An aluminum alloy for high-strength body and its preparation method

Abstract

This application relates to the technical field of automotive alloys, and specifically discloses an aluminum alloy for high-strength vehicle bodies and a preparation method thereof. An aluminum alloy for high-strength vehicle bodies is made from raw materials comprising the following mass percentages: magnesium 0.5 - 1.5%; silicon 1 - 2%; copper 0.4 - 1%; tin 0.1 - 0.5%; manganese 0.01 - 0.05%; iron 0.05 - 0.1%; boron 0.1 - 0.2%; rare earth element mixture 0.3 - 1.5%; the balance being aluminum; the rare earth element mixture consists of niobium, scandium and cobalt, and the weight ratio of niobium, scandium and cobalt is 1:(3.4 - 4.4):(12 - 15). The preparation method is as follows: under the protection of an inert gas, aluminum is melted, and then magnesium, silicon, copper, tin, manganese, iron, boron, and rare earth element mixture are added in proportion for mixing and melting to obtain a molten solution; a refining agent is added to the molten solution for refining treatment, and after slag removal and degassing treatment, it is cast to obtain a semi-finished alloy; the semi-finished alloy is subjected to solution treatment and then aging treatment. The aluminum alloy for high-strength vehicle bodies of this application has relatively high strength, and also takes into account excellent ductility, with better overall quality.

Description

Technical Field

[0001] This application relates to the technical field of automotive alloys, and more specifically, it relates to an aluminum alloy for high-strength vehicle bodies and a preparation method thereof. Background Art

[0002] Aluminum alloy is an alloy mainly composed of aluminum and added with other metal elements through specific processes. It belongs to light metal materials and plays a crucial role in the industrial field. At the same time, due to the characteristics of lightweight, high strength, and good formability of aluminum alloy, its application in automotive body structures is becoming increasingly widespread, mainly used in components such as body frames, doors, hoods, and trunk lids, improving fuel economy and collision safety.

[0003] Currently, in the automotive industry, Al-Mg-Si series aluminum alloys are widely used in body frame structures due to their low density, good formability, and recycling value. However, with the continuous improvement of vehicle safety requirements in the automotive industry, traditional Al-Mg-Si alloys are difficult to meet the needs of the new generation of high-performance body designs due to their low yield strength and tensile strength. In recent years, by adding trace alloy elements such as Cu and Sn, or through heat treatment and other methods to improve the strength of aluminum alloys, although the above methods can improve the strength to a certain extent, they often come at the cost of sacrificing ductility, resulting in limitations in the actual application of aluminum alloys in automotive bodies.

[0004] Regarding the above related technologies, a high-strength aluminum alloy body can better absorb energy, thus effectively resisting collisions and impacts and protecting the safety of passengers; a high-ductility aluminum alloy body can better resist deformation and cracking and maintain the integrity of the body structure. When the ductility of aluminum alloy is poor, its application in the manufacture of complex shapes is also limited. Therefore, how to improve the strength of aluminum alloy while maintaining or even improving its ductility has become one of the problems that the industry urgently needs to break through. Currently, there is an urgent need to propose a solution to solve the above technical problems. Summary of the Invention

[0005] In order to improve the strength of aluminum alloy while making the aluminum alloy have excellent ductility, this application provides an aluminum alloy for high-strength vehicle bodies and a preparation method thereof.

[0006] In the first aspect, this application provides an aluminum alloy for high-strength vehicle bodies, adopting the following technical solution:

[0007] An aluminum alloy for high-strength vehicle bodies is made from raw materials containing the following mass percentages:

[0008] Magnesium 0.5 - 1.5%;

[0009] Silicon 1 - 2%;

[0010] Copper: 0.4 - 1%;

[0011] Tin: 0.1 - 0.5%;

[0012] Manganese: 0.01 - 0.05%;

[0013] Iron: 0.05 - 0.1%;

[0014] Boron: 0.1 - 0.2%;

[0015] Rare earth element mixture: 0.3 - 1.5%;

[0016] The balance is aluminum;

[0017] The said rare earth element mixture is composed of niobium, scandium and cobalt, and the weight ratio of niobium, scandium and cobalt is 1:(3.4 - 4.4):(12 - 15).

