An aluminum alloy material for vehicle body and its preparation method

Abstract

The present application discloses an aluminum alloy material for vehicle body and its preparation method, relating to the technical field of aluminum alloys. The aluminum alloy material includes elements in the following mass percentages: Si: 7.5 - 9.5 wt%, Mg: 0.12 - 0.3 wt%, Mn: 0.25 - 0.75 wt%, Fe: 0.08 - 0.45 wt%, Ti: 0.05 - 0.2 wt%, Sr: 0.015 - 0.03 wt%, Ce: 0.01 - 0.03 wt%, Sm: 0.005 - 0.015 wt%, Zn: 0 - 0.6 wt%, Cu: 0 - 0.2 wt%, and the remaining components are Al and impurities. Due to the combined effects of the elements in various proportions in the present application, the strength and toughness of the prepared aluminum alloy material both meet the relevant standards. At the same time, it can effectively control the iron-rich phase, enabling the prepared aluminum alloy material to still have excellent strength and toughness even when a higher proportion of recycled materials is added.

Description

Technical Field

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

[0002] Aluminum alloys for vehicle bodies are used in the processing of castings. The manufacturing processes of aluminum alloys in the automotive field mainly include stamping, die-casting, and extrusion forming. Die-casting is the main production method for aluminum alloy components. The usage of aluminum alloy die-castings in the automotive field accounts for about 80%, and the proportions of extruded parts and rolled parts are each about 10%. Under the requirements of environmental protection and energy conservation, automotive manufacturing is constantly moving towards lightweight, which promotes the application of aluminum and magnesium alloys with low density and high strength in automotive parts.

[0003] In some related technologies, the aluminum alloy castings currently in preparation and use generally have the problems of relatively high strength and relatively low toughness. Especially when the content of impurity iron element is relatively high, the above problems are more prominent, which makes it impossible to add a relatively high proportion of recycled waste to the existing heat-treatment-free aluminum alloys, and is not conducive to energy conservation and carbon reduction. At the same time, precious metal elements such as copper, vanadium, zirconium, and gallium are generally added to the existing aluminum alloy materials, increasing the manufacturing cost of the materials. Summary of the Invention

[0004] In order to solve at least one of the problems mentioned in the above background art, this application provides an aluminum alloy material for vehicle bodies and a preparation method thereof. By effectively controlling the iron-rich phase, it is realized that under the condition of adding a higher proportion of recycled materials, the prepared aluminum alloy material still has excellent strength and toughness, not only achieving energy conservation and carbon reduction, but also effectively reducing the processing material cost.

[0005] The specific technical solutions provided by the embodiments of this application are as follows:

[0006] In the first aspect, an aluminum alloy material for vehicle bodies is provided. The aluminum alloy material includes the following elements in mass percentages: Si: 7.5 - 9.5 wt%, Mg: 0.12 - 0.3 wt%, Mn: 0.25 - 0.75 wt%, Fe: 0.08 - 0.45 wt%, Ti: 0.05 - 0.2 wt%, Sr: 0.015 - 0.03 wt%, Ce: 0.01 - 0.03 wt%, Sm: 0.005 - 0.015 wt%, Zn: 0 - 0.6 wt%, Cu: 0 - 0.2 wt%, and the remaining components are Al and impurities, and the mass percentage of the impurities is: 0 - 0.15 wt%.

[0007] In a specific embodiment, the sum of the mass percentages of Mn and Fe is 0.6 - 0.75 wt%.

[0008] In a specific embodiment, the ratio of the mass percentages of Ce and Sm is 1.8 to 2.2.

[0009] In a specific embodiment, the mass percentage of Si is 7.5 to 8.5 wt%.

[0010] Furthermore, the mass percentage of Si is 7.7 to 8.3 wt%.

[0011] In a specific embodiment, the mass percentage of Mg is 0.16 to 0.24 wt%.

[0012] In a specific embodiment, the mass percentage of Sr is 0.01 to 0.03 wt%.

