Aluminum alloy, preparation method therefor and use thereof

Abstract

Disclosed in the present invention are an aluminum alloy, a preparation method therefor and the use thereof. The aluminum alloy is based on an Al-Mg alloy system, and simultaneously contains Mn, Cr, Cu, Zn, and X elements (at least two of Sr, Mo and Zr) by means of optimization of an alloy formulation, with further control over the contents thereof. The combination can reduce the damage to strength and formability caused by coarse second-phase particles, and improve the tolerance of the alloy to impurity elements such as Fe and Si, and to Mn, thus enabling use of recycled materials in production, decreasing the proportion of primary aluminum used, and achieving good recyclability. The alloy has the features of being economical, low carbon and energy saving. During preparation, an ingot is prepared first, followed by homogenization, hot rough rolling, hot finish rolling, cold rolling, and annealing. In practice, the aluminum alloy of the present invention is shown to at least achieve balance among alloy properties such as tensile strength, yield strength, and elongation after fracture, thus being suitable for use in fields such as the manufacturing of automotive body components.

Description

An aluminum alloy, its preparation method and application Technical Field

[0001] This invention relates to the field of aluminum alloy technology, specifically to an aluminum alloy, its preparation method, and its applications. Background Technology

[0002] 5754 aluminum alloy is a non-heat-treatable aluminum alloy that is mainly strengthened by solid solution of Mg atoms and work hardening. It is a typical alloy in the Al-Mg system. Due to its moderate strength, good formability, corrosion resistance and weldability, it is widely used in automobiles, rail transportation, shipbuilding and other fields.

[0003] Currently, 5754 aluminum alloys typically have strictly limited impurity elements such as Fe and Si, and the Mn content is controlled at a low level to ensure the alloy's strength, formability, surface quality, and electrical conductivity. For example, patent CN113337760A discloses a method for improving the O-state electrical conductivity of 5754 alloy, in which Si≤0.10wt.%, Fe≤0.10wt.%, Cu≤0.10wt.%, Mn=0.10wt.%~0.12wt.%, Mg=2.6wt.%~2.7wt.%, Cr≤0.001wt.%, Zn≤0.001wt.%, Ti≤0.001wt.%, and the remainder is Al and other unavoidable elements, with each of these unavoidable elements ≤0.05wt.%, totaling ≤0.15wt.%; another example is CN1170... 11913A discloses a 5754-O state aluminum alloy sheet for automotive structural parts and its production method. The alloy contains Si ≤ 0.1 wt.%, Fe ≤ 0.2 wt.%, Cu ≤ 0.08 wt.%, Mn 0.25 wt.%–0.4 wt.%, Mg 2.8 wt.%–3.4 wt.%, Cr 0.05 wt.%–0.2 wt.%, Zn ≤ 0.2 wt.%, Ti ≤ 0.025 wt.%, with the balance being Al and other impurity elements, including V, Zr, Be, B, Li, Na, Ca, Pb, Sn, and Bi, with a total content ≤ 0.15 wt.%.

[0004] Recycled aluminum alloys consume only 4% to 6% of the energy of electrolytic aluminum, making them one of the most efficient ways to achieve energy conservation and emission reduction. However, the high content of Fe, Mn, Si and other elements in recycled aluminum alloys has long been a major reason that has limited their application in fields such as automotive body panels or rail transportation vehicles.

[0005] Specifically, Fe is the main impurity in aluminum alloys. According to the Al-Fe binary phase diagram, the maximum solubility of Fe in the aluminum matrix at room temperature is approximately 0.025 wt.%. Therefore, during solidification, Fe atoms will form needle-like iron-rich intermetallic compounds Al3Fe. Due to their brittle characteristics and the stress concentration caused by their needle-like morphology, this type of intermetallic compound is considered to be the most detrimental to the mechanical properties of the alloy. Meanwhile, Mn is usually added to aluminum alloys to compensate for the negative effects of iron-rich intermetallic compounds Al3Fe. After adding Mn to low-Fe alloys, the long needle-like Al3Fe phase transforms into the Chinese character-shaped Al6(Fe,Mn). It is generally believed that intermetallic compounds with Chinese character-shaped structures have a relatively small impact on the mechanical properties of the alloy. In addition, Mn improves the overall properties of the alloy through solid solution strengthening and dispersion strengthening. However, in high-Fe aluminum alloys, as the Mn content increases, the size and quantity of intermetallic compounds Al6(Fe,Mn) also increase, exhibiting complex morphologies such as fishbone-like, flower-like, and coarse blocky structures, which significantly reduces the mechanical properties of the alloy. Furthermore, the presence of Si in recycled aluminum alloys, in addition to forming coarse Mg2Si phases, also forms long needle-like Al5FeSi and Al8Fe2Si phases with Fe, which severely reduces the plasticity and strength of the alloy.

[0006] Therefore, when the Fe content in the alloy system is low, the presence of Mn and Si has little effect on the alloy, and the presence of Mn may even improve the alloy's performance to some extent. However, once the Fe content increases, it is equivalent to amplifying the negative effects of Mn and Si, leading to a significant deterioration in the alloy's performance. Since recycled aluminum alloys usually have high contents of Fe, Si, and Mn, they contain large-sized, complex-morphological Fe-rich phases, which significantly reduce the alloy's strength and plasticity, severely limiting the recycling and reuse of aluminum alloys. Summary of the Invention

[0007] The purpose of this invention is to overcome one or more shortcomings in the prior art and provide an improved aluminum alloy that has high tolerance for elements such as Fe, Mn, and Si, and good strength and plasticity matching. Based on the aforementioned characteristics, even using recycled aluminum alloys (such as recycled aluminum cans, automobile sheets, etc.), an aluminum alloy with medium strength and excellent formability can be produced, which can be used to replace 5754 aluminum alloy, not only saving energy and reducing emissions, but also reducing production costs.

[0008] The present invention also provides a method for preparing the above-mentioned aluminum alloy with high tolerance to elements such as Fe, Mn, and Si and good strength-ductility matching, and its application in the fields of automobile body parts (e.g., automobile body inner panels), rail transit vehicle structural parts, or ship structural parts.

[0009] To achieve the above objectives, the present invention employs the following technical solution:

[0010] An aluminum alloy, by weight percentage, comprises: 2.0 wt.% to 3.2 wt.% Mg, 0.05 wt.% to 0.3 wt.% Cu, 0.4 wt.% to 1.2 wt.% Mn, 0.05 wt.% to 0.3 wt.% Cr, 0.01 wt.% to 0.3 wt.% Zn, less than or equal to 0.15 wt.% Ti, 0 to 0.14 wt.% X1, 0 to 0.14 wt.% X2, 0 to 0.14 wt.% X3, and impurities;

[0011] The impurities include Fe, Si, and other impurities besides Fe and Si; by weight percentage, the aluminum alloy contains 0.35 wt.% to 0.7 wt.% Fe, 0.1 wt.% to 0.4 wt.% Si, and the total content of other impurities is less than or equal to 0.2 wt.%.