[0018] By adopting the above technical solution, magnesium can promote the grain refinement and strain hardening of aluminum alloy, and thus can improve the strength of aluminum alloy; silicon forms a solid solution with aluminum, enhancing the crystal structure of aluminum, thereby improving the mechanical properties of the alloy; copper can strengthen the grain boundary strength and solid solution strength of aluminum alloy, and thus can significantly improve the strength and hardness of aluminum alloy; the compound formed by tin and aluminum plays a role of dispersion strengthening in the alloy, and thus improves the strength and hardness of aluminum alloy; the combination of magnesium, silicon, copper, tin and aluminum can form a relatively stable phase structure of aluminum alloy, which not only performs excellently in terms of strength, corrosion resistance and processing performance, but also can easily accept and incorporate other different elements.

[0019] An appropriate manganese content can improve the corrosion resistance of aluminum alloy, while an excessive manganese content will increase the brittleness of aluminum alloy and instead reduce its hardness; an appropriate amount of iron in aluminum alloy can improve the high-temperature fluidity of the alloy, reduce the shrinkage rate of aluminum alloy, and bring about the improvement of processing performance, while an excessive iron content will lead to a decrease in the plasticity of aluminum alloy and a decline in strength and hardness; therefore, the above dosage ranges of manganese and iron can bring about the above excellent effects while not easily causing the above adverse effects, and thus ensure the overall stability of aluminum alloy.

[0020] The rare earth element mixture is composed of niobium, scandium and cobalt. Among them, niobium and cobalt can accelerate the dissolution and diffusion of rare elements in aluminum alloy. Scandium regulates the grain size and distribution by controlling the growth rate of the crystal lattice. The combination of the three can bring a comprehensive improvement in the hardness and ductility of aluminum alloy. Boron in aluminum alloy mainly forms fine crystal nuclei with aluminum. These crystal nuclei stably exist in the molten aluminum and become the starting point for grain growth, thus significantly refining the grains in the molten aluminum and improving the strength, plasticity and toughness of aluminum alloy. At the same time, when the rare earth element mixture composed of niobium, scandium and cobalt is used, it can combine with boron to promote the formation of crystal nuclei and refine grains, thereby improving the microstructure of the alloy. And these small particles that grow in combination are evenly distributed in the grain boundaries and can also coordinate deformation through grain boundary slip, thus bringing a significant improvement in the strength of aluminum alloy and a remarkable improvement in the ductility of aluminum alloy.

[0021] Preferably, the weight ratio of niobium, scandium and cobalt is 1:4:14.

[0022] By adopting the above technical solution, when the rare earth element mixture composed of niobium, scandium and cobalt with the above weight ratio is used, it can not only stably exert its own excellent effect, but also cooperate with boron to exert an excellent synergistic effect in aluminum alloy. It can not only form stable hard phase particles to disperse strengthen the aluminum alloy and bring a significant increase in strength, but also bring a better grain boundary slip coordination deformation effect, and then show better ductility.

[0023] Preferably, the weight ratio of boron and the rare earth element mixture is 1:5.

[0024] By adopting the above technical solution, when the boron and the rare earth element mixture with the above weight ratio are used in combination, the coordination system formed in the aluminum alloy is relatively uniform and the corresponding effect is better. It can improve the strength of the aluminum alloy while making the aluminum alloy have excellent ductility, and the overall performance is better.

[0025] Preferably, the mass percentages of magnesium, silicon, copper and tin are:

[0026] Magnesium 0.8 - 1.2%;

[0027] Silicon 1.2 - 1.8%;

[0028] Copper 0.6 - 0.8%;

[0029] Tin 0.2 - 0.4%.

[0030] By adopting the above technical solution, when the magnesium, silicon, copper, and tin with the above mass percentages are mixed, the formation of the precipitated phase in the aluminum alloy after solution treatment can be made more balanced, which is beneficial to subsequent age hardening. Moreover, it can make the mixing of boron and rare earth elements more easily cooperate in the alloy system and exert better corresponding effects, thereby obtaining an aluminum alloy for high-strength vehicle bodies with better quality.

