High-toughness aluminum alloy material as well as preparation method and application thereof

Abstract

The invention relates to a high-strength and high-toughness aluminum alloy material as well as a preparation method and application thereof. The alloy is particularly suitable for production of new energy automobile parts such as an auxiliary frame and a battery tray. In order to solve the problems that an existing AlSi7Mg alloy is serious in deformation, low in yield strength qualification rate and the like during high-temperature heat treatment, a proper amount of Cu and Mg are introduced on the basis of the AlSi7 alloy, alloy components are optimized, and the content of harmful elements is strictly controlled. By reducing the solid solution temperature to about 490 DEG C and combining proper solid solution time and an artificial aging process, the alloy disclosed by the invention can obviously reduce the heat treatment deformation of a casting while ensuring the tensile strength and the yield strength. Test results show that after the alloy is adopted, the yield ratio of a casting is higher than 0.73, and the ductility and the tensile strength both meet the design requirements of automobile parts. In addition, according to the alloy, the energy consumption is reduced, the shaping workload after heat treatment is reduced, the production efficiency and economic benefits are remarkably improved, and the alloy has wide industrial application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of alloy preparation, and in particular to a high-strength and toughness aluminum alloy material and a preparation method and application thereof. Background Art

[0002] With the rapid development of new energy vehicles, lightweight design has become an important trend in the automotive manufacturing field, especially the increasing demand for key structural parts such as subframes and battery trays. These parts not only need to meet high mechanical performance requirements, but also have to achieve larger sizes and thinner wall thicknesses to achieve lightweight effects. At present, aluminum alloys have been widely used in the automotive industry due to their good comprehensive properties, especially in the production of key automotive components.

[0003] In the prior art, the materials commonly used in automobile manufacturing include deformed aluminum alloys (such as 6 series aluminum alloys) and cast aluminum alloys (such as Al-Si-Mg series alloys). Taking the subframe and battery tray as examples, foreign manufacturing processes mostly use deformed aluminum alloys and cast aluminum alloys to produce parts. Although this type of design can provide better mechanical properties, the production process is complicated and there are problems such as welding defects and low assembly accuracy. With the rapid improvement of domestic aluminum alloy casting technology and equipment, the integrated and integrated manufacturing process of aluminum alloy casting has gradually become the mainstream, which enables more complex and larger castings to be formed in one go, simplifies the production process and improves the structural integrity and production efficiency of parts.

[0004] At present, the domestic production of the above-mentioned key components mostly adopts AlSi7Mg cast aluminum alloy (chemical composition see Table 1), combined with T6 heat treatment process, in order to meet the mechanical properties requirements such as tensile strength (Rm ≥ 280MPa), yield strength (Rp0.2 ≥ 220MPa) and elongation (A ≥ 6%), while ensuring that the aluminum alloy components have good toughness and yield strength ratio.

[0005] Table 1: Chemical composition ratio of AlSi7Mg casting aluminum alloy (wt%)

[0006] Si Feb Cu Mr Mg Cr Ni Zn Pb Mr Tea <![CDATA[ENAC-42100ENAC-AlSi7Mg 0.3 ]]> 6.5～7.5 0.19 0.05 0.1 0.25～0.45 0.03 0.03 0.07 0.03 0.03 0.25

[0007] However, this process has a series of problems in practical application, which are mainly manifested in the following points:

[0008] Unstable yield strength: In the production process of AlSi7Mg cast aluminum alloy, the yield strength is often difficult to meet the design requirements, and the yield strength qualification rate is low, which directly affects the actual bearing capacity of aluminum alloy castings and reduces their service life and safety.

[0009] Severe deformation during heat treatment: Existing processes usually use a higher solution temperature (about 535±5℃). Although this temperature helps to improve the tensile strength, it also leads to aggravated deformation of castings during heat treatment. Large-sized thin-walled castings are particularly prone to excessive deformation under high-temperature treatment, which increases the difficulty of subsequent shaping and processing and reduces production efficiency.

[0010] High energy consumption and production cost: The high-temperature solution treatment required in the T6 heat treatment process not only consumes a lot of energy, but also the long processing time further increases the production cost. In addition, the welding process of deformed aluminum alloy and cast aluminum alloy is relatively complicated, and welding defects may also affect the overall quality of the product.