[0013] Second, a method for preparing an aluminum alloy material for a vehicle body is provided. The method is used to prepare the aluminum alloy material for a vehicle body as described above, and the method includes:

[0014] Melting aluminum ingots, industrial silicon, iron agents, aluminum-manganese master alloy, aluminum-titanium master alloy, aluminum-cerium master alloy, and aluminum-samarium master alloy according to the mass percentages of preset elements to form a first alloy liquid;

[0015] Adding magnesium ingots and aluminum-strontium master alloy to the first alloy liquid according to the mass percentages of preset elements, and melting and mixing to form a second alloy liquid;

[0016] Adding a modifying agent to the second alloy liquid according to the mass percentages of preset elements, and melting and mixing to form a third alloy liquid;

[0017] Performing degassing, slag removal, and filtration on the third alloy liquid to obtain an aluminum alloy material.

[0018] In a specific embodiment, the melting temperature of the first alloy liquid is 760 to 770 °C; the melting temperature of the second alloy liquid is 700 to 720 °C; the melting temperature of the third alloy liquid is 700 to 710 °C.

[0019] In a specific embodiment, the modifying agent is an Al-Sr-Ti-C combined refinement and modification agent, and the mass percentage of the modifying agent is 0.1 to 0.3 wt%.

[0020] In a specific embodiment, the degassing is online degassing with an inert gas, and when setting the online inert gas degassing furnace, the melting furnace temperature is 680 to 700 °C.

[0021] In a specific embodiment, the flow rate of the inert gas is 15 to 25 LPM;

[0022] and / or, the outlet pressure of the inert gas is 0.4 to 0.6 Mpa;

[0023] And / or, the degassing time is greater than or equal to 40 min.

[0024] In a specific embodiment, the rotational speed of the degasser for online degassing of inert gas is 400 - 450 rpm.

[0025] In a specific embodiment, a refining agent is used for purification treatment during the slag removal process; the refining agent includes one or more of sodium chloride, potassium chloride, magnesium chloride, potassium fluoroaluminate, calcium fluoride, sodium fluorosilicate, sodium carbonate, magnesium carbonate, and calcium carbonate.

[0026] In a third aspect, a vehicle is provided, including the aluminum alloy material for vehicle body as described above, or the vehicle body material is prepared by the preparation method of the aluminum alloy material for vehicle body as described above.

[0027] The embodiments of the present application have the following beneficial effects:

[0028] 1. Through the combined action of elements in various proportions in the embodiments of the present application, the strength and toughness of the prepared aluminum alloy material reach relevant standards. At the same time, through the combined addition of microalloying elements Ce and Sm, the primary iron-rich phase is effectively modified, realizing effective control of the iron-rich phase, minimizing the influence of the iron-rich phase on the alloy toughness. Even when a higher proportion of recycled aluminum is added, it still has excellent strength and toughness, which can not only reduce carbon but also effectively reduce the material cost.

[0029] 2. Instead of using the traditional aluminum-titanium-boron grain refiner, the present application uses the method of adding a modifier after the material is modified by traditional aluminum strontium. The addition of the modifier further strengthens the modification and can effectively refine the grains, enabling the prepared aluminum alloy material in the present application to be applied to large-sized, complex-structured, and high-strength and toughness-required automotive structural parts.

[0030] 3. In terms of purification treatment, the present invention effectively removes non-metallic inclusions, oxides, and gas in the aluminum liquid, ensuring that the aluminum liquid has a high purity and avoiding the generation of defective products in the later stage due to poor purification treatment effect of the gas content in the aluminum liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0032] Figure 1Schematic diagram showing the preparation method of the aluminum alloy material for vehicle body according to the present application;

[0033] Figure 2 Schematic diagram showing the specimen prepared by the flat die according to the present application;

[0034] Figure 3 Schematic diagram showing the metallographic microstructure of the flat specimen according to the present application;

[0035] Figure 4 Schematic diagram showing the scanning electron microscope of the flat specimen according to the present application;

[0036] Figure 5 Schematic diagram showing the EDS energy spectrum analysis results of the spherical phase according to the present application;

[0037] Figure 6 Schematic diagram showing the content of each element in the EDS energy spectrum analysis results of the spherical phase according to the present application. Detailed implementation manners

[0038] To make the objectives, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used in the specification of this application herein are only for the purpose of describing specific implementation manners and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0040] Example 1

[0041] An aluminum alloy material for vehicle body, the aluminum alloy material includes the following elements by mass percentage: Si: 7.5 - 9.5 wt%, Mg: 0.12 - 0.3 wt%, Mn: 0.25 - 0.75 wt%, Fe: 0.08 - 0.45 wt%, Ti: 0.05 - 0.2 wt%, Sr: 0.015 - 0.03 wt%, Ce: 0.01 - 0.03 wt%, Sm: 0.005 - 0.015 wt%, Zn: 0 - 0.6 wt%, Cu: 0 - 0.2 wt%, and the remaining components are Al and impurities, and the mass percentage of the impurities is: 0 - 0.15 wt%.