[0012] The Al content was adjusted so that the total amount of the aluminum alloy was 100 wt.%.

[0013] Wherein, X1, X2, and X3 are independently selected from Sr, Mo, and Zr, and each of X1, X2, and X3 is different and at least two exist simultaneously, and the total amount of X1, X2, and X3 is less than or equal to 0.15 wt.%.

[0014] According to the present invention, in some embodiments, the area percentage of the iron-rich phase in the as-cast microstructure of the aluminum alloy is less than or equal to 3.5%, and the average equivalent diameter is less than or equal to 3.5 μm.

[0015] Iron-rich phases typically refer to iron-containing phases, such as Al. x (FeMn), α-Al(FeMnCr)Si, β-AlFeSi, etc.

[0016] According to the present invention, in some embodiments, the area percentage of the Mg2Si phase in the as-cast microstructure of the aluminum alloy is less than or equal to 1.5%, and the average equivalent diameter is less than or equal to 1.2 μm.

[0017] According to the present invention, in some embodiments, the average equivalent diameter of the iron-rich phase in the microstructure of the aluminum alloy in the O state (the O state is a state of aluminum alloy, i.e., aluminum alloy products after full annealing) is 0.8 to 1.5 μm.

[0018] In some embodiments of the present invention, the alloy microstructure of the aluminum alloy comprises dispersed particles, wherein the dispersed particles include:

[0019] (1) Selected from one or more of Al6Mn dispersed phase particles, Al4Mn dispersed phase particles, Al6(FeMn) dispersed phase particles, Al(FeMnCr)Si dispersed phase particles, and Al7Cr dispersed phase particles;

[0020] (2) Selected from Al 12 Mo dispersed phase particles, Al 38 Mg 58 Two or three of the following: Sr4 dispersed phase particles and Al3Zr dispersed phase particles.

[0021] According to the present invention, the average equivalent diameter of the dispersed particles is less than or equal to 100 nm, and the number density of the dispersed particles is 5-20 particles / μm. 2 Further, 8-15 cells / μm 2 .

[0022] According to some preferred aspects of the invention, the total amount of Mg, Cu and Mn is greater than or equal to 2.5 wt.%.

[0023] According to some preferred aspects of the invention, the aluminum alloy, by weight percentage, comprises: 2.0 wt.% to 3.0 wt.% Mg, 0.05 wt.% to 0.3 wt.% Cu, 0.5 wt.% to 1.2 wt.% Mn, 0.05 wt.% to 0.3 wt.% Cr, 0.05 wt.% to 0.25 wt.% Zn, less than or equal to 0.1 wt.% Ti, 0 to 0.12 wt.% X1, 0 to 0.12 wt.% X2, 0 to 0.12 wt.% X3, and 0.4 wt.% to 0.7 wt.% Fe, 0.15 wt.% to 0.4 wt.% Si, less than or equal to 0.15 wt.% other impurities, with the Al content adjusted so that the total amount of the aluminum alloy is 100 wt.%.

[0024] Further, by weight percentage, the aluminum alloy comprises: 2.0 wt.% to 3.0 wt.% Mg, 0.05 wt.% to 0.3 wt.% Cu, 0.6 wt.% to 1.0 wt.% Mn, 0.05 wt.% to 0.3 wt.% Cr, 0.15 wt.% to 0.25 wt.% Zn, 0.02 wt.% to 0.06 wt.% Ti, 0.01 wt.% to 0.12 wt.% X1, 0.01 wt.% to 0.12 wt.% X2, 0.01 wt.% to 0.12 wt.% X3, and 0.4 wt.% to 0.7 wt.% Fe, 0.15 wt.% to 0.4 wt.% Si, and other impurities less than or equal to 0.15 wt.%, with the Al content adjusted to make the total amount of the aluminum alloy 100 wt.%.

[0025] In some embodiments of the present invention, the aluminum alloy contains 0.45 wt.% to 0.7 wt.% Fe by weight.

[0026] According to some preferred aspects of the invention, the ratio of the total amount of Mg and Mn to the content of Cr is 10-70:1.

[0027] According to some preferred aspects of the invention, the ratio of Mg content to Cu content is 8-55:1.

[0028] In this invention, the aluminum alloy in the O state has a yield strength greater than or equal to 140 MPa, a tensile strength greater than or equal to 260 MPa, and an elongation after fracture greater than or equal to 20%.

[0029] Furthermore, the aluminum alloy, in the O state, has a yield strength greater than or equal to 145 MPa, a tensile strength greater than or equal to 260 MPa, and an elongation after fracture greater than or equal to 21.5%.

[0030] According to one specific aspect of the invention, the aluminum alloy is a 5-series aluminum alloy.

[0031] Another technical solution provided by the present invention: a method for preparing the above-mentioned aluminum alloy, the method comprising:

[0032] Provide an aluminum alloy melt containing at least 10 wt.% recycled aluminum alloy material, and form the aluminum alloy melt into an aluminum alloy ingot;

[0033] The aluminum alloy ingot is homogenized to obtain a first intermediate.

[0034] The first intermediate is subjected to a first hot rolling process, and the deformation per pass of the first hot rolling is controlled to be greater than or equal to 5%, and the total deformation is greater than or equal to 90%, to obtain a second intermediate.

[0035] The second intermediate is subjected to a second hot rolling process, and the total deformation is controlled to be greater than or equal to 85% to obtain the third intermediate.

[0036] The third intermediate is subjected to cold rolling deformation with a deformation amount of 60%-90%;

[0037] Annealing.

[0038] In some embodiments of the present invention, the content of recycled aluminum alloy material in the aluminum alloy melt is greater than or equal to 20%, for example, it can be greater than or equal to 25%, greater than or equal to 30%, greater than or equal to 35%, etc.

[0039] In some embodiments of the present invention, the content of recycled aluminum alloy material in the aluminum alloy melt is greater than or equal to 40%, for example, it can be greater than or equal to 45%, greater than or equal to 50%, greater than or equal to 55%, greater than or equal to 60%, greater than or equal to 65%, etc.

[0040] In some embodiments of the present invention, the content of recycled aluminum alloy material in the aluminum alloy melt is greater than or equal to 70%, for example, it can be greater than or equal to 75%, greater than or equal to 80%, greater than or equal to 85%, greater than or equal to 90%, etc.

[0041] In some embodiments of the present invention, the content of recycled aluminum alloy material in the aluminum alloy melt is greater than or equal to 95%, for example, it can be greater than or equal to 96%, greater than or equal to 97%, greater than or equal to 98%, etc.

[0042] According to some preferred aspects of the invention, the homogenization treatment is performed at a temperature of 480-540°C for a time of 2-12 hours.

[0043] According to some preferred aspects of the invention, in the first hot rolling, the deformation per pass is greater than or equal to 6%, and the total deformation is greater than or equal to 93%.

