Aluminum alloy material for vehicle body and preparation method of aluminum alloy material

Abstract

The invention discloses an aluminum alloy material for a vehicle body and a preparation method of the aluminum alloy material, and relates to the technical field of aluminum alloys, and the aluminum alloy material comprises the following elements in percentage by mass: 7.5 to 9.5 wt% of Si, 0.12 to 0.3 wt% of Mg, 0.25 to 0.75 wt% of Mn, 0.08 to 0.45 wt% of Fe, 0.05 to 0.2 wt% of Ti, 0.015 to 0.03 wt% of Sr, 0.01 to 0.03 wt% of Ce, 0.005 to 0.015 wt% of Sm, 0 to 0.6 wt% of Zn, 0 to 0.2 wt% of Cu, and the balance of Al and impurities. According to the aluminum alloy material and the preparation method thereof, the strength and the toughness of the prepared aluminum alloy material both reach related standards through the matching effect of all proportional elements, meanwhile, effective control over an iron-rich phase can be achieved, and the prepared aluminum alloy material still has excellent strength and toughness under the condition that a higher proportion of regenerated materials is added.

Description

Technical Field

[0001] The present application relates to the technical field of aluminum alloys, and in particular to an aluminum alloy material for a vehicle body and a preparation method thereof. Background Art

[0002] Aluminum alloys for automobile bodies are used in the processing of castings. The main manufacturing processes of aluminum alloys in the automotive field are stamping, die casting and extrusion molding. Die casting is the main production method of aluminum alloy parts. Aluminum alloy die castings are used in the automotive field for about 80%, and extrusions and rolled parts account for about 10% each. Under the requirements of environmental protection and energy conservation, automobile manufacturing is constantly moving towards lightweight, which has promoted the application of low-density, high-strength aluminum and magnesium alloys in automotive parts.

[0003] In some related technologies, the aluminum alloy castings currently being prepared and used generally have the problem of high strength and low toughness, especially when the content of impurity iron elements is high, the above problems are more prominent, which makes it impossible to add a high proportion of recycled waste to the existing heat-treatment-free aluminum alloys, which is not conducive to energy saving 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, which increases 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 technology, the present application provides an aluminum alloy material for a car body and a preparation method thereof. By effectively controlling the iron-rich phase, the prepared aluminum alloy material still has excellent strength and toughness when a higher proportion of recycled materials is added, which not only achieves energy saving and carbon reduction, but also effectively reduces the cost of processing materials.

[0005] The specific technical solutions provided by the embodiments of this application are as follows: In a first aspect, an aluminum alloy material for a vehicle body is provided, wherein the aluminum alloy material comprises the following elements in percentage by mass: 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%.

[0006] In a specific embodiment, the sum of the mass percentages of Mn and Fe is 0.6-0.75wt%.

[0007] In a specific embodiment, the mass percentage ratio of Ce to Sm is 1.8-2.2.

[0008] In a specific embodiment, the mass percentage of Si is 7.5-8.5wt%.

[0009] Furthermore, the mass percentage of Si is 7.7-8.3wt%.

[0010] In a specific embodiment, the mass percentage of Mg is 0.16-0.24wt%.

[0011] In a specific embodiment, the mass percentage of Sr is 0.01-0.03wt%.

[0012] In a second aspect, a method for preparing an aluminum alloy material for a vehicle body is provided, wherein the method is used to prepare the aluminum alloy material for a vehicle body as described above, 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.

[0013] In a specific embodiment, 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.

[0014] In a specific embodiment, the modifier is an Al-Sr-Ti-C combined refining modifier, and the mass percentage of the modifier is 0.1-0.3wt%.

[0015] In a specific embodiment, the degassing is inert gas online degassing, and the furnace temperature is 680-700°C when the inert gas online degassing furnace is set.

[0016] In a specific embodiment, the inert gas flow rate is 15-25 LPM; 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.

[0017] In a specific embodiment, the rotation speed of the degasser for online inert gas degassing is 400-450 rpm.

[0018] In a specific embodiment, a refining agent is used for purification 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.

[0019] In a third aspect, a vehicle is provided, comprising the aluminum alloy material for a vehicle body as described above, or the vehicle body material is prepared by the method for preparing the aluminum alloy material for a vehicle body as described above.

