A heat distortion resistant aluminum alloy and a preparation method and application thereof

Abstract

The application discloses a heat-resistant deformation aluminum alloy and a preparation method and application thereof. The heat-resistant deformation aluminum alloy comprises the following components in a mass fraction: Si 0.10%-0.30%, Fe 0.5%-1.5%, Cu 1.5%-3.0%, Mg 1.0%-2.0%, Ni 0.5%-1.5%, Ti 0%-0.10%, single impurity ≤0.05%, total impurities ≤0.15%, and the balance is Al. The application precisely controls the components of the aluminum alloy, so that the chemical components of the heat-resistant deformation aluminum alloy are more suitable for processing requirements, thereby obtaining the heat-resistant deformation aluminum alloy with O-state soft state and T6-state strong and tough performance dual-state compatibility, and solving the technical problems of the traditional process, such as the too high hardness of the soft state and the insufficient strength of the hard state.

Description

Technical Field

[0001] This application relates to the field of non-ferrous metal material processing technology, specifically to an Al-Cu-Mg-Ni system heat-resistant wrought aluminum alloy extruded bar, its preparation method and application, and more particularly to a heat-resistant wrought aluminum alloy, its preparation method and application. Background Technology

[0002] Heat-resistant wrought aluminum alloys are high-temperature aluminum materials that can be pressure-processed (rolled, extruded, forged). They balance the lightweight nature of the aluminum matrix with high-temperature mechanical properties and are widely used in internal combustion engine pistons / connecting rods, turbine compressor blades, high-temperature pipe profiles, aerospace medium-temperature structural components, rail transit heat-resistant components, and industrial high-temperature heat dissipation components. For example, 2618 aluminum alloy (corresponding to the national standard grade 2A70) belongs to the Al-Cu-Mg-Ni system of heat-treatable aluminum alloys. The Al9FeNi and Al2CuMg phases formed in the alloy give it good heat resistance and high-temperature strength retention. It can still maintain high mechanical properties at operating temperatures of 150℃~200℃, so it is widely used in high-temperature structural components such as aero-engine pistons, turbochargers, and compressor impellers.

[0003] However, the 2618 aluminum alloy currently produced domestically has defects such as excessively high hardness in the O state, difficulty in balancing soft and hard state properties, numerous microstructural defects, and poor batch stability, which limit the further application and development of 2618 aluminum alloy in high-temperature load-bearing structural components such as turbocharger compressor impellers.

[0004] In view of this, this application provides a heat-resistant wrought aluminum alloy, its preparation method, and its application. Summary of the Invention

[0005] Based on the above problems, this application aims to provide a heat-resistant wrought aluminum alloy, its preparation method, and its application.

[0006] In one aspect, this application provides a heat-resistant deformable aluminum alloy.

[0007] The heat-resistant wrought aluminum alloy of the first aspect of this application, by mass fraction, comprises the following chemical composition: Si 0.10%~0.30%, Fe 0.5%~1.5%, Cu 1.5%~3.0%, Mg 1.0%~2.0%, Ni 0.5%~1.5%, Ti 0%~0.10%, individual impurities ≤0.05%, total impurities ≤0.15%, and the balance being Al.

[0008] Based on the above scheme, this application introduces Si element into the Al-Cu-Mg-Ni heat-treatable strengthened aluminum alloy. The introduced Si element mainly forms the Mg2Si phase (strengthening phase) and a small amount of free Si in the aluminum matrix. In the O state (annealed state), the formed Mg2Si phase exhibits a fine, dispersed distribution or partial solid solution state in the aluminum matrix, avoiding the problem of excessively high soft hardness caused by an excessive amount of strengthening phase. Furthermore, it interacts with the S phase (Al2CuMg phase) to form a high-density, uniformly distributed nanoscale precipitate within the grains, significantly improving the alloy's strength and contributing to enhanced heat resistance. In particular, when Si is introduced into the aluminum alloy matrix and the Si content is controlled to meet the range of 0.10% to 0.30%, a more suitable amount of Mg2Si can be formed, producing a certain dispersion strengthening effect without excessively increasing the matrix hardness. Specifically, this application introduces Si into the aluminum alloy matrix and, by combining Fe, Cu, Mg, Ni, and Ti elements, further controls the chemical composition of the heat-resistant wrought aluminum alloy to meet the following requirements: Si 0.10%~0.30%, Fe 0.5%~1.5%, Cu 1.5%~3.0%, Mg 1.0%~2.0%, Ni 0.5%~1.5%, Ti 0%~0.10%, individual impurities ≤0.05%, total impurities ≤0.15%, with the balance being Al. This achieves precise control over the aluminum alloy composition, making the chemical composition of the heat-resistant wrought aluminum alloy more suitable for processing requirements. As a result, it is possible to prepare a heat-resistant wrought aluminum alloy with dual-state compatibility of O-state softness and T6-state strength and toughness, solving the technical problem of excessively high soft-state hardness and insufficient hard-state strength in traditional processes.Specifically, this application designs the alloy composition to ensure that Cu and Mg, within the aforementioned content range, serve as core strengthening elements. Their proportion control makes the S phase the primary strengthening phase. The high-density S phase in the T6 state provides the main strength contribution, while the S phase dissolution or coarsening during O-state annealing ensures low hardness in the soft state. Ni (0.5%~1.5%) forms heat-resistant phases such as Al3Ni and Al7Cu4Ni with Cu and Al, distributed at grain boundaries and subgrain boundaries, pinning grain boundary migration to inhibit high-temperature grain growth and creep deformation, significantly improving high-temperature endurance strength and creep resistance, while simultaneously hindering crack propagation along grain boundaries to improve high-temperature toughness. Fe (0.5%~1.5%) forms dispersed multi-metallic compounds with Ni and Al, which are stable at high temperatures. It hinders dislocation movement and acts as a heterogeneous nucleation substrate to promote grain refinement. Controlling its content can avoid the formation of coarse needle-like phases that would deteriorate toughness. Ti (0%~0.10%) forms the Al3Ti phase as a casting nucleating agent, refining the as-cast grains to make the subsequent microstructure uniform and fine. In the O state, it is beneficial to obtain uniform low hardness. In the T6 state, it improves the strength and toughness matching through the synergistic effect of grain refinement strengthening and precipitation strengthening. Si and Fe interact to form fine AlFeSi phase to optimize the uniformity of phase distribution. Si and Mg interact to form a Mg2Si+S phase dual strengthening system to achieve hierarchical strengthening and uniform dispersion precipitation. Si and Ni interact to promote the formation of finer multi-element phases. Finally, through the synergistic effect of multiple elements, the technical problems of excessively high soft hardness and insufficient hard strength in traditional processes are solved.

[0009] In some embodiments of the first aspect of this application, the heat-resistant wrought aluminum alloy satisfies at least one of the following conditions: (1) Ti 0.05%~0.10%; (2) The mass ratio of Cu to Mg is 1~3:1.

[0010] In some embodiments of the first aspect of this application, the heat-resistant wrought aluminum alloy satisfies at least one of the following conditions: (1) When delivered in the O state, the following conditions must be met: Brinell hardness ≤ 60 HBW; (2) Under T6 conditions, the following conditions must be met: tensile strength ≥ 410 MPa, yield strength ≥ 370 MPa, elongation after fracture ≥ 6%, and Brinell hardness ≥ 150 HBW.

[0011] In some embodiments of the first aspect of this application, the heat-resistant wrought aluminum alloy further satisfies at least one of the following conditions: (1) The microstructure analysis results of the heat-resistant deformable aluminum alloy in the O-state delivery state show that the crack length of the whole cross section is ≤15 mm and the surface roughness Ra is ≤3.5 μm; (2) The microstructure observation and analysis results of the heat-resistant deformable aluminum alloy in the T6 state showed that Al9FeNi phase and Al2CuMg phase were dispersed in the matrix, and the area fraction of non-metallic oxide inclusions was ≤0.005%.

[0012] Secondly, this application provides a method for preparing a heat-resistant deformable aluminum alloy.

