Aluminum alloy and preparation method therefor, and aluminum alloy die casting

Abstract

The present application relates to the technical field of aluminum alloys and provides an aluminum alloy and a preparation method therefor, and an aluminum alloy die casting. On the basis of 100% of the total mass of the aluminum alloy, the aluminum alloy comprises the following components: 6.5-8.5% of Si; less than or equal to 0.3% of Fe; less than or equal to 0.3% of Cu; less than or equal to 0.5% of Mn; less than or equal to 0.5% of Mg; less than or equal to 0.2% of Cr; 0.002-0.02% of V; 10-100 ppm of Nb; 0.01-0.03% of Sr; 10-100 ppm of a rare earth element, wherein the rare earth element is La and / or Ce; and the balance of Al and inevitable impurities. By means of the design of the alloy components of the aluminum alloy material, particularly by means of the addition of appropriate amounts of the element V, the rare earth element La and / or Ce and element Nb, the obtained aluminum alloy has relatively high strength and excellent ductility, toughness, corrosion resistance, and flow formability, and no heat treatment is required during subsequent preparation of the aluminum alloy die casting.

Description

Aluminum alloy, preparation method thereof, and aluminum alloy die casting

[0001] This application claims priority to the Chinese patent application filed with the Patent Office of China on March 21, 2024, with application number 202410324467.5 and application name “An aluminum alloy, its preparation method and aluminum alloy die casting”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application belongs to the technical field of aluminum alloys, and specifically relates to an aluminum alloy, a preparation method thereof, and an aluminum alloy die-casting. Background Art

[0003] With the rapid development of new energy vehicles and the increasing demand for lightweighting, large, integrated thin-walled structural parts (such as shock towers, rear bodies, longitudinal beams, and front cabins) have seen rapid development. Currently, aluminum alloy die-castings, made from die-cast aluminum alloys, are commonly used for thin-walled structural parts in vehicles.

[0004] However, traditional Al□Si-based die-cast aluminum alloys only have moderate strength and low plastic toughness, making it difficult to meet the needs of thin-walled vehicle structural parts. Therefore, in order to improve the mechanical properties of cast aluminum alloys, the processing technology of traditional aluminum alloy die-castings usually includes heat treatment (solid solution + aging), but this not only increases the complexity of the process and consumes a lot of energy, but also causes deformation of the aluminum alloy castings due to the heating and cooling effects, affecting the assembly accuracy and even causing the aluminum alloy castings to be scrapped. In addition, in order to facilitate demolding of aluminum alloy die-castings during production, a certain amount of Fe is added to the die-cast aluminum alloy, but the addition of Fe elements will lead to a decrease in the plastic toughness, corrosion resistance and flow formability of the die-cast aluminum alloy. The above factors jointly restrict the further application of die-cast aluminum alloys and aluminum alloy die-castings.

[0005] Therefore, it is urgently necessary to develop an aluminum alloy, its preparation method and aluminum alloy die-castings by optimizing the alloy material composition. The aluminum alloy has high strength and excellent plasticity, toughness, corrosion resistance, and flow formability, and does not require heat treatment. It has good mechanical properties in the cast state, so that the aluminum alloy die-castings made of the aluminum alloy can fully meet the needs of thin-walled structural parts of vehicles. Summary of the Invention

[0006] The present application aims to address, at least to some extent, one of the technical problems in the prior art. To this end, the embodiments of the present application provide an aluminum alloy, a preparation method thereof, and an aluminum alloy die-casting. This aluminum alloy exhibits high strength, excellent plasticity, toughness, corrosion resistance, and flowability, and does not require heat treatment, exhibiting good mechanical properties in the as-cast state. This supports the application of large, integrated aluminum alloy die-castings.

[0007] An embodiment of the present application provides an aluminum alloy, which, based on the total mass of the aluminum alloy as 100%, includes the following components: Si content is 6.5-8.5%; Fe content is ≤0.3%; Cu content is ≤0.3%; Mn content is ≤0.5%; Mg content is ≤0.5%; Cr content is ≤0.2%; V content is 0.002-0.02%; Nb content is 10-100 ppm; Sr content is 0.01-0.03%; rare earth element content is 10-100 ppm, and the rare earth element is La and / or Ce; the balance is Al and unavoidable impurities.

[0008] The advantages and technical effects brought by the aluminum alloy of the embodiment of the present application are:

[0009] (1) An appropriate amount of V element is added to the aluminum alloy of the embodiment of the present application, which, on the one hand, plays a role in grain refinement strengthening, and on the other hand, precipitates fine AlV phase in the aluminum matrix, which plays a role in precipitation strengthening. The two together improve the strength and toughness of the aluminum alloy; in addition, the added V element combines with the Fe element to form an AlSiVFe phase, which consumes a part of the impurity Fe element, reduces the negative effect of the Fe element, and thereby improves the toughness, corrosion resistance and flow formability of the aluminum alloy.

[0010] (2) The aluminum alloy of the embodiment of the present application is added with an appropriate amount of rare earth elements La and / or Ce, which form intermetallic compounds with aluminum and other alloying elements to improve the strength and toughness of the material; in addition, the added rare earth elements La and / or Ce serve as surface active elements, which reduce the surface tension of the alloy melt and are beneficial to improving the flow formability of the material.

[0011] (3) An appropriate amount of Nb element is added to the aluminum alloy in the embodiment of the present application, which can refine the metal structure of the Al-Si alloy and improve the strength and toughness of the material.

