain growth and improve the overall performance of the alloy. Iron (Fe), as an impurity element, must be strictly controlled to have a content of ≤0.25%, because excessive iron will form coarse intermetallic compounds, reducing the plasticity and corrosion resistance of the alloy.

[0033] The dynamic recrystallized grains and the wide, layered alternating structure of subgrains in aluminum alloys affect their properties. The layered structure with a single layer width of 50-200 μm imparts anisotropy to the alloy. Under stress, the layered structure can effectively hinder dislocation movement, thereby improving the strength and hardness of the alloy. The subgrain boundary density reaches 3-5 boundaries / μm. The large number of subgrain boundaries increases the resistance to dislocation movement, further strengthening the alloy. At the same time, this structure can also improve the alloy's machinability. During hot working, the layered structure is conducive to uniform deformation and reduces machining defects.

[0034] Furthermore, the uniformly distributed (Zr,Ti) nano-precipitates within the grains are a key factor in improving the alloy's properties. These nano-precipitates, with a particle size of 20-40 nm and a density ≥8×10², are crucial for enhancing the alloy's performance. 0These nano-precipitates, distributed uniformly and diffusely in the matrix, effectively suppress dislocation movement and grain growth by pinning dislocations and grain boundaries. During the service life of the alloy, the nano-precipitates can stabilize the microstructure of the alloy, maintain its strength and hardness, and improve its fatigue resistance and corrosion resistance.

[0035] The above-mentioned aluminum alloy processing technology includes the following steps:

[0036] S1 Melting and Casting: Alloying elements containing 4.0-5.0% Zn, 1.2-1.8% Mg, 0.1-0.3% Cu, 0.08-0.12% Zr, 0.02-0.06% Ti, and ≤0.25% Fe are added to a melting furnace along with pure aluminum and melted at 700-750℃ to form a melt. Inert gas is introduced or a refining agent is added to refine the melt, removing gases and inclusions. The melt is then transferred to casting equipment and cast into ingots or billets using a semi-continuous or continuous casting method at a cooling rate of 5-15℃ / s.

[0037] High-temperature asynchronous rolling S2: A differential speed rolling mill is used, with the upper roll speed at 20-25 rpm and the lower roll speed at 25-30 rpm, and the lower roll speed ratio at 1:1.0-1.2. The rolling temperature is 480-500℃, the total deformation is 60-70%, and multi-directional forging is performed immediately after rolling, with strain path changes ≥3 times and single deformation of 10-15%.

[0038] Gradient aging treatment S3: The first stage uses a solution treatment at 475℃×1h followed by water quenching to room temperature. The second stage uses a two-stage aging process of 120℃×8h+180℃×2h with a heating rate ≤5℃ / min.

[0039] High-temperature asynchronous rolling is a crucial initial step in aluminum alloy profile processing. Its process parameters are set based on the principles of materials processing science. A differential speed rolling mill is used, with the upper roll speed at 20-25 rpm and the lower roll speed at 25-30 rpm. The speed ratio of the lower roll is controlled at 1:1.0-1.2. This speed difference breaks the uniform deformation pattern of metal in traditional synchronous rolling. During asynchronous rolling, the speed difference between the upper and lower rolls and the aluminum alloy billet causes the billet to be subjected to shear force in the rolling direction. This shear force promotes the plastic flow of the metal, breaks up the coarse cast structure, and achieves grain refinement. At the same time, it increases the dislocation density inside the metal, creating conditions for subsequent recrystallization and structure optimization. The rolling temperature is set at 480-500℃, which is within the hot working temperature range of aluminum alloys. Within this temperature range, aluminum alloys have good plasticity and can achieve large deformation with relatively small rolling force. Higher temperatures reduce the metal's resistance to deformation, decrease roll wear, and promote dynamic recrystallization. Dynamic recrystallization can eliminate work hardening and ensure that aluminum alloys maintain good plasticity and processing performance under large deformation. The total deformation is controlled at 60-70%, which further refines the grains, increases the alloy density, and enhances the mechanical properties of the profile.