[0011] Difficulty in optimizing mechanical properties: Although AlSi7Mg alloys have good comprehensive properties, the composition adjustment space in the existing process is limited, especially when meeting high tensile strength, it is often difficult to maintain a high elongation. At the same time, due to the high solution treatment temperature, it is difficult to significantly improve the strength and toughness of the product through the optimization of the aging process, and the yield strength ratio still needs to be further optimized.

[0012] Based on the above shortcomings of the existing technology, the automotive industry has increasingly stringent requirements for cast aluminum alloy materials, especially the increasing demand for improving yield strength, reducing heat treatment deformation, and reducing energy consumption and production costs. To this end, the development of a high-strength and tough aluminum alloy that can reduce the solid solution temperature, optimize the composition ratio, and effectively improve the mechanical properties of the aluminum alloy has become a key technical breakthrough to solve this series of problems. Summary of the invention

[0013] The technical problem to be solved by the present invention is to provide a high-strength and tough aluminum alloy with reduced heat treatment deformation, so as to solve the problem in the prior art that the aluminum alloy is easily deformed after high-temperature heat treatment and it is difficult to achieve both strength and toughness.

[0014] In order to solve the above technical problems, the present invention provides a high-strength and toughness aluminum alloy material, which is composed of the following elements in weight percentage: Si: 6.4% to 7.5%, Cu: 0.8% to 1.1%, Mg: 0.3% to 0.45%, Fe: ≤0.2%, Mn: ≤0.05%, Ti: 0.1% to 0.2%, Cr: ≤0.05%, Ni: ≤0.05%, Zn: ≤0.05%, Pb: ≤0.05%, Sn: ≤0.05%, Sr: ≤0.10%, and the balance is Al and unavoidable impurities.

[0015] Compared with the prior art, the high-strength and tough aluminum alloy material in the present application has the following advantages: the present application adjusts the content ratio of Si, Cu and Mg in the prior art to a more precise range: the content of Si is controlled in the range of 6.4%-7.5%, Cu is controlled in the range of 0.8%-1.1%, and Mg is controlled in the range of 0.3%-0.45%, which optimizes the solid solution strengthening effect in the alloy. Si, as the main strengthening element, can form an Al-Si eutectic structure, which improves the strength and hardness of the material; Cu and Mg further improve the comprehensive performance of the alloy through solid solution strengthening and precipitation strengthening, especially in terms of corrosion resistance and tensile strength. The direct technical effect is that the overall strength, ductility and fatigue resistance of the alloy material are improved through the synergistic effect of these elements; microelements such as Ti and Sr are used to refine the grains: in the present invention, the addition of Ti element (0.1%-0.2%) can effectively refine the grains in the casting process and reduce casting defects; the introduction of Sr (≤0.10%) further improves the toughness and plasticity of the material. Grain refinement technology can reduce the deformation of aluminum alloys after high-temperature heat treatment and improve the mechanical properties of the material. The direct technical principle is to improve the ductility of the material and reduce casting defects by refining the grain structure, and ultimately improve the comprehensive mechanical properties of the material; the content of impurity elements such as Fe, Mn, and Cr is strictly controlled: in the present invention, the Fe content is strictly limited to ≤0.20%, and the content of elements such as Mn and Cr is controlled at ≤0.05%. Excessive Fe content will induce the formation of brittle phases and reduce the toughness of the alloy; while precise control of Mn and Cr can prevent unnecessary precipitation of strengthening phases and reduce the embrittlement tendency of the alloy. This element optimization helps to improve the fatigue resistance of the alloy and reduce the risk of fracture under complex working conditions, further enhancing the comprehensive fatigue resistance and long-term stability of the material.

[0016] Through the above formula, the synergistic effect of the optimization of alloy components (Si, Cu, Mg, Ti) directly affects the strength and toughness of the material. By refining the grain structure and inhibiting the formation of brittle phases, the material has both high strength and good toughness, effectively improving the material's performance in load-bearing components such as new energy vehicle subframes and battery trays. The alloy material shows excellent strengthening effects during solution treatment and heat treatment, ultimately significantly improving the tensile strength, yield strength and ductility.