[0031] In a second aspect, the present application provides a method for preparing an aluminum alloy for high-strength vehicle bodies, adopting the following technical solution:

[0032] A method for preparing an aluminum alloy for high-strength vehicle bodies includes the following steps:

[0033] (1) Prepare raw materials including magnesium, silicon, copper, tin, manganese, iron, a mixture of boron and rare earth elements, and aluminum according to the ratio;

[0034] (2) Under the protection of an inert gas, melt the aluminum in step (1), and then add magnesium, silicon, copper, tin, manganese, iron, a mixture of boron and rare earth elements in proportion for mixing and melting to obtain a molten liquid;

[0035] (3) Add a refining agent to the molten liquid obtained in step (2) for refining treatment. After slag removal and degassing treatment, pour to obtain a semi-finished alloy;

[0036] (4) First perform solution treatment on the semi-finished alloy obtained in step (3), and then perform age treatment, and cool to obtain an aluminum alloy for high-strength vehicle bodies.

[0037] By adopting the above technical solution, the above preparation steps are fewer, the process is simple, and it is convenient for large-scale industrial production. At the same time, melting the aluminum first and then mixing and melting it with other component raw materials can ensure that all raw materials can be fully combined and exert excellent corresponding effect; moreover, after the mixing and melting of all raw materials, the refining treatment, solution treatment, and age treatment can also ensure obtaining an aluminum alloy for high-strength vehicle bodies with excellent and stable quality.

[0038] Preferably, in step (2), the melting temperature is 700 - 800 °C, and the melting time is 2 - 3 h.

[0039] By adopting the above technical solution, the above melting temperature and melting time can ensure the full mixing of all component raw materials, making it difficult for alloying elements to be burned out, and thus being beneficial to finally obtaining an aluminum alloy with excellent and stable quality.

[0040] Preferably, in step (3), the refining temperature is 820 - 860 °C, and the refining time is 30 - 40 min.

[0041] By adopting the above technical solution, refining is carried out by adding a refining agent to the molten metal for degassing and slag removal. The above refining temperature and refining time are beneficial to the dissolution of alloying elements and the discharge of gases and inclusions, thereby enabling the finally obtained aluminum alloy to have excellent quality.

[0042] Preferably, in step (3), the dosage of the refining agent is 0.1-0.2% of the mass of the molten metal, and the refining agent is any one or a combination of sodium chloride, potassium chloride, sodium fluoride and calcium fluoride.

[0043] By adopting the above technical solution, the refining agent composed of the above raw materials has strong impurity removal and degassing capabilities. It can not only improve the uniformity of the aluminum alloy, but also play a role in modifying and refining the aluminum alloy structure, and improve the melt properties such as the fluidity, wettability and solidification shrinkage of the aluminum alloy, bringing about the improvement of the casting performance and forming performance of the aluminum alloy, which is beneficial to ensuring the high-quality and stable high-strength aluminum alloy for vehicle bodies.

[0044] Preferably, in step (4), the solution treatment temperature is 520-540 °C and the holding time is 3-4 h.

[0045] By adopting the above technical solution, solution treatment can optimize the organizational structure of the aluminum alloy, reduce organizational non-uniformity, and thus improve the overall performance of the aluminum alloy; and the combination of the above solution treatment temperature and solution time can bring better corresponding effects, and finally obtain a high-quality and stable high-strength aluminum alloy for vehicle bodies.

[0046] Preferably, in step (4), the aging treatment temperature is 160-180 °C and the holding time is 3-4 h.

[0047] By adopting the above technical solution, aging treatment significantly improves the strength and hardness of the aluminum alloy by precipitating strengthening phases, and significantly improves the processing performance, and a dense oxide film will be formed on the surface of the aluminum material. This oxide film can effectively improve the corrosion resistance of the aluminum material; and the combination of the above aging treatment temperature and time can bring better corresponding effects, and finally obtain a high-quality and stable high-strength aluminum alloy for vehicle bodies.