[0013] The preparation method of the second aspect of this application includes the following steps: S1. Batching and Smelting: Weigh out the corresponding mass of pure aluminum ingots, aluminum-copper master alloy, aluminum-iron master alloy, aluminum-nickel master alloy and magnesium ingots according to the alloy composition ratio of the target heat-resistant deformable aluminum alloy; and smelt them in a smelting furnace to obtain aluminum alloy melt; S2. Refining: Add a refining agent to the aluminum alloy melt and perform refining treatment at least twice; S3. Refining: Add a grain refiner to the refined aluminum alloy melt to refine the grains; S4. Degassing: Degassing the refined aluminum alloy melt; S5. Filtration and casting: After degassing, the aluminum alloy melt is filtered and then semi-continuously cast. The temperature at the casting head is controlled at 710℃~730℃ to obtain an aluminum alloy billet. S6. Homogenization treatment: The aluminum alloy billet is subjected to homogenization treatment; S7. Hot extrusion forming: Hot extrusion is performed on the homogenized aluminum alloy billet to obtain the extruded semi-finished product; S8. Quenching and straightening: The extruded semi-finished product is placed in a water-cooling device for online quenching and then stretched and straightened. S9. Step annealing: The extruded semi-finished product after quenching and straightening is subjected to step low temperature annealing. First, it is held at a temperature of T1, then held at a temperature of T2, and then cooled in the furnace to below 100°C to obtain O-state aluminum alloy; where T1>T2. S10. Machining and T6 heat treatment: The O-state aluminum alloy is machined according to actual needs and then subjected to T6 heat treatment to obtain the heat-resistant deformable aluminum alloy.

[0014] Based on the above, this application, through the sequential execution of the aforementioned steps, can better coordinate with the above-mentioned aluminum alloy composition for processing, achieving dual-state compatibility of O-state soft state and T6-state strength and toughness, solving the technical problem of excessively high hardness in the soft state and insufficient strength in the hard state in traditional processes. The O-state delivery hardness is ≤60 HBW, with no cracking after bending at 90°, good flaring and welding, and no tearing under full-section compression, meeting the requirements for precision cold forming of impellers. After T6 heat treatment, the tensile strength is ≥410 MPa, the yield strength is ≥370 MPa, the elongation after fracture is ≥6%, and the hardness is ≥150 HBW, exhibiting excellent high-temperature load-bearing performance. Specifically, this application, through the synergistic effect of at least two refining, degassing, and filtration processes, can effectively reduce the impurity content in the aluminum alloy melt with the above-mentioned aluminum alloy composition, achieving a non-metallic oxide inclusion area fraction ≤0.005%, and low-magnification microstructure free of cracks, inclusions, delamination, and shrinkage tails, significantly improving the material's microstructure purity and fatigue reliability, and extending the impeller's service life. Through processes such as hot extrusion forming, quenching and straightening combined with stepped annealing, the thickness of the coarse-grained layer of aluminum alloy can be stably controlled within 0.3 mm. The microstructure is free from overheating, with clean grain boundaries, and the Al9FeNi and Al2CuMg phases are dispersedly distributed with a grain size ≥3. The material has a uniform and stable microstructure and good batch consistency. Moreover, the preparation method of this application is stable and controllable, and the process is suitable for industrial mass production without special complex equipment requirements. The heat-resistant deformable aluminum alloy prepared has excellent surface quality, with a roughness Ra≤3.5 μm, and is free from defects such as cracks, peeling, and porosity. It can be directly used in the manufacture of high-temperature structural components such as turbochargers and compressor impellers, significantly reducing the processing scrap rate and improving production efficiency.

[0015] In some embodiments of the second aspect of this application, in S9, T1 satisfies 400℃≤T1≤430℃, and T2 satisfies 380℃≤T2≤400℃.

[0016] In some embodiments of the second aspect of this application, the temperature is maintained at T1 for 2 h to 3 h.

[0017] In some embodiments of the second aspect of this application, the temperature is maintained at T2 for 3 h to 6 h.

[0018] In some embodiments of the second aspect of this application, in S2, the refining agent includes a sodium-free environmentally friendly refining agent.

[0019] In some embodiments of the second aspect of this application, the amount of refining agent added is 0.25% to 0.35% based on the mass of the aluminum alloy melt.

[0020] In some embodiments of the second aspect of this application, the refining temperature during each refining process is 720°C to 760°C, and the refining time is 5 min to 10 min.

[0021] In some embodiments of the second aspect of this application, in S2, the mixture is left to stand for 20 to 30 minutes after the final refining.

[0022] In some embodiments of the second aspect of this application, the refining agent comprises aluminum titanium boron wire.

[0023] In some embodiments of the second aspect of this application, the amount of the refining agent added is 0.15% to 0.25% of the mass of the aluminum alloy melt.

[0024] In some embodiments of the second aspect of this application, the refining agent is added by online fiber feeding, and the fiber feeding speed is 2.5 m / min to 3.5 m / min.

[0025] In some embodiments of the second aspect of this application, the T6 heat treatment includes a solution treatment and an artificial aging treatment performed sequentially.

[0026] In some embodiments of the second aspect of this application, the solution treatment is performed at a temperature of 500°C to 520°C for a time of 30 min to 90 min, followed by water quenching.

[0027] In some embodiments of the second aspect of this application, the temperature of the artificial aging treatment is 150°C to 170°C, and the time is 6 h to 10 h.

[0028] Thirdly, this application provides an application of a heat-resistant wrought aluminum alloy.

[0029] In a third aspect of this application, the application includes the use of the heat-resistant deformable aluminum alloy in the manufacture of turbocharger compressor impellers and high-temperature structural components for engines.

[0030] It should be noted that the heat-resistant wrought aluminum alloy is any one of the heat-resistant wrought aluminum alloys in the first aspect, or a heat-resistant wrought aluminum alloy prepared according to any one of the preparation methods in the second aspect. Therefore, the third aspect of this application has all the beneficial effects of the first or second aspect, so this application will not repeat them here. Please refer to the relevant content in the first or second aspect of this application.

[0031] The beneficial effects of the technical solutions provided in some embodiments of this application include at least the following: This application introduces Si into a heat-treatable Al-Cu-Mg-Ni aluminum alloy. The introduced Si primarily forms the Mg2Si phase (strengthening phase) and a small amount of free Si in the aluminum matrix. In the O state (annealed state), the Mg2Si phase exhibits a fine, dispersed distribution or partial solid solution state within the aluminum matrix, avoiding excessive hardness in the soft state caused by an excessive amount of strengthening phase. Furthermore, it interacts with the S phase (Al2CuMg phase) to form a high-density, uniformly distributed nanoscale precipitate within the grains, significantly improving the alloy's strength and heat resistance. In particular, when Si is introduced into the aluminum alloy matrix and the Si content is controlled to meet the range of 0.10% to 0.30%, a more suitable amount of Mg2Si can be formed, achieving a certain dispersion strengthening effect without excessively increasing the matrix hardness. Specifically, this application introduces Si into the aluminum alloy matrix and further controls the chemical composition of the heat-resistant deformable aluminum alloy by combining it with Fe, Cu, Mg, Ni, and Ti elements to meet the following requirements: Si 0.10%~0.30%, Fe 0.5%~1.5%, Cu 1.5%~3.0%, Mg 1.0%~2.0%, Ni 0.5%~1.5%, Ti 0%~0.10%, individual impurities ≤0.05%, total impurities ≤0.15%, and the balance being Al. This achieves precise control over the aluminum alloy composition, making the chemical composition of the heat-resistant deformable aluminum alloy more suitable for processing requirements and achieving dual-state compatibility of O-state soft state and T6-state strength and toughness.

[0032] This application employs a sequential process of batching and melting, refining, fine refining, degassing, filtration and casting, homogenization, hot extrusion molding, quenching and straightening, stepped annealing, and machining followed by T6 heat treatment. This allows the preparation method to better complement the aforementioned aluminum alloy composition, achieving compatibility between the O-state (soft state) and the T6-state (strong and tough state). This solves the technical problem of excessively high hardness in the soft state and insufficient strength in the hard state inherent in traditional processes. In particular, through the synergistic effect of at least two refining, degassing, and filtration processes, this application effectively reduces the impurity content in the aluminum alloy melt containing the aforementioned composition. The area fraction of non-metallic oxide inclusions is ≤0.005%, and the low-magnification microstructure is free of cracks, inclusions, delamination, and shrinkage tails, significantly improving the material's microstructure purity and fatigue reliability, and extending the impeller's service life. Through processes such as hot extrusion forming, quenching and straightening combined with stepped annealing, the thickness of the coarse-grained layer of aluminum alloy can be stably controlled within 0.3 mm. The microstructure is free from overheating, with clean grain boundaries, and the Al9FeNi and Al2CuMg phases are dispersedly distributed with a grain size ≥3. The material has a uniform and stable microstructure and good batch consistency. Moreover, the preparation method of this application is stable and controllable, and the process is suitable for industrial mass production without special complex equipment requirements. The heat-resistant deformable aluminum alloy prepared has excellent surface quality, with a roughness Ra≤3.5 μm, and is free from defects such as cracks, peeling, and porosity. It can be directly used in the manufacture of high-temperature structural components such as turbochargers and compressor impellers, significantly reducing the processing scrap rate and improving production efficiency. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 The image shows the metallographic structure of the aluminum alloy extruded bar prepared in Example 1, magnified 50×.

[0035] Figure 2 The image shows the metallographic structure of the aluminum alloy extruded bar prepared in Example 1, magnified 100×.