[0017] In a possible embodiment, the high-strength and toughness aluminum alloy material is composed of the following elements in weight percentage: Si: 6.7% to 7.3%, Cu: 0.8% to 0.9%, Mg: 0.35% to 0.45%, Fe: ≤0.15%, Mn: ≤0.02%, Ti: 0.1% to 0.15%, Cr: ≤0.01%, Ni: ≤0.01%, Zn: ≤0.12%, Pb: ≤0.01%, Sn: ≤0.01%, Sr: ≤0.05%, and the balance is Al and unavoidable impurities.

[0018] Compared with the prior art, the above technical solution is adopted to adjust the ratio of Si, Cu and Mg, and the strengthening effect of the alloy is significantly improved, so that the tensile strength and yield strength are significantly improved compared with the existing alloy. At the same time, in this further optimized alloy formula, the Si content is controlled in the range of 6.7%-7.3%, which enhances the strengthening effect of the matrix alloy. Si not only improves the strength of the aluminum alloy, but also can form a stable Al-Si eutectic structure, enhance wear resistance and hardness; Cu and Mg further improve the yield strength and tensile strength of the material through solid solution strengthening and precipitation strengthening (mainly Cu-Mg phase); the Mg content is slightly higher than the prior art, so that it maintains ductility while the strengthening effect is more obvious.

[0019] In a possible implementation manner, the aluminum alloy material has a tensile strength Rm≥280 MPa, a yield strength Rp0.2≥220 MPa, and an elongation A≥6%.

[0020] Compared with the prior art, by adopting the above technical solution, the aluminum alloy material of the present application has excellent mechanical properties and has an excellent balance between strength and toughness.

[0021] Another technical problem to be solved by the present invention is to provide a method for preparing a high-strength and tough aluminum alloy with reduced heat treatment deformation, so as to solve the problem in the prior art that the aluminum alloy is easily deformed during the heat treatment process, resulting in the dimensional accuracy and mechanical properties of the final product not meeting the requirements.

[0022] In order to solve the above technical problems, the present invention also provides a method for preparing the high-strength and toughness aluminum alloy material, comprising the following steps:

[0023] S1: Ingredient smelting: adding raw materials according to the composition ratio of the high-strength and toughness aluminum alloy material;

[0024] S2: Casting: The aluminum alloy obtained after smelting in step S1 is formed by casting;

[0025] S3: Heat treatment: The aluminum alloy cast in step S2 is heat treated, wherein the heat treatment includes solution treatment and aging treatment, wherein the temperature of the solution treatment is 450-550°C, and the temperature of the aging treatment is 150-200°C; after the heat treatment, a high-strength and tough aluminum alloy material is obtained.

[0026] Compared with the prior art (related art), the preparation method of a high-strength and tough aluminum alloy material of the present application has the following advantages: Compared with the prior art, the preparation method of a high-strength and tough aluminum alloy material of the present application has the following advantages: Reduce heat treatment deformation: The heat treatment temperature range in the prior art is optimized to 450-550°C, and the deformation during the heat treatment process is controlled. By reasonably selecting the temperature of the solid solution treatment and the aging treatment, the deformation risk of the aluminum alloy during the heat treatment process is effectively reduced, thereby improving the dimensional accuracy and mechanical properties of the material; Improve mechanical properties: Through a reasonable heat treatment process, the microstructure of the aluminum alloy is optimized. The solid solution treatment allows the alloying elements in the alloy to be fully dissolved to form a uniform solid solution; while the aging treatment promotes the formation of the precipitation phase and enhances the strength and toughness of the material. The direct technical effect is that the tensile strength and yield strength of the aluminum alloy are significantly improved; Improve production efficiency: The cumbersome heat treatment process in the prior art is simplified to two main steps, which reduces the production cycle and energy consumption, and improves production efficiency and material utilization. This improvement provides a more efficient production solution for the manufacturing industry; through the preparation method of the present invention, the probability of deformation during the heat treatment process is significantly reduced, the mechanical properties of the aluminum alloy are improved, and the production efficiency is improved.

[0027] In a possible implementation, in step S3, the temperature of the solution treatment is 480-500°C, the treatment time is 4 hours, and water cooling is adopted after the solution treatment, and the water temperature is less than or equal to 40°C.