[0040] Immediately after rolling, multi-directional forging is carried out, with strain path changes ≥3 times and single deformation amount of 10-15%. This step is a deepening of the effect of high-temperature asynchronous rolling. Multi-directional forging, by changing the strain direction multiple times, makes the aluminum alloy subject to compression and shear in different directions. This complex deformation method further breaks up coarse grains, making the microstructure more uniform. The interaction of strains in different directions promotes dislocation interaction and recombination, forming a more stable substructure. Multiple strain path changes can eliminate the anisotropy that may be generated by rolling, balance the performance of aluminum alloy profiles in all directions, and improve the comprehensive performance and application range of the profiles.

[0041] Gradient aging treatment S3: The first stage uses a solution treatment at 475℃×1h followed by water quenching to room temperature. The second stage uses a two-stage aging process of 120℃×8h+180℃×2h with a heating rate ≤5℃ / min.

[0042] The first stage uses a solution treatment at 475℃ for 1 hour, which is close to the solution line temperature of aluminum alloy. At this temperature, the alloy strengthening phase is fully dissolved in the matrix to form a uniform supersaturated solid solution. The 1-hour solution treatment time ensures that the strengthening phase is fully dissolved and prevents grain growth due to excessive time. The rapid cooling method of water quenching to room temperature inhibits the precipitation of the strengthening phase and retains the supersaturated solid solution state, creating conditions for subsequent aging strengthening.

[0043] The second stage employs a two-stage aging process: 120℃×8h + 180℃×2h, with a heating rate ≤5℃ / min. This two-stage aging process aims to induce the precipitation of strengthening phases of different sizes and types. The first stage, 120℃×8h low-temperature aging, promotes the formation of fine GP regions. GP regions are enriched areas of solute atoms in the matrix, typically several nanometers in size, which hinder dislocation movement, producing an age-hardening effect and increasing the alloy's strength. The second stage, 180℃×2h high-temperature aging, transforms the GP regions into larger ones. Harmony The phase further strengthens the alloy and works synergistically with the GP zone formed by low-temperature aging to achieve a balance between strength and toughness. The slow heating rate (≤5℃ / min) avoids uneven microstructure and internal stress caused by excessively rapid temperature changes, ensuring uniform precipitation of the strengthening phase during the aging process. Compared with the traditional single-stage aging process, the gradient aging treatment controls the temperature and time at different stages to regulate the precipitation process and size distribution of the strengthening phase, enabling aluminum alloy profiles to have both high strength and good plasticity and toughness, thereby improving the comprehensive mechanical properties and service performance of the profiles.

[0044] Hot-press electromagnetic bending S4: The mold is preheated to 300-350℃, the bending rate is 1.0-1.2m / min, and an axial pressure of 80-100MPa and an alternating magnetic field of 0.8-1.2T are applied simultaneously. The magnetic field frequency is dynamically adjusted according to f=8×σ, where σ is the real-time compressive stress.

[0045] The bending rate is set at 1.0-1.2 m / min. This rate allows the profile sufficient time for plastic flow during deformation, avoiding local stress concentration and uneven deformation caused by excessively rapid deformation. It also helps to control the profile forming specifications, ensuring that the bending angle and shape meet the design requirements. Simultaneously, an axial pressure of 80-100 MPa is applied. This force acts along the profile axis during bending, suppressing thinning and wrinkling at the bending point, making the metal flow in the bending area more uniform, and improving the profile forming quality and dimensional accuracy.

[0046] Then, an alternating magnetic field of 0.8-1.2T is applied, with the magnetic field frequency dynamically adjusted according to f=8×σ (σ being the real-time compressive stress). This is the innovation of hot-press electromagnetic bending. The alternating magnetic field acts on electrons and atoms in the aluminum alloy through Lorentz force, changing the movement and diffusion behavior of dislocations inside the metal. The dynamically adjusted magnetic field frequency is related to the real-time compressive stress, allowing the magnetic field to adaptively adjust according to the stress state during the bending process. In areas with high compressive stress, the magnetic field frequency is correspondingly increased, enhancing the effect of the magnetic field on the metal, promoting dislocation slip and reorganization, reducing the metal's deformation resistance, and facilitating the plastic deformation of the profile. At the same time, the alternating magnetic field can refine the grains, improve the profile's microstructure and properties, and enhance its fatigue resistance and corrosion resistance. Compared with traditional bending processes, the hot-press electromagnetic bending process improves the forming quality and performance of aluminum alloy profiles through the synergistic effect of mold preheating, moderate bending rate, axial pressure, and dynamically adjusted alternating magnetic field, providing technical support for the application of aluminum alloy profiles in complex structural components.