[0042] In a specific embodiment, the mass percentage of Si is 7.5 - 8.5 wt%. Further, the mass percentage of Si is 7.7 - 8.3 wt%. In this embodiment, the Si element is the first main alloying element of the aluminum alloy material in this application embodiment. The presence of Si ensures that the aluminum alloy material has good filling ability while having high strength and toughness. When the content of silicon is lower than 7.5 wt%, the alloy strength does not reach the peak region, and the casting performance of the alloy is poor; when the silicon content is higher than 9.5 wt%, the strength increase is limited, and the toughness decreases rapidly. By controlling the addition amount of silicon element, the aluminum alloy material can realize various integrated die-casting processes for large structural parts based on good filling ability.

[0043] In a specific embodiment, the mass percentage of Mg is 0.16 - 0.24 wt%. The Mg element in this embodiment is the second main alloying element for preparing the aluminum alloy material. Magnesium will combine with silicon to form magnesium silicide strengthening phase, which can significantly improve the room temperature strength of the alloy, but also significantly reduce the toughness of the alloy; by controlling the addition amount of Mg element within a certain range, the magnesium-containing cast Al-Si alloy has the potential to further improve its mechanical properties through heat treatment or natural aging, making the prepared aluminum alloy material take into account both the strength and toughness and thermal stability of the alloy.

[0044] Further, the sum of the mass percentages of Mn and Fe is 0.6 - 0.75 wt%. The Mn element is the third main alloying element for preparing the aluminum alloy material in this embodiment. By adding manganese element, it can dissolve the impurity iron, reduce the harmful effect of iron, prevent sticking to the mold, and improve the mold life; and as a strengthening element, it forms Mn-Al6 phase with aluminum, and the addition of manganese has the effect of improving the corrosion resistance of the alloy.

[0045] Further, the mass percentage ratio of Ce and Sm is 1.8 - 2.2.

[0046] This embodiment also includes Fe element. Fe is a non-main alloying element for preparing the aluminum alloy material in this embodiment. By controlling its mass percentage to 0.08 - 0.45 wt%, the prepared aluminum alloy material does not stick to the mold, improving the mold life; at the same time, the Fe content range directly determines the actual production of aluminum alloy ingots. By controlling the selection of recycled aluminum, it directly determines the final material cost and carbon reduction ratio. Considering that the relative content of Fe has a greater negative impact on the toughness of the alloy, in this embodiment, by reducing the negative impact of the iron-rich phase on the toughness of the alloy, that is, by controlling the sum of the masses of Mn and Fe, and the ratio of Ce and Sm, and further controlling the range of the sum of the mass percentages of Mn and Fe to 0.6 - 0.75 wt%, the control of the iron-rich phase in the aluminum alloy material is realized.

[0047] In a specific embodiment, Sr is a microalloying element in the high-strength and high-toughness die-cast aluminum alloy of the present invention, and its content is controlled within 0.01 - 0.03 wt%. The main role of Sr in the aluminum alloy is to modify the eutectic Si phase and the Fe-containing phase. In this embodiment, by controlling the two additions of Sr, a good modification effect on the Fe-containing phase is achieved. During the preparation of the high-strength and high-toughness die-cast aluminum alloy, the first addition is in the form of an AlSr10 master alloy, and the second addition is in the form of a modifier. The total content range is controlled within 0.01 - 0.03 wt%.

[0048] Furthermore, the aluminum alloy material in this embodiment also includes Zn element. Zn is controlled as an impurity element in the aluminum alloy material, and its total mass percentage is controlled to be less than or equal to 0.6 wt%. By controlling the Zn element within the above range, it can be achieved that the Zn element has no obvious influence on the strength and toughness of the alloy. At the same time, during the actual manufacturing process of the aluminum alloy, by adding as much recycled aluminum as possible, the material cost can be reduced while ensuring the strength and toughness of the aluminum alloy.