[0012] (4) In summary, by designing the alloy composition of the aluminum alloy material, especially adding an appropriate amount of V element, rare earth element La and / or Ce and Nb element, the aluminum alloy of the embodiment of the present application has higher strength and excellent plasticity, toughness, corrosion resistance and flow formability compared to the traditional Al-Si die-casting aluminum alloy, which meets the needs of thin-walled structural parts of vehicles; in addition, the aluminum alloy of the embodiment of the present application does not need to be heat treated subsequently, which can effectively simplify the processing technology of aluminum alloy die-casting parts, avoid deformation, and improve the qualified rate of aluminum alloy die-casting parts.

[0013] In some embodiments, the Si content is 6.5-7.5%; and / or the Fe content is ≤0.15%; and / or the Cu content is 0.001-0.3%; and / or the Mn content is 0.3-0.5%; and / or the Mg content is 0.1-0.5%; and / or the Cr content is 0.1-0.2%; and / or the V content is 0.005-0.02%; and / or the Nb content is 30-80 ppm; and / or the Sr content is 0.02-0.03%; and / or the rare earth element content is 20-80 ppm.

[0014] In some embodiments, the content of V is 0.005-0.01%.

[0015] In some embodiments, the Nb content is 40-60 ppm.

[0016] In some embodiments, the content of rare earth elements is 20-50 ppm.

[0017] In addition, the present invention also provides a method for preparing an aluminum alloy, comprising the following steps:

[0018] placing an aluminum raw material in a smelting furnace to melt to obtain an aluminum melt, and then adding a Si raw material, a Cu raw material, a Mn raw material, a Cr raw material, a V raw material, and a rare earth raw material to the aluminum melt for a first smelting to obtain a first alloy melt;

[0019] Adding a slag remover to the first alloy melt to perform a first slag removal treatment, then adding a Mg raw material, a Cr raw material, a Nb raw material, and a Sr raw material to perform a second smelting, and then performing a first standing and then a second slag removal treatment to obtain a second alloy melt;

[0020] introducing an inert gas mixed with a refining agent into the second alloy melt for degassing and refining to obtain a third alloy melt;

[0021] The third alloy melt is tested for component content. If the test result is qualified, the third alloy melt is allowed to stand for a second time and then subjected to a third slag removal process to obtain a fourth alloy melt.

[0022] The fourth alloy melt is cast into a mold, and after the alloy melt is solidified and formed, an aluminum alloy ingot is obtained.

[0023] The advantages and technical effects brought by the preparation method of the aluminum alloy in the embodiment of the present application are as follows:

[0024] The aluminum alloy preparation method of the embodiment of the present application has excellent comprehensive performance of the obtained aluminum alloy, and the aluminum alloy die-casting can be produced without the need for a subsequent heat treatment process, which simplifies the processing technology of the aluminum alloy die-casting. It can also solve the problem of deformation of the aluminum alloy die-casting due to heat treatment, thereby improving the yield of the aluminum alloy die-casting.

[0025] In some embodiments, the V raw material is an Al-V master alloy, the Nb raw material is an Al-Nb-B refiner, and the rare earth raw material is an Al-rare earth master alloy.

[0026] In some embodiments, the temperature of the first smelting is above 760° C., and the time of the first smelting is not less than 20 minutes.

[0027] In some embodiments, the temperature of the first deslagging treatment is above 730° C., the temperature of the second smelting is above 720° C., and the time of the second smelting is no less than 10 minutes.

[0028] In some embodiments, the degassing and refining temperature is above 720° C., and the degassing and refining time is not less than 10 minutes.

[0029] In some embodiments, the casting temperature is 690-720°C.

[0030] In addition, an embodiment of the present application also provides an aluminum alloy die-casting, which is made of the aluminum alloy of the embodiment of the present application.

[0031] The advantages and technical effects brought by the aluminum alloy die casting of the embodiment of the present application are as follows:

[0032] Since the aluminum alloy of the embodiment of the present application is used, the aluminum alloy die-castings of the embodiment of the present application have high strength and excellent plasticity, toughness and corrosion resistance, which can meet the needs of automobile thin-walled structural parts such as shock towers, rear bodies, longitudinal beams and front cabins. In addition, the aluminum alloy die-castings of the embodiment of the present application can be obtained without heat treatment, which can effectively simplify the processing technology, avoid deformation, and improve the qualified rate of aluminum alloy die-castings.

[0033] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0035] FIG1 is a schematic flow chart of a method for preparing an aluminum alloy according to an embodiment of the present application. Specific embodiments

[0036] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, 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 part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0037] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present application, but should not be understood as limiting the present application.

[0038] An embodiment of the present application provides an aluminum alloy, which, based on the total mass of the aluminum alloy as 100%, includes the following components: Si content is 6.5-8.5%; Fe content is ≤0.3%; Cu content is ≤0.3%; Mn content is ≤0.5%; Mg content is ≤0.5%; Cr content is ≤0.2%; V content is 0.002-0.02%; Nb content is 10-100 ppm; Sr content is 0.01-0.03%; rare earth element content is 10-100 ppm, and the rare earth element is La and / or Ce; the balance is Al and unavoidable impurities.

[0039] The embodiment of the present application optimizes the design of the aluminum alloy composition, especially by adding appropriate amounts of V elements, rare earth elements (La and / or Ce) and Nb elements, to obtain an aluminum alloy with excellent comprehensive performance such as strength (tensile strength above 240 MPa, yield strength above 120 MPa), plasticity and toughness (elongation above 10%, bending angle above 30°), and corrosion resistance (corrosion pit depth ≤150 μm after 240 hours of salt spray corrosion); in addition, the aluminum alloy in the embodiment of the present application does not need to be subsequently heat treated, which can effectively simplify the processing technology of aluminum alloy die-castings, avoid deformation, and improve the pass rate of aluminum alloy die-castings.