[0020] The embodiments of the present application have the following beneficial effects: 1. The embodiment of the present application achieves the strength and toughness of the prepared aluminum alloy material to meet the relevant standards through the coordinated effect of elements in various proportions. At the same time, the primary iron-rich phase is effectively modified through the joint addition of micro-alloying elements Ce and Sm, thereby achieving effective control of the iron-rich phase, minimizing the influence of the iron-rich phase on the toughness of the alloy. Even when a higher proportion of recycled aluminum is added, the alloy still has excellent strength and toughness, which can not only reduce carbon but also effectively reduce material costs.

[0021] 2. This application does not use the traditional aluminum-titanium-boron grain refiner. Instead, the material is modified with traditional aluminum strontium and then a modifier is added. The addition of the modifier further strengthens the modification while effectively refining the grains, so that the aluminum alloy material prepared in this application can be used in large-size, complex-structured, and high-toughness automotive structural parts.

[0022] 3. In terms of purification treatment, the present invention ensures that the aluminum liquid has a high purity by efficiently removing non-metallic inclusions, oxides and gas in the aluminum liquid, thereby avoiding the production of defective products in the later stage due to poor purification effect of the gas content in the aluminum liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 A schematic diagram showing a method for preparing an aluminum alloy material for a vehicle body according to the present application is shown; Figure 2 A schematic diagram of a sample prepared by a flat plate mold according to the present application is shown; Figure 3 The metallographic microstructure diagram of the flat plate sample according to the present application is shown; Figure 4A schematic diagram of a scanning electron microscope of a flat plate sample according to the present application is shown; Figure 5 A schematic diagram showing the results of EDS spectrum analysis of a spherical phase according to the present application is shown; Figure 6 A schematic diagram showing the content of each element in the EDS spectrum analysis results of the spherical phase according to the present application is shown. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments 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.

[0027] Embodiment 1 A vehicle body aluminum alloy material, comprising the following elements in percentage by mass: 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%.

[0028] In a specific embodiment, the mass percentage of Si is 7.5-8.5wt%. Further, the mass percentage of Si is 7.7-8.3wt%. In this embodiment, the Si element is the first main alloying element of the aluminum alloy material in the embodiment of the present application. The presence of Si ensures that the aluminum alloy material has good filling capacity and high toughness. When the silicon content is lower than 7.5wt%, the alloy strength does not reach the peak area, and the alloy casting performance deviation; when the silicon content is higher than 9.5wt%, the strength increase is limited and the toughness decreases faster. By controlling the amount of silicon added, the aluminum alloy material can be determined based on good filling capacity. Large structural parts can realize a variety of integrated die-casting processes.

[0029] In a specific embodiment, the mass percentage of Mg is 0.16-0.24wt%. The Mg element in this embodiment is the second main alloying element for preparing aluminum alloy materials, wherein magnesium combines with silicon to form a 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 the 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, so that the prepared aluminum alloy material takes into account the strength, toughness and thermal stability of the alloy.

[0030] Furthermore, the sum of the mass percentages of Mn and Fe is 0.6-0.75 wt%. Mn is the third main alloying element for preparing the aluminum alloy material in this embodiment. By adding manganese, impurity iron can be dissolved, the harmful effects of iron can be reduced, sticking to the mold can be prevented, and the life of the mold can be improved; and as a strengthening element, it forms a Mn-Al6 phase with aluminum, and the addition of manganese has the effect of improving the corrosion resistance of the alloy.

[0031] Furthermore, the mass percentage ratio of Ce to Sm is 1.8-2.2.

[0032] The present embodiment also includes Fe element, which is a non-main alloying element for preparing the aluminum alloy material in the present embodiment. By controlling its mass percentage to 0.08-0.45wt%, the prepared aluminum alloy material does not stick to the mold, thereby improving the mold life; at the same time, the Fe content range directly determines the actual production of aluminum alloy ingots, and by controlling the selection of recycled aluminum, the final material cost and carbon reduction ratio are directly determined. Considering that the Fe-containing phase has a greater negative impact on the toughness of the alloy, the present embodiment reduces the negative impact of the iron-rich phase on the toughness of the alloy, that is, by controlling the mass sum of Mn and Fe, and the ratio of Ce to Sm, and further controlling the sum of the mass percentages of Mn and Fe to be in the range of 0.6-0.75wt%, so as to achieve control of the iron-rich phase in the aluminum alloy material.

[0033] In a specific embodiment, Sr is a microalloying element in the high-strength and toughness die-casting aluminum alloy of the present invention, and the content is controlled to be 0.01-0.03wt%. The main function 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, the Fe-containing phase has a good modification effect. In the preparation process of the high-strength and toughness die-casting aluminum alloy, the first addition is added in the form of AlSr10 master alloy, and the second addition is added in the form of a modifier. The total content range is controlled to be 0.01-0.03wt%.