[0047] Surface treatment S5: Anodizing, electrophoretic coating or powder coating are performed on the shaped profile.

[0048] Example 1: Conventional materials + conventional processes;

[0049] Material composition: Zn 4.5%, Mg 1.4%, Cu 0.2%, Fe 0.2%, balance Al (complies with the standard composition of 7N01 aluminum alloy in GB / T3190-2020).

[0050] Processing technology:

[0051] Hot rolling: constant speed rolling mill (roll speed 20 rpm), rolling temperature 400℃, total deformation 60%;

[0052] Aging treatment: T6 single-level aging (120℃×24h);

[0053] Bending: Bending at room temperature, speed 0.5m / min, without auxiliary pressure or magnetic field;

[0054] Performance data:

[0055] Fatigue strength: 245 MPa (ASTM E466, R=-1, 10) 7 (nth iteration)

[0056] Shear strength: 235MPa (GB / T6396);

[0057] Bending performance: minimum bending radius 1.5 times wall thickness, springback angle 3.5°;

[0058] Microstructure: Equiaxed crystals (average grain size 50 μm), without layered subcrystalline structure;

[0059] The coarse equiaxed crystals and lack of layered subgrain structure result in less resistance to dislocation movement under stress and a weaker grain boundary strengthening effect. This structure makes it difficult to effectively prevent crack propagation, and the material performance is poor under stress conditions such as fatigue and shear. It is also not conducive to controlling the shape accuracy of profiles during bending and other forming processes.

[0060] Specific performance parameters of the aluminum alloy are shown in Table 1:

[0061] Table 1: Performance of Aluminum Alloy Profiles Using Conventional Materials and Constant Speed ​​Rolling Process

[0062] Example 2: The above-mentioned aluminum alloy material + conventional process;

[0063] Material composition: Zn 4.8%, Mg 1.6%, Cu 0.25%, Zr 0.1%, Ti 0.04%, Fe ≤ 0.15%;

[0064] Processing technology: Same as the conventional process in Example 1;

[0065] Performance data:

[0066] Fatigue strength: 280 MPa (14% higher than in Example 1);

[0067] Shear strength: 265 MPa (up 13%);

[0068] Characteristics of the precipitated phase: (Zr,Ti) phase density 5×10² 0 Particles / m³, particle size 35nm (TEM analysis).

[0069] Defect: Due to insufficient conventional rolling temperature, the layered structure did not form, and the crack propagation rate was reduced by only 8%.

[0070] Specific performance parameters of the aluminum alloy are shown in Table 2:

[0071] Table 2: Performance Parameters of Aluminum Alloy Profiles Combining New Materials with Conventional Processes

[0072] Example 3: Conventional materials + the above process

[0073] Material composition: Same as the conventional components of 7N01 in Example 1;

[0074] Processing technology:

[0075] High-temperature asynchronous rolling: upper roll 20 rpm / lower roll 25 rpm, 480℃, total deformation 65% further subjected to multi-directional forging 4 times (strain path 90°).

[0076] Gradient aging: 475℃×1h solution treatment + 120℃×8h - 180℃×2h (heating rate 4℃ / min);

[0077] Hot-press electromagnetic bending: mold temperature 320℃, magnetic field strength 1.0T, speed 1.0m / min;

[0078] Performance data:

[0079] Fatigue strength: 295 MPa (120% higher than the control group);

[0080] Microstructure: Locally formed layered subgrains (coverage 40%), with significant differences in grain size (10-80 μm);

[0081] Bending limit: Minimum radius 1.0t (limited by the material's own plasticity);

[0082] Specific performance parameters for aluminum alloys are shown in Table 3:

[0083] Table 3: Performance Comparison of Aluminum Alloy Profiles Using Conventional Materials and New Processing Technologies

[0084] Example 4: The above materials + the above process

[0085] Material composition: Zn 4.8%, Mg 1.6%, Cu 0.25%, Zr 0.1%, Ti 0.04%, Fe ≤ 0.15%;

[0086] Processing technology:

[0087] High-temperature asynchronous rolling:

[0088] Differential speed rolling mill (upper 20 rpm / lower 24 rpm), rolling at 485℃, further controlled by infrared temperature measurement and dynamic temperature control (±3℃);

[0089] Multi-directional forging 5 times (strain path 90°±3°, single deformation 14%);

[0090] Gradient aging + magnetic field coupling:

[0091] Solution treated at 475℃ for 1 hour, followed by further water quenching;

[0092] Two-stage aging: 120℃×8h followed by 180℃×2h (heating rate 4℃ / min + 50Hz / 0.7T pulsed magnetic field);

[0093] Hot pressing electromagnetic bending:

[0094] Mold temperature 340℃ (B = 0.003 × 340 + 0.2 = 1.22T magnetic field);

[0095] Speed ​​1.1 m / min, axial pressure 90 MPa (satisfying 1.1 × 90 = 99 MPa < σ_s × 0.8 = 125 MPa);

[0096] Localized micro-arc oxidation after bending (SiC composite layer, 25μm thick);

[0097] Performance data:

[0098] Fatigue strength: 335 MPa (137% improvement compared to the control group);

[0099] Shear strength: 320 MPa (GB / T6396);

[0100] Bending accuracy: 90° bending angle deviation ≤ 0.3°, minimum radius 0.8t;

[0101] Microscopic features:

[0102] EBSD revealed a layered structure with a single layer width of 150 μm and a subgrain boundary density of 4.5 lines / μm;

[0103] TEM display (Zr,Ti) precipitate density: 9.2 × 10² 0 Particles per m³, particle size 28 nm;

[0104] Specific performance parameters of the aluminum alloy are shown in Table 4:

[0105] Table 4: Comprehensive Performance Data of Aluminum Alloy Profiles under the Synergistic Effect of New Materials and Innovative Processes

[0106] The above embodiments explore the impact of different combinations of material composition and processing technology on the performance of aluminum alloy profiles by comparing them. The specific summary is as follows:

[0107] Adding elements such as Zr and Ti to the basic aluminum alloy composition creates a uniformly distributed... (Zr,Ti) nano-precipitates can significantly improve alloy properties. For example, compared with Example 1, under the same conventional processing technology, the fatigue strength of Example 2 increased by 14%, the shear strength increased by 13%, and the salt spray corrosion resistance time was extended from 500h to 800h due to the addition of Zr and Ti elements. This proves the positive role of alloying elements in improving the strength, corrosion resistance and other properties of alloys.

[0108] Example 3 employs high-temperature asynchronous rolling and multi-directional forging processes. Compared to the conventional hot rolling process in Example 1, although the material composition is the same, the fatigue strength is increased by 120%, the salt spray corrosion resistance time increases from 500h to 1200h, and a layered subcrystalline structure is formed locally. This indicates that the process can refine the grains and improve the overall performance of the alloy. Gradient aging treatment strengthens the precipitation of phases by controlling the temperature and time at different stages, achieving a balance between strength and toughness. Compared with traditional single-stage aging, it can enable aluminum alloy profiles to have both higher strength and good plasticity and toughness.

[0109] Example 4 employs a hot-press electromagnetic bending process. Under the combined effects of mold preheating, moderate bending rate, axial pressure, and dynamically adjusted alternating magnetic field, compared to the room temperature bending in Example 1, its 90° bending angle deviation is ≤0.3° and the minimum radius reaches 0.8t, significantly improving forming accuracy and quality. It also has a positive effect on improving the fatigue resistance and corrosion resistance of the profile.

[0110] Example 4 combines novel material composition with innovative processing technology to achieve optimal performance improvement. Its fatigue strength reaches 335 MPa, an increase of 137% compared to Example 1, shear strength reaches 320 MPa, and salt spray corrosion resistance time reaches 3000 hours. It forms an ideal dynamic recrystallized grain and subgrain alternating layered structure. The density and particle size of the (Zr,Ti) precipitated phases also reached a relatively optimal state, fully demonstrating the synergistic effect of material composition optimization and processing technology innovation.

[0111] In summary, optimizing the composition of aluminum alloy materials, combined with innovative processing techniques such as high-temperature asynchronous rolling, multi-directional forging, gradient aging treatment, and hot-pressing electromagnetic bending, and especially the effective combination of the two, can significantly improve the comprehensive performance of aluminum alloy profiles, including strength, plasticity, toughness, corrosion resistance, and forming accuracy, providing strong support for the application of aluminum alloy profiles in complex structural components.

[0112] In this invention’s research on aluminum alloys and aluminum alloy profiles, relevant performance data charts were generated to comprehensively explore the effects of different combinations of material composition and processing technology on the performance of aluminum alloy profiles.