[0040] It should be noted that ppm is one part per million, that is, 1% = 10,000 ppm.

[0041] The content of Si element in the aluminum alloy of the embodiment of the present application is 6.5-8.5%, for example, 6.5%, 6.8%, 7%, 7.2%, 7.4%, 7.6%, 7.8%, 8%, 8.2%, 8.8%, etc. Si element is the main alloying element, and adding an appropriate amount of Si element can improve the strength and flow formability of the aluminum alloy. When the content of Si element is lower than 6.5%, the fluidity and die-casting performance of the aluminum alloy are poor. When the content of Si element is too high, the toughness of the aluminum alloy is reduced. Preferably, the content of Si element is 6.5-7.5%. When the content of Si element is too high, it is not conducive to improving the toughness of the aluminum alloy.

[0042] The content of Fe in the aluminum alloy of the embodiment of the present application is ≤0.3%, for example, 0%, 0.05%, 0.1%, 0.2%, 0.25%, 0.3%, etc. The Fe element is an impurity in the aluminum alloy of the embodiment of the present application, so the content of Fe in the aluminum alloy should be reduced as much as possible. When the content of Fe is higher than 0.3%, the plasticity, toughness, corrosion resistance, and flow formability of the aluminum alloy will decrease. Preferably, the content of Fe is ≤0.15%. When the content of Fe is too high, it is not conducive to improving the plasticity and toughness of the aluminum alloy.

[0043] The content of Cu in the aluminum alloy of the embodiment of the present application is ≤0.3%, for example, 0.001%, 0.005%, 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, etc. Cu is a strengthening element. Adding an appropriate amount of Cu can play the role of solid solution strengthening and precipitation strengthening, which can improve the strength of the aluminum alloy. When the content of Cu is higher than 0.3%, the corrosion resistance of the aluminum alloy decreases. Preferably, the content of Cu is 0.001 to 0.3%. When the content of Cu is too low, it is not conducive to improving the strength of the aluminum alloy.

[0044] The content of Mn in the aluminum alloy of the embodiments of the present application is ≤0.5%, for example, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, etc. Adding an appropriate amount of Mn facilitates demolding and subsequent die casting. When the Mn content exceeds 0.5%, the toughness of the aluminum alloy decreases. Preferably, the Mn content is 0.3-0.5%. When the Mn content is too low, it is not conducive to improving the die-casting performance of the aluminum alloy.

[0045] The Mg content in the aluminum alloy of the embodiments of the present application is ≤0.5%, for example, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, etc. Adding an appropriate amount of Mg can improve the strength of the aluminum alloy. When the Mg content is higher than 0.5%, the toughness of the aluminum alloy is poor. Preferably, the Mg content is 0.1-0.5%. When the Mg content is too low, it is not conducive to improving the strength of the aluminum alloy.

[0046] The Cr content in the aluminum alloy of the embodiment of the present application is ≤0.2%. Adding an appropriate amount of Cr can, on the one hand, refine the metal structure of the Al-Si alloy, thereby improving the toughness of the aluminum alloy, and on the other hand, facilitate demolding and subsequent die casting. When the Cr content is higher than 0.2%, the toughness of the aluminum alloy decreases. Preferably, the Cr content is 0.1-0.2%. When the Cr content is too low, it is not conducive to improving the toughness of the aluminum alloy.

[0047] The content of V in the aluminum alloy of the embodiments of the present application is 0.002% to 0.02%, such as 0.002%, 0.004%, 0.006%, 0.008%, 0.01%, 0.012%, 0.014%, 0.016%, 0.018%, 0.02%, etc. Adding an appropriate amount of V can, on the one hand, play a role in grain refinement strengthening, and on the other hand, precipitate fine AlV phases in the aluminum matrix, which can play a precipitation strengthening role. The above two effects together improve the strength and toughness of the aluminum alloy; in addition, the added V element can combine with the Fe element to form the AlSiVFe phase, consuming some of the impurity Fe element and reducing the negative effects of the Fe element, thereby improving the plasticity, toughness, corrosion resistance, and flow formability of the aluminum alloy. When the content of V is less than 0.002%, the strength, toughness, plasticity, corrosion resistance, and flow formability of the aluminum alloy are all poor. When the content of V element is higher than 0.02%, coarse compounds will be formed, resulting in poor strength of the aluminum alloy.

[0048] Preferably, the content of V is 0.005-0.02%. More preferably, the content of V is 0.005-0.01%. When the content of V is too low, it is not conducive to improving the toughness, plasticity, etc. of the aluminum alloy. When the content of V is too high, it is not conducive to maintaining a high strength of the aluminum alloy.

[0049] The content of Nb element in the aluminum alloy of the embodiment of the present application is 10 to 100 ppm, for example, 10 ppm, 20 ppm, 30 ppm, 40 ppm, 50 ppm, 60 ppm, 70 ppm, 80 ppm, 90 ppm, 100 ppm, etc. Adding an appropriate amount of Nb element can refine the metal structure of the Al-Si alloy, thereby improving the strength and toughness of the aluminum alloy. When the content of Nb element is lower than 10 ppm, the alloy coarsens and the strength and toughness of the aluminum alloy are poor. When the content of Nb element is higher than 100 ppm, Nb element agglomerates and fails to play a role in refining the structure, resulting in poor strength and toughness of the aluminum alloy. Preferably, the content of Nb element is 30 to 80 ppm; more preferably, the content of Nb element is 40 to 60 ppm. When the content of Nb element is too low or too high, it is not conducive to improving the strength and toughness of the aluminum alloy.