[0034] Furthermore, the aluminum alloy material in this embodiment also includes Zn element, which 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 0.6wt%. By controlling the zinc element within the above range, it can be achieved that the Zn element has no significant effect on the strength and toughness of the alloy; at the same time, in 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.

[0035] In this embodiment, Cu element is also added. As an impurity element in the aluminum alloy manufacturing process, the mass percentage of Cu element is controlled to be less than or equal to 0.2wt%. By controlling the copper element within the above mass percentage range, Cu can strengthen the aluminum alloy material without significantly increasing the toughness of the material. By controlling the increase in copper content, the strength of the aluminum alloy material can be improved, and the selection range of recycled aluminum can be expanded in the process of manufacturing the aluminum alloy material, which is conducive to reducing material costs.

[0036] In this embodiment, in the manufacture of high-strength and toughness aluminum alloy materials, the primary iron-rich phase is effectively modified by the combined addition of microalloying elements Ce and Sm. When the rare earth elements Ce and Sm are added together and the Ce / Sm ratio is controlled to be 1.8-2.2, the primary iron-rich phase can be effectively modified, thereby minimizing the influence of the iron-rich phase on the toughness of the alloy.

[0037] Embodiment 2 Corresponding to the above embodiment, the present application provides a method for preparing an aluminum alloy material for a vehicle body, wherein the method is used to prepare the aluminum alloy material for a vehicle body as described above, such as Figure 1 As shown, the method includes: 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 percentage of preset elements to form a first alloy liquid.

[0038] Step 102: adding magnesium ingot and aluminum-strontium master alloy into the first alloy liquid according to the preset mass percentage of the elements, and melting and mixing to form a second alloy liquid.

[0039] Step 103: 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.

[0040] In a specific embodiment, the raw materials of this embodiment, aluminum ingots, industrial silicon, iron agent, aluminum-manganese master alloy, aluminum-titanium master alloy, aluminum-cerium master alloy, aluminum-samarium master alloy, magnesium ingot, aluminum-strontium master alloy and modifier, are added according to the following mass percentages of elements, including 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%.

[0041] In a specific embodiment, the raw material selection configuration in this embodiment is aluminum ingot for remelting, industrial silicon, pure magnesium ingot, 80% iron agent, AlMn10 master alloy, AlSr10 master alloy, AlTi10 master alloy, AlCe10 master alloy, AlSm10 master alloy and Al-Sr-Ti-C combined refining modifier.

[0042] Furthermore, when the aluminum ingot, industrial silicon, 80% iron agent, AlMn10 master alloy, AlTi10 master alloy, AlCe10 master alloy and AlSm10 master alloy are put into remelting, the furnace temperature is set to 760-770° C. to fully melt the above raw materials to obtain the first alloy liquid.

[0043] In a specific embodiment, when preparing the second alloy liquid, the temperature of the aluminum liquid is controlled to be heated to 700-720° C.; and when preparing the third alloy liquid, the temperature of the aluminum liquid is controlled to be heated to 700-710° C. to melt the raw materials.

[0044] It should be noted that the modifier in this embodiment is AlSr10Ti5C combined refining modifier, and the mass percentage of the modifier is 0.1-0.3wt%.

[0045] Step 104: degas, remove slag, and filter the third alloy liquid to obtain an aluminum alloy material.

[0046] Furthermore, the degassing inert gas is degassing online, and the furnace temperature is set to 680-700° C. The inert gas in this embodiment includes but is not limited to one or more of nitrogen, helium, neon, argon, krypton and xenon.

[0047] In a specific embodiment, the degasser rotation speed of the online degassing is 400-450 rpm, the inert gas flow rate is 15-25 LPM; the inert gas outlet pressure is 0.4-0.6 MPa, and the degassing time is greater than or equal to 40 min.

[0048] Specifically, a refining agent is used for purification 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.

[0049] In this embodiment, when selecting raw materials, the high-strength and toughness heat-free aluminum alloy of the present invention has a higher upper limit of Fe, Zn, and Cu elements compared with Alcoa C611 and other heat-free alloys. Therefore, in terms of raw material selection, a higher proportion of recycled aluminum can be selected; compared with existing alloy materials, no more expensive alloying elements such as Mo, V, and Zr are added. Compared with other heat-free aluminum alloys, the high-strength and toughness heat-free aluminum alloy of the present invention has obvious cost advantages and carbon reduction advantages while ensuring performance.