[0048] In summary, the present application has the following beneficial effects:

[0049] The present application uses a rare earth element mixture composed of niobium, scandium and cobalt, and cooperates with boron synergistically. It can not only improve the microstructure of the alloy, but also enable the uniformly distributed fine particles formed by combination to be evenly distributed in the grain boundaries, bringing about the effect of grain boundary slip coordinated deformation. Thus, while improving the strength of the aluminum alloy, the aluminum alloy also has excellent ductility. Specific embodiments

[0050] The present application will be further described in detail below in conjunction with embodiments.

[0051] Embodiment 1

[0052] An aluminum alloy for high-strength vehicle bodies, with each raw material and its corresponding percentage as shown in Table 1, is prepared through the following steps:

[0053] (1) Prepare raw materials containing a mixture of magnesium, silicon, copper, tin, manganese, iron, boron, rare earth elements and aluminum according to the ratio;

[0054] (2) Under the protection of an inert gas, melt the aluminum in step (1), and then add the mixture of magnesium, silicon, copper, tin, manganese, iron, boron, and rare earth elements in proportion for mixing and melting to obtain a molten metal;

[0055] (3) Add a refining agent to the molten metal obtained in step (2) for refining treatment. After slag removal and degassing treatment, pour it to obtain a semi-finished alloy;

[0056] (4) First perform solution treatment on the semi-finished alloy obtained in step (3), then perform aging treatment, and cool to obtain the aluminum alloy for high-strength vehicle bodies.

[0057] Note: In the above operations, the rare earth element mixture consists of niobium, scandium, and cobalt, and the weight ratio of niobium, scandium, and cobalt is 1:4:14. In step (2), the melting temperature is 750 °C and the melting time is 2.5 h. In step (3), the refining temperature is 840 °C, the refining time is 35 min, the dosage of the refining agent is 0.15% of the mass of the molten metal, and the refining agent consists of sodium chloride, potassium chloride, and calcium fluoride in a weight ratio of 11:7:8. In step (4), the solution treatment temperature is 530 °C and the holding time is 3.5 h; the aging treatment temperature is 170 °C and the holding time is 3.5 h.

[0058] Embodiments 2-3

[0059] An aluminum alloy for high-strength vehicle bodies, which is different from Embodiment 1 in that each raw material and its weight are as shown in Table 1.

[0060] Table 1 Raw materials and their corresponding mass percentages (%) in Embodiments 1-3

[0061] Raw materials Example 1 Example 2 Example 3 Magnesium 1 0.5 1.5 Silicon 1.5 1 2 Copper 0.7 0.4 1 Tin 0.3 0.1 0.5 Manganese 0.03 0.01 0.05 Iron 0.075 0.05 0.1 Boron 0.15 0.1 0.2 Rare earth element mixture 0.9 0.3 1.5 Aluminum 95.345 97.54 93.15

[0062] Embodiment 4

[0063] An aluminum alloy for high-strength vehicle bodies, which is different from Embodiment 1 in that the rare earth element mixture consists of niobium, scandium, and cobalt, and the weight ratio of niobium, scandium, and cobalt is 1:3.9:13.5.

[0064] Embodiment 5

[0065] An aluminum alloy for high-strength body, which is different from that of Example 1 in that the rare earth element mixture consists of niobium, scandium and cobalt, and the weight ratio of niobium, scandium and cobalt is 1:3.4:12.

[0066] Example 6

[0067] An aluminum alloy for high-strength body, which is different from that of Example 1 in that the rare earth element mixture consists of niobium, scandium and cobalt, and the weight ratio of niobium, scandium and cobalt is 1:4.4:15.

[0068] Example 7

[0069] An aluminum alloy for high-strength body, which is different from that of Example 1 in that the total amount of boron and rare earth element mixture remains unchanged, and the weight ratio of the two is adjusted to 1:5.

[0070] Examples 8 - 11

[0071] An aluminum alloy for high-strength body, which is different from that of Example 1 in that each raw material and its corresponding weight are shown in Table 2.