[0028] Compared with the prior art, the above technical solution can control the microstructure of the alloy, and the microstructure of the aluminum alloy can be optimized by selecting an appropriate solution treatment temperature (480-500°C) and cooling method (water cooling). Within this temperature range, the alloying elements (such as Si, Cu, Mg, etc.) in the aluminum alloy can be fully dissolved and form a uniform solid solution. At the same time, water cooling can quickly reduce the temperature and inhibit the formation of unfavorable phases, thereby maintaining the good performance of the material.

[0029] In a possible implementation, in step S3, the temperature of the solution treatment is 500-540° C., the treatment time is 4 hours, and air cooling is adopted after the solution treatment, and the cooling time is 15 minutes.

[0030] Compared with the prior art, the above technical solution can optimize the microstructure and microorganism of aluminum alloy and improve its mechanical properties by setting the solution treatment temperature at 500-540℃ and using air cooling, and can also effectively reduce the deformation that may occur during the heat treatment process. Air cooling is gentler than water cooling, and can effectively avoid the stress concentration caused by the rapid cooling process after the solution treatment, thereby reducing deformation. This makes the aluminum alloy have better dimensional stability and shape retention ability in subsequent processing and use.

[0031] In the above two possible implementations, the principles of using different cooling methods are:

[0032] Water-cooled quenching (below 500°C): At a lower solution treatment temperature (below 500°C), water-cooled quenching can achieve a faster cooling rate, thereby more effectively preventing the precipitation and phase change of alloying elements. This rapid cooling can help the aluminum alloy maintain a uniform solid solution state, which helps to obtain higher strength and toughness.

[0033] Air-cooled quenching (above 500°C): When the solution treatment temperature exceeds 500°C, the phase change behavior of the material may become more complicated. At this temperature, the alloying elements in the aluminum alloy are more likely to reach a higher solid solution state, so rapid cooling may lead to excessive stress concentration and brittleness. Therefore, choosing air-cooled quenching can provide a milder cooling rate, reduce the thermal stress caused by rapid cooling, and avoid cracks or deformation of the material during the cooling process.

[0034] In a possible implementation, in step S3, the aging treatment temperature is 175° C., and the treatment time is 4 hours.

[0035] Compared with the existing technology, the above technical scheme is adopted to further optimize the temperature and time of aging treatment. The design scheme of 175℃ aging treatment helps to reduce thermal stress and avoid unnecessary deformation of aluminum alloy during processing, thereby improving production yield and stability. It not only improves the mechanical properties of high-strength and toughness aluminum alloy materials, but also ensures stability and reliability in practical applications.

[0036] Another technical problem to be solved by the present invention is to provide an application of a high-strength and tough aluminum alloy that reduces heat treatment deformation, so as to solve the problem in the prior art that aluminum alloys are prone to deformation and insufficient strength during application due to high-temperature heat treatment.

[0037] In order to solve the above technical problems, the present invention also provides an application of the high-strength and toughness aluminum alloy material, characterized in that the application includes the application of the high-strength and toughness aluminum alloy material on the subframe and battery tray materials of new energy vehicles.

[0038] Compared with the prior art, the application of the high-strength and tough aluminum alloy material described in the present application has the following advantages: Improved mechanical properties: The low-strength aluminum alloys in the prior art (such as 6061, 6063, etc.) are replaced with the high-strength and tough aluminum alloys of the present invention, which have higher tensile strength and yield strength, so that the load-bearing capacity of automotive structural parts is significantly improved. Reduced deformation: The present invention significantly reduces the thermal stress generated by the material during the heat treatment process by optimizing the alloy composition (such as the ratio of Si, Cu, Mg, etc.) and the heat treatment process (such as solution treatment, aging treatment), thereby reducing the deformation problem of the aluminum alloy. This improvement directly solves the problem of severe deformation of aluminum alloys during heat treatment under high temperature environments in the prior art. Superior application performance: Since the high-strength and tough aluminum alloy has better strength and toughness, it can effectively improve the safety and stability of the entire vehicle in the application of key components such as subframes and battery trays, and reduce the risk of accidents caused by material defects. DETAILED DESCRIPTION

[0039] First, those skilled in the art should understand that these implementations are only used to explain the technical principles of the embodiments of the present application, and are not intended to limit the protection scope of the embodiments of the present application. Those skilled in the art can make adjustments to them as needed to adapt to specific application scenarios.