[0044] According to some preferred aspects of the invention, in the second hot rolling, the total deformation is controlled to be greater than or equal to 88%.

[0045] According to some preferred aspects of the present invention, the annealing treatment is performed at a temperature of 320-400°C for 2-6 hours, or the annealing treatment is carried out on a continuous annealing line, heated to 460-520°C, and held for 0-120 seconds. In this invention, 0 seconds indicates that the room temperature sheet is heated to the target annealing temperature (e.g., 460-520°C) in the furnace from the time it enters the furnace to the time it exits the furnace, without holding at that temperature. This process can be implemented on a continuous annealing line (e.g., a continuous air cushion annealing furnace).

[0046] In some embodiments of the present invention, the initial rolling temperature in the first hot rolling is 400-500°C; and the final rolling temperature in the second hot rolling is 320-360°C.

[0047] Another technical solution provided by the present invention: a 5-series aluminum alloy, wherein, by weight percentage, the 5-series aluminum alloy comprises: 2.0 wt.% to 3.2 wt.% Mg, 0.05 wt.% to 0.3 wt.% Cu, 0.6 wt.% to 1.2 wt.% Mn, 0.05 wt.% to 0.3 wt.% Cr, 0.01 wt.% to 0.3 wt.% Zn, less than or equal to 0.15 wt.% Ti, 0.02 wt.% to 0.14 wt.% Sr, 0.02 wt.% to 0.14 wt.% Zr, and impurities;

[0048] The impurities include Fe, Si, and other impurities besides Fe and Si; by weight percentage, in the 5-series aluminum alloy, Fe is 0.4 wt.% to 0.7 wt.%, Si is 0.1 wt.% to 0.4 wt.%, and the total content of other impurities is less than or equal to 0.2 wt.%.

[0049] The total amount of Sr and Zr is less than or equal to 0.15 wt.%, and the Al content is adjusted so that the total amount of the 5-series aluminum alloy is 100 wt.%.

[0050] Another technical solution provided by the present invention: a 5-series aluminum alloy, wherein, by weight percentage, the 5-series aluminum alloy comprises: 2.0 wt.% to 3.2 wt.% Mg, 0.05 wt.% to 0.3 wt.% Cu, 0.6 wt.% to 1.2 wt.% Mn, 0.05 wt.% to 0.3 wt.% Cr, 0.01 wt.% to 0.3 wt.% Zn, less than or equal to 0.15 wt.% Ti, 0.02 wt.% to 0.14 wt.% Mo, 0.02 wt.% to 0.14 wt.% Zr, and impurities;

[0051] The impurities include Fe, Si, and other impurities besides Fe and Si; by weight percentage, in the 5-series aluminum alloy, Fe is 0.4 wt.% to 0.7 wt.%, Si is 0.1 wt.% to 0.4 wt.%, and the total content of other impurities is less than or equal to 0.2 wt.%.

[0052] The total amount of Mo and Zr is less than or equal to 0.15 wt.%, and the Al content is adjusted so that the total amount of the 5-series aluminum alloy is 100 wt.%.

[0053] Another technical solution provided by the present invention: a 5-series aluminum alloy, wherein, by weight percentage, the 5-series aluminum alloy comprises: 2.0 wt.% to 3.2 wt.% Mg, 0.05 wt.% to 0.3 wt.% Cu, 0.4 wt.% to 1.2 wt.% Mn, 0.05 wt.% to 0.3 wt.% Cr, 0.01 wt.% to 0.3 wt.% Zn, less than or equal to 0.15 wt.% Ti, 0.01 wt.% to 0.08 wt.% Sr, 0.01 wt.% to 0.08 wt.% Mo, 0.01 wt.% to 0.08 wt.% Zr, and impurities;

[0054] The impurities include Fe, Si, and other impurities besides Fe and Si; by weight percentage, the 5-series aluminum alloy contains 0.35 wt.% to 0.7 wt.% Fe, 0.1 wt.% to 0.4 wt.% Si, and the total content of other impurities is less than or equal to 0.2 wt.%.

[0055] The total amount of Sr, Mo, and Zr is less than or equal to 0.15 wt.%, and the Al content is adjusted so that the total amount of the 5-series aluminum alloy is 100 wt.%.

[0056] Another technical solution provided by the present invention: a 5-series aluminum alloy, wherein, by weight percentage, the 5-series aluminum alloy comprises: 2.0 wt.% to 3.2 wt.% Mg, 0.05 wt.% to 0.3 wt.% Cu, 0.4 wt.% to 1.2 wt.% Mn, 0.05 wt.% to 0.3 wt.% Cr, 0.01 wt.% to 0.3 wt.% Zn, less than or equal to 0.15 wt.% Ti, and impurities;

[0057] The impurities include Fe, Si, and other impurities besides Fe and Si; by weight percentage, the 5-series aluminum alloy contains 0.35 wt.% to 0.7 wt.% Fe, 0.1 wt.% to 0.4 wt.% Si, and the total content of other impurities is less than or equal to 0.2 wt.%.

[0058] The 5-series aluminum alloy also contains two or three of Sr, Mo, and Zr as additives, the content of the additives is less than or equal to 0.15 wt.%, and the content of any one element in the additives is 0.1-10 times the content of the other elements;

[0059] The Al content was adjusted so that the total amount of the 5-series aluminum alloy was 100 wt.%.

[0060] Furthermore, in the additive, the content of any one element is 0.2-8 times that of the other elements.

[0061] Furthermore, in the additive, the content of any one element is 0.4-5 times that of the other elements, for example, 0.5 times, 0.6 times, 0.8 times, 1.0 times, 1.2 times, 1.5 times, 1.6 times, 2.0 times, 2.5 times, 3.0 times, 3.5 times, etc.

[0062] Another technical solution provided by the present invention: an aluminum alloy, which is prepared by the following method:

[0063] (1) A raw material containing at least 10 wt.% recycled aluminum alloy material is provided, and then smelted, first refined, alloyed, second refined, and cast in sequence to produce an aluminum alloy ingot; wherein, by weight percentage, the aluminum alloy contains: 2.0 wt.% to 3.2 wt.% Mg, 0.05 wt.% to 0.3 wt.% Cu, 0.4 wt.% to 1.2 wt.% Mn, 0.05 wt.% to 0.3 wt.% Cr, 0.01 wt.% to 0.3 wt.% Zn, less than or equal to 0.15 wt.% Ti, 0 to 0.14 wt.% Sr, 0 to 0.14 wt.% Mo, 0 to 0.14 wt.% Zr, and impurities;

[0064] The impurities include Fe, Si, and other impurities besides Fe and Si; by weight percentage, the aluminum alloy contains 0.35 wt.% to 0.7 wt.% Fe, 0.1 wt.% to 0.4 wt.% Si, and the total content of other impurities is less than or equal to 0.2 wt.%.

[0065] The Al content was adjusted so that the total amount of the aluminum alloy was 100 wt.%.