[0049] In this embodiment, Cu element is also added. Cu element is an impurity element during the manufacturing process of the aluminum alloy, and its mass percentage is controlled to be less than or equal to 0.2 wt%. By controlling the Cu element within the above mass percentage range, Cu can play a strengthening role on the aluminum alloy material, and the influence on the toughness of the material does not increase significantly. By controlling the increase of the Cu content, the strength of the aluminum alloy material can be improved, and the selection range of recycled aluminum can be expanded during the manufacturing process of the aluminum alloy material, which is beneficial to reducing the material cost.

[0050] In this embodiment, during the manufacturing of the high-strength and high-toughness aluminum alloy material, by jointly adding the microalloying elements Ce and Sm, the primary iron-rich phase can be effectively modified. When the rare earth elements Ce and Sm are jointly added and the Ce / Sm ratio is controlled within 1.8 - 2.2, the primary iron-rich phase can be effectively modified, thereby minimizing the influence of the iron-rich phase on the alloy toughness.

[0051] Embodiment Two

[0052] Corresponding to the above embodiment, the present application provides a preparation method for an aluminum alloy material for a vehicle body. The method is used to prepare the aluminum alloy material for a vehicle body as described above. As Figure 1 shown, the method includes:

[0053] Step 101, melt aluminum ingots, industrial silicon, iron agent, aluminum-manganese master alloy, aluminum-titanium master alloy, aluminum-cerium master alloy, and aluminum-samarium master alloy according to the mass percentages of preset elements to form a first alloy liquid.

[0054] Step 102: Add magnesium ingots and aluminum strontium master alloy to the first alloy liquid according to the mass percentages of preset elements, melt and mix them to form a second alloy liquid.

[0055] Step 103: Add a modifier to the second alloy liquid according to the mass percentages of preset elements, melt and mix them to form a third alloy liquid.

[0056] In a specific embodiment, for the raw materials of this embodiment, namely aluminum ingots, industrial silicon, iron agent, aluminum manganese master alloy, aluminum titanium master alloy, aluminum cerium master alloy, aluminum samarium master alloy, magnesium ingots, aluminum strontium master alloy, and the modifier, the elements are added to the above raw materials according to the following mass percentages, including Si: 7.5 - 9.5 wt%, Mg: 0.12 - 0.3 wt%, Mn: 0.25 - 0.75 wt%, Fe: 0.08 - 0.45 wt%, Ti: 0.05 - 0.2 wt%, Sr: 0.015 - 0.03 wt%, Ce: 0.01 - 0.03 wt%, Sm: 0.005 - 0.015 wt%, Zn: 0 - 0.6 wt%, Cu: 0 - 0.2 wt%, and the remaining components are Al and impurities, and the mass percentage of the impurities is: 0 - 0.15 wt%.

[0057] In a specific embodiment, the raw materials in this embodiment are selected and configured as remelted aluminum ingots, industrial silicon, pure magnesium ingots, 80% iron agent, AlMn10 master alloy, AlSr10 master alloy, AlTi10 master alloy, AlCe10 master alloy, AlSm10 master alloy, and an Al - Sr - Ti - C combined refining modifier.

[0058] Furthermore, when putting aluminum ingots, industrial silicon, 80% iron agent, AlMn10 master alloy, AlTi10 master alloy, AlCe10 master alloy, and AlSm10 master alloy into remelting, set the furnace temperature to 760 - 770 °C to fully melt the above raw materials and obtain the first alloy liquid.

[0059] In a specific embodiment, when preparing the second alloy liquid, control the aluminum liquid temperature to be heated to 700 - 720 °C; and when preparing the third alloy liquid, control the aluminum liquid temperature to be heated to 700 - 710 °C to melt the raw materials.

[0060] It should be noted that the modifier in this embodiment is an AlSr10Ti5C combined refining modifier, and the mass percentage of the modifier is 0.1 - 0.3 wt%.

[0061] Step 104: Degas, deslag, and filter the third alloy liquid to obtain an aluminum alloy material.

[0062] Further, the degassing inert gas is degassed online, and the furnace temperature is set to 680 - 700 °C when the inert gas is degassed online. The inert gas in this embodiment includes, but is not limited to, one or several of nitrogen, helium, neon, argon, krypton, and xenon.

[0063] In a specific embodiment, the rotational speed of the degassing machine for the online degassing is 400 - 450 rpm, and the flow rate of the inert gas is 15 - 25 LPM; the outlet pressure of the inert gas is 0.4 - 0.6 Mpa, and the degassing time is greater than or equal to 40 min.