[0050] The content of Sr in the aluminum alloy of the embodiment of the present application is 0.01% to 0.03%, for example, 0.01%, 0.012%, 0.014%, 0.016%, 0.018%, 0.02%, 0.022%, 0.024%, 0.026%, 0.028%, 0.03%, etc. Adding an appropriate amount of Sr can refine the metal structure of the Al-Si alloy, thereby improving the strength and toughness of the aluminum alloy. When the content of Sr is less than 0.01%, the alloy structure coarsens, resulting in a decrease in the strength and toughness of the aluminum alloy. When the content of Sr is higher than 0.03%, the alloy melt easily absorbs H, which also causes an increase in the porosity content inside the aluminum alloy, resulting in a decrease in strength and toughness. Preferably, the content of Sr is 0.02% to 0.03%. When the content of Sr is too low, it is not conducive to improving the strength and toughness of the aluminum alloy.

[0051] The content of rare earth elements (La and / or Ce) in the aluminum alloy of the embodiment of the present application is 10-100ppm, for example, 10ppm, 20ppm, 30ppm, 40ppm, 50ppm, 60ppm, 70ppm, 80ppm, 90ppm, 100ppm, etc. Adding an appropriate amount of rare earth elements (La and / or Ce) can form intermetallic compounds with aluminum and other alloying elements, thereby improving the toughness of the aluminum alloy; in addition, the added rare earth elements (La and / or Ce) as surface active elements can also reduce the surface tension of the alloy melt, thereby improving the flow formability of the aluminum alloy. However, when rare earth elements other than La and / or Ce are used, the above effects cannot be achieved. When the content of rare earth elements (La and / or Ce) is less than 10ppm, the toughness and flow formability of the aluminum alloy are poor. When the content of rare earth elements (La and / or Ce) is higher than 100ppm, rare earth element agglomeration occurs, resulting in poor toughness of the aluminum alloy.

[0052] Preferably, the rare earth element content is 20 to 80 ppm. More preferably, the rare earth element content is 20 to 50 ppm. When the rare earth element content is too low, it is not conducive to improving the strength and toughness of the aluminum alloy. When the rare earth element content is too high, it is not conducive to improving the toughness of the aluminum alloy.

[0053] In the aluminum alloy of the embodiment of the present application, when the rare earth element is a mixture of La and Ce, the mass ratio of La to Ce can be set arbitrarily.

[0054] The inevitable impurities in the aluminum alloy of the embodiment of the present application are P, S, and O. The content of a single impurity is ≤0.05%, and the total content of impurities is ≤0.15%.

[0055] In addition, the present invention also provides a method for preparing an aluminum alloy, as shown in FIG1 , comprising the following steps:

[0056] S1. Melting an aluminum raw material in a smelting furnace to obtain an aluminum melt, and then adding a Si raw material, a Cu raw material, a Mn raw material, a Cr raw material, a V raw material, and a rare earth raw material to the aluminum melt for a first smelting to obtain a first alloy melt;

[0057] S2. Adding a slag remover to the first alloy melt to perform a first slag removal treatment, then adding a Mg raw material, a Nb raw material, and a Sr raw material to perform a second smelting, and then performing a first standing and then a second slag removal treatment to obtain a second alloy melt;

[0058] S3, introducing an inert gas mixed with a refining agent into the second alloy melt for degassing and refining to obtain a third alloy melt;

[0059] S4. Detecting the composition content of the third alloy melt. If the test result is qualified, the alloy melt is allowed to stand for a second time and then subjected to a third slag removal process to obtain a fourth alloy melt. If the test result is unqualified, the alloy melt needs to be re-adjusted in composition and subjected to slag removal process until the test result is qualified.

[0060] S5. Casting the fourth alloy melt into a mold, and after the alloy melt is solidified and formed, obtaining an aluminum alloy ingot.

[0061] The aluminum alloy preparation method of the embodiment of the present application has excellent comprehensive performance of the obtained aluminum alloy, and the aluminum alloy die-casting can be produced without the need for a subsequent heat treatment process, which simplifies the processing technology of the aluminum alloy die-casting. It can also solve the problem of deformation of the aluminum alloy die-casting due to heat treatment, thereby improving the yield of the aluminum alloy die-casting.

[0062] In the preparation method of the aluminum alloy of the embodiment of the present application, step S1 first adds various raw materials that are difficult to melt and not easy to burn, and then in step S2, various raw materials that are fusible and easy to burn are added after they are melted into the melt, which can effectively reduce the burning of the elements added in step S2.

[0063] In some embodiments, the V raw material is an Al-V master alloy, the Nb raw material is an Al-Nb-B refiner, and the rare earth raw material is an Al-rare earth master alloy. Adding these elements as single elements requires higher temperatures, which can easily cause burnout of other easily burnable elements. Therefore, these elements are preferably added as master alloys. Other elements can be added as single elements or as master alloys formed with Al.

[0064] Based on the feeding form of each raw material described above, in some embodiments, the temperature of the first smelting is above 760°C, and the time of the first smelting is not less than 20 minutes. When the temperature of the alloy melt is too low or the time is too short in this step, it is easy to cause incomplete melting of the added raw materials. Preferably, the temperature of the first smelting is 760-800°C, for example, 760°C, 770°C, 780°C, 790°C, 800°C, etc., and the time of the first smelting is 20-40 minutes, for example, 20 minutes, 30 minutes, 40 minutes, etc. When the temperature of the alloy melt is too high or the time is too long in this step, it is easy to cause burn damage to the added raw materials.