[0066] The Sr, Mo, and Zr are present in at least two of them at the same time, and the total amount of Sr, Mo, and Zr is less than or equal to 0.15 wt.%.

[0067] (2) The aluminum alloy ingot is homogenized at a temperature of 480-540℃ and held for 2-12 hours.

[0068] (3) After homogenization, hot rough rolling is carried out with 12-18 rolling passes, the total deformation is greater than 93%, and the initial rolling temperature is greater than 400℃.

[0069] (4) After the hot roughing is completed, hot finishing is performed with a total deformation of more than 85% and a final rolling temperature of more than 330℃.

[0070] (5) The hot-rolled material obtained after step (4) is subjected to cold rolling deformation with a deformation amount of 60%-90%;

[0071] (6) Annealing is carried out in a box-type annealing furnace at a temperature of 320-400℃ for 2-6 hours, or on a continuous annealing line at a temperature of 460-520℃ for 0-120 seconds.

[0072] Further, in step (1), a raw material containing at least 20 wt.% recycled aluminum alloy material is provided, or a raw material containing at least 30 wt.% recycled aluminum alloy material is provided, or a raw material containing at least 40 wt.% recycled aluminum alloy material is provided, or a raw material containing at least 50 wt.% recycled aluminum alloy material is provided.

[0073] Another technical solution provided by the present invention is the application of the above-mentioned aluminum alloy in the manufacture of automobile body parts, rail transit vehicle structural parts or ship structural parts.

[0074] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0075] To meet the current demand for recycling and reusing aluminum alloy scrap in order to reduce carbon emissions and lower production costs, and to address the common problems of poor performance in aluminum alloys, especially 5754 aluminum alloys, which are often produced from recycled aluminum alloy scrap, such as the difficulty in achieving the desired tensile strength, yield strength, and elongation after fracture. Based on extensive experimental research, the inventors have innovatively provided an improved aluminum alloy formulation. In the Al-Mg alloy system, Mn, Cr, Cu, Zn, and selective X1-X3 elements (Sr, Mo, Zr) are used to compensate for the strength loss caused by the reduced Mg content. Furthermore, analysis suggests that the addition of Cr can improve the morphology and size of the primary second-phase particles in the aluminum alloy, refining the particles. In addition, the addition of Cr can significantly improve the nucleation, precipitation, and coarsening behavior of the dispersed phase during homogenization heat treatment, increasing the number density of the dispersed phase and reducing its size. Moreover, in this invention, the addition of X1-X3 elements can significantly refine the size of the primary second-phase particles and the grain size. Furthermore, X1-X3 elements can precipitate fine and uniformly distributed dispersed phase particles, such as Al, during homogenization heat treatment. 12 Mo, Al 38 Mg 58Sr4, Al3Zr, and other dispersed phases can regulate the microstructure of aluminum alloy sheets and act as dispersed phase reinforcement, improving the formability and strength of the product. This achieves at least a balance of alloy properties such as tensile strength, yield strength, and elongation after fracture. Furthermore, in the preparation method of this invention, by controlling the hot rolling deformation, especially the deformation amount per pass during the first hot rolling process to be greater than or equal to 5%, the second phase is destroyed and its particle size is reduced. Further combining this with secondary hot rolling and cold rolling further improves the alloy properties of the aluminum alloy of this invention. Based on the aforementioned characteristics, even using recycled aluminum alloys (such as recycled aluminum cans, automotive sheets, etc.), an aluminum alloy with medium strength and excellent formability can be produced, which can be used to replace 5754 aluminum alloy, not only saving energy and reducing emissions but also lowering production costs. Attached Figure Description

[0076] Figure 1 shows a metallographic photograph of the as-cast microstructure of AA5754 alloy;

[0077] Figure 2 shows the metallographic photograph of the as-cast microstructure of the Al-1 alloy;

[0078] Figure 3 shows the metallographic photograph of the as-cast microstructure of alloy A1-2;

[0079] Figure 4 shows the metallographic photograph of the as-cast microstructure of the A1-3 alloy;

[0080] Figure 5 shows the metallographic photograph of the as-cast microstructure of alloy A1-4;

[0081] Figure 6 shows the metallographic photograph of the as-cast microstructure of alloy A2;

[0082] Figure 7 shows the metallographic photograph of the as-cast microstructure of alloy A3;

[0083] Figure 8 shows the metallographic photograph of the as-cast microstructure of alloy A4;

[0084] Figure 9 shows a metallographic photograph of the as-cast microstructure of alloy A5;

[0085] Figure 10 shows the metallographic photograph of the as-cast microstructure of alloy A6;

[0086] Figure 11 shows a metallographic photograph of the as-cast microstructure of alloy A7;

[0087] Figure 12 shows the metallographic photograph of the as-cast microstructure of alloy A8;

[0088] Figure 13 is a bar chart showing the percentage of iron-rich phase area in the as-cast state for alloys AA5754, A1-1 to A1-4, and A2 to A8.

[0089] Figure 14 is a bar chart of the average equivalent diameter of the iron-rich phase in the as-cast state of alloys AA5754, A1-1 to A1-4, and A2 to A8.

[0090] Figure 15 is a bar chart of the as-cast Mg2Si phase area percentage for alloys AA5754, A1-1 to A1-4, and A2 to A8.

[0091] Figure 16 is a bar chart of the average equivalent diameter of the Mg2Si phase in the as-cast state of alloys AA5754, A1-1 to A1-4, and A2 to A8.

[0092] Figure 17 shows a metallographic photograph of the AA5754-H1 alloy after homogenization treatment.

[0093] Figure 18 shows a metallographic photograph of the AA5754-H2 alloy after homogenization treatment.

[0094] Figure 19 shows a metallographic photograph of the A1-1-H1 alloy after homogenization treatment;

[0095] Figure 20 shows a metallographic photograph of the Al-1-H2 alloy after homogenization treatment;

[0096] Figure 21 shows a metallographic photograph of Al-2-H alloy after homogenization treatment;

[0097] Figure 22 shows a metallographic photograph of Al-3-H alloy after homogenization treatment;

[0098] Figure 23 shows a metallographic photograph of Al-4-H alloy after homogenization treatment;

[0099] Figure 24 shows a metallographic photograph of the A2-H alloy after homogenization treatment;

[0100] Figure 25 shows a metallographic photograph of the A3-H alloy after homogenization treatment;

[0101] Figure 26 shows a metallographic photograph of the A4-H alloy after homogenization treatment;

[0102] Figure 27 shows a metallographic photograph of the A5-H alloy after homogenization treatment;

[0103] Figure 28 shows a metallographic photograph of the A6-H alloy after homogenization treatment;

[0104] Figure 29 shows a metallographic photograph of the A7-H alloy after homogenization treatment;

[0105] Figure 30 shows a metallographic photograph of the A8-H alloy after homogenization treatment;

[0106] Figure 31 shows a metallographic photograph of the dispersed phase of the AA5754-H1 alloy after homogenization treatment.