[0036] Figure 3 The image shows the metallographic structure of the aluminum alloy extruded bar prepared in Example 1, magnified 200×.

[0037] Figure 4 The image shows the metallographic structure of the aluminum alloy extruded bar prepared in Example 2, magnified 50×.

[0038] Figure 5 The image shows the metallographic structure of the aluminum alloy extruded bar prepared in Example 2, magnified 100×.

[0039] Figure 6 The image shows the metallographic structure of the aluminum alloy extruded bar prepared in Example 2, magnified 200×. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0041] In the description of this application, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings, and are used only for ease of description and simplification of operation. They 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 application. In addition, the terms "first" and "second" are used only for descriptive distinction and have no special meaning.

[0042] The endpoints and any values ​​of the ranges disclosed in this application are not limited to the precise ranges or values, and such ranges or values ​​should be understood to include values ​​close to such ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0043] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions. Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions. Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc. Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included. Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0044] It should be emphasized that the preparation methods or operation steps not specifically described in this application all refer to the prior art in this field, which should be known by those skilled in the art, and therefore will not be described again in this application.

[0045] Heat-resistant wrought aluminum alloys are high-temperature aluminum materials that can be pressure-processed (rolled, extruded, forged). They balance lightweight aluminum matrix with high-temperature mechanical properties and are widely used in internal combustion engine pistons / connecting rods, turbine compressor blades, high-temperature pipe profiles, aerospace medium-temperature structural components, rail transit heat-resistant components, and industrial high-temperature heat dissipation components. Among them, 2618 aluminum alloy (corresponding to the national standard grade 2A70) has excellent heat resistance and high-temperature strength retention, maintaining high mechanical properties even at operating temperatures of 150℃~200℃. Therefore, it is widely used in high-temperature structural components such as aero-engine pistons and turbocharger compressor impellers.

[0046] In the actual manufacturing process of turbocharger compressor impellers, manufacturers typically require 2618 aluminum alloy bars to be supplied in a fully annealed state (often referred to as the "O-state"). O-state bars must possess low hardness and high plasticity to meet the requirements of subsequent cold forming processes such as milling, bending, flaring, and compression. After the impeller blank is machined, it undergoes T6 heat treatment (solution treatment + artificial aging) to enhance its strength, ensuring the final product meets the mechanical performance requirements under high temperature and high speed conditions. This manufacturing model, which involves supplying in the O-state—cold forming—T6 strengthening, imposes stringent requirements on the bar's ability to control both its soft and hard states.

[0047] However, the current methods for preparing 2618 aluminum alloy extruded bars mainly have the following technical problems: First, the hardness control in the O-state is unstable. 2618 aluminum alloy bars prepared using conventional annealing processes typically have a Brinell hardness in the annealed state ranging from 55 HBW to 70 HBW, making it difficult to stably control below 60 HBW. Excessive hardness leads to surface cracking and peeling during subsequent bending and flaring processes, increasing the scrap rate and failing to meet the precision forming requirements of impellers.

[0048] Second, it is difficult to achieve both soft formability and hard strength. Some companies achieve softening by extending the annealing time or increasing the annealing temperature, but excessive annealing leads to a reduction in the amount and uneven distribution of strengthening phases during subsequent T6 heat treatment. As a result, the tensile strength is difficult to reach above 410 MPa, the yield strength is below 370 MPa, and the elongation after fracture drops to below 4%, indicating insufficient plasticity.

[0049] Third, controlling the coarse grain layer and structural defects is difficult. The thickness of the coarse grain layer on the surface of extruded bars often exceeds 0.5 mm, and defects such as cracks, inclusions, delamination, and tailing appear in the low magnification structure; the microstructure is prone to problems such as overheating, grain boundary coarsening, and compound segregation, which affect the fatigue life of the material.

[0050] Fourth, the purity of the melt is substandard. The area fraction of non-metallic oxide inclusions often exceeds 0.01%, which becomes a source of fatigue crack initiation under high-speed impeller rotation, reducing product reliability.

[0051] Fifth, there is a lack of systematic control methods for the processing characteristics of impellers. Existing technologies mostly focus on the performance indicators of a single heat treatment state, without combining key forming indicators such as no cracking when bending 90°, good flaring and welding, and no tearing under full-section compression in the impeller manufacturing process for whole-process design, resulting in poor matching between material properties and processing requirements.

[0052] In view of this, this application provides a heat-resistant wrought aluminum alloy, its preparation method and application. By precisely controlling the composition of 2618 aluminum alloy, it can improve the matching with processing requirements and solve the technical problems of excessively high soft hardness and insufficient hard strength in traditional processes. In particular, it addresses the technical problems of excessively high O-state hardness, difficulty in balancing soft and hard state properties, numerous microstructural defects, and poor batch stability of existing 2618 aluminum alloy bars. It achieves a coordinated unity of low hardness and high plasticity in the O-state and high strength and high heat resistance in the T6 state.

[0053] The first aspect of this application provides a heat-resistant wrought aluminum alloy.

[0054] The heat-resistant wrought aluminum alloy provided in the first aspect of this application has the following chemical composition by mass fraction: Si 0.10%~0.30%, Fe 0.5%~1.5%, Cu 1.5%~3.0%, Mg 1.0%~2.0%, Ni 0.5%~1.5%, Ti 0%~0.10%, individual impurities ≤0.05%, total impurities ≤0.15%, and the balance being Al.

[0055] Based on the above scheme, this application introduces Si element into the Al-Cu-Mg-Ni heat-treatable strengthened aluminum alloy, so that the introduced Si element mainly forms Mg2Si phase (strengthening phase) and a small amount of free Si in the aluminum matrix. In the O state (annealed state), the formed Mg2Si phase is finely dispersed or partially dissolved in the aluminum matrix, avoiding the problem of excessive soft hardness caused by too much strengthening phase; on the other hand, it cooperates with the S phase (Al2CuMg phase) to form a high-density, uniformly distributed nanoscale precipitate phase in the crystal, which significantly improves the strength of the alloy and helps to improve the heat resistance of the alloy.

[0056] In particular, when the Si content is controlled to meet the range of 0.10% to 0.30%, a more suitable amount of Mg2Si can be formed, which can produce a certain dispersion strengthening effect without excessively increasing the hardness of the matrix. Moreover, when the Cu content meets the range of 1.5% to 3.0% and the Mg content meets the range of 1.0% to 2.0%, Cu and Mg act as core strengthening elements, and their ratio control makes the S phase the main strengthening phase. The high-density S phase in the T6 state provides the main strength contribution, and the S phase dissolution or coarsening during O-state annealing ensures low hardness in the soft state. Ni (0.5% to 1.5%) forms heat-resistant phases such as Al3Ni and Al7Cu4Ni with Cu and Al, which are distributed at grain boundaries and subgrain boundaries. They pin grain boundary migration to inhibit high-temperature grain growth and creep deformation, significantly improving high-temperature endurance strength and creep resistance, while also hindering crack propagation along grain boundaries to improve high-temperature toughness. When Fe content is between 0.5% and 1.5%, it can form a dispersed multi-element intermetallic compound with Ni and Al, which is stable at high temperatures to hinder dislocation movement and acts as a heterogeneous nucleation substrate to promote grain refinement. Controlling its content can prevent the formation of coarse acicular phases that would deteriorate toughness. When Ti content is ≤0.10%, it can form an Al3Ti phase in the aluminum alloy matrix as a casting nucleating agent, refining the as-cast grains to ensure uniform and fine microstructure in the subsequent process. In the O state, it is beneficial to obtain uniform low hardness, and in the T6 state, it improves the strength-toughness match through the synergistic effect of grain refinement and precipitation strengthening. In addition, Si and Fe interact to form a fine AlFeSi phase to optimize phase distribution uniformity, Si and Mg interact to form a Mg2Si+S phase dual strengthening system to achieve hierarchical strengthening and uniform dispersed precipitation, and Si and Ni interact to promote the formation of even finer multi-element phases. Ultimately, through the synergistic effect of multiple elements, the technical problems of excessively high soft-state hardness and insufficient hard-state strength in traditional processes are solved.

[0057] In summary, this application introduces Si into the aluminum alloy matrix and combines it with Fe, Cu, Mg, Ni, and Ti elements. Furthermore, by controlling the chemical composition of the heat-resistant wrought aluminum alloy to meet the following requirements: Si 0.10%~0.30%, Fe 0.5%~1.5%, Cu 1.5%~3.0%, Mg 1.0%~2.0%, Ni 0.5%~1.5%, Ti 0%~0.10%, individual impurities ≤0.05%, total impurities ≤0.15%, and the balance being Al, precise control of the aluminum alloy composition is achieved. This makes the chemical composition of the heat-resistant wrought aluminum alloy more suitable for processing requirements, thereby enabling the preparation of heat-resistant wrought aluminum alloys with dual-state compatibility of O-state softness and T6-state strength and toughness. This solves the technical problem of excessively high soft-state hardness and insufficient hard-state strength in traditional processes.