[0040] The invention provides a high-strength and toughness aluminum alloy material, which is composed of the following elements in weight percentage: Si: 6.4% to 7.5%, Cu: 0.8% to 1.1%, Mg: 0.3% to 0.45%, Fe: ≤0.2%, Mn: ≤0.05%, Ti: 0.1% to 0.2%, Cr: ≤0.05%, Ni: ≤0.05%, Zn: ≤0.05%, Pb: ≤0.05%, Sn: ≤0.05%, Sr: ≤0.10%, and the balance is Al and unavoidable impurities.

[0041] As a preferred scheme, the high-strength and toughness aluminum alloy material is composed of the following elements in weight percentage: Si: 6.7% to 7.3%, Cu: 0.8% to 0.9%, Mg: 0.35% to 0.45%, Fe: ≤0.15%, Mn: ≤0.02%, Ti: 0.1% to 0.15%, Cr: ≤0.01%, Ni: ≤0.01%, Zn: ≤0.12%, Pb: ≤0.01%, Sn: ≤0.01%, Sr: ≤0.05%, and the balance is Al and unavoidable impurities.

[0042] As a preferred solution, the aluminum alloy material has a tensile strength Rm≥280Mpa, a yield strength Rp0.2≥220Mpa, and an elongation A≥6%.

[0043] The present invention also provides a method for preparing the high-strength and toughness aluminum alloy material, comprising the following steps:

[0044] S1: Ingredient smelting: adding raw materials according to the composition ratio of the high-strength and toughness aluminum alloy material;

[0045] S2: Casting: The aluminum alloy obtained after smelting in step S1 is formed by casting;

[0046] S3: Heat treatment: The aluminum alloy cast in step S2 is heat treated, wherein the heat treatment includes solution treatment and aging treatment, wherein the temperature of the solution treatment is 450-550°C, and the temperature of the aging treatment is 150-200°C; after the heat treatment, a high-strength and tough aluminum alloy material is obtained.

[0047] As a preferred solution, in step S3, the temperature of the solution treatment is 480-500°C, the treatment time is 4 hours, and water cooling is adopted after the solution treatment, and the water temperature is less than or equal to 40°C.

[0048] As a preferred solution, in step S3, the temperature of the solution treatment is 500-540°C, the treatment time is 4 hours, and air cooling is adopted after the solution treatment, and the cooling time is 15 minutes.

[0049] As a preferred solution, in step S3, the aging treatment temperature is 175° C. and the treatment time is 4 hours.

[0050] The present invention also provides an application of the high-strength and toughness aluminum alloy material, characterized in that the application includes application of the high-strength and toughness aluminum alloy material on a subframe and a battery tray material of a new energy vehicle.

[0051] The design principle of this application is expanded below to demonstrate the advantages and implementation effects of the technical solution of the present invention:

[0052] In this application, the basic design idea of ​​the new alloy is: using AlSi7 as the basic alloy, strictly controlling the content of harmful elements in the alloy, adjusting the CuMgZn content according to 3 levels, and combining different heat treatment schemes for screening to select a combination of better chemical composition and lower solution temperature and shorter heat treatment time to meet the performance requirements of the sample tensile strength Rm ≥ 280Mpa, yield strength Rp0.2 ≥ 220Mpa, and elongation A ≥ 6%;

[0053] Table 2 shows the factors and level ranges that affect the mechanical properties of the alloy. In order to reduce the workload of the preliminary experiments, an L8(27) orthogonal experiment was initially designed based on this to optimize the chemical composition and heat treatment process parameters. The specific data are shown in Table 3.

[0054] Table 2 Influencing factors and levels: Effects of composition and heat treatment on properties

[0055]

[0056] Table 3L8(2 7 ) Influence of composition and heat treatment on performance

[0057]

[0058] Through the calculation and analysis of the orthogonal test results in Table 3, taking into account the interactive factors, the optimal combination scheme is preliminarily selected as follows: Cu takes 0.80%, Mg takes 0.40%, although Zn can improve the strength, it reduces the elongation too much, so Zn is not added (as an impurity element control), the solution temperature is 490℃, the solution time is 3h, the artificial aging temperature is 175℃, and the artificial aging time is 3h. Table 4 shows the influence of factors and levels on the performance.