[0107] Figure 32 shows a metallographic photograph of the dispersed phase of the Al-1-H1 alloy after homogenization treatment;

[0108] Figure 33 shows a metallographic photograph of the dispersed phase after homogenization treatment of the A2-H alloy;

[0109] Figure 34 is a bar chart showing the average equivalent diameter of the iron-rich phase after the alloys AA5754-H1, AA5754-H2, A1-1-H1, A1-1-H2, A1-2-H to A1-4-H, and A2-H to A8-H are processed into the final product. Detailed Implementation

[0110] This invention provides an aluminum alloy product and its processing technology that achieve significant performance improvements, particularly in tensile strength, yield strength, and elongation after fracture. The aluminum alloy of this invention overcomes the deterioration of alloy properties caused by high iron impurity content. Specifically, it reduces and / or eliminates the amplified negative impact of Fe impurities on Mn and Si when Fe, Si, and Mn impurities are all present in high amounts, thereby fundamentally avoiding the deterioration of alloy properties.

[0111] The performance of aluminum alloys primarily depends on their composition, which directly determines their most fundamental properties such as mechanical and formability. Furthermore, in some embodiments, recycled aluminum alloys inevitably contain Si elements, which form coarse Mg2Si phases during the casting process, severely deteriorating formability. Simultaneously, in addition to introducing high levels of Fe and Si elements, recycled materials also introduce large amounts of Mn elements, which promote the formation of coarse Al phases. x The formation of (Fe,Mn,Cr) or Al(Fe,Mn,Cr)Si phases significantly deteriorates the formability. Generally, although Cu can compensate for the insufficient strength caused by the reduction of Mg content, Cu combines with Fe to form the refractory Al7Cu2Fe phase. The coarse Al7Cu2Fe phase further deteriorates the alloy's formability. In addition, Cu can also form coarse S phase (i.e., Al2CuMg phase) with Mg or directly form coarse Al2Cu phase, which reduces the alloy's formability.

[0112] This invention addresses at least the aforementioned problems by adjusting the combination and controlling the content of the formulation components. Furthermore, by optimizing the preparation method, it further improves the alloy properties. Based on the concept of this invention, it is possible to produce aluminum alloys using recycled aluminum alloy waste, which exhibits excellent mechanical and forming properties. Moreover, the aluminum alloy itself is highly recyclable, offering significant advantages in reducing carbon emissions from aluminum alloy production.

[0113] Aluminum alloy composition:

[0114] In some embodiments, the aluminum alloy of the present invention may have the elemental composition shown in Table 1.

[0115] Table 1

[0116] Preparation method:

[0117] Using scrap aluminum such as can stock as raw material, it is melted in a smelting furnace to 740-790℃ to obtain aluminum alloy melt; more preferably, intermediate alloys such as Al-Mn, Al-Cr, Al-Mo, Al-Zr, and Al-Sr, as well as Mg ingots, are selectively added to obtain aluminum alloy melt with qualified composition.

[0118] Specifically, by sequentially melting, first refining, alloying, second refining, and casting the raw materials, an aluminum alloy ingot with the target aluminum alloy composition is obtained.

[0119] The smelting process parameters are as follows: First, recycled aluminum alloys such as canister materials are added to a smelting furnace along with a small amount of electrolytic aluminum or primary aluminum ingots and melted to 740-790℃ to obtain aluminum alloy melt.

[0120] The process parameters for the first refining are as follows: the first refining is carried out in the range of 735-745℃, and electromagnetic stirring is turned on simultaneously during the refining process. Granular refining agent is used for refining (the amount is 1wt.%-2.5wt.% of the aluminum alloy melt). The refining agent can be a commonly used refining agent for melt refining in the aluminum processing industry (e.g., NaCl, KCl, MgCl2, BaCl2, MgO, KAlF4, Na3AlF6, CaF2, etc.). After refining, the melt is allowed to stand for more than 30 minutes. Then, the slag on the surface of the melt is slowly removed using a slag removal tool. During the slag removal process, the melt is avoided from being disturbed, and a pure aluminum alloy melt is obtained.

[0121] The alloying process parameters are as follows: take samples of the above aluminum alloy melt for composition pre-analysis, selectively add intermediate alloys such as Al-Mn, Al-Cr, Al-Mo, Al-Zr, and Al-Sr, as well as Mg ingots according to the composition test results, and turn on electromagnetic stirring for more than 15 minutes to obtain aluminum alloy melt with uniform and qualified composition.

[0122] The process parameters for the second refining are as follows: After alloying, the above-mentioned aluminum alloy melt is transferred to a holding furnace for the second refining. The melt temperature is controlled at 730-750℃, and the refining media are high-purity argon (purity ≥ 99%) and high-purity chlorine (purity ≥ 99%), with an argon flow rate of 10-25 Nm³. 3 / h, chlorine flow rate 4-8 Nm 3 / h, rotor speed 220-280rpm, refining for more than 30 minutes, after refining, remove slag to ensure that there are no large pieces of slag on the surface of the melt;

[0123] The casting process parameters are as follows: casting temperature is controlled at 705-725℃, casting speed is 40~60mm / min, Ti element is introduced in the form of Al-5Ti-1B to refine the grains, and the addition position is in the trough between the holding furnace and the casting machine using an online addition method. The wire feeder speed is calculated based on the amount of Ti element added in the melt to obtain qualified aluminum alloy ingots.

[0124] The above-mentioned ingots are subjected to homogenization treatment: the aluminum alloy ingots are homogenized at 480-540℃ for 2-12 hours.

[0125] After homogenization, hot rough rolling is performed with 12-18 rolling passes, the total deformation is greater than 93%, and the initial rolling temperature is greater than 400℃.

[0126] After hot roughing, hot finishing rolling is carried out, with a total deformation of more than 85% and a final rolling temperature of more than 330℃.

[0127] The hot-rolled material obtained after hot rough rolling is subjected to cold rolling deformation with a deformation amount of 60%-90%.

[0128] Annealing is performed in a box-type annealing furnace at a temperature of 320-400℃ for 2-6 hours, or on a continuous annealing line at a temperature of 460-520℃ for 0-120 seconds.

[0129] The above-mentioned solution will be further described below with reference to specific embodiments; it should be understood that these embodiments are used to illustrate the basic principles, main features and advantages of the present invention, and the present invention is not limited to the scope of the following embodiments; the implementation conditions used in the embodiments can be further adjusted according to specific requirements, and the implementation conditions not specified are usually the conditions in conventional experiments.

[0130] Unless otherwise specified in the following examples, all raw materials are commercially available or prepared by conventional methods in the art.