[0072] Table 2 Raw materials and their corresponding mass percentages (%) of Examples 8 - 11

[0073] Raw materials Example 8 Example 9 Example 10 Example 11 Magnesium 0.8 1.2 0.7 1.3 Silicon 1.2 1.8 1.1 1.9 Copper 0.6 0.8 0.5 0.9 Tin 0.2 0.4 0.1 0.5 Manganese 0.03 0.03 0.03 0.03 Iron 0.075 0.075 0.075 0.075 Boron 0.15 0.15 0.15 0.15 Rare earth element mixture 0.9 0.9 0.9 0.9 Aluminum 96.045 94.645 96.445 94.245

[0074] Example 12

[0075] An aluminum alloy for high-strength body, which is different from that of Example 1 in that in step (2), the melting temperature is 700 °C and the melting time is 3 h.

[0076] Example 13

[0077] An aluminum alloy for high-strength body, which is different from that of Example 1 in that in step (2), the melting temperature is 800 °C and the melting time is 2 h.

[0078] Example 14

[0079] An aluminum alloy for high-strength body, which is different from that of Example 1 in that in step (3), the refining temperature is 820 °C and the refining time is 40 min.

[0080] Example 15

[0081] An aluminum alloy for high-strength body, which is different from that of Example 1 in that in step (3), the refining temperature is 860 °C and the refining time is 30 min.

[0082] Example 16

[0083] An aluminum alloy for high-strength body, which is different from that of Example 1. In step (3), the dosage of the refining agent is 0.2% of the mass of the melting liquid.

[0084] Example 17

[0085] An aluminum alloy for high-strength body, which is different from that of Example 1. In step (3), the dosage of the refining agent is 0.1% of the mass of the melting liquid.

[0086] Example 18

[0087] An aluminum alloy for high-strength body, which is different from that of Example 1. In step (4), the solution treatment temperature is 520 °C and the holding time is 4 h.

[0088] Example 19

[0089] An aluminum alloy for high-strength body, which is different from that of Example 1. In step (4), the solution treatment temperature is 540 °C and the holding time is 3 h.

[0090] Example 20

[0091] An aluminum alloy for high-strength body, which is different from that of Example 1. In step (4), the aging treatment temperature is 160 °C and the holding time is 4 h.

[0092] Example 21

[0093] An aluminum alloy for high-strength body, which is different from that of Example 1. In step (4), the aging treatment temperature is 180 °C and the holding time is 3 h.

[0094] Comparative Example 1

[0095] An aluminum alloy for high-strength body, which is different from that of Example 1. In the raw materials, boron is replaced with aluminum in equal mass.

[0096] Comparative Example 2

[0097] An aluminum alloy for high-strength body, which is different from that of Example 1. In the raw materials, the rare earth element mixture is replaced with aluminum in equal mass.

[0098] Comparative Example 3

[0099] An aluminum alloy for high-strength body, which is different from that of Example 1. In the raw materials, boron and the rare earth element mixture are replaced with aluminum in equal mass.

[0100] Comparative Example 4

[0101] An aluminum alloy for high-strength body, which is different from that of Example 1. In the rare earth element mixture, niobium and cobalt are not used.

[0102] Comparative Example 5

[0103] An aluminum alloy for high-strength body, which is different from that in Example 1 in that scandium and cobalt are not used in the rare-earth element mixture.

[0104] Comparative Example 6

[0105] An aluminum alloy for high-strength body, which is different from that in Example 1 in that niobium and scandium are not used in the rare-earth element mixture.

[0106] Comparative Example 7

[0107] An aluminum alloy for high-strength body, which is different from that in Example 1 in that niobium is not used in the rare-earth element mixture.

[0108] Comparative Example 8

[0109] An aluminum alloy for high-strength body, which is different from that in Example 1 in that scandium is not used in the rare-earth element mixture.

[0110] Comparative Example 9

[0111] An aluminum alloy for high-strength body, which is different from that in Example 1 in that cobalt is not used in the rare-earth element mixture.

[0112] Performance Detection Test

[0113] Test Samples: The aluminum alloys for high-strength body obtained in Examples 1-21 were used as Test Samples 1-21, and the aluminum alloys for high-strength body obtained in Comparative Examples 1-9 were used as Control Samples 1-9.