[0059] Table 4 Effects of factors and levels on performance

[0060]

[0061] The next step of optimization sample and scheme verification is arranged through the scheme in Table 4. At the same time:

[0062] 1) Introduce the strengthening and toughening index, based on the cast performance (inner belt), examine the performance of the alloy in various heat treatment states (acquired), and quickly predict whether the performance of the alloy in the heat treatment state can meet the requirements:

[0063] Strengthening and toughening index K value = (Rm1 / Rm2+Rp1 / Rp2+A1 / A2);

[0064] (For a batch of samples with the same composition in the same melting furnace, Rm1 is in heat-treated state, Rm2 is in cast state; Rp1 is in heat-treated state, Rp2 is in cast state; A1 is in heat-treated state, A2 is in cast state)

[0065] 2) Investigate the feasibility of as-cast quenching (water cooling / air cooling) + T1 to meet the performance of some products;

[0066] 3) When as-cast quenching + T1 cannot meet the product performance, low temperature T4 (water cooling / air cooling) + T1 is used to meet the product performance (taking into account the roasting and sand removal of the casting).

[0067] The performance verification test data are shown in Tables 5 to 10 below:

[0068] Table 5 Chemical composition of verification test (NO1)

[0069]

[0070] Table 6 Verification test (NO1) Mechanical properties

[0071]

[0072] Table 7 Verification test (NO1) Mechanical properties

[0073]

[0074] Table 8 Verification test (NO2) Effect of Cu on performance

[0075]

[0076]

[0077] Table 9 Verification test (NO2) Effect of Cu on performance

[0078]

[0079] Table 10 Verification test (NO2) Effect of Cu on performance

[0080]

[0081] The verification and testing of Tables 5 to 10 above further prove that:

[0082] 1) For AlSi7Mg alloys, controlling the Cu content to 0.8-1.1% can reduce the solution temperature and shorten the solution and aging holding time;

[0083] 2) The high-strength and tough aluminum alloy material of the present invention uses AlSi7 as the basic alloy, strictly controls the content of harmful elements (Fe, Mn) in the alloy, and adds appropriate Mg and Cu elements. When the solid solution temperature is reduced by about 50°C, the performance requirements of the tensile strength Rm ≥ 280Mpa, the yield strength Rp0.2 ≥ 220Mpa, and the elongation A ≥ 6% can still be achieved;

[0084] Moreover, when the solution temperature is greater than 480°C (water-cooled quenching), the performance requirements can be met in the T4+T1 state, and the yield strength is greatly improved, and the yield strength ratio is basically above 0.73; when the solution temperature is greater than 500°C (air-cooled quenching), the performance requirements can be met in the T4+T1 state, and the roasting and sand removal of some castings can be taken into account, realizing a two-in-one process.

[0085] In combination with the above implementation principle and the scope of the technical solution of the present invention, specific embodiments within the above scope are given below to further demonstrate the feasibility of the present invention:

[0086] Embodiment 1:

[0087] Example 1 provides a high-strength and toughness aluminum alloy material, a preparation method and application thereof, wherein the application includes application of the high-strength and toughness aluminum alloy material to a subframe and a battery tray material of a new energy vehicle.

[0088] The high-strength and toughness aluminum alloy material is composed of the following elements in weight percentage: Si: 7.0%, Cu: 0.8%, Mg: 0.355%, Fe: ≤0.15%, Mn: ≤0.02%, Ti: 0.15%, Cr: ≤0.01%, Ni: ≤0.01%, Zn: ≤0.12%, Pb: ≤0.01%, Sn: ≤0.01%, Sr: ≤0.05%, and the balance is Al and unavoidable impurities.

[0089] The aluminum alloy material has a tensile strength Rm≥280Mpa, a yield strength Rp0.2≥220Mpa, and an elongation A≥6%.

[0090] The method for preparing the high-strength and toughness aluminum alloy material comprises the following steps:

[0091] S1: Ingredient smelting: adding raw materials according to the composition ratio of the high-strength and toughness aluminum alloy material;

[0092] S2: Casting: The aluminum alloy obtained after smelting in step S1 is formed by casting;

[0093] S3: Heat treatment: The aluminum alloy cast in step S2 is heat treated, wherein the heat treatment includes solution treatment and aging treatment, and the temperature of the solution treatment is 490°C, the treatment time is 4 hours, and water cooling is adopted after the solution treatment, and the water temperature is less than or equal to 40°C.