[0131] Examples 1-7 and Comparative Examples 1-5:

[0132] To determine the properties of the aluminum alloys described in this invention, alloys AA5754, A1-1, A1-2, A1-3, A1-4, and A2 to A8, as shown in Table 2, were prepared according to the method described in this invention. As shown in Table 2, alloy AA5754 is a typical 5754 alloy composition in the AA (Aluminum Association of America) standard; A1-1, A1-2, A1-3, and A1-4 are 5-series aluminum alloys with high Fe, Si, and Mn elements prepared using recycled materials; and A2 to A8 are the novel 5-series aluminum alloys described in this invention.

[0133] Table 2 Alloy Composition

[0134] Preparation methods include:

[0135] First, the scrap aluminum from the can is mixed with a small amount of molten electrolytic aluminum or primary aluminum ingots and added to a smelting furnace to be melted at 760±5℃ to obtain an aluminum alloy melt.

[0136] The first refining was carried out at 740±5℃. During the refining process, electromagnetic stirring was turned on simultaneously. Granular refining agent was used for refining (the refining agent was NaCl, and its amount was 1.5wt.% of the aluminum alloy melt). After the refining was completed, the mixture was allowed to stand for more than 30 minutes. Then, the slag on the surface of the melt was slowly removed using a slag removal tool. During the slag removal process, the melt was kept undisturbed to obtain a pure aluminum alloy melt.

[0137] The alloying process parameters are as follows: take samples of the above aluminum alloy melt for composition pre-analysis, selectively add intermediate alloys such as Al-Mn, Al-Cr, Al-Mo, Al-Zr, Al-Sr, and Al-Sc as well as Mg ingots according to the composition test results, and turn on electromagnetic stirring for more than 15 minutes to obtain aluminum alloy melt with uniform and qualified composition.

[0138] The process parameters for the second refining are as follows: After alloying, the above-mentioned aluminum alloy melt is transferred to a holding furnace for the second refining. The melt temperature is controlled at 740±5℃, and the refining media are high-purity argon and high-purity chlorine, with an argon flow rate of 15 Nm³. 3 / h, chlorine flow rate 5Nm 3 / h, rotor speed 250rpm, refining for more than 30 minutes, after refining, remove slag to ensure that there are no large pieces of slag on the surface of the melt;

[0139] The casting process parameters are as follows: casting temperature is controlled at 715±5℃, casting speed is 48mm / min, Ti element is introduced in the form of Al-5Ti-1B to refine the grains, the addition location is in the trough between the holding furnace and the casting machine using an online addition method, the wire feeder speed is calculated based on the amount of Ti element added in the melt, and an aluminum alloy ingot with the target aluminum alloy composition is obtained.

[0140] The above-mentioned ingots were homogenized. The aluminum alloy ingots were homogenized at 480-540℃ for 2-12 hours. The homogenization process of each embodiment and comparative example is shown in Table 3.

[0141] Table 3 Homogenization Heat Treatment

[0142] The above-mentioned aluminum alloy ingots are first subjected to hot rough rolling at a starting temperature of 450°C and then hot rolled to an intermediate billet in 14 passes, with a hot rough rolling deformation of 95%.

[0143] The intermediate billet is hot-rolled with a deformation of 90% and a final rolling temperature of 340℃.

[0144] The hot-rolled coil was cold-rolled to 1 mm with a cold-rolling deformation of 75%.

[0145] The above-mentioned cold-rolled coils were annealed in a box annealing furnace and held at 360°C for 3 hours to obtain sheet-like aluminum alloy.

[0146] Performance testing:

[0147] (1) Referring to Figures 1 to 12, the as-cast microstructures of each alloy in Table 2 are shown. Figures 13 to 16 show the statistical results of the area percentage and average equivalent diameter of the Fe-rich phase and Mg2Si phase in the as-cast microstructure of the alloys, respectively. Since the Si, Fe, and Mn contents in the conventional AA5754 alloy are low, its as-cast microstructure contains only a small amount of Mg2Si phase and iron-rich phase. Compared with the AA5754 alloy (Comparative Example 1), the Fe-rich phase content and equivalent diameter of the Al-1 alloy (Comparative Example 2) with high Fe and Mn content increased to about 4.4% and 6 μm, respectively. It can be seen that coarse second-phase particles will seriously damage the forming properties of the alloy.

[0148] In Comparative Example 3, the total Sr+Mo content was 0.3 wt%, and the contents of other elements were the same as in Example 1. As can be seen from Figure 3, although the iron-rich phase was refined to a certain extent, large blocky Al particles appeared in the alloy as the Sr+Mo content increased. 12 The Mo and Al4Sr phases form at high temperatures, making them difficult to re-dissolve during subsequent heat treatment and difficult to break down by rolling. The coarse second phases inevitably lead to a reduction in the mechanical properties and plasticity of the alloy.

[0149] In Comparative Example 4, no Sr or Mo elements were added, only 0.1% Zr element was added, and the remaining components were the same as in Example 1. As can be seen from Figure 4, adding Zr alone has almost no refining effect on the Fe-rich phase and Mg2Si phase.

[0150] Comparative Example 5 shows the changes in the alloy microstructure when microalloyed with Zr+Sc, as shown in Figure 5. The alloy contains large-sized and complex Fe-rich phases and Mg2Si phases.

[0151] Although the A2-A8 alloys produced by this invention still contain a large amount of Fe, Si, and Mn elements due to the use of recycled materials, the as-cast microstructure of the A2-A8 alloys has changed significantly compared with the A1-1 alloy through alloy composition optimization, as shown in Figures 6-12; the content and average equivalent diameter of Fe-rich phase and Mg2Si phase in the alloy have been significantly reduced, as shown in the statistics of Figures 13-16.

[0152] (2) Referring to Figures 17-30, the evolution of Fe-rich phase and Mg2Si phase after homogenization treatment of all alloys in Comparative Examples 1-5 and Examples 1-7 can be clearly seen. Even though the AA5754 alloy has extremely low Si and Fe content, after homogenization treatment (two homogenization treatment processes, resulting in AA5754-H1 alloy and AA5754-H2 alloy respectively), the Fe-rich phase and Mg2Si phase cannot be completely dissolved, and the Mg2Si phase content even tends to increase. Due to the increase in Fe, Mn, and Si elements, the Fe-rich phase and Mg2Si phase content and size of alloys A1-1 to A1-4 are significantly increased compared to the AA5754 alloy, and there is no significant change after homogenization treatment (resulting in A1-1-H1 alloy, A1-1-H2 alloy, A1-2-H alloy, A1-3-H alloy, and A1-4-H alloy respectively). However, the A2-A8 alloys produced by this invention (which, after homogenization treatment, yielded A2-H alloy to A8-H alloy respectively) exhibit significantly different variation patterns. After homogenization treatment, the content of the iron-rich phase is significantly reduced compared to the as-cast alloy. Furthermore, the presence of the Mg2Si phase, which is almost difficult to observe, can be observed in the A2-A8 alloys after homogenization treatment.