[0064] Specifically, a refining agent is used for purification treatment during the slag removal process; the refining agent includes, but is not limited to, one or more of sodium chloride, potassium chloride, magnesium chloride, potassium fluoroaluminate, calcium fluoride, sodium fluorosilicate, sodium carbonate, magnesium carbonate, and calcium carbonate.

[0065] In this embodiment, when selecting raw materials, the high-strength and tough heat-treatment-free aluminum alloy of the present invention has an increased upper limit of Fe, Zn, and Cu elements compared with heat-treatment-free alloys such as Alcoa C611. Therefore, in terms of raw material selection, a higher proportion of recycled aluminum can be selected; compared with existing alloy materials, relatively expensive alloying elements such as Mo, V, and Zr are not added. Compared with other heat-treatment-free aluminum alloys, the high-strength and tough heat-treatment-free aluminum alloy of the present invention has obvious cost advantages and carbon reduction advantages while ensuring service performance.

[0066] At the same time, in view of the high requirements for the strength and toughness of materials for large structural parts and the characteristics of aluminum-silicon-based cast aluminum alloys, instead of using traditional aluminum-titanium-boron grain refiners, after the material is conventionally modified with aluminum strontium, an AlSr10Ti5C combined refining and modifying agent is further added. By adding the modifying agent, while further strengthening the modification, the grains can be effectively refined. In addition, the present invention effectively removes non-metallic inclusions, oxides, and gas in the alloy liquid, ensuring that the aluminum liquid has a high purity and avoiding the generation of defective products in the later stage due to poor purification treatment of the gas content in the aluminum liquid.

[0067] Example 3

[0068] Corresponding to the above embodiment, this embodiment provides a vehicle, which includes the aluminum alloy material for the vehicle body as described above or the vehicle body material in the vehicle is prepared by the preparation method of the aluminum alloy material for the vehicle body as described above.

[0069] Example 4

[0070] Corresponding to the above embodiments, in this embodiment, the mass percentages of the configured elements are as follows: Si: 8.12 wt%; Mg: 0.19 wt%; Mn: 0.62 wt%; Fe: 0.09 wt%; Sr: 0.018 wt%; Ti: 0.09 wt%; Ce: 0.02 wt%; Sm: 0.01 wt%, and the balance is Al.

[0071] Based on this, the mass ratios of the following raw materials are configured as follows: remelted aluminum ingot Al99.70, 84.3 wt%; 3303 industrial silicon, 8.0 wt%; pure magnesium ingot g99.95, 0.2 wt%; AlMn10 master alloy, 6.0 wt%; AlSr10 master alloy, 0.2 wt%; AlTi10 master alloy, 1.0 wt%; AlCe10 master alloy, 0.2 wt%; AlSm10 master alloy, 0.1 wt%.

[0072] The specific preparation process includes: preparing raw materials according to the above ratios, namely remelted aluminum ingot Al99.70, 3303 industrial silicon, AlMn10 master alloy, AlTi10 master alloy, AlCe10 master alloy, and AlSm10 master alloy, controlling the furnace temperature at 760 - 770 °C and heating until fully melted to obtain the first alloy liquid. Controlling the aluminum liquid temperature at 720 °C, adding pure magnesium ingot and AlSr10 master alloy to the first alloy liquid in proportion to obtain the second alloy liquid. Controlling the aluminum liquid temperature at 710 °C, adding 0.1 - 0.3 wt% of AlSr10Ti5C combined refining and modifying agent to obtain the third alloy liquid. Degassing, slag removing, and filtering the third alloy liquid online to obtain a high-strength and tough die-casting available aluminum alloy melt. The actual process parameters are: controlling the furnace temperature at 700 °C, adding 3 wt‰ of refining agent for purification treatment, and the refining agent is selected as a mixture of sodium chloride, potassium chloride, magnesium chloride, potassium fluoroaluminate, calcium fluoride, sodium fluorosilicate, sodium carbonate, magnesium carbonate, and calcium carbonate; the inert gas for online degassing is selected as argon, with an argon outlet pressure of 0.5 Mpa, a degassing time of 40 min; the rotation speed of the degassing machine for online degassing with inert gas is 450 rpm, and the argon flow rate is 20 LPM.

[0073] Adding the high-strength and tough die-casting melt material to the die-casting machine's melting furnace, controlling the aluminum liquid temperature at 700 - 710 °C, introducing argon and continuously stirring the melt for 30 min to further remove the gas in the melt; skimming the slag and then standing for 10 min, controlling the aluminum liquid temperature at 705 °C to obtain the aluminum alloy material.