[0050] At the same time, in view of the high requirements of large structural parts for material toughness and the characteristics of aluminum-silicon cast aluminum alloys, the traditional aluminum-titanium-boron grain refiner is not used. Instead, the material is modified with traditional aluminum-strontium and then AlSr10Ti5C combined with a refinement modifier is added. By adding a modifier, the grains can be effectively refined while further strengthening the modification. In addition, the present invention ensures that the aluminum liquid has a high purity by efficiently removing non-metallic inclusions, oxides and gas in the alloy liquid, avoiding the generation of defective products in the later stage due to poor purification effect of the gas content in the aluminum liquid.

[0051] Embodiment 3 Corresponding to the above embodiment, this embodiment provides a vehicle, wherein the vehicle includes the aluminum alloy material for a vehicle body as described above, or the vehicle body material in the vehicle is prepared by the method for preparing the aluminum alloy material for a vehicle body as described above.

[0052] Embodiment 4 Corresponding to the above embodiment, the mass percentage of each element configured in this embodiment is Si: 8.12wt%; Mg: 0.19wt%; Mn: 0.62wt%; Fe: 0.09wt%; Sr: 0.018wt%; Ti: 0.09wt%; Ce: 0.02wt%; Sm: 0.01wt%, and the balance is Al.

[0053] The mass proportions of the following raw materials are configured as follows: aluminum ingot Al99.70 for remelting, 84.3wt%; 3303 industrial silicon, 8.0wt%; pure magnesium ingot g99.95, 0.2wt%; AlMn10 master alloy, 6.0wt%; AlSr10 master alloy, 0.2wt%; AlTi10 master alloy, 1.0wt%; AlCe10 master alloy, 0.2% wt%; AlSm10 master alloy, 0.1% wt%.

[0054] The specific preparation process includes: preparing raw materials according to the above proportions, remelting aluminum ingots 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℃ and heating until fully melted to obtain the first alloy liquid. The aluminum liquid temperature is controlled at 720℃, and pure magnesium ingots and AlSr10 master alloy are added to the first alloy liquid in proportion to obtain the second alloy liquid. The aluminum liquid temperature is controlled at 710℃, and 0.1~0.3wt% of AlSr10Ti5C combined refining modifier is added to obtain the third alloy liquid. The third alloy liquid is degassed and deslaged online, and filtered to obtain a high-strength and tough aluminum alloy melt that can be used for die casting. The actual process parameters are: the furnace temperature is controlled at 700°C, and 3wt‰ refining agent is added for purification treatment, wherein 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 in the inert gas online degassing is selected as argon, wherein the argon outlet pressure is 0.5Mpa, and the degassing time is 40min; the degasser speed of the inert gas online degassing is 450rpm, and the argon flow rate is 20LPM.

[0055] The high-strength and tough die-casting melt material is added to the aluminum melting furnace of the die-casting machine, the aluminum liquid temperature is controlled at 700-710°C, argon gas is introduced and the melt is continuously stirred for 30 minutes to further remove the gas in the melt; after slagging, it is allowed to stand for 10 minutes, and the aluminum liquid temperature is controlled at 705°C to obtain an aluminum alloy material.

[0056] Vacuum high pressure casting was performed using a LK IMPRESS-Ⅲ DCC500 die casting machine with a casting pressure of 1000 bar, a slow shot speed of 0.2 m / s, a fast shot speed of 5 m / s, a mold temperature and a barrel temperature of 180 °C, and a flat mold with a length of 200 mm and a width of 65 mm and a wall thickness of 3 mm. The samples prepared with the corresponding flat mold are shown in Figure 2 The vacuum machine used is the Aigaia HG600 vacuum machine, and the cavity vacuum degree is <50mbar.