[0065] Based on the feeding method of the raw materials described above, in some embodiments, the temperature of the first deslagging treatment is above 730°C. If the temperature of the alloy melt is too low during this step, insufficient deslagging may occur. Preferably, the temperature of the first deslagging treatment is between 730°C and 750°C, for example, 730°C, 735°C, 740°C, 745°C, 750°C, etc. If the temperature of the alloy melt is too high during this step, the added elements may be burned.

[0066] Based on the feeding form of each raw material described above, in some embodiments, the temperature of the second smelting is above 720°C, and the time of the second smelting is not less than 10 minutes. When the temperature of the alloy melt in this step is too low or the time is too short, it is easy to cause incomplete melting of the added raw materials. Preferably, the temperature of the second smelting is 720-750°C, for example, 720°C, 725°C, 730°C, 735°C, 740°C, 745°C, 750°C, etc., and the time of the second smelting is 10-20 minutes, for example, 10 minutes, 15 minutes, 20 minutes, etc. When the temperature of the alloy melt in this step is too high or the time is too long, it is easy to cause burnout of the added elements.

[0067] The temperature of the second smelting is higher than the temperature of the first smelting, and the time of the second smelting is longer than the time of the first smelting because the raw materials added in step S1 are relatively difficult to melt, while the elements added in step S2 are relatively fusible and easy to burn.

[0068] In some embodiments, the degassing refining temperature is above 720°C, and the degassing refining time is not less than 10 minutes. When the alloy melt temperature is too low or the time is too short in this step, it is not conducive to sufficient degassing. Preferably, the degassing refining temperature is 720-730°C, for example, 720°C, 722°C, 724°C, 726°C, 728°C, 730°C, etc., and the degassing refining time is 10-20 minutes, for example, 10 minutes, 12 minutes, 14 minutes, 16 minutes, 18 minutes, 20 minutes, etc. When the alloy melt temperature is too high or the time is too long in this step, it is easy to cause burnout of various elements in the alloy melt.

[0069] In some embodiments, the first and second standing times are both 5 to 15 minutes, such as 5 minutes, 8 minutes, 10 minutes, 12 minutes, 14 minutes, 15 minutes, etc. The purpose of standing is to allow the slag in the alloy melt to float to the surface, which is beneficial to the purification of the alloy melt.

[0070] In some embodiments, the fourth alloy melt is poured into a mold at a casting temperature of 690°C to 720°C, for example, 690°C, 695°C, 700°C, 705°C, 710°C, 715°C, 720°C, etc. After the alloy melt solidifies and forms, an aluminum alloy ingot is obtained. If the casting temperature is too low, defects such as cold shut on the aluminum alloy surface may occur. If the casting temperature is too high, the hydrogen content in the aluminum alloy may increase and shrinkage may be severe.

[0071] In addition, an embodiment of the present application also provides an aluminum alloy die-casting, which is made of the aluminum alloy of the embodiment of the present application.

[0072] Since the aluminum alloy of the embodiment of the present application is used, the aluminum alloy die-castings of the embodiment of the present application have high strength and excellent plasticity, toughness and corrosion resistance, which can meet the needs of automobile thin-walled structural parts such as shock towers, rear bodies, longitudinal beams and front cabins. In addition, aluminum alloy die-castings with qualified performance can be obtained without subsequent heat treatment, which simplifies the processing technology of aluminum alloy die-castings, avoids deformation problems caused by heat treatment, and improves the yield of aluminum alloy die-castings.

[0073] In addition, an embodiment of the present application also provides a method for preparing an aluminum alloy die-casting, comprising the following steps: melting the aluminum alloy of the embodiment of the present application to obtain an aluminum alloy melt; and then die-casting and trimming the aluminum alloy melt to obtain an aluminum alloy die-casting.

[0074] Alternatively, the method for preparing the aluminum alloy die casting comprises the following steps:

[0075] S1. Melting an aluminum raw material in a smelting furnace to obtain an aluminum melt, and then adding a Si raw material, a Cu raw material, a Mn raw material, a Cr raw material, a V raw material, and a rare earth raw material to the aluminum melt for a first smelting to obtain a first alloy melt;

[0076] S2. Adding a slag remover to the first alloy melt to perform a first slag removal treatment, then adding a Mg raw material, a Nb raw material, and a Sr raw material to perform a second smelting, and then performing a first standing and then a second slag removal treatment to obtain a second alloy melt;

[0077] S3, introducing an inert gas mixed with a refining agent into the second alloy melt for degassing and refining to obtain a third alloy melt;

[0078] S4. Testing the composition content of the third alloy melt. If the test result is qualified, performing a second standing and then a third slag removal process to obtain a fourth alloy melt. If the test result is unqualified, re-adjusting the composition and performing slag removal process until the test result is qualified.

[0079] S5. Directly pouring the fourth alloy melt into a die-casting mold for die-casting, and then trimming the mold to obtain the aluminum alloy casting.

[0080] Both methods can produce aluminum alloy castings. The former is suitable for situations where the target casting shape is unknown, and aluminum alloy ingots are first cast to facilitate transportation. The latter is suitable for situations where the target casting shape is known. When the latter method is used to produce aluminum alloy castings, the specific conditions in steps S1-S5 can refer to the aluminum alloy preparation method.