[0114] Test Methods: (1) Measure the hardness of the aluminum alloys of Test Samples 1-21 and Control Samples 1-9 according to the content in YS / T 420-2023 "Test Method for Vickers Hardness of Aluminum Alloys";

[0115] (2) Detect the yield strength of Test Samples 1-21 and Control Samples 1-9 according to ASTM E8 / E8M;

[0116] (3) Detect the tensile strength of Test Samples 1-21 and Control Samples 1-9 according to ASTM E8 / E8M;

[0117] (4) The elongation refers to the percentage of the total elongation to the original gauge length after the material is stretched and fractured; if the length of the material changes by ΔL before and after stretching, and the original length is L0, then the elongation can be calculated by the formula: Elongation = ΔL / L0×100%.

[0118] After the above tests were successively completed on Test Samples 1-21 and Control Samples 1-9, the corresponding results were recorded in Table 3.

[0119] Table 3 Test Results of Test Samples 1-21 and Control Samples 1-9

[0120] Samples Hardness (HV) Yield strength (MPa) Tensile strength (MPa) Elongation rate (%) Test sample 1 165.5 309.1 386.8 16.7 Test sample 2 163.2 306.8 384.5 14.4 Test sample 3 163.1 306.7 384.4 14.3 Test sample 4 164.1 307.7 385.4 15.3 Test sample 5 163.9 307.5 385.2 15.1 Test sample 6 164.3 307.9 385.6 15.5 Test sample 7 165.3 308.9 386.6 16.5 Test sample 8 165.1 308.7 386.4 16.3 Test sample 9 164.9 308.5 386.2 16.1 Test sample 10 163.5 307.1 384.8 14.7 Test sample 11 163.7 307.3 385.0 14.9 Test sample 12 164.5 308.1 385.8 15.7 Test sample 13 164.7 308.3 386.0 15.9 Test sample 14 164.0 307.6 385.3 15.2 Test sample 15 164.2 307.8 385.5 15.4 Test sample 16 164.8 308.4 386.1 16.0 Test sample 17 163.9 307.5 385.2 15.1 Test sample 18 164.4 308.0 385.7 15.6 Test sample 19 165.0 308.6 386.3 16.2 Test sample 20 164.6 308.2 385.9 15.8 Test sample 21 165.2 308.8 386.5 16.4 Control sample 1 150.8 294.4 372.1 13.1 Control sample 2 148.4 292.1 369.7 12.8 Control sample 3 141.1 284.7 362.4 11.2 Control sample 4 151.8 295.4 373.1 13.3 Control sample 5 152.7 296.3 374.0 13.5 Control sample 6 152.1 295.7 373.4 13.4 Control sample 7 155.5 299.1 376.8 13.7 Control sample 8 156.4 300.0 377.6 13.9 Control sample 9 156.1 299.7 377.4 13.8

[0121] Combined with Example 1 and Comparative Examples 1-3 and Table 3, it can be seen that in this application, by using a rare earth element mixture composed of niobium, scandium and cobalt and cooperating with boron, good ductility of the aluminum alloy under high hardness, yield strength and high tensile strength is achieved, and the hardness, yield strength, high tensile strength and ductility values obtained through the above tests can all be significantly improved; while if boron or the rare earth element mixture is applied alone to the aluminum alloy system, although the corresponding effects can be improved, the improvement amplitude is limited and far less excellent than the effect brought by the combination of the two. Thus, it can be seen that the combination between boron and the rare earth element mixture can bring a significant improvement effect of 1+1>2. Combining with Comparative Examples 4-9 and Table 3, it can be seen that in the rare earth element mixture, if only any one or two of niobium, scandium and cobalt are used, the corresponding effects brought are all limited, and they are only a simple superposition of effects, and only when the three are used in combination can a relatively prominent and significant corresponding effect be brought, thereby while improving the overall strength of the aluminum alloy, making the aluminum alloy have excellent ductility.

[0122] Combined with Example 1 and Examples 4-6 and Table 3, it can be seen that when the weight ratio of niobium, scandium and cobalt in the rare earth element mixture is 1:(3.4-4.4):(12-15), stable and better application effects can be exerted. Among them, when the weight ratio of niobium, scandium and cobalt is 1:4:14, the application effect of the rare earth element mixture is better. Combining with Example 7 and Table 3, it can be seen that when the weight ratio of boron and the rare earth element mixture is 1:5, the cooperation system formed by the two shows better performance in the aluminum alloy, and thus the high-strength aluminum alloy for vehicle body obtained shows better performance in hardness, yield strength, high tensile strength and ductility.