[0057] The metallographic microstructure of the flat sample is shown in Figure 3 The microstructure is mainly composed of α-Al and Al-Si binary eutectic structures. The alloy eutectic silicon modification effect is good, the modification grade is better than grade 2, and the average grain size is about 10μm. At the same time, there is no obvious large-sized needle-shaped iron-rich phase in the matrix. The scanning electron microscope photo of the flat sample is shown in Figure 4 The matrix is ​​distributed with spherical phases, and there is no obvious needle-shaped iron-rich phase. The EDS spectrum analysis results of the spherical phase are shown in Figure 5 and Figure 6 , showing that the spherical phase elements are Al, Mn, Si and Fe, and the atomic ratio of each element is shown in Table 1; it can be seen that it is also an iron-rich phase, but compared with the traditional needle-shaped iron-rich phase, the Fe content is significantly lower. In general, due to the use of AlSr10 and AlSr10Ti5C combined refinement modifiers, combined with the rare earth elements Ce and Sm composite addition, the alloy modification effect is better, the grain size is small, and the iron-rich phase in the matrix is ​​obviously spheroidized, and there is no obvious needle-shaped iron-rich phase, which will comprehensively improve the strength of the alloy while improving plasticity.

[0058] Table 1 Atomic ratios of spherical phase elements

[0059] Embodiment 5 Corresponding to the above embodiment, the difference between this embodiment and the fourth embodiment is that the addition ratio of each element is controlled to be Si: 8.31wt%; Mg: 0.19wt%; Mn: 0.58wt%; Fe: 0.16wt%; Sr: 0.019wt%; Ti: 0.1wt%; Ce: 0.02wt%; Sm: 0.01wt%, and the balance is Al. The ratio of each raw material component is configured by the above element ratio, and the rest of the preparation process is the same as in the fourth embodiment.

[0060] Embodiment 6 Corresponding to the above embodiment, the difference between this embodiment and the fourth embodiment is that the addition ratio of each element is controlled to be Si: 7.86wt%; Mg: 0.19wt%; Mn: 0.4wt%; Fe: 0.22wt%; Sr: 0.23wt%; Ti: 0.13wt%; Ce: 0.02wt%; Sm: 0.01wt%, and the balance is Al. The ratio of each raw material component is configured by the above element ratio, and the rest of the preparation process is the same as in the fourth embodiment.

[0061] Embodiment 7 Corresponding to the above embodiment, the difference between this embodiment and the fourth embodiment is that the addition ratio of each element is controlled to be Si: 7.94wt%; Mg: 0.2wt%; Mn: 0.37wt%; Fe: 0.28wt%; Sr: 0.21wt%; Ti: 0.11wt%; Ce: 0.02wt%; Sm: 0.01wt%, and the balance is Al. The ratio of each raw material component is configured by the above element ratio, and the rest of the preparation process is the same as in the fourth embodiment.

[0062] Embodiment 8 Corresponding to the above embodiment, the difference between this embodiment and the fourth embodiment is that the addition ratio of each element is controlled to be Si: 8.06wt%; Mg: 0.21wt%; Mn: 0.29wt%; Fe: 0.42wt%; Sr: 0.22wt%; Ti: 0.12wt%; Ce: 0.02wt%; Sm: 0.01wt%, and the balance is Al. The ratio of each raw material component is configured by the above element ratio, and the rest of the preparation process is the same as in the fourth embodiment.

[0063] Embodiment 9 Corresponding to the above embodiment, the difference between this embodiment and the eighth embodiment is that the addition ratio of each element is controlled to be Zn: 0.52wt%; Cu: 0.14wt%. The ratio of each raw material component is configured by the above element ratio, and the rest of the preparation process is the same as that in the eighth embodiment.

[0064] The die-cast aluminum alloy prepared in the above-mentioned embodiments 4 to 9, other components and contents are shown in Table 1 (the balance is aluminum and unavoidable impurities, not shown); vacuum high-pressure casting is performed using a LJ IMPRESS-Ⅲ DCC500 die-casting machine, the casting pressure is 1000 bar, the slow injection speed is 0.2 m / s; the fast injection speed is 5 m / s; the mold temperature and the barrel temperature are 180°C; the mold used is a flat mold with a length of 200 mm and a width of 65 mm, and a wall thickness of 3 mm; the vacuum machine used is an Aigaia HG600 vacuum machine, and the cavity vacuum degree is <50 mbar. The obtained aluminum alloy is vacuum die-cast, and the mechanical properties of the 3 mm die-cast test piece are tested, including tensile strength, yield strength, elongation after fracture and standard deviation. The results are shown in Table 2.