[0058] In some embodiments of the first aspect of this application, the Ti element content is 0.05% to 0.10%. Based on the above scheme, it is beneficial for the Ti element to better achieve the above-mentioned functions.

[0059] In some embodiments of the first aspect of this application, the mass ratio of Cu to Mg is 1 to 3:1. Based on the above scheme, Cu and Mg are advantageous as core strengthening elements, and can better achieve the above-mentioned effects.

[0060] The heat-resistant deformable aluminum alloy satisfies at least one of the following conditions; In some embodiments of the first aspect of this application, the heat-resistant wrought aluminum alloy satisfies at least one of the following conditions; (1) When delivered in the O state, the following conditions must be met: Brinell hardness ≤ 60 HBW; (2) Under T6 conditions, the following conditions must be met: tensile strength ≥ 410 MPa, yield strength ≥ 370 MPa, elongation after fracture ≥ 6%, and Brinell hardness ≥ 150 HBW.

[0061] Based on the above scheme, this application, through optimizing the alloy composition ratio, can better adapt to processing requirements, thereby achieving stable control of the hardness of the heat-resistant wrought aluminum alloy in the O state below 60 HBW. This effectively avoids surface cracking and peeling of the bar stock during subsequent bending and flaring processes due to excessive hardness, leading to increased processing scrap rates. Furthermore, it promotes the dispersion of strengthening phases (Al9FeNi phase and Al2CuMg phase) on the matrix of the heat-resistant wrought aluminum alloy during subsequent T6 heat treatment, resulting in a tensile strength ≥410 MPa, yield strength ≥370 MPa, elongation after fracture ≥6%, and Brinell hardness ≥150 HBW for the heat-resistant wrought aluminum alloy in the T6 state. This achieves a balance between soft-state formability and hard-state strength, obtaining a heat-resistant wrought aluminum alloy with dual-state compatibility of soft O state and T6 state strength and toughness, solving the technical problem of excessively high soft-state hardness and insufficient hard-state strength in traditional processes.

[0062] In some embodiments of the first aspect of this application, the heat-resistant deformable aluminum alloy also satisfies at least one of the following conditions; (1) The heat-resistant deformable aluminum alloy delivered in the O state shall meet the following requirements: no cracking when bent at 90°, good flaring and welding, no tearing under full cross-section compression, crack length ≤15 mm, and surface roughness Ra≤3.5 μm; (2) The microstructure observation and analysis results of the heat-resistant deformable aluminum alloy in the T6 state showed that Al9FeNi phase and Al2CuMg phase were dispersed in the matrix, and the area fraction of non-metallic oxide inclusions was ≤0.005%.

[0063] Based on the above scheme, this application, through the optimization of alloy composition ratio, can better adapt to processing requirements, enabling the heat-resistant wrought aluminum alloy of this application to achieve advantages such as no cracking when bent at 90°, good flaring and welding, no tearing under full cross-section compression, and crack length ≤15 mm. Moreover, it is conducive to the control of coarse grain layer and microstructural defects, so that the low magnification microstructure of the heat-resistant wrought aluminum alloy is free of cracks, inclusions, delamination, and shrinkage tails, and the coarse grain layer thickness is ≤0.3 mm. It can also promote the dispersion of strengthening phases (Al9FeNi phase and Al2CuMg phase) on the matrix of the heat-resistant wrought aluminum alloy during subsequent T6 heat treatment. The microstructure is free of overheating, the grain boundaries are clean, and the area fraction of non-metallic oxide inclusions is ≤0.005%, thereby effectively avoiding the occurrence of problems such as overheating, grain boundary coarsening, and compound segregation in the microstructure that affect the fatigue life of the final product, which is conducive to improving product reliability. Moreover, it also helps to improve the surface roughness of heat-resistant deformable aluminum alloys (surface roughness Ra≤3.5 μm), making its surface free of cracks, peeling, pores, scratches and mechanical damage.

[0064] Secondly, this application provides a method for preparing a heat-resistant deformable aluminum alloy.

[0065] The preparation method provided in the second aspect of this application is used to prepare the heat-resistant deformable aluminum alloy described in any one of the first aspects above.

[0066] The second aspect of this application provides a method for preparing a heat-resistant wrought aluminum alloy, comprising the following steps: S1. Batching and Smelting: Weigh out the corresponding mass of pure aluminum ingots, aluminum-copper master alloy, aluminum-iron master alloy, aluminum-nickel master alloy and magnesium ingot according to the alloy composition ratio of the target heat-resistant deformable aluminum alloy; and smelt them in a smelting furnace to obtain aluminum alloy melt.

[0067] It should be noted that in this application, Cu, Fe and Ni are all added in the form of aluminum-based master alloys, that is, in the form of aluminum-copper master alloy, aluminum-iron master alloy and aluminum-nickel master alloy respectively, to avoid the oxidation of raw materials and the resulting aluminum alloy melt having substandard purity.

[0068] In some embodiments of the second aspect of this application, the purity of the pure aluminum ingots used in this application is ≥99.99%, the purity of the aluminum-copper master alloy is ≥99%, the purity of the aluminum-iron master alloy is ≥99%, the purity of the aluminum-nickel master alloy is ≥99%, and the purity of the magnesium ingots is ≥99.99%. Here, the purity of the aluminum-copper master alloy refers to the sum of the contents of Al and Cu elements in the master alloy; the purity of the aluminum-iron master alloy refers to the sum of the contents of Al and Fe elements in the master alloy; and the purity of the aluminum-nickel master alloy refers to the sum of the contents of Al and Ni elements in the master alloy. Based on the above scheme, by reducing the impurity content in the raw materials, the purity of the subsequently obtained aluminum alloy melt can be further improved, thereby helping to reduce the area fraction of non-metallic oxide inclusions (and achieving a non-metallic oxide inclusion area fraction ≤0.005%), which is beneficial to improving the product reliability of heat-resistant deformable aluminum alloys under high-speed impeller rotation conditions.

[0069] This application does not limit the specific smelting method, as long as a uniform aluminum alloy melt can be obtained.

[0070] Exemplarily, in some embodiments of the second aspect of this application, the smelting includes the following steps: Pure aluminum ingots, aluminum-copper master alloys, aluminum-iron master alloys, and aluminum-nickel master alloys are sequentially added to a melting furnace and smelted at 720℃~760℃ until completely melted. Magnesium ingots are then added, and smelting continues to yield an aluminum alloy melt. This method ensures complete melting of all raw materials, avoids component segregation, and results in a more homogeneous and pure aluminum alloy melt.

[0071] In some embodiments of the second aspect of this application, electromagnetic stirring is introduced throughout the entire melting process to better promote the complete melting of the raw materials, avoid component segregation, and thus make the resulting aluminum alloy melt more uniform and pure in composition. This application does not limit the specific electromagnetic stirring process parameters, as long as they achieve the desired effect. For example, the electromagnetic stirring current can be 10A~60A, the electromagnetic frequency 20Hz~50Hz, and the stirring speed 40r / min~60r / min.

[0072] In some embodiments of the second aspect of this application, after adding magnesium ingots, electromagnetic stirring is continued for 15 to 20 minutes. Based on the above scheme, a more uniform and pure aluminum alloy melt can be obtained.

[0073] S2. Refining: Add a refining agent to the aluminum alloy melt and perform refining treatment at least twice.

[0074] It should be noted that this application does not limit the specific type or category of refining agent, as long as it can achieve the function of this application. For example, in some embodiments of the second aspect of this application, the refining agent includes a sodium-free environmentally friendly refining agent, which includes potassium chloride, magnesium chloride, and potassium fluoroaluminate. Based on the above scheme, when the refining agent used includes a sodium-free environmentally friendly refining agent, the sodium embrittlement defect can be avoided, the aluminum liquid can be deeply purified, and the microstructure and composition of the 2618 aluminum alloy extruded bar can be ensured to be pure and stable. This better balances the O-state forming and processing performance with the T6-state high strength and heat resistance performance, and the process is environmentally friendly and suitable for mass production.

[0075] This application does not limit the specific amount of refining agent added; the amount of refining agent added should be based on the actual mass of the obtained aluminum alloy melt. For example, in some embodiments of the second aspect of this application, the amount of refining agent added is 0.25% to 0.35% based on the mass of the aluminum alloy melt. Exemplarily, the amount of refining agent added is 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, 0.3%, 0.31%, 0.32%, 0.33%, 0.34%, 0.35%, or any range between two of the above values, based on the mass of the aluminum alloy melt. Based on the above scheme, a better balance can be achieved between processing costs and refining effects.

