High-strength and high-toughness regenerated Al-Mn-Mg aluminum alloy and preparation method and application thereof

Abstract

The invention discloses a high-strength and high-toughness regenerated Al-Mn-Mg aluminum alloy as well as a preparation method and application thereof. The high-strength and high-toughness regenerated Al-Mn-Mg aluminum alloy consists of the following components in percentage by mass: 0.50-0.75% of Mn, 0.50-0.75% of Mg, 0.50-0.75% of 0.2%-0.4% of Si; 1.0% to 1.5% of Mg; 0.4%-1.0% of Fe; 0.01%-0.05% of RE (rare earth); 0.005% to 0.020% of Sr; 0.01% to 0.02% of Ti; b: 0.002% to 0.004%; less than or equal to 0.15% of inevitable impurity elements; al: the balance; rE is at least one of La and Ce. According to the method, the waste aluminum alloy is utilized in a low-cost manner, and the regenerated aluminum alloy with excellent processability and mechanical property is finally prepared.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloy recycling, and in particular to a high-strength and high-toughness recycled Al-Mn-Mg aluminum alloy and a preparation method and application thereof. Background Art

[0002] Aluminum alloys have the advantages of low density, good corrosion resistance and excellent ductility, and are widely used in packaging, construction, and household appliances. 3XXX series aluminum alloys have good corrosion resistance and deep drawing properties, and are often used in the body of aluminum cans. According to statistics, the production and sales volume of aluminum cans in my country will reach 60 billion cans in 2023, with an average service life of 0.2 years, and the vast majority of aluminum cans are recycled. However, due to the influence of the use environment and recycling conditions, impurity elements (such as Fe, Si, etc.) will inevitably be introduced during the recycling process of aluminum cans, which will affect the mechanical properties of the recycled materials.

[0003] Iron usually exists in the form of Al6(FeMn) phase and α-Al(MnFe)Si phase in 3XXX series aluminum alloys. When the Fe content is high (>0.25%), the iron-rich phase is formed in the shape of coarse Chinese characters, showing a network-connected coupling structure in three-dimensional space. This structure is composed of multiple thin-sheet dendrites interconnected with each other, which greatly splits the aluminum matrix and ultimately reduces the processing and mechanical properties of the aluminum alloy. Therefore, improving the microstructure of high-Fe content Al-Mn-Mg aluminum alloys is critical for the grade-preserving utilization of aluminum cans.

[0004] CN 108374109 A discloses a method for preparing recycled aluminum alloy from discarded cans, by adding 0.4% to 1.3% Ce to improve the grain size and distribution, thereby improving the performance of the recycled aluminum alloy. However, the purpose of adding a high content of Ce to the aluminum alloy is to refine the grain structure, and there is no obvious improvement effect on the iron-rich phase. CN107400806 A discloses an intermediate alloy AlMn for the modification of the iron-rich phase of recycled aluminum. 10 W x (x = 1 ~ 5), the master alloy can be used for the modification and regeneration of the iron-rich phase in the cast aluminum alloy, which can not only reduce the addition of manganese, but also further reduce the iron-rich phase. 10 W xThe W element is contained in the iron-rich phase, and its preparation cost is high and the preparation difficulty is great. CN108998687 A discloses an iron-rich phase modifier containing Si, Fe, Mn and B, and obtains fine α-Fe particles by hot extrusion, which are used as nucleation inhibition points of the iron-rich phase for modifying the iron-rich phase. However, since the iron-rich phase modifier contains a high content of Si and Fe, it is easy to cause an increase in the content of impurity elements in the aluminum alloy. It can be seen that the above three methods are difficult to achieve the ideal aluminum alloy regeneration effect.

[0005] Therefore, it is of great significance to develop a low-cost aluminum alloy recycling method that can achieve grade-preserving utilization of waste aluminum alloys and prepare recycled aluminum alloys with excellent processing properties and mechanical properties. Summary of the invention

[0006] One of the purposes of the present invention is to overcome the problems of existing aluminum alloy recycling methods, such as high cost, increased impurity content of aluminum alloy and deterioration of performance, and to provide a low-cost aluminum alloy recycling method that can achieve grade-preserving utilization of waste aluminum alloy.

[0007] A second object of the present invention is to provide a recycled Al-Mn-Mg aluminum alloy with excellent processing performance and mechanical properties.

[0008] A third object of the present invention is to provide an application of recycled Al-Mn-Mg aluminum alloy.

[0009] The technical solution adopted by the present invention is:

[0010] A high-strength and high-toughness recycled Al-Mn-Mg aluminum alloy, which consists of the following components in mass percentage:

[0011] Mn: 0.50%~0.75%;

[0012] Si: 0.2%~0.4%;

[0013] Mg: 1.0%~1.5%;

[0014] Fe: 0.4%~1.0%;

[0015] RE: 0.01%~0.05%;

[0016] Sr: 0.005%~0.020%;

[0017] Ti: 0.01%~0.02%;

[0018] B: 0.002%~0.004%;

[0019] Unavoidable impurity elements: ≤0.15%;

[0020] Al: margin;

[0021] The RE is at least one of La and Ce.

[0022] Preferably, the RE and Sr are added in the form of Al-Sr-RE.

[0023] Preferably, the Ti and B are added in the form of Al-Ti-B.

[0024] Preferably, the content of Fe is 1.5 times or more of the content of Si.

[0025] A method for preparing the high-strength and high-toughness recycled Al-Mn-Mg aluminum alloy as described above comprises the following steps:

[0026] 1) Melting: adding discarded aluminum cans, 3XXX series aluminum waste and 5XXX series aluminum waste into aluminum liquid for melting to obtain a melt;

[0027] 2) First refining: Heat the melt to 730℃~750℃, add refining agent and let stand;

[0028] 3) Adjust alloy composition: Take samples to test alloy composition, replenish raw materials according to the designed composition, and then take samples to test to ensure that the alloy composition is qualified;

[0029] 4) Second refining: add refining agent and let stand;

[0030] 5) Composite modification: remove the scum on the surface of the melt, add Al-Sr-RE composite modifier for modification, add covering agent and let it stand;

[0031] 6) Casting: Add Al-Ti-B refiner into the melt, and then cast it to obtain high-strength and high-toughness recycled Al-Mn-Mg aluminum alloy.

[0032] Preferably, the discarded aluminum cans in step 1) are pretreated, and the pretreatment operations include crushing, removing impurities and drying.

[0033] Preferably, the standing time in step 2) is 10 min to 30 min.

[0034] Preferably, the standing time in step 4) is 10 min to 30 min.

[0035] Preferably, the standing time in step 5) is 10 min to 30 min.

[0036] A can comprises the above-mentioned high-strength and high-toughness recycled Al-Mn-Mg aluminum alloy.

[0037] Preferably, the body of the can comprises a high-strength and high-toughness recycled Al-Mn-Mg aluminum alloy.

[0038] The beneficial effects of the present invention are as follows: the present invention improves the type, morphology and distribution of iron-rich phases in high-Fe content recycled Al-Mn-Mg aluminum alloys through component optimization design and Al-Sr-RE composite modification, realizes the grade-preserving utilization of waste aluminum alloys through a low-cost method, and finally prepares recycled aluminum alloys with excellent processing properties and mechanical properties.

[0039] Specifically:

[0040] 1) In terms of composition design, the present invention is based on recycled waste aluminum cans, greatly increases the allowable amount of Fe, and correspondingly reduces the content of Mn, keeping the total amount of Mn and Fe relatively constant, that is, the total amount of iron-rich phase remains unchanged, which is beneficial to inhibiting the growth of grains during thermal deformation. On