[0081] The present application is described in detail below with reference to the embodiments and drawings.

[0082] Example 1

[0083] A die-cast aluminum alloy, comprising Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce having a mass ratio of 1:1), with the total mass of the die-cast aluminum alloy being 100%. The specific contents are shown in Table 1, and the remainder is Al and unavoidable impurities such as P, S, and O. The content of a single impurity is ≤0.05%, and the total impurity content is ≤0.15%.

[0084] The method for preparing the die-cast aluminum alloy comprises the following steps:

[0085] S1. Placing an aluminum raw material in a melting furnace and melting it at 720° C. to obtain an aluminum melt, then heating the aluminum melt to 760° C., adding an Al-Si master alloy, an Al-Cu master alloy, an Al-Mn master alloy, an Al-Cr master alloy, an Al-V master alloy, and an Al-rare earth master alloy to the aluminum melt, and stirring at the same temperature for 20 minutes to obtain a first alloy melt;

[0086] S2. Add a slag remover to the first alloy melt, control the temperature of the alloy melt at 730° C., and scrape off the slag on the surface of the alloy melt after slag removal. Then, add Mg, Al-Nb-B refiner, and Al-Sr master alloy, control the temperature of the alloy melt at 720° C., and stir at this temperature for 10 minutes. Then, let it stand for the first time for 5 minutes to obtain a second alloy melt.

[0087] S3. Argon mixed with a refining agent is introduced into the second alloy melt, and the temperature of the alloy melt is controlled at 720° C. and maintained for 10 minutes for degassing and refining to obtain a third alloy melt.

[0088] S4. Detecting the composition content of the third alloy melt. If the test result is qualified, performing a second standing for 5 minutes and then a third slag removal treatment to obtain a fourth alloy melt;

[0089] S5. Casting the fourth alloy melt into a mold, and after the alloy melt solidifies and forms, obtaining a die-cast aluminum alloy ingot.

[0090] Example 2

[0091] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La) in the die-cast aluminum alloy of this embodiment are shown in Table 1, and other conditions are the same as those in Example 1.

[0092] The method for preparing the die-cast aluminum alloy comprises the following steps:

[0093] S1. Placing an aluminum raw material in a smelting furnace and melting it at 740° C. to obtain an aluminum melt, then heating the aluminum melt to 780° C., adding Si, Cu, Mn, an Al-Cr master alloy, an Al-V master alloy, La, and a mixed rare earth of Ce to the aluminum melt, and stirring the mixture at the same temperature for 30 minutes to obtain a first alloy melt;

[0094] S2. Add a slag remover to the first alloy melt, control the temperature of the alloy melt at 750° C., and scrape off the slag on the surface of the alloy melt after the slag removal is completed; then add Mg, Al-Nb-B refiner and Al-Sr master alloy, control the temperature of the alloy melt at 750° C., stir at this temperature for 20 minutes, and then let it stand for the first time for 15 minutes to obtain a second alloy melt.

[0095] S3. Argon mixed with a refining agent is introduced into the second alloy melt, and the temperature of the alloy melt is controlled at 730° C. and maintained for 20 minutes for degassing and refining to obtain a third alloy melt.

[0096] S4. Testing the composition content of the third alloy melt. If the test result is qualified, the melt is allowed to stand for a second time for 15 minutes to obtain a fourth alloy melt.

[0097] S5. Casting the fourth alloy melt into a mold, and after the alloy melt solidifies and forms, obtaining a die-cast aluminum alloy ingot.

[0098] Example 3

[0099] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (Ce) in the die-cast aluminum alloy of this embodiment are shown in Table 1, and other conditions are the same as those in Example 1. The preparation method of the die-cast aluminum alloy of this embodiment is the same as that in Example 1.

[0100] Example 4

[0101] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this embodiment are shown in Table 1, and other conditions are the same as those in Example 1. The preparation method of the die-cast aluminum alloy of this embodiment is the same as that in Example 1.

[0102] Example 5

[0103] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this embodiment are shown in Table 1, and other conditions are the same as those in Example 1. The preparation method of the die-cast aluminum alloy of this embodiment is the same as that in Example 1.

[0104] Example 6

[0105] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this embodiment are shown in Table 2. Other conditions are the same as those in Example 1. The preparation method of the die-cast aluminum alloy of this embodiment is the same as that in Example 1.

[0106] Example 7

[0107] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this embodiment are shown in Table 2. Other conditions are the same as those in Example 1. The preparation method of the die-cast aluminum alloy of this embodiment is the same as that in Example 1.

[0108] Example 8

[0109] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this embodiment are shown in Table 2. Other conditions are the same as those in Example 1. The preparation method of the die-cast aluminum alloy of this embodiment is the same as that in Example 1.

[0110] Example 9

[0111] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this embodiment are shown in Table 2. Other conditions are the same as those in Example 1. The preparation method of the die-cast aluminum alloy of this embodiment is the same as that in Example 1.

[0112] Example 10

[0113] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this embodiment are shown in Table 2. Other conditions are the same as those in Example 1. The preparation method of the die-cast aluminum alloy of this embodiment is the same as that in Example 1.

[0114] Example 11

[0115] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this embodiment are shown in Table 2. Other conditions are the same as those in Example 1. The preparation method of the die-cast aluminum alloy of this embodiment is the same as that in Example 1.

[0116] Comparative Example 1

[0117] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this comparative example are shown in Table 3, and other conditions are the same as those in Example 1. The preparation method of the die-cast aluminum alloy of this comparative example is the same as that in Example 1.