[0076] This application does not limit the specific method of adding the refining agent, as long as it enables sufficient contact between the refining agent and the molten aluminum alloy. For example, in some embodiments of the second aspect of this application, a W-type and Z-type dual-tube method is used to deliver the refining agent into the molten aluminum alloy to improve the contact effect between the refining agent and the molten aluminum alloy, thereby promoting the flotation and aggregation of oxide inclusions and slag.

[0077] This application does not limit the specific number of refining operations; the number can be selected based on actual circumstances, as long as the purpose of this application can be achieved. For example, in some embodiments of the second aspect of this application, at least two refining operations are performed, and the mixture is allowed to stand for 20 to 30 minutes after the last refining operation to allow oxide inclusions and slag to fully float and aggregate. This facilitates the removal of surface slag after refining, thereby further improving the purity of the aluminum alloy melt.

[0078] This application does not limit the specific process parameters for each refining process. Appropriate refining process parameters can be selected based on the refining agent used, to ensure a better match between the refining agent and the refining process parameters, thereby improving the refining effect and efficiency. For example, in some embodiments of the second aspect of this application, when the refining agent used includes a sodium-free environmentally friendly refining agent, the refining temperature for each refining process is 720℃~760℃, and the refining time is 5 min~10 min.

[0079] Exemplarily, in some embodiments of the second aspect of this application, the refining includes the following steps: A sodium-free, environmentally friendly refining agent is used as the refining agent. The refining agent is fed into the aluminum alloy melt using W-type and Z-type dual tubes, and then the refining is carried out twice. The refining temperature during each refining is 720℃~760℃, and the refining time is 5min~10min. The amount of the refining agent added is 0.25%~0.35% based on the mass of the aluminum alloy melt. After the first refining, the slag is removed, and after the furnace is opened, the slag is removed again for the second refining. After the last refining, the mixture is allowed to stand for 20min~30min.

[0080] S3. Refining: Add a grain refiner to the refined aluminum alloy melt to refine the grain size.

[0081] It should be noted that this application does not limit the specific type or category of the refining agent, as long as it can achieve the function of this application. For example, in some embodiments of the second aspect of this application, the refining agent includes aluminum titanium boron wire.

[0082] This application does not limit the specific amount of grain refiner added. The appropriate amount of grain refiner is selected based on the actual mass of the aluminum alloy melt, as long as the desired effect of this application is achieved. For example, in some embodiments of the second aspect of this application, when the grain refiner includes aluminum-titanium-boron wire, the amount of grain refiner added is 0.15% to 0.25% of the mass of the aluminum alloy melt. Exemplarily, the amount of grain refiner added is 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.2%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25% of the mass of the aluminum alloy melt, or a range between any two of the above values. Based on the above scheme, it is beneficial for the grain refiner to better cooperate with the aluminum alloy melt to achieve grain refinement, further improve the uniformity of microstructure distribution, reduce segregation, and thus better improve the mechanical properties of the product.

[0083] This application does not limit the specific method of adding the grain refiner, as long as it achieves the intended effect. For example, in some embodiments of the second aspect of this application, when the grain refiner includes aluminum-titanium-boron wire, it is added via online wire feeding, combined with electromagnetic stirring to ensure uniform distribution of the refined particles. This application also does not limit the specific wire feeding speed, as long as it achieves the intended effect. For example, the wire feeding speed is controlled between 2.5 m / min and 3.5 m / min. Exemplarily, the wire feeding speed is controlled within the range of 2.5 m / min, 2.6 m / min, 2.7 m / min, 2.8 m / min, 2.9 m / min, 3.0 m / min, 3.1 m / min, 3.2 m / min, 3.3 m / min, 3.4 m / min, 3.5 m / min, or any two of the above values. Based on the above scheme, it is beneficial to combine electromagnetic stirring to ensure a more uniform distribution of the grain refiner in the aluminum alloy melt, thereby better achieving uniform grain refinement.

[0084] S4. Degassing: Degas the refined aluminum alloy melt.

[0085] It should be noted that this application does not limit the specific degassing method, as long as it can achieve the purpose of this application. For example, in some embodiments of the second aspect of this application, a rotary degassing box technology is used for degassing, so as to adsorb hydrogen and suspended inclusions in the aluminum alloy melt by the rising of bubbles.

[0086] It should be understood that the rotary degassing technology involves blowing high-purity inert gas into a sealed, insulated chamber during rotor rotation. The rotor atomizes the high-purity inert gas into micron-sized bubbles, which are then uniformly dispersed and floated within the molten aluminum alloy. This adsorption of hydrogen and suspended inclusions in the molten aluminum alloy further improves its cleanliness. In this application, "high-purity inert gas" refers to an inert gas with a purity ≥ 99.99%. The inert gas used in this application includes at least one of argon and nitrogen, specifically argon with a purity ≥ 99.99% and nitrogen with a purity ≥ 99.99%.

[0087] This application does not limit the specific rotational speed of the rotor, as long as it achieves the intended function. For example, in some embodiments of the second aspect of this application, the rotor rotational speed is 350 r / min to 450 r / min. Exemplarily, the rotor rotational speed is 350 r / min, 360 r / min, 370 r / min, 380 r / min, 390 r / min, 400 r / min, 410 r / min, 420 r / min, 430 r / min, 440 r / min, 450 r / min, or a range between any two of the above values. Based on the above scheme, it is beneficial to better atomize the high-purity inert gas into micron-sized bubbles, thereby better achieving the adsorption and removal of hydrogen and suspended inclusions in the aluminum alloy melt.

[0088] S5. Filtration and Casting: After degassing, the aluminum alloy melt is filtered and then semi-continuously cast. The temperature at the casting head is controlled at 710℃~730℃ to obtain an aluminum alloy billet.

[0089] It should be noted that this application does not limit the specific filtering method, as long as it can achieve the purpose of this application. For example, in some embodiments of the second aspect of this application, a 40 ppi ceramic filter plate is used for filtration to further purify the aluminum alloy melt.

[0090] It should be understood that the term "semi-continuous casting process" in this application refers to casting using a semi-continuous hot-top casting platform. The aluminum alloy melt flows smoothly into the hot-top crystallizer through a flow channel or guide plate. The aluminum alloy melt cools on the inner wall of the crystallizer to form a solidified shell. Primary cooling water circulates through the crystallizer jacket. After the ingot leaves the crystallizer with the dummy head, secondary cooling water is directly sprayed onto the surface of the ingot. The casting yields an aluminum alloy ingot. Considering that the aluminum alloy ingot may have defects such as looseness at the head and tail, shrinkage cavities, and cold shuts, the looseness at the head and tail, shrinkage cavities, and cold shuts of the aluminum alloy ingot are removed, and the dense middle part is retained as the aluminum alloy billet.

[0091] It is worth mentioning that this application controls the casting head temperature at 710℃~730℃. Based on the above scheme, when controlled within this temperature range, it can ensure that the multi-element alloy melt has good fluidity, achieve stable filling, and eliminate defects such as cold shuts, incomplete filling, and casting cracks; it can also suppress high-temperature gas absorption and secondary oxidation of the melt, reduce the formation of hydrogen and alumina inclusions, and form a synergistic effect with the previous double refining, rotary degassing, and filtration purification to ensure high purity of the billet. At the same time, a uniform solidification rate can reduce alloy element segregation, refine casting grains, and reduce solidification residual stress, controlling the original coarse grain region from the source, which is conducive to controlling the thickness of the coarse grain layer of the finished product to within 0.3 mm. After casting, the loose, shrinkage-cavity, cold shut and other defective sections of the casting rod are removed, and the dense and qualified billet is retained to enter the next process.

[0092] S6. Homogenization treatment: The aluminum alloy billet is subjected to homogenization treatment.

[0093] This application does not limit the specific process parameters of the homogenization treatment, which can be adjusted according to the actual composition of the aluminum alloy, as long as the function of this application can be achieved. For example, in some embodiments of the second aspect of this application, the homogenization treatment includes the following steps: placing the aluminum alloy billet obtained in S5 in a homogenization furnace and holding it at 480℃~510℃, followed by cooling to below 350℃. Based on the above scheme, intragranular compositional segregation is eliminated, and coarse and brittle second phases are dissolved.

[0094] This application does not limit the specific holding time, and it can be adjusted according to the actual holding temperature, as long as the function of this application can be achieved. For example, in some embodiments of the second aspect of this application, the holding time is 8 h to 12 h at 480℃ to 510℃. Exemplarily, the holding time is 8 h, 9 h, 10 h, 11 h, 12 h, or any range between two of the above values. Based on the above scheme, it is beneficial to better eliminate intracrystalline segregation and dissolve coarse and brittle second phase.