[0153] Referring to Figures 31 to 33, it can be seen that after homogenization treatment, the uniformity of the dispersed phase distribution of the alloy described in this invention is significantly increased, the number density is improved, and the size of the dispersed phase is reduced, as shown in Figure 33 for alloy A2-H. In contrast, the number density of the dispersed phase in AA5754-H1 is significantly reduced, and severe coarsening occurs (see Figure 31). Although A1-1-H1 has a high number density of dispersed phase, its distribution shows obvious differences, with obvious low number density and coarse areas of dispersed phase at the grain center (see Figure 32).

[0154] (3) As shown in Figure 34, the average equivalent diameter of the second-phase particles in the A2-A8 alloys produced by the method described in this invention after rolling is approximately 0.8-1.5 μm, which is much lower than the average equivalent diameter of the second-phase particles in the comparative examples. The cold-rolled final thickness product was annealed to obtain the final product by treating the sheet to the O state. The tensile properties of the final product were tested according to ISO 6892 standard, and the results are shown in Table 4.

[0155] Table 4 Tensile properties of alloys

[0156] As shown in Table 4, the A2-A8 alloys produced by this invention exhibit higher mechanical properties than conventional 5754 alloys, while possessing similar elongation after fracture. However, the yield strength and tensile strength of the A1-1 to A1-4 alloys and the A1-1 to A1-3 alloys with high Fe, Mn, and Si content are significantly lower than those of the A2-A8 alloys produced by this invention. In particular, the plasticity of the A1-1 to A1-4 alloys is significantly reduced, making it difficult to meet the requirements.

[0157] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

[0158] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

Claims

1. An aluminum alloy, characterized in that, The aluminum alloy comprises, by weight percentage: 2.0 wt.% to 3.2 wt.% Mg, 0.05 wt.% to 0.3 wt.% Cu, 0.4 wt.% to 1.2 wt.% Mn, 0.05 wt.% to 0.3 wt.% Cr, 0.01 wt.% to 0.3 wt.% Zn, less than or equal to 0.15 wt.% Ti, 0 to 0.14 wt.% X1, 0 to 0.14 wt.% X2, 0 to 0.14 wt.% X3, and impurities; The impurities include Fe, Si, and other impurities besides Fe and Si; by weight percentage, the aluminum alloy contains 0.45 wt.% to 0.7 wt.% Fe, 0.1 wt.% to 0.4 wt.% Si, and the total content of other impurities is less than or equal to 0.2 wt.%. The Al content was adjusted so that the total amount of the aluminum alloy was 100 wt.%. Wherein, X1, X2, and X3 are independently selected from Sr, Mo, and Zr, and each of X1, X2, and X3 is different and at least two exist simultaneously, and the total amount of X1, X2, and X3 is less than or equal to 0.15 wt.%. In the alloy microstructure of the aluminum alloy in the O state, the average equivalent diameter of the iron-rich phase is 0.8 to 1.5 μm; in the preparation of the aluminum alloy, at least 10 wt.% of recycled aluminum alloy material is used to prepare the aluminum alloy melt.

2. An aluminum alloy, characterized in that, The aluminum alloy comprises, by weight percentage: 2.0 wt.% to 3.2 wt.% Mg, 0.05 wt.% to 0.3 wt.% Cu, 0.4 wt.% to 1.2 wt.% Mn, 0.05 wt.% to 0.3 wt.% Cr, 0.01 wt.% to 0.3 wt.% Zn, less than or equal to 0.15 wt.% Ti, 0 to 0.14 wt.% X1, 0 to 0.14 wt.% X2, 0 to 0.14 wt.% X3, and impurities; The impurities include Fe, Si, and other impurities besides Fe and Si; by weight percentage, the aluminum alloy contains 0.35 wt.% to 0.7 wt.% Fe, 0.1 wt.% to 0.4 wt.% Si, and the total content of other impurities is less than or equal to 0.2 wt.%. The Al content was adjusted so that the total amount of the aluminum alloy was 100 wt.%. Wherein, X1, X2, and X3 are independently selected from Sr, Mo, and Zr, and each of X1, X2, and X3 is different and at least two exist simultaneously, and the total amount of X1, X2, and X3 is less than or equal to 0.15 wt.%.

3. The aluminum alloy according to claim 2, characterized in that, In the as-cast microstructure of the aluminum alloy, the area percentage of the iron-rich phase is less than or equal to 3.5%, and the average equivalent diameter is less than or equal to 3.5 μm.

4. The aluminum alloy according to claim 2, characterized in that, In the as-cast microstructure of the aluminum alloy, the area percentage of the Mg2Si phase is less than or equal to 1.5%, and the average equivalent diameter is less than or equal to 1.2 μm.

5. The aluminum alloy according to claim 2, 3 or 4, characterized in that, In the alloy microstructure of the aluminum alloy in the O state, the average equivalent diameter of the iron-rich phase is 0.8–1.5 μm.

6. The aluminum alloy according to claim 2, characterized in that, The alloy microstructure of the aluminum alloy comprises dispersed particles, wherein the dispersed particles include: (1) Selected from one or more of Al6Mn dispersed phase particles, Al4Mn dispersed phase particles, Al6(FeMn) dispersed phase particles, Al(FeMnCr)Si dispersed phase particles, and Al7Cr dispersed phase particles; (2) Selected from Al 12 Mo dispersed phase particles, Al 38 Mg 58 Two or three of the following: Sr4 dispersed phase particles and Al3Zr dispersed phase particles.

7. The aluminum alloy according to claim 6, characterized in that, The average equivalent diameter of the dispersed particles is less than or equal to 100 nm, and the number density of the dispersed particles is 5-20 particles / μm. 2 Further, 8-15 cells / μm 2 .

8. The aluminum alloy according to claim 2, characterized in that, The total amount of Mg, Cu and Mn is greater than or equal to 2.5 wt.%.

9. The aluminum alloy according to claim 2, characterized in that, The aluminum alloy, by weight percentage, comprises: 2.0 wt.% to 3.0 wt.% Mg, 0.05 wt.% to 0.3 wt.% Cu, 0.5 wt.% to 1.2 wt.% Mn, 0.05 wt.% to 0.3 wt.% Cr, 0.05 wt.% to 0.25 wt.% Zn, less than or equal to 0.1 wt.% Ti, 0 to 0.12 wt.% X1, 0 to 0.12 wt.% X2, 0 to 0.12 wt.% X3, and 0.4 wt.% to 0.7 wt.% Fe, 0.15 wt.% to 0.4 wt.% Si, and less than or equal to 0.15 wt.% other impurities, with the Al content adjusted to make the total amount of the aluminum alloy 100 wt.%.