[0118] Comparative Example 2

[0119] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this comparative example are shown in Table 3, and other conditions are the same as those in Example 1. The preparation method of the die-cast aluminum alloy of this comparative example is the same as that in Example 1.

[0120] Comparative Example 3

[0121] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this comparative example are shown in Table 3, and other conditions are the same as those in Example 1. The preparation method of the die-cast aluminum alloy of this comparative example is the same as that in Example 1.

[0122] Comparative Example 4

[0123] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this comparative example are shown in Table 3, and other conditions are the same as those in Example 1. The preparation method of the die-cast aluminum alloy of this comparative example is the same as that in Example 1.

[0124] Comparative Example 5

[0125] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this comparative example are shown in Table 3, and other conditions are the same as those in Example 1. The preparation method of the die-cast aluminum alloy of this comparative example is the same as that in Example 1.

[0126] Comparative Example 6

[0127] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this comparative example are shown in Table 4, and other conditions are the same as those in Example 1. The preparation method of the die-cast aluminum alloy of this comparative example is the same as that in Example 1.

[0128] Comparative Example 7

[0129] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this comparative example are shown in Table 4, and other conditions are the same as those in Example 1. The preparation method of the die-cast aluminum alloy of this comparative example is the same as that in Example 1.

[0130] Comparative Example 8

[0131] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this comparative example are shown in Table 4, and other conditions are the same as those in Example 1. The preparation method of the die-cast aluminum alloy of this comparative example is the same as that in Example 1.

[0132] Comparative Example 9

[0133] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this comparative example are shown in Table 4, and other conditions are the same as those in Example 1. The preparation method of the die-cast aluminum alloy of this comparative example is the same as that in Example 1.

[0134] Comparative Example 10

[0135] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this comparative example are shown in Table 4, and other conditions are the same as those in Example 1. The preparation method of the die-cast aluminum alloy of this comparative example is the same as that in Example 1.

[0136] Comparative Example 11

[0137] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this comparative example are shown in Table 4, and other conditions are the same as those in Example 1. The preparation method of the die-cast aluminum alloy of this comparative example is the same as that in Example 1.

[0138] Comparative Example 12

[0139] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (Y) in the die-cast aluminum alloy of this comparative example are shown in Table 4, and other conditions are the same as those in Example 1. The preparation method of the die-cast aluminum alloy of this comparative example is the same as that in Example 1.

[0140] Mechanical property tests were performed on the die-cast aluminum alloy ingots from each example and comparative example. Yield strength, tensile strength, and elongation were measured according to the GB / 228 standard for tensile mechanical properties of metal materials; bending angle was measured according to the VDA-238 standard for bending angle of metal materials. The mechanical property test results for the die-cast aluminum alloy ingots from each example and comparative example are shown in Tables 1-4.

[0141] Table 1. Chemical composition and mechanical properties of die-cast aluminum alloys of Examples 1-5

[0142] Table 2. Chemical composition and mechanical properties of die-cast aluminum alloys of Examples 6-11

[0143] Table 3. Chemical composition and mechanical properties of die-cast aluminum alloys of Comparative Examples 1-5

[0144] Table 4. Chemical composition and mechanical properties of die-cast aluminum alloys of Comparative Examples 6-11

[0145] Judging from the die-cast aluminum alloys of Examples 1-11 in Tables 1 and 2, their mechanical properties simultaneously meet the following requirements: yield strength ≥120 MPa, tensile strength ≥240 MPa, elongation ≥10%, and bending angle ≥30°, making them qualified materials for thin-walled structural parts of vehicles.

[0146] From the comparison between Example 1 and Comparative Example 1, the Si content in Comparative Example 1 is 6.0%, which is lower than the lower limit specified in the examples of this application, resulting in low yield strength and tensile strength of the die-cast aluminum alloy, which does not meet the above qualification standards.

[0147] From the comparison between Example 1 and Comparative Example 2, the Si content in Comparative Example 2 is 9.0%, which is higher than the upper limit specified in the embodiments of the present application, resulting in a lower bending angle of the die-cast aluminum alloy, which does not meet the above qualification standards, indicating that the toughness of the die-cast aluminum alloy is poor.

[0148] From the comparison between Example 5 and Comparative Example 3, the Mn content in Comparative Example 3 is 0.6%, which is higher than the upper limit specified in the embodiments of the present application, resulting in lower elongation and bending angle of the die-cast aluminum alloy, which does not meet the above qualification standards, indicating that the plastic toughness of the die-cast aluminum alloy is poor.

[0149] From the comparison between Example 7 and Comparative Example 4, the Mg content in Comparative Example 4 is 0.6%, which is higher than the upper limit specified in the embodiments of the present application, resulting in lower elongation and bending angle of the die-cast aluminum alloy, which does not meet the above qualification standards, indicating that the plastic toughness of the die-cast aluminum alloy is poor.

[0150] From the comparison between Examples 8-9 and Comparative Example 5, it can be seen that the V content in Comparative Example 5 is 0, which is lower than the lower limit specified in the examples of this application, resulting in low yield strength and tensile strength of the die-cast aluminum alloy, which does not meet the above qualification standards.

[0151] From the comparison between Examples 8-9 and Comparative Example 6, the V content in Comparative Example 6 is 0.05%, which is higher than the upper limit specified in the examples of this application, resulting in low yield strength and tensile strength of the die-cast aluminum alloy, which does not meet the above qualification standards.