[0074] Vacuum high-pressure casting was carried out using a LK IMPRESS-Ⅲ DCC500 die-casting machine, with a casting pressure of 1000 bar, a slow injection speed of 0.2 m / s, and a fast injection speed of 5 m / s. The mold temperature and barrel temperature were 180 °C. The mold used was a flat mold with a length of 200 mm and a width of 65 mm, and the wall thickness was 3 mm. The specimens prepared from the corresponding flat mold are shown in Figure 2 ; The vacuum machine used was an Aijiaya HG600 vacuum machine, and the cavity vacuum was <50 mbar.

[0075] The metallographic microstructure of the flat specimens is shown in Figure 3 , and the microstructure is mainly composed of α-Al and Al-Si binary eutectic structure. The modification effect of the eutectic silicon in the alloy is good, the modification grade is better than grade 2, and the average grain size reaches about 10 μm. At the same time, there are no obvious large-sized needle-shaped iron-rich phases in the matrix. The scanning electron microscope photos of the flat specimens are shown in Figure 4 , and spherical phases are distributed in the matrix, without obvious needle-shaped iron-rich phases. The EDS energy spectrum analysis results of the spherical phases are shown in Figure 5 and Figure 6 , showing that the elements of the spherical phase are Al, Mn, Si, and Fe, and the atomic ratios of each element are shown in Table 1; it can be seen that although they are also iron-rich phases, compared with the traditional needle-shaped iron-rich phases, the Fe content is significantly lower. Generally speaking, due to the use of AlSr10 and AlSr10Ti5C combined refining and modification agents, and the combined addition of rare earth elements Ce and Sm, the alloy has a good modification effect, small grain size, and obvious spheroidization of the iron-rich phase in the matrix, and there are no obvious needle-shaped iron-rich phases, which will comprehensively improve the strength of the alloy and improve the plasticity at the same time.

[0076] Table 1 Atomic ratios of each element in the spherical phase

[0077]

[0078] Example 5

[0079] Corresponding to the above example, the difference between this example and Example 4 is that the addition ratios of each element are controlled as follows: Si: 8.31 wt%; Mg: 0.19 wt%; Mn: 0.58 wt%; Fe: 0.16 wt%; Sr: 0.019 wt%; Ti: 0.1 wt%; Ce: 0.02 wt%; Sm: 0.01 wt%, and the balance is Al. The proportions of each raw material component are configured according to the above element ratios, and the rest of the preparation process is the same as that in Example 4.

[0080] Example 6

[0081] Corresponding to the above embodiments, the difference between this embodiment and the fourth embodiment lies in that the addition ratios of the respective elements are controlled as follows: Si: 7.86 wt%; Mg: 0.19 wt%; Mn: 0.4 wt%; Fe: 0.22 wt%; Sr: 0.23 wt%; Ti: 0.13 wt%; Ce: 0.02 wt%; Sm: 0.01 wt%, and the balance is Al. The ratios of the respective raw material components are configured according to the above element ratios, and the remaining preparation processes are the same as those in the fourth embodiment.

[0082] Example 7

[0083] Corresponding to the above embodiments, the difference between this embodiment and the fourth embodiment lies in that the addition ratios of the respective elements are controlled as follows: Si: 7.94 wt%; Mg: 0.2 wt%; Mn: 0.37 wt%; Fe: 0.28 wt%; Sr: 0.21 wt%; Ti: 0.11 wt%; Ce: 0.02 wt%; Sm: 0.01 wt%, and the balance is Al. The ratios of the respective raw material components are configured according to the above element ratios, and the remaining preparation processes are the same as those in the fourth embodiment.

[0084] Example 8

[0085] Corresponding to the above embodiments, the difference between this embodiment and the fourth embodiment lies in that the addition ratios of the respective elements are controlled as follows: Si: 8.06 wt%; Mg: 0.21 wt%; Mn: 0.29 wt%; Fe: 0.42 wt%; Sr: 0.22 wt%; Ti: 0.12 wt%; Ce: 0.02 wt%; Sm: 0.01 wt%, and the balance is Al. The ratios of the respective raw material components are configured according to the above element ratios, and the remaining preparation processes are the same as those in the fourth embodiment.