[0095] This application does not limit the cooling method after heat preservation, as long as it can achieve the purpose of this application. For example, in some embodiments of the second aspect of this application, the aluminum alloy billet is cooled to below 350°C in the furnace and then removed from the furnace to obtain a homogeneous aluminum alloy billet.

[0096] S7. Hot extrusion molding: The homogenized aluminum alloy billet is hot extruded to obtain the extruded semi-finished product.

[0097] It should be noted that this application does not limit the specific hot extrusion process; the appropriate process parameters can be selected according to the actual situation.

[0098] For example, when the target heat-resistant deformable aluminum alloy is an aluminum alloy extruded bar, the hot extrusion forming includes the following steps: extruding the homogenized billet, maintaining the extrusion cylinder temperature within the range of 380~420℃ (allowing ±10℃ within this range), preheating the die to 350~400±10℃, and holding it at this temperature for 2 h~6 h; controlling the extrusion speed at 1.0~2.0±0.5m / min, and the traction elongation rate at 0.5%~2.0%. Based on the above scheme, it is beneficial to better control the coarse grain layer thickness of the aluminum alloy extruded bar within 0.3 mm. The extruded product is straightened and cut to length to obtain the extruded semi-finished product.

[0099] S8. Quenching and straightening: The extruded semi-finished product is quenched online and then stretched and straightened.

[0100] It should be noted that this application does not limit the specific online quenching process, as long as it can eliminate the residual stress of extrusion deformation and achieve the function of this application. For example, in some embodiments of the second aspect of this application, the online quenching process includes: directly quenching the extruded semi-finished product in a water-cooling device, controlling the water temperature at 380℃~430℃, using circulating clean water at 20℃~35℃ for cooling, cooling the material surface temperature to below 80℃, and then performing stretching and straightening to achieve rapid shaping of the extruded structure.

[0101] In some embodiments of the second aspect of this application, when the target heat-resistant deformable aluminum alloy is an aluminum alloy extruded bar, the stretching amount during tension straightening is controlled at 0.5% to 2.0%. Based on the above scheme, residual stress from extrusion deformation can be better eliminated, while ensuring the straightness of the bar.

[0102] S9. Step annealing: The extruded semi-finished product after quenching and straightening is subjected to step low temperature annealing. First, it is held at a temperature of T1, then held at a temperature of T2, and then cooled in the furnace to below 100°C to obtain O-state aluminum alloy; wherein, T1>T2.

[0103] It should be noted that this application, through stepped low-temperature annealing, can be combined with the above-mentioned quenching and straightening to stably control the coarse grain layer thickness of the O-state aluminum alloy bar to within 0.3 mm. The microstructure is free from overheating, with clean grain boundaries, and the Al9FeNi phase and Al2CuMg phase are dispersedly distributed with a grain size ≥ 3. The material microstructure is uniform and stable, which is beneficial to improving the batch consistency of the product.

[0104] This application does not limit the specific annealing temperatures T1 and T2 for stepped low-temperature annealing; they can be selected based on the actual aluminum alloy composition.

[0105] For example, when the target heat-resistant deformable aluminum alloy is an extruded aluminum alloy bar, T1 satisfies 400℃≤T1≤430℃, and T2 satisfies 380℃≤T2≤400℃. Based on the above scheme, it is possible to better coordinate with the above quenching and straightening, stably control the coarse grain layer thickness of the O-state aluminum alloy bar to within 0.3 mm, ensure that the microstructure is free from overheating, has clean grain boundaries, and features dispersed distribution of Al9FeNi and Al2CuMg phases with a grain size ≥3. The material microstructure is uniform and stable, which is beneficial to improving the batch consistency of the product.

[0106] This application does not limit the specific annealing time of the stepped annealing, as long as the function of this application can be achieved. For example, in some embodiments of the second aspect of this application, when T1 satisfies 400℃≤T1≤430℃ and T2 satisfies 380℃≤T2≤400℃, the temperature is maintained at T1 for 2 h~3 h and at T2 for 3 h~6 h. Based on the above scheme, the matrix can be gradually softened through temperature-decreasing annealing, effectively avoiding uneven microstructure, further improving the uniformity and stability of the material microstructure, and making it more conducive to improving batch consistency of products.

[0107] S10. Machining and T6 heat treatment: The O-state aluminum alloy is machined according to actual needs and then subjected to T6 heat treatment to obtain the heat-resistant deformable aluminum alloy.

[0108] In some embodiments of the second aspect of this application, the T6 heat treatment includes a solution treatment and an artificial aging treatment performed sequentially to disperse the Al2CuMg strengthening phase and the Al9FeNi heat-resistant phase, thereby obtaining a high-strength, heat-resistant, heat-deformable aluminum alloy.

[0109] This application does not limit the specific solution treatment process, as long as it can achieve the function of this application. For example, in some embodiments of the second aspect of this application, the solution treatment temperature is 500℃~520℃, the time is 30 min~90 min, followed by water quenching.

[0110] This application does not limit the specific artificial aging process, as long as it can achieve the function of this application. For example, in some embodiments of the second aspect of this application, the temperature of the artificial aging process is 150℃~170℃, and the time is 6 h~10 h.

[0111] This application does not limit the specific machining process. Based on actual usage requirements, the O-state aluminum alloy can be machined to obtain a blank with the corresponding structural features. For example, commonly used or existing machining processes in this field can be referenced, as those skilled in the art should know, and therefore will not be elaborated upon here. For instance, when the blank needs to be applied to an impeller, the O-state aluminum alloy can be milled, bent, flared, or compression formed to obtain the impeller blank.

[0112] It should be noted that, in some embodiments of the second aspect of this application, the preparation method further includes S11, finished product inspection and packaging: the T6 state bar is cut to length, visually inspected, ultrasonically tested, mechanically tested, and low-magnification microstructure tested, qualified products are screened, and after cleaning the surface, they are classified, packaged and stored.

[0113] Thirdly, this application provides an application of a heat-resistant wrought aluminum alloy.

[0114] In the third aspect of this application, the application includes the use of the above-mentioned heat-resistant wrought aluminum alloy in the manufacture of turbocharger compressor impellers and high-temperature structural components of engines.

[0115] It should be noted that the heat-resistant wrought aluminum alloy is any one of the heat-resistant wrought aluminum alloys in the first aspect, or a heat-resistant wrought aluminum alloy prepared according to any one of the preparation methods in the second aspect. Therefore, the third aspect of this application has all the beneficial effects of the first or second aspect, so this application will not repeat them here. Please refer to the relevant content in the first or second aspect of this application.

[0116] Test methods and equipment: (a) Testing of mechanical properties 1. Brinell hardness test: The test shall be conducted in accordance with the test method in GB / T 231.1-2018 "Metallic materials - Brinell hardness test - Part 1: Test method".

[0117] 2. Testing of mechanical tensile properties: All tests were conducted in accordance with the test methods in GB / T 228.1-2021 "Metallic materials - Tensile testing - Part 1: Test method at room temperature" to obtain the test results of tensile strength, yield strength and elongation after fracture.

[0118] (ii) Morphological examination: 1. Testing of microstructure morphology: According to the test methods in GB / T 3246.1-2024 "Test Methods for Microstructure of Wrought Aluminum and Aluminum Alloy Products - Part 1: Microstructure Test Methods", optical (metallographic) microscopy was used to test and obtain the performance test results such as grain size, overheating, coarse grain layer thickness, precipitate distribution, and non-metallic oxide inclusion area fraction.

[0119] 2. Low-magnification tissue testing: The tests were conducted in accordance with the test methods in GB / T 3246.2-2012 "Test Methods for Microstructure of Wrought Aluminum and Aluminum Alloy Products - Part 2: Low Magnification Microstructure Test Methods" to obtain the test results for properties such as cracks, inclusions, delamination, and tail shrinkage.

[0120] 3. Grain size testing (and its measurement): The test was conducted in accordance with the test method in GB / T 6394-2017 "Method for Determination of Average Grain Size of Metals".

[0121] 4. Surface roughness test: The test shall be conducted in accordance with the test methods in GB / T 1031-2009 "Surface Roughness Parameters and Their Values".

[0122] The following examples and comparative examples illustrate the implementation of this application in more detail. Unless otherwise stated, all parts, percentages, and ratios listed are based on weight.

[0123] It should be noted that the refining agents used in the following examples or comparative examples are all sodium-free environmentally friendly refining agents, and these sodium-free environmentally friendly refining agents are commercially available C2Cl6 (hexachloroethane) type sodium-free refining agents. The aluminum-titanium-boron wire used is a commercially available grade AlTi5B. 0.2 Aluminum titanium boron wire with a diameter of 9mm~12mm.