[0113] The following is a bar chart comparing salt spray corrosion resistance time ( Figure 1 ), Shear strength bar chart ( Figure 2 ) and a bar chart comparing the minimum bending radius ( Figure 3 The data changes are analyzed progressively to clearly present the mechanism and synergistic effect of each factor on the performance of aluminum alloy profiles.

[0114] In the research on aluminum alloy profiles involved in this invention, salt spray corrosion resistance time is a key indicator for evaluating its corrosion resistance performance. A bar chart comparing salt spray corrosion resistance time is provided (…). Figure 1 According to the data, the salt spray corrosion resistance time of Example 1 was 500 hours, that of Example 2 was increased to 800 hours, that of Example 3 was further increased to 1200 hours, and that of Example 4 reached 3000 hours. This series of data changes shows a clear progressive increasing trend;

[0115] Adding elements such as Zr and Ti to the basic aluminum alloy composition creates a uniformly distributed... (Zr,Ti) nano-precipitates play a positive role in improving corrosion resistance. For example, in Example 2, the salt spray corrosion resistance time was extended from 500 hours to 800 hours compared to Example 1. Simultaneously, innovative processing techniques such as high-temperature asynchronous rolling, multi-directional forging, and gradient aging treatment can further refine the grains and improve the alloy microstructure, thereby significantly enhancing corrosion resistance. In Example 3, the salt spray corrosion resistance time increased to 1200 hours compared to Example 1. Example 4, combining novel material composition with innovative processing techniques, especially hot-pressing and electromagnetic bending, achieved optimal corrosion resistance for the aluminum alloy profile, with a salt spray corrosion resistance time as long as 3000 hours. Therefore, the synergistic effect of optimizing the aluminum alloy material composition and innovative processing techniques can effectively extend the salt spray corrosion resistance time of aluminum alloy profiles and significantly improve their corrosion resistance.

[0116] Shear strength is an important parameter for evaluating the mechanical properties of aluminum alloy profiles. (See the bar chart comparing shear strength.) Figure 2 The shear strength of Example 1 was 235 MPa, that of Example 2 increased to 265 MPa, that of Example 4 reached 320 MPa, and that of Example 3 was 300 MPa. The data show a gradually increasing trend.

[0117] Adding alloying elements such as Zr and Ti can form strengthening phases, hindering dislocation movement and thus improving the shear strength of the alloy. In Example 2, compared to Example 1 under the same conventional process, the shear strength increased by 13% due to the addition of Zr and Ti. Innovative processing techniques, such as high-temperature asynchronous rolling, multi-directional forging, and gradient aging treatment, further enhance the strength of the alloy by refining grains and optimizing the microstructure. In Example 3, the shear strength is higher than that of Example 1 after adopting these innovative processes. Example 4 combines a new material composition with innovative processing techniques, especially hot-press electromagnetic bending. Under the synergistic effect of mold preheating, axial pressure, and alternating magnetic field, the internal microstructure of the aluminum alloy profile is made more dense and uniform, and the shear strength reaches 320 MPa, which is significantly improved compared to Example 1. This shows that the synergy between optimizing the material composition and innovative processing techniques has a significant effect on improving the shear strength of aluminum alloy profiles.

[0118] Furthermore, the minimum bending radius reflects the bending and forming performance of aluminum alloy profiles; the smaller the value, the better the forming performance. A bar chart comparing minimum bending radii is provided. Figure 3 As can be seen, the minimum bending radius in Example 1 is 1.5 times the wall thickness, in Example 2 it is 1.3 times the wall thickness, in Example 3 it is 1.0 times the wall thickness, and in Example 4 it is the smallest, at 0.8 times the wall thickness. The data show a gradually decreasing progressive change;

[0119] The addition of alloying elements such as Zr and Ti improved the overall performance of the alloy and enhanced its bending performance to a certain extent; the minimum bending radius of Example 2 was smaller than that of Example 1. Innovative processing techniques such as high-temperature asynchronous rolling and multi-directional forging refined the grains, making the alloy microstructure more uniform and further reducing the minimum bending radius; the minimum bending radius of Example 3 was smaller than that of Example 2. Example 4 employed a hot-press electromagnetic bending process. Through the synergistic effect of mold preheating, a moderate bending rate, axial pressure, and a dynamically adjusted alternating magnetic field, the forming accuracy and quality of the aluminum alloy profile were greatly improved, reducing the minimum bending radius to 0.8 times the wall thickness, a significant reduction compared to Example 1. This fully demonstrates that the synergistic effect of optimizing the aluminum alloy material composition and innovative processing techniques can effectively reduce the minimum bending radius of aluminum alloy profiles and improve their bending and forming performance.