[0065] Table 2 Mechanical test results of aluminum alloy materials in various examples

[0066] Note: The standard "standard deviation" data is obtained by statistical analysis of 30 sets of elongation data. It can be seen from the test results of the aluminum alloy in the above embodiment that the content of each component is changed, and the prepared aluminum alloy test piece can meet the production requirements of automobile structural parts with tensile strength ≥260Mpa, yield strength ≥110Mpa, and elongation ≥10% without heat treatment. The aluminum alloy material can be used for the production of large-sized, complex-structured, high-toughness, and difficult-to-heat-treat large-scale automotive structural parts by controlling the iron-rich phase. The material preparation process further controls the purification, degassing, and composite metamorphism and refinement process, thereby achieving excellent toughness in the iron content control range of 0.05-0.45wt%, so that in actual production, the selection range of recycled scrap aluminum is greatly relaxed, which can not only reduce carbon but also effectively reduce costs.

[0067] Comparative Example 1 The only difference from Example 4 is that the Mn content is changed to 0.4wt%, the total mass percentage of Mn and Fe is 0.48wt%, and the other components and contents are shown in Table 2 (the balance is aluminum and inevitable impurities, not shown). The obtained aluminum alloy is vacuum die-casted using the same process as Example 4, and the test piece is tested for mechanical properties. The results are shown in Table 2.

[0068] Comparative Example 2 The only difference from Example 7 is 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 vacuum die-casted using the same process as Example 7, and the test pieces are tested for mechanical properties. The results are shown in Table 2.

[0069] Comparative Example 3 The only difference from Example 7 is the addition ratio of Ce and Sm. The Ce / Sm content ratio is 0.5. The other components and contents are shown in Table 2 (the balance is aluminum and inevitable impurities, not shown). The obtained aluminum alloy is vacuum die-casted using the same process as Example 7, and the test piece is subjected to mechanical property testing. The results are shown in Table 2.

[0070] Comparative Example 4 The only difference from Example 8 is that the Mn content is changed to 0.5wt%, the total mass percentage of Mn and Fe is 0.92wt%, and 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 vacuum die-casted using the same process as Example 4, and the test rod is subjected to mechanical property testing, and the results are shown in Table 2.

[0071] Comparative Example 5 The only difference from Example 8 is that no AlSr10Ti5C joint refining modifier is added during the preparation of the high-strength and toughness die-casting aluminum alloy. The obtained aluminum alloy is vacuum die-casted using the same process as Example 8, and the mechanical properties of the test bars are tested. The results are shown in Table 3.

[0072] Table 3 Test results of each group of comparative examples

[0073] Note: The standard "standard deviation" data is obtained by statistical analysis of 30 sets of elongation data. Combined with the test results in Table 3, it can be seen that the performance of Comparative Example 1 is insufficient in strength compared with that of Example 4. The performance of Comparative Example 2 is lower than that of Example 7 in that the mean value of elongation after fracture is reduced, especially the data standard deviation of 30 groups of data of elongation after fracture is significantly increased, which will cause a significant increase in the performance differences between different parts of large structural parts. The performance of Comparative Example 3 is lower than that of Example 7 in that the mean value of elongation after fracture is reduced, especially the data standard deviation of 30 groups of data of elongation after fracture is significantly increased, which will cause a significant increase in the performance differences between different parts of large structural parts. The performance of Comparative Example 4 is lower than that of Example 8 in that the mean value of elongation after fracture is reduced, especially the data standard deviation of 30 groups of data of elongation after fracture is significantly increased, which will cause a significant increase in the performance differences between different parts of large structural parts. The main difference between the performance of Comparative Example 5 and Example 8 is that the data standard deviation of 30 groups of data of elongation after fracture is significantly increased, which will cause a significant increase in the performance differences between different parts of large structural parts.

[0074] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the embodiments of the present application.

[0075] 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 equivalents, the present application is also intended 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 mass: 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%.

2. The aluminum alloy material for vehicle body according to claim 1, characterized in that: The mass percentage ratio of Ce to Sm is 1.8-2.

2.

3. The aluminum alloy material for vehicle body according to claim 1 or 2, characterized in that: The sum of the mass percentages of Mn and Fe is 0.6-0.75wt%.

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

5. 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 to 4, 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.

6. The method for preparing the aluminum alloy material for vehicle body according to claim 5, 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.

7. The method for preparing an aluminum alloy material for a vehicle body according to claim 5, 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%.

8. The method for preparing the aluminum alloy material for vehicle body according to claim 5, 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.

9. The method for preparing the aluminum alloy material for vehicle body according to claim 8, 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.

10. A vehicle, characterized in that: The vehicle body aluminum alloy material according to any one of claims 1 to 4 or the vehicle body material is prepared by the method for preparing the vehicle body aluminum alloy material according to any one of claims 5 to 9.

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