[0124] Example 1 This embodiment provides a method for preparing a heat-resistant wrought aluminum alloy, including the following steps: S1. Batching and Smelting: Weigh out the corresponding masses of industrial pure aluminum ingots, aluminum-copper master alloys, aluminum-iron master alloys, aluminum-nickel master alloys, and magnesium ingots according to the following composition ratio: Si 0.18%, Fe 1.1%, Cu 2.4%, Mg 1.7%, Ni 1.0%, Ti 0.07%, individual impurities ≤0.05%, total impurities ≤0.12%, balance Al.

[0125] The weighed industrial pure aluminum, aluminum-copper master alloy, aluminum-iron master alloy and aluminum-nickel master alloy were added to the melting furnace in sequence and melted at 740°C until completely melted. Then, the weighed magnesium ingots were added and the mixture was stirred electromagnetically for 18 minutes to obtain aluminum alloy melt.

[0126] S2, Refining: Using a W-type and Z-type double tube, the above-mentioned refining agent is added to the aluminum alloy melt obtained from S1, and the amount of refining agent is 0.30% of the mass of the aluminum alloy melt. The refining is carried out twice, and the refining temperature is 740℃ and the refining time is 8min for each refining. After the first refining, the slag is removed, and after the furnace is opened, the slag is removed again, and then the second refining is carried out. After the second refining, the mixture is allowed to stand for 25min.

[0127] S3, Refinement: Aluminum-titanium-boron wire was used as a refining agent and added to the S2 refined aluminum alloy melt using an online wire feeding method. The amount of aluminum-titanium-boron wire added was 0.20% of the mass of the aluminum alloy melt, the online wire feeding speed was 3.0 m / min, and electromagnetic stirring was used in conjunction with the process.

[0128] S4, Degassing: The degassing process employs a rotary degassing chamber, using argon gas with a purity ≥99.99% for rotary degassing, with a rotor speed of 400 r / min and a degassing time of 15 min.

[0129] S5, Filtration and Casting: The aluminum alloy melt after S4 degassing was filtered using a 40 ppi ceramic filter plate, and then semi-continuous casting was performed. The casting head temperature was controlled at 720℃, and 300 mm defect sections at both ends were removed to obtain an aluminum alloy casting rod with a diameter of φ32 mm.

[0130] S6. Homogenization process: The aluminum alloy casting rod with a diameter of φ32 mm obtained by S5 above was placed in a homogenizing furnace and held at 495℃ for 10 h. It was then cooled in the furnace to 300℃ and removed from the furnace.

[0131] S7. Hot extrusion molding: The aluminum alloy billet homogenized by S6 was subjected to hot extrusion. The extrusion cylinder temperature was 400℃, the die temperature was 380℃ and held for 4 hours. The billet was heated to 400℃, the extrusion speed was 1.5 m / min, the traction stretching rate was 1.0%, and the extrusion ratio was about 16. After extrusion, it was straightened and sawn to obtain the extruded semi-finished product.

[0132] S8. Quenching and straightening: The extruded semi-finished product obtained in S7 above is placed in a water cooling device for water cooling and quenching, with a water temperature of 25℃~35℃ and a tensile straightening amount of 1.0%.

[0133] S9, Stepped Annealing: The extruded semi-finished product after S8 quenching and straightening was subjected to step-by-step low-temperature annealing, first held at 420℃ for 3 hours, then held at 390℃ for 2 hours, and then cooled in the furnace to 80℃ before being air-cooled to obtain O-state bar stock.

[0134] S10, Machining and T6 Heat Treatment: After the O-state bar is machined into an aluminum alloy casting bar with a diameter of φ32mm, it is first solution-treated at 510℃ for 60 min and then water-quenched; then artificially aged at 165℃ for 8 h to obtain the T6 state bar, i.e., aluminum alloy extruded bar.

[0135] This application tested and analyzed the mechanical properties and morphology of the O-state rods obtained in S9. The O-state rods prepared in Example 1 have the following properties: Brinell hardness 48 HBW; no cracking when bent at 90°; good flaring and welding; no tearing under full cross-section compression, with a crack length of 8 mm; no defects in low magnification structure; coarse grain layer thickness 0.2 mm; grain size grade 3, average grain size 12 μm, maximum grain size 180 μm; surface roughness Ra 3.2 μm.

[0136] This application tests and analyzes the mechanical properties and morphology of the T6 state bars obtained from S10, wherein the morphology is as follows: Figures 1 to 3As shown, based on the above test results, the T6 state bar prepared in Example 1 has the following properties: tensile strength 419 MPa, yield strength 378 MPa, elongation after fracture 6.7%, Brinell hardness 158 HBW; the microstructure is free from overheating, with clean grain boundaries, and Al9FeNi and Al2CuMg phases are dispersedly distributed; the area fraction of non-metallic oxide inclusions is 0.003%.

[0137] Example 2 This embodiment provides a method for preparing a heat-resistant wrought aluminum alloy, including the following steps: S1. Batching and Smelting: Weigh out the corresponding masses of industrial pure aluminum ingots, aluminum-copper master alloys, aluminum-iron master alloys, aluminum-nickel master alloys, and magnesium ingots according to the following composition ratio: Si 0.22%, Fe 1.2%, Cu 2.5%, Mg 1.6%, Ni 1.1%, Ti 0.08%, individual impurities ≤0.05%, total impurities ≤0.13%, balance Al.

[0138] The weighed industrial pure aluminum, aluminum-copper master alloy, aluminum-iron master alloy and aluminum-nickel master alloy were added to the melting furnace in sequence and melted at 750°C until completely melted. Then, the weighed magnesium ingots were added and the mixture was electromagnetically stirred for 18 minutes to obtain aluminum alloy melt.

[0139] S2, Refining: Using a W-type and Z-type double tube, the above-mentioned refining agent is added to the aluminum alloy melt obtained from S1, and the amount of refining agent is 0.32% of the mass of the aluminum alloy melt. The refining is carried out twice, and the refining temperature is 750℃ and the refining time is 8min for each refining. After the first refining, the slag is removed, and after the furnace is opened, the slag is removed again, and then the second refining is carried out. After the second refining, the mixture is allowed to stand for 30min.

[0140] S3, Refinement: Aluminum-titanium-boron wire was used as a refining agent and added to the S2 refined aluminum alloy melt using an online wire feeding method. The amount of aluminum-titanium-boron wire added was 0.22% of the mass of the aluminum alloy melt, the online wire feeding speed was 3.2 m / min, and electromagnetic stirring was used in conjunction with the process.

[0141] S4, Degassing: The degassing process was carried out using a rotary degassing chamber, with argon gas of ≥99.99% purity used for rotary degassing. The rotor speed was 420 r / min, and the degassing time was 18 min.

[0142] S5, Filtration and Casting: The aluminum alloy melt after S4 degassing was filtered using a 40 ppi ceramic filter plate, and then semi-continuous casting was performed. The casting head temperature was controlled at 725℃, and 400 mm defect sections at both ends were removed to obtain an aluminum alloy casting rod with a diameter of 55 mm.

[0143] S6. Homogenization process: The aluminum alloy casting rod with a diameter of φ32 mm obtained by S5 above was placed in a homogenizing furnace and held at 505℃ for 12 h. It was then cooled in the furnace to 280℃ before being taken out.

[0144] S7. Hot extrusion molding: The aluminum alloy billet homogenized by S6 was subjected to hot extrusion. The extrusion barrel temperature was 410℃, the die temperature was 390℃ and held for 5 hours. The billet was heated to 410℃, the extrusion speed was 1.2 m / min, the traction stretching rate was 1.5%, and the extrusion ratio was about 18. After extrusion, it was straightened and sawn to obtain the extruded semi-finished product.

[0145] S8. Quenching and straightening: The extruded semi-finished product obtained in S7 above is placed in a water cooling device for water cooling and quenching, with a water temperature of 25℃~35℃ and a tensile straightening amount of 1.5%.

[0146] S9, Stepped Annealing: The extruded semi-finished product after S8 quenching and straightening was subjected to step-by-step low-temperature annealing, first held at 425℃ for 3 hours, then held at 395℃ for 3 hours, and then cooled in the furnace to 70℃ before being air-cooled to obtain O-state bar stock.

[0147] S10, Machining and T6 Heat Treatment: After the O-state bar is machined into φ55 mm aluminum alloy cast bars, it is first solution-treated at 515℃ for 75 min and then water-quenched; then artificially aged at 170℃ for 9 h to obtain T6 state bar, i.e. aluminum alloy extruded bar.

[0148] This application conducted tests and analyses on the mechanical properties and morphology of the O-state rods obtained in S9. The results showed that the O-state rods prepared in Example 2 had the following properties: Brinell hardness 46 HBW; no cracking when bent at 90°; good flaring and welding; no tearing under full cross-section compression, with a crack length of 10 mm; no defects in the low-magnification structure; coarse grain layer thickness 0.25 mm; grain size grade 3, with an average grain size of 14 μm and a maximum grain size of 220 μm; and surface roughness Ra 3.0 μm.