[0094] Embodiment 2:

[0095] Example 2 provides a high-strength and toughness aluminum alloy material, a preparation method and application thereof, wherein the application includes application of the high-strength and toughness aluminum alloy material to a subframe and a battery tray material of a new energy vehicle.

[0096] The high-strength and toughness aluminum alloy material is composed of the following elements in weight percentage: Si: 6.4%, Cu: 0.8%, Mg: 0.3%, Fe: ≤0.15%, Mn: ≤0.02%, Ti: 0.1%, Cr: ≤0.01%, Ni: ≤0.01%, Zn: ≤0.12%, Pb: ≤0.01%, Sn: ≤0.01%, Sr: ≤0.05%, and the balance is Al and unavoidable impurities.

[0097] As a preferred solution, the aluminum alloy material has a tensile strength Rm≥280Mpa, a yield strength Rp0.2≥220Mpa, and an elongation A≥6%.

[0098] The method for preparing the high-strength and toughness aluminum alloy material comprises the following steps:

[0099] S1: Ingredient smelting: adding raw materials according to the composition ratio of the high-strength and toughness aluminum alloy material;

[0100] S2: Casting: The aluminum alloy obtained after smelting in step S1 is formed by casting;

[0101] S3: Heat treatment: The aluminum alloy cast in step S2 is heat treated, and the heat treatment includes solution treatment and aging treatment. The temperature of the solution treatment is 480°C, and the treatment time is 4 hours. After the solution treatment, water cooling is adopted, and the water temperature is less than or equal to 40°C; the temperature of the aging treatment is 150°C, and the treatment time is 4 hours. After the heat treatment, a high-strength and tough aluminum alloy material is obtained.

[0102] Embodiment 3:

[0103] Example 3 provides a high-strength and toughness aluminum alloy material, a preparation method and application thereof, wherein the application includes application of the high-strength and toughness aluminum alloy material to a subframe and a battery tray material of a new energy vehicle.

[0104] The high-strength and toughness aluminum alloy material is composed of the following elements in weight percentage: Si: 7.5%, Cu: 1.1%, Mg: 0.45%, Fe: ≤0.2%, Mn: ≤0.05%, Ti: 0.1%~0.2%, Cr: ≤0.05%, Ni: ≤0.05%, Zn: ≤0.05%, Pb: ≤0.05%, Sn: ≤0.05%, Sr: ≤0.10%, and the balance is Al and unavoidable impurities.

[0105] The aluminum alloy material has a tensile strength Rm≥280Mpa, a yield strength Rp0.2≥220Mpa, and an elongation A≥6%.

[0106] The method for preparing the high-strength and toughness aluminum alloy material comprises the following steps:

[0107] S1: Ingredient smelting: adding raw materials according to the composition ratio of the high-strength and toughness aluminum alloy material;

[0108] S2: Casting: The aluminum alloy obtained after smelting in step S1 is formed by casting;

[0109] S3: Heat treatment: The aluminum alloy cast in step S2 is heat treated, and the heat treatment includes solution treatment and aging treatment. The temperature of the solution treatment is 540°C, and the treatment time is 4 hours. After the solution treatment, air cooling is adopted, and the cooling time is 15 minutes. The temperature of the aging treatment is 200°C, and the time is 4 hours. After the heat treatment, a high-strength and toughness aluminum alloy material is obtained.

[0110] The high-strength and tough aluminum alloy materials prepared in the above-mentioned embodiments 1 and 3 of the present invention and the conventional A356 prepared by the same method in the present invention were treated to compare the relevant properties. The comparison results are shown in Table 11. In Table 11, A356 is an A356 alloy, A356+Cu(0.8) corresponds to the alloy formula of embodiment 1 of the present invention, A356+Cu(1.1) corresponds to the alloy formula of embodiment 3 of the present invention, 540°C / 5h+200°C / 4.5h is the heat treatment method used in embodiment 3, and 490°C / 5h+175°C / 4.5h is the heat treatment method used in embodiment 1. The comparison results are as follows:

[0111] Table 11 Performance parameters of Example 1, Example 3 and A356 alloy after different heat treatments:

[0112]

[0113] Through the above-mentioned embodiments and the comparison with the comparative examples, it is further proved that the new alloy made by the present invention, which takes AlSi7 as the basic alloy, strictly controls the content of harmful elements (FeMn) in the alloy, and adds appropriate Mg and Cu elements, has the advantages of low solid solution temperature, high and stable yield strength compared with the AlSi7Mg material currently commonly used for lightweight components, and has a broad market application prospect. In addition, the application of the alloy in the present invention to the production of oversized sub-frame battery tray products using the new alloy has obvious benefits in reducing product heat treatment deformation and stabilizing product mechanical properties. The energy consumption of the alloy is reduced due to the reduction of the solid solution temperature, which can basically offset the cost of adding the Cu element, and the reduction in production cost due to the reduction of product deformation is also obvious. The application of the alloy will change the current material selection pattern of oversized aluminum alloy castings.

[0114] In the description of the present application, the description with reference to the terms "one embodiment", "some embodiments", "in the present embodiment", "specific example", or "some examples" etc. means that the specific features, mechanisms, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, mechanisms, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0115] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A high-strength and tough aluminum alloy material, characterized in that: The high-strength and tough aluminum alloy material is composed of the following elements in weight percentage: Composition: Si: 6.4% ~ 7.5%, Cu: 0.8% ~ 1.1%, Mg: 0.3% ~ 0.45%, Fe: ≤ 0.2%, Mn: ≤ 0.05%, Ti: 0.1% ~ 0.2%, Cr: ≤ 0.05%, Ni: ≤ 0.05%, Zn: ≤ 0.05%, Pb: ≤ 0.05%, Sn: ≤ 0.05%, Sr: ≤ 0.10%, the balance is Al and unavoidable impurities.

2. The high-strength and toughness aluminum alloy material according to claim 1, characterized in that: The high-strength and tough aluminum alloy material is composed of the following elements in weight percentage: Composition: Si: 6.7% ~ 7.3%, Cu: 0.8% ~ 0.9%, Mg: 0.35% ~ 0.45%, Fe: ≤0.15%, Mn: ≤0.02%, Ti: 0.1% ~ 0.15%, Cr: ≤0.01%, Ni: ≤0.01%, Zn: ≤0.12%, Pb: ≤0.01%, Sn: ≤0.01%, Sr: ≤0.05%, the balance is Al and unavoidable impurities.

3. The high-strength and toughness aluminum alloy material according to claim 1, characterized in that: The aluminum alloy material has a tensile strength Rm≥280Mpa, a yield strength Rp0.2≥220Mpa, and an elongation A≥6%.

4. A method for preparing the high-strength and toughness aluminum alloy material according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1: Ingredient smelting: adding raw materials according to the composition ratio of the high-strength and toughness aluminum alloy material; S2: Casting: The aluminum alloy obtained after smelting in step S1 is formed by casting; S3: Heat treatment: The aluminum alloy cast in step S2 is heat treated, wherein the heat treatment includes solution treatment and aging treatment, wherein the temperature of the solution treatment is 450-550°C, and the temperature of the aging treatment is 150-200°C; after the heat treatment, a high-strength and tough aluminum alloy material is obtained.

5. The method for preparing the high-strength and toughness aluminum alloy material according to claim 4, characterized in that: In step S3, the temperature of the solution treatment is 480-500°C, the treatment time is 4 hours, and water cooling is adopted after the solution treatment, and the water temperature is less than or equal to 40°C.

6. The method for preparing the high-strength and toughness aluminum alloy material according to claim 4, characterized in that: In the step S3, the temperature of the solution treatment is 500-540° C., the treatment time is 4 hours, and air cooling is adopted after the solution treatment, and the cooling time is 15 minutes.

7. The method for preparing the high-strength and toughness aluminum alloy material according to claim 4, characterized in that: In the step S3, the aging treatment temperature is 175° C. and the treatment time is 4 hours.

8. An application of the high-strength and toughness aluminum alloy material according to any one of claims 1 to 3, characterized in that: The application includes the application of the high-strength and toughness aluminum alloy material in the subframe and battery tray materials of new energy vehicles.

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