[0152] From the comparison between Examples 10-11 and Comparative Example 7, it can be seen that the content of rare earth elements in Comparative Example 7 is 0, which is lower than the lower limit specified in the embodiments of this application, resulting in low yield strength and tensile strength of the die-cast aluminum alloy, which does not meet the above qualification standards.

[0153] From the comparison between Examples 10-11 and Comparative Example 8, it can be seen that the content of rare earth elements in Comparative Example 8 is 500 ppm, which is higher than the upper limit specified in the embodiments of the present application, resulting in lower elongation and bending angle of the die-cast aluminum alloy, which does not meet the above qualification standards, indicating that the plastic toughness of the die-cast aluminum alloy is poor.

[0154] From the comparison between Example 11 and Comparative Example 9, the content of Fe element in Comparative Example 9 is 0.5%, which is higher than the upper limit specified in the embodiments of the present application, resulting in lower elongation and bending angle of the die-cast aluminum alloy, which does not meet the above qualification standards, indicating that the plastic toughness of the die-cast aluminum alloy is poor.

[0155] From the comparison between Example 11 and Comparative Example 10, it can be seen that the content of Nb element in Comparative Example 10 is 0, which is lower than the lower limit specified in the embodiments of the present application, resulting in low elongation and bending angle of the die-cast aluminum alloy, which does not meet the above qualification standards, indicating that the plastic toughness of the die-cast aluminum alloy is poor.

[0156] From the comparison between Example 11 and Comparative Example 11, the content of Nb element in Comparative Example 11 is 200 ppm, which is higher than the upper limit specified in the embodiments of the present application, resulting in lower elongation and bending angle of the die-cast aluminum alloy, which does not meet the above qualification standards, indicating that the plastic toughness of the die-cast aluminum alloy is poor.

[0157] From the comparison between Example 9 and Comparative Example 12, it can be seen that the rare earth element in Comparative Example 12 uses Y instead of La and / or Ce, resulting in lower elongation and bending angle of the die-cast aluminum alloy, which does not meet the above qualification standards, indicating that the plastic toughness of the die-cast aluminum alloy is poor.

[0158] In this application, the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0159] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. An aluminum alloy, characterized in that: Based on the total mass of the aluminum alloy as 100%, it includes the following components: Si content is 6.5-8.5%; Fe content is ≤0.3%; Cu content is ≤0.3%; Mn content is ≤0.5%; Mg content is ≤0.5%; Cr content is ≤0.2%; V content is 0.002-0.02%; Nb content is 10-100ppm; Sr content is 0.01-0.03%; rare earth element content is 10-100ppm, and the rare earth element is La and / or Ce; the balance is Al and unavoidable impurities.

2. The aluminum alloy according to claim 1, characterized in that The Si content is 6.5-7.5%; and / or the Fe content is ≤0.15%; and / or the Cu content is 0.001-0.3%; and / or the Mn content is 0.3-0.5%; and / or the Mg content is 0.1-0.5%; and / or the Cr content is 0.1-0.2%; and / or the V content is 0.005-0.02%; and / or the Nb content is 30-80 ppm; and / or the Sr content is 0.02-0.03%; and / or the rare earth element content is 20-80 ppm.

3. The aluminum alloy according to claim 2, characterized in that The V content is 0.005 to 0.01%.

4. The aluminum alloy according to claim 2, characterized in that The Nb content is 40 to 60 ppm.

5. The aluminum alloy according to claim 2, characterized in that The content of rare earth elements is 20 to 50 ppm.

6. The aluminum alloy according to any one of claims 1 to 5, characterized in that The aluminum alloy has a tensile strength of 240 MPa or more, a yield strength of 120 MPa or more, an elongation of 10% or more, and a bending angle of 30° or more.

7. A method for preparing the aluminum alloy according to any one of claims 1 to 6, characterized in that: The following steps are involved: placing an aluminum raw material in a smelting furnace to melt to obtain an aluminum melt, and then adding a Si raw material, a Cu raw material, a Mn raw material, a Cr raw material, a V raw material, and a rare earth raw material to the aluminum melt for a first smelting to obtain a first alloy melt; Adding a slag remover to the first alloy melt to perform a first slag removal treatment, then adding a Mg raw material, a Nb raw material, and a Sr raw material to perform a second smelting, and then performing a first standing and then a second slag removal treatment to obtain a second alloy melt; introducing an inert gas mixed with a refining agent into the second alloy melt for degassing and refining to obtain a third alloy melt; The third alloy melt is subjected to a component content test. If the test result is qualified, the third alloy melt is subjected to a second standing process and then a third slag removal process to obtain a fourth alloy melt. The fourth alloy melt is cast into a mold, and after the alloy melt is solidified and formed, an aluminum alloy ingot is obtained.

8. The method for preparing the aluminum alloy according to claim 7, wherein: The V raw material is an Al-V master alloy, the Nb raw material is an Al-Nb-B refiner, and the rare earth raw material is an Al-rare earth master alloy.

9. The method for preparing the aluminum alloy according to claim 7 or 8, characterized in that: The temperature of the first smelting is above 760°C, and the time of the first smelting is not less than 20 minutes; and / or, the temperature of the first slag removal treatment is above 730°C, the temperature of the second smelting is above 720°C, and the time of the second smelting is not less than 10 minutes; and / or, the temperature of the degassing refining is above 720°C, and the time of the degassing refining is not less than 10 minutes; and / or, the casting temperature is 690-720°C.

10. An aluminum alloy die casting, characterized in that: Made from the aluminum alloy according to any one of claims 1 to 6.

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