[0086] Example 9

[0087] Corresponding to the above embodiments, the difference between this embodiment and the eighth embodiment lies in that the addition ratios of the respective elements are controlled as follows: Zn: 0.52 wt%; Cu: 0.14 wt%. The ratios of the respective raw material components are configured according to the above element ratios, and the remaining preparation processes are the same as those in the eighth embodiment.

[0088] The die-casting aluminum alloys prepared in Examples 4 to 9 above, with other components and their contents shown in Table 1 (the balance is aluminum and unavoidable impurities, not shown); vacuum high-pressure casting was carried out using a LK IMPRESS-Ⅲ DCC500 die-casting machine, with a casting pressure of 1000 bar, a slow injection speed of 0.2 m / s; a fast injection speed of 5 m / s; the mold temperature and the barrel temperature were 180 °C; the mold used was a flat mold with a length of 200 mm and a width of 65 mm, and the wall thickness was 3 mm; the vacuum machine used was an Aijiaya HG600 vacuum machine, and the cavity vacuum was <50 mbar. The prepared aluminum alloy was subjected to vacuum die-casting, and mechanical property tests were carried out on 3-mm die-casting specimens, including tensile strength, yield strength, elongation after fracture, and standard deviation. The results are shown in Table 2.

[0089] Table 2 Mechanical test results of aluminum alloy materials in each example

[0090]

[0091] Note: The "standard deviation" data of the standard is obtained from the statistics of 30 groups of elongation after fracture data

[0092] From the test results of the aluminum alloys in the above examples, it can be seen that by changing the contents of each component, the prepared aluminum alloy specimens can meet the production requirements of automotive structural parts with a tensile strength ≥ 260 Mpa, a yield strength ≥ 110 Mpa, and an elongation ≥ 10% without heat treatment. This aluminum alloy material realizes that the aluminum alloy material can be used for the production of large-sized, structurally complex automotive large structural parts with high strength and toughness requirements and difficult heat treatment by controlling the iron-rich phase. Further controlling the purification, degassing, and composite modification and refinement processes in the material preparation process, so as to achieve excellent strength and toughness within the iron content control range of 0.05 - 0.45 wt%, which greatly broadens the selection range of recycled waste aluminum during actual production, not only can reduce carbon, but also can effectively reduce costs.

[0093] Comparative Example 1

[0094] The difference from Example 4 is only that the content of Mn is changed to 0.4 wt%, and the total mass percentage of Mn and Fe is 0.48 wt%. Other components and their contents are shown in Table 2 (the balance is aluminum and unavoidable impurities, not shown). The prepared aluminum alloy was subjected to vacuum die-casting using the same process as in Example 4, and mechanical property tests were carried out on the specimens. The results are shown in Table 2.

[0095] Comparative Example 2

[0096] The difference from Example 7 is only that Ce and Sm are not added. The other components and their contents are shown in Table 2 (the balance is aluminum and inevitable impurities, not shown). The obtained aluminum alloy is subjected to vacuum die-casting using the same process as in Example 7, and the mechanical properties of the test pieces are tested. The results are shown in Table 2.

[0097] Comparative Example 3

[0098] The difference from Example 7 is only that the addition ratios of Ce and Sm are different, and the Ce / Sm content ratio is 0.5. The other components and their contents are shown in Table 2 (the balance is aluminum and inevitable impurities, not shown). The obtained aluminum alloy is subjected to vacuum die-casting using the same process as in Example 7, and the mechanical properties of the test pieces are tested. The results are shown in Table 2.

[0099] Comparative Example 4

[0100] The difference from Example 8 is only that the content of Mn is changed to 0.5 wt%, and the total mass percentage of Mn and Fe is 0.92 wt%. The other components and their contents are shown in Table 2 (the balance is aluminum and inevitable impurities, not shown). The obtained aluminum alloy is subjected to vacuum die-casting using the same process as in Example 4, and the mechanical properties of the test bars are tested. The results are shown in Table 2.

[0101] Comparative Example 5

[0102] The difference from Example 8 is only that the AlSr10Ti5C combined refinement and modification agent is not added during the preparation of the high-strength and high-toughness die-cast aluminum alloy. The obtained aluminum alloy is subjected to vacuum die-casting using the same process as in Example 8, and the mechanical properties of the test bars are tested. The results are shown in Table 3.