[0149] This application tests and analyzes the mechanical properties and morphology of the T6 state bars obtained from S10, wherein the morphology is as follows: Figures 4 to 6As shown, based on the above test results, the T6 state bar prepared in Example 2 has the following properties: tensile strength 428 MPa, yield strength 385 MPa, elongation after fracture 7.0%, Brinell hardness 162 HBW; the microstructure is free from overheating, with clean grain boundaries, and Al9FeNi and Al2CuMg phases are dispersedly distributed; the area fraction of non-metallic oxide inclusions is 0.004%.

[0150] Comparative Example 1 The only difference between this comparative example and Example 1 is that: The S9 stepped annealing was changed to conventional single-stage annealing: 450℃ for 4 hours, followed by air cooling.

[0151] The mechanical properties and morphology of the O-state rods obtained by S9 were tested and analyzed. The O-state rods prepared by Comparative Example 1 have the following properties: Brinell hardness 62 HBW; microcracks appear when bent at 90°; coarse grain layer thickness 0.45 mm; grain size grade 2, average grain size 28 μm.

[0152] This application conducted tests and analyses on the mechanical properties and morphology of the T6-state bars obtained from S10. The results showed that the T6-state bars prepared in Comparative Example 1 possessed the following properties: tensile strength 385 MPa, yield strength 320 MPa, elongation after fracture 4.2%, and Brinell hardness 125 HBW. These properties do not meet the requirements for dual-state performance.

[0153] Comparative Example 2 The only difference between this comparative example and Example 1 is that: Change S2 from two refinements to a single refinement.

[0154] The mechanical properties and morphology of the O-state rods obtained by S9 were tested and analyzed. It was found that the O-state rods prepared by Comparative Example 2 have the following properties: inclusion defects were found in the low magnification structure; the area fraction of non-metallic oxide inclusions was 0.012%.

[0155] The mechanical properties and morphology of the T6 bar obtained by S10 were tested and analyzed. It was found that the T6 bar prepared by Comparative Example 2 has the following properties: tensile strength of 402 MPa, but fatigue life is reduced by about 30% compared with Example 1.

[0156] Comparative Example 3 The only difference between this comparative example and Example 1 is that: By adjusting the Al content, the Si content was adjusted to 0.35%, while the contents of the other components remained unchanged.

[0157] The mechanical properties and morphology of the O-state rods obtained by this application were tested and analyzed. It was found that the O-state rods prepared by Comparative Example 3 have the following properties: Brinell hardness 49 HBW.

[0158] This application conducted tests and analyses on the mechanical properties and morphology of the T6-state rods obtained from S10. The results showed that the T6-state rods prepared in Comparative Example 3 possessed the following properties: tensile strength 388 MPa, yield strength 335 MPa, and Brinell hardness 128 HBW. The strength was below standard, and coarse blocky Si phases appeared in the microstructure, affecting heat resistance.

[0159] In summary, the heat-resistant deformable aluminum alloy prepared in this application achieves compatible control of soft and hard states, stable matching of formability and high-temperature strength, high microstructure purity, and is compatible with the mainstream manufacturing mode of "O-state supply - cold working forming - T6 heat treatment strengthening" for impellers. It has stable matching of formability and high-temperature strength, is suitable for high-temperature load-bearing structural components such as turbocharger compressor impellers, and has reliable process and is suitable for mass production.

[0160] Obviously, the above embodiments of this application are merely examples for clear illustration and are not intended to limit the implementation of this application. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection claimed by this application.

Claims

1. A heat-resistant wrought aluminum alloy, characterized in that, The chemical composition of the heat-resistant deformable aluminum alloy, by mass fraction, includes: Si 0.10%~0.30%, Fe 0.5%~1.5%, Cu 1.5%~3.0%, Mg 1.0%~2.0%, Ni 0.5%~1.5%, Ti≤0.10%, individual impurities≤0.05%, total impurities≤0.15%, and the balance is Al.

2. The heat-resistant deformable aluminum alloy according to claim 1, characterized in that, The heat-resistant deformable aluminum alloy satisfies at least one of the following conditions; (1) Ti 0.05%~0.10%; (2) The mass ratio of Cu to Mg is 1~3:

1.

3. The heat-resistant deformable aluminum alloy according to claim 1, characterized in that, The heat-resistant wrought aluminum alloy satisfies at least one of the following conditions: (1) When delivered in the O state, the following conditions must be met: Brinell hardness ≤ 60 HBW; (2) Under T6 conditions, the following conditions must be met: tensile strength ≥ 410 MPa, yield strength ≥ 370 MPa, elongation after fracture ≥ 6%, and Brinell hardness ≥ 150 HBW.

4. The heat-resistant deformable aluminum alloy according to claim 1, characterized in that, The heat-resistant wrought aluminum alloy also meets at least one of the following conditions: (1) The microstructure analysis results of the heat-resistant deformable aluminum alloy in the O-state delivery state show that the crack length of the whole cross section is ≤15 mm and the surface roughness Ra is ≤3.5 μm; (2) The microstructure observation and analysis results of the heat-resistant deformable aluminum alloy in the T6 state showed that Al9FeNi phase and Al2CuMg phase were dispersed in the matrix, and the area fraction of non-metallic oxide inclusions was ≤0.005%.

5. A method for preparing a heat-resistant wrought aluminum alloy, used to prepare the heat-resistant wrought aluminum alloy according to any one of claims 1 to 4, characterized in that, Includes the following steps: S1. Batching and Smelting: Weigh out the corresponding mass of pure aluminum ingots, aluminum-copper master alloy, aluminum-iron master alloy, aluminum-nickel master alloy and magnesium ingots according to the alloy composition ratio of the target heat-resistant deformable aluminum alloy; and smelt them in a smelting furnace to obtain aluminum alloy melt; S2. Refining: Add a refining agent to the aluminum alloy melt and perform refining treatment at least twice; S3. Refining: Add a grain refiner to the refined aluminum alloy melt to refine the grains; S4. Degassing: Degassing the refined aluminum alloy melt; S5. Filtration and casting: After degassing, the aluminum alloy melt is filtered and then semi-continuously cast. The temperature at the casting head is controlled at 710℃~730℃ to obtain an aluminum alloy billet. S6. Homogenization treatment: The aluminum alloy billet is subjected to homogenization treatment; S7. Hot extrusion forming: Hot extrusion is performed on the homogenized aluminum alloy billet to obtain the extruded semi-finished product; S8. Quenching and straightening: The extruded semi-finished product is placed in a water-cooling device for online quenching and then stretched and straightened. S9. Step annealing: The extruded semi-finished product after quenching and straightening is subjected to step low temperature annealing. First, it is held at a temperature of T1, then held at a temperature of T2, and then cooled in the furnace to below 100°C to obtain O-state aluminum alloy; where T1>T2. S10. Machining and T6 heat treatment: The O-state aluminum alloy is machined according to actual needs and then subjected to T6 heat treatment to obtain the heat-resistant deformable aluminum alloy.

6. The preparation method according to claim 5, characterized in that, In S9, T1 satisfies 400℃≤T1≤430℃, and T2 satisfies 380℃≤T2≤400℃; Furthermore, it was kept at T1 for 2-3 hours and at T2 for 3-6 hours.

7. The preparation method according to claim 5, characterized in that, In S2, the refining agent includes a sodium-free environmentally friendly refining agent; Based on the mass of the aluminum alloy melt, the amount of refining agent added is 0.25%~0.35%; The refining temperature during each refining process is 720℃~760℃, and the refining time is 5 min~10 min. In S2, let it stand for 20 to 30 minutes after the final refining.

8. The preparation method according to claim 5, characterized in that, The refining agent includes aluminum-titanium-boron wire; The amount of the refining agent added is 0.15% to 0.25% of the mass of the aluminum alloy melt; The fiber refining agent is added online by feeding fibers at a speed of 2.5 m / min to 3.5 m / min.

9. The preparation method according to claim 5, characterized in that, The T6 heat treatment includes a solution treatment and an artificial aging treatment performed sequentially. The solution treatment is performed at a temperature of 500℃~520℃ for 30 min~90 min, followed by water quenching. The artificial aging treatment is performed at a temperature of 150℃~170℃ for a time of 6 h~10 h.

10. An application of a heat-resistant wrought aluminum alloy, characterized in that, The applications include the use of the heat-resistant wrought aluminum alloy in the manufacture of turbocharger compressor impellers and high-temperature structural components for engines; The heat-resistant wrought aluminum alloy is the heat-resistant wrought aluminum alloy according to any one of claims 1 to 4, or the heat-resistant wrought aluminum alloy prepared by any one of the preparation methods of claims 5 to 9.

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