10. The aluminum alloy according to claim 9, characterized in that, The aluminum alloy, by weight percentage, comprises: 2.0 wt.% to 3.0 wt.% Mg, 0.05 wt.% to 0.3 wt.% Cu, 0.6 wt.% to 1.0 wt.% Mn, 0.05 wt.% to 0.3 wt.% Cr, 0.15 wt.% to 0.25 wt.% Zn, 0.02 wt.% to 0.06 wt.% Ti, 0.01 wt.% to 0.12 wt.% X1, 0.01 wt.% to 0.12 wt.% X2, 0.01 wt.% to 0.12 wt.% X3, and 0.4 wt.% to 0.7 wt.% Fe, 0.15 wt.% to 0.4 wt.% Si, and other impurities less than or equal to 0.15 wt.%, with the Al content adjusted to bring the total amount of the aluminum alloy to 100 wt.%.

11. The aluminum alloy according to claim 2, 9, or 10, characterized in that, The aluminum alloy contains 0.45 wt.% to 0.7 wt.% Fe by weight.

12. The aluminum alloy according to any one of claims 2, 8-10, characterized in that, The ratio of the total amount of Mg and Mn to the content of Cr is 10-70:

1.

13. The aluminum alloy according to any one of claims 2, 8-10, characterized in that, The ratio of Mg content to Cu content is 8-55:

1.

14. The aluminum alloy according to any one of claims 2, 8-10, characterized in that, The aluminum alloy, in the O state, has a yield strength greater than or equal to 140 MPa, a tensile strength greater than or equal to 260 MPa, and an elongation after fracture greater than or equal to 20%; further, the aluminum alloy, in the O state, has a yield strength greater than or equal to 145 MPa, a tensile strength greater than or equal to 260 MPa, and an elongation after fracture greater than or equal to 21.5%.

15. The aluminum alloy according to any one of claims 2, 8-10, characterized in that, The aluminum alloy is a 5-series aluminum alloy.

16. A method for preparing the aluminum alloy according to any one of claims 1-15, characterized in that, The preparation method includes: Provide an aluminum alloy melt containing at least 10 wt.% recycled aluminum alloy material, and form the aluminum alloy melt into an aluminum alloy ingot; The aluminum alloy ingot is homogenized to obtain a first intermediate. The first intermediate is subjected to a first hot rolling process, and the deformation per pass of the first hot rolling is controlled to be greater than or equal to 5%, and the total deformation is greater than or equal to 90%, to obtain a second intermediate. The second intermediate is subjected to a second hot rolling process, and the total deformation is controlled to be greater than or equal to 85% to obtain the third intermediate. The third intermediate is subjected to cold rolling deformation with a deformation amount of 60%-90%; Annealing treatment.

17. The method for preparing the aluminum alloy according to claim 16, characterized in that, The content of recycled aluminum alloy material in the aluminum alloy melt is greater than or equal to 20%, preferably greater than or equal to 30%, more preferably greater than or equal to 40%, and even more preferably greater than or equal to 50%.

18. The method for preparing the aluminum alloy according to claim 17, characterized in that, The content of recycled aluminum alloy material in the aluminum alloy melt is greater than or equal to 60%, preferably greater than or equal to 70%, more preferably greater than or equal to 85%, and even more preferably greater than or equal to 95%.

19. The method for preparing the aluminum alloy according to claim 16, characterized in that, In the first hot rolling, the deformation per pass is greater than or equal to 6%, and the total deformation is greater than or equal to 93%; and / or, in the second hot rolling, the total deformation is controlled to be greater than or equal to 88%.

20. The method for preparing the aluminum alloy according to claim 16, characterized in that, The homogenization treatment is performed at a temperature of 480-540℃ for a time of 2-12 hours; and / or, In the first hot rolling, the initial rolling temperature is 400-500℃; in the second hot rolling, the final rolling temperature is 320-360℃; and / or, The annealing process is performed at a temperature of 320-400℃ for 2-6 hours, or the annealing process is carried out on a continuous annealing line, heated to 460-520℃ and held for 0-120 seconds.

21. An aluminum alloy, characterized in that, The aluminum alloy comprises, by weight percentage: 2.0 wt.% to 3.2 wt.% Mg, 0.05 wt.% to 0.3 wt.% Cu, 0.4 wt.% to 1.2 wt.% Mn, 0.05 wt.% to 0.3 wt.% Cr, 0.01 wt.% to 0.3 wt.% Zn, less than or equal to 0.15 wt.% Ti, and impurities; The impurities include Fe, Si, and other impurities besides Fe and Si; by weight percentage, the aluminum alloy contains 0.35 wt.% to 0.7 wt.% Fe, 0.1 wt.% to 0.4 wt.% Si, and the total content of other impurities is less than or equal to 0.2 wt.%. The aluminum alloy also contains two or three of Sr, Mo, and Zr as additives, the content of the additives is less than or equal to 0.15 wt.%, and the content of any one element in the additives is 0.1-10 times the content of the other elements; The Al content was adjusted so that the total amount of the aluminum alloy was 100 wt.%.

22. The aluminum alloy according to claim 21, characterized in that, In the additive, the content of any one element is 0.2-8 times, and more specifically 0.4-5 times, that of the other elements.

23. An aluminum alloy, characterized in that, The aluminum alloy was prepared using the following method: (1) A raw material containing at least 10 wt.% recycled aluminum alloy material is provided, and then smelted, first refined, alloyed, second refined, and cast in sequence to produce an aluminum alloy ingot; wherein, by weight percentage, the aluminum alloy contains: 2.0 wt.% to 3.2 wt.% Mg, 0.05 wt.% to 0.3 wt.% Cu, 0.4 wt.% to 1.2 wt.% Mn, 0.05 wt.% to 0.3 wt.% Cr, 0.01 wt.% to 0.3 wt.% Zn, less than or equal to 0.15 wt.% Ti, 0 to 0.14 wt.% Sr, 0 to 0.14 wt.% Mo, 0 to 0.14 wt.% Zr, and impurities; The impurities include Fe, Si, and other impurities besides Fe and Si; by weight percentage, the aluminum alloy contains 0.35 wt.% to 0.7 wt.% Fe, 0.1 wt.% to 0.4 wt.% Si, and the total content of other impurities is less than or equal to 0.2 wt.%. The Al content was adjusted so that the total amount of the aluminum alloy was 100 wt.%. The Sr, Mo, and Zr are present in at least two of them at the same time, and the total amount of Sr, Mo, and Zr is less than or equal to 0.15 wt.%. (2) The aluminum alloy ingot is homogenized at a temperature of 480-540℃ and held for 2-12 hours. (3) Hot roughing is carried out with 12-18 rolling passes, the total deformation is greater than 93%, and the initial rolling temperature is greater than 400℃. (4) Hot finishing rolling is carried out with a total deformation of more than 85% and a final rolling temperature of more than 330℃. (5) Perform cold rolling deformation with a deformation amount of 60%-90%; (6) Annealing is carried out in a box-type annealing furnace at a temperature of 320-400℃ for 2-6 hours, or on a continuous annealing line at a temperature of 460-520℃ for 0-120 seconds.

24. The use of an aluminum alloy as described in any one of claims 1-15, or an aluminum alloy as described in any one of claims 21-23, in the manufacture of automobile body parts, rail vehicle structural parts, or ship structural parts.

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