[0123] Combined with Example 1 and Examples 8-11 and Table 3, it can be seen that when the mass percentages of magnesium, silicon, copper and tin are: magnesium 0.8-1.2%, silicon 1.2-1.8%, copper 0.6-0.8%, tin 0.2-0.4%, it can make the formation of precipitated phases more balanced after solution treatment of the aluminum alloy, which is beneficial to subsequent age hardening, and can make the boron and rare earth element mixture more easily cooperate in the alloy system, and finally a high-strength aluminum alloy for vehicle body with better quality can be obtained.

[0124] Combined with Example 1 and Examples 12 - 21 and in combination with Table 3, it can be seen that in the preparation of the aluminum alloy for high-strength vehicle bodies in this application, the selection and coordination of parameters in each operation can ensure that all raw materials can be fully coordinated, exert excellent corresponding effects, and ultimately obtain an aluminum alloy for high-strength vehicle bodies with excellent and stable quality.

[0125] This specific embodiment is only an interpretation of this application, and it is not a limitation of this application. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as it is within the scope of the claims of this application, it is protected by the patent law.

Claims

1. An aluminum alloy for high-strength body, characterized in that It is made from raw materials containing the following mass percentages: Magnesium 0.8 - 1.2%; Silicon 1.2 - 1.8%; Copper 0.6 - 0.8%; Tin 0.2 - 0.4%; Manganese 0.01 - 0.05%; Iron 0.05 - 0.1%; Boron 0.1 - 0.2%; Rare earth element mixture 0.3 - 1.5%; The balance is aluminum; The rare earth element mixture is composed of niobium, scandium and cobalt, and the weight ratio of niobium, scandium and cobalt is 1:(3.4 - 4.4):(12 - 15); The weight ratio of the boron to the rare earth element mixture is 1:

5.

2. The aluminum alloy for high-strength vehicle body according to claim 1, wherein: The weight ratio of the niobium, scandium and cobalt is 1:4:

14.

3. The preparation method of the aluminum alloy for high-strength vehicle body according to claim 1, characterized in that: It includes the following steps: (1) Prepare raw materials containing magnesium, silicon, copper, tin, manganese, iron, boron, rare earth element mixture and aluminum according to the ratio; (2) Under the protection of inert gas, melt the aluminum in step (1), and then add magnesium, silicon, copper, tin, manganese, iron, boron, rare earth element mixture in proportion for mixing and melting to obtain a molten liquid; (3) Add a refining agent to the molten liquid obtained in step (2) for refining treatment. After slag removal and degassing treatment, it is poured to obtain a semi-finished alloy; (4) First perform solution treatment on the semi-finished alloy obtained in step (3), then perform aging treatment, and cool to obtain an aluminum alloy for high-strength body.

4. The preparation method of the aluminum alloy for high-strength vehicle body according to claim 3, characterized in that: In step (2), the melting temperature is 700 - 800 °C, and the melting time is 2 - 3 h.

5. The preparation method of the aluminum alloy for high-strength vehicle body according to claim 3, wherein: In step (3), the refining temperature is 820 - 860 °C, and the refining time is 30 - 40 min.

6. The preparation method of the aluminum alloy for high-strength vehicle body according to claim 3, characterized in that: In step (3), the dosage of the refining agent is 0.1 - 0.2% of the mass of the molten liquid, and the refining agent is any one or several combinations of sodium chloride, potassium chloride, sodium fluoride and calcium fluoride.

7. The preparation method of the aluminum alloy for high-strength vehicle body according to claim 3, characterized in that: In step (4), the solution treatment temperature is 520 - 540 °C, and the heat preservation time is 3 - 4 h.

8. The preparation method of the aluminum alloy for high-strength vehicle body according to claim 3, characterized in that: In step (4), the aging treatment temperature is 160 - 180 °C, and the heat preservation time is 3 - 4 h.