[0120] All embodiments of the present invention are within the scope of protection of this patent.

[0121] The embodiments of the present invention are given for the purposes of illustration and description. Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. An aluminum alloy, characterized in that, The composition by mass percentage is as follows: Zn 4.0-5.0%, Mg 1.2-1.8%, Cu 0.1-0.3%, Zr 0.08-0.12%, Ti 0.02-0.06%, Fe ≤ 0.25%, with the balance being Al; The above-mentioned aluminum alloy processing technology includes the following steps: S1 Melting and Casting: Alloying elements containing 4.0-5.0% Zn, 1.2-1.8% Mg, 0.1-0.3% Cu, 0.08-0.12% Zr, 0.02-0.06% Ti, and ≤0.25% Fe are added to a melting furnace along with pure aluminum and melted at 700-750℃ to form a melt. Inert gas is introduced or a refining agent is added to refine the melt, removing gases and inclusions. The melt is then transferred to casting equipment and cast into ingots or billets using a semi-continuous or continuous casting method at a cooling rate of 5-15℃ / s. High-temperature asynchronous rolling S2: A differential speed rolling mill is used, with the upper roll speed at 20-25 rpm and the lower roll speed at 25-30 rpm, and the lower roll speed ratio at 1:1.0-1.

2. The rolling temperature is 480-500℃, the total deformation is 60-70%, and multi-directional forging is performed immediately after rolling, with strain path changes ≥3 times and single deformation of 10-15%. Gradient aging treatment S3: The first stage uses a solution treatment at 475℃×1h followed by water quenching to room temperature. The second stage uses a two-stage aging process of 120℃×8h+180℃×2h with a heating rate ≤5℃ / min. Hot-press electromagnetic bending S4: The mold is preheated to 300-350℃, the bending rate is 1.0-1.2m / min, and an axial pressure of 80-100MPa and an alternating magnetic field of 0.8-1.2T are applied simultaneously. The magnetic field frequency is dynamically adjusted according to f=8×σ, where σ is the real-time compressive stress. Surface treatment S5: Anodizing, electrophoretic coating or powder coating are performed on the shaped profile.

2. The aluminum alloy according to claim 1, characterized in that, The core temperature of the rolled plate is fed back in real time through infrared thermometry, and the speed of the rolls is dynamically adjusted to keep the temperature fluctuation ≤ ±5℃.

3. An aluminum alloy according to claim 1, characterized in that, The bent portion undergoes localized micro-arc oxidation treatment, wherein the micro-arc oxidation treatment uses an electrolyte containing... 25g / L + 15g / L SiC nanoparticles, voltage 500V, time 6-8min.

4. An aluminum alloy according to claim 1, characterized in that, In the second stage of the gradient aging treatment S3, the heating rate from 120℃ to 180℃ is 3-5℃ / min, and a pulsed magnetic field with a frequency of 50Hz and a magnetic field strength of 0.5-0.8T is applied during the heating process.

5. An aluminum alloy according to claim 1, characterized in that, In the multiple forging processes of the high-temperature asynchronous rolling S2, the strain path changes 4-6 times, the deformation amount per forging is controlled at 12-15%, and the included angle between two adjacent forging directions is 90°±5°.

6. An aluminum alloy according to claim 1, characterized in that, The material is in a dynamic recrystallization temperature window during bending, and the product of the bending rate and the axial pressure does not exceed 80% of the material's yield strength.

7. An aluminum alloy according to claim 1, characterized in that, The flow rate of inert gas during the refining process is controlled at 5-10 m³ / h, and the refining time is 15-25 min.

8. An aluminum alloy according to claim 1, characterized in that, The rolling force applied to the workpiece during the rolling process is 1000-1500kN, and an emulsion is used for cooling and lubrication during the rolling process, with the emulsion concentration controlled at 3%-5%.

9. An aluminum alloy according to claim 1, characterized in that, Product model and batch identification information are engraved on the surface of the profile. The laser engraving power is 10-20W and the engraving speed is 50-100mm / s.

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