[0103] Table 3 Test results of each comparative example

[0104]

[0105] Note: The standard "standard deviation" data is obtained from the statistics of 30 sets of elongation after fracture data

[0106] Combined with the test results in Table 3, it can be seen that, compared with Example 4, Comparative Example 1 has insufficient strength in terms of performance. Compared with Example 7, Comparative Example 2 has a decrease in the average value of the elongation after fracture, especially the data standard deviation of 30 groups of data of the elongation after fracture is significantly increased, which will cause a significant increase in the performance difference of different parts of large structural parts. Compared with Example 7, Comparative Example 3 has a decrease in the average value of the elongation after fracture, especially the data standard deviation of 30 groups of data of the elongation after fracture is significantly increased, which will cause a significant increase in the performance difference of different parts of large structural parts. Compared with Example 8, Comparative Example 4 has a decrease in the average value of the elongation after fracture, especially the data standard deviation of 30 groups of data of the elongation after fracture is significantly increased, which will cause a significant increase in the performance difference of different parts of large structural parts. The main difference in performance between Comparative Example 5 and Example 8 is that the data standard deviation of 30 groups of data of the elongation after fracture is significantly increased, which will cause a significant increase in the performance difference of different parts of large structural parts.

[0107] Although the preferred embodiments in the embodiments of the present application have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be construed to include the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present application.

[0108] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application also intends to include these modifications and variations.

Claims

1. An aluminum alloy material for a vehicle body, characterized in that: The aluminum alloy material includes the following elements in percentage by weight: Si: 7.5-9.5wt%, Mg: 0.12-0.3wt%, Mn: 0.25-0.75wt%, Fe: 0.08-0.45wt%, Ti: 0.05-0.2wt%, Sr: 0.015-0.03wt%, Ce: 0.01-0.03wt%, Sm: 0.005-0.015wt%, Zn: 0-0.6wt%, Cu: 0-0.2wt%, and the remaining components are Al and impurities, and the mass percentage of the impurities is: 0-0.15wt%; Among them, the ratio of the mass percentages of Ce and Sm is 1.8~2.2, the sum of the mass percentages of Mn and Fe is 0.6~0.75wt%, and the iron-rich phase in the aluminum alloy material is controlled by controlling the mass sum of Mn and Fe and the ratio of Ce and Sm.

2. The aluminum alloy material for vehicle body according to claim 1, characterized in that: The mass percentage of Si is 7.5-8.5wt%.

3. A method for preparing an aluminum alloy material for a vehicle body, characterized in that: The method is used to prepare the aluminum alloy material for a vehicle body according to any one of claims 1 or 2, and the method comprises: Melting aluminum ingots, industrial silicon, iron agent, aluminum-manganese master alloy, aluminum-titanium master alloy, aluminum-cerium master alloy and aluminum-samarium master alloy according to the mass percentage of the preset elements to form a first alloy liquid; Adding magnesium ingots and aluminum-strontium master alloys to the first alloy liquid according to the preset mass percentage of the elements, and melting and mixing to form a second alloy liquid; adding a modifier to the second alloy liquid according to a preset mass percentage of the elements, and melting and mixing to form a third alloy liquid; The third alloy liquid is degassed, deslagged and filtered to obtain an aluminum alloy material.

4. The method for preparing the aluminum alloy material for vehicle body according to claim 3, characterized in that: The melting temperature of the first alloy liquid is 760-770°C; the melting temperature of the second alloy liquid is 700-720°C; and the melting temperature of the third alloy liquid is 700-710°C.

5. The method for preparing the aluminum alloy material for vehicle body according to claim 3, characterized in that: The modifier is an Al-Sr-Ti-C combined refining modifier, and the mass percentage of the modifier is 0.1-0.3wt%.

6. The method for preparing the aluminum alloy material for vehicle body according to claim 3, characterized in that: The degassing is online degassing with inert gas, and the furnace temperature is set to 680-700°C when the inert gas is online degassing.

7. The method for preparing the aluminum alloy material for vehicle body according to claim 6, characterized in that: The inert gas flow rate is 15~25LPM; And / or, the inert gas outlet pressure is 0.4~0.6Mpa; And / or, the degassing time is greater than or equal to 40 minutes.

8. A vehicle, characterized in that: The vehicle body aluminum alloy material according to any one of claims 1 or 2 or the vehicle body material is prepared by the method for preparing the vehicle body aluminum alloy material according to any one of claims 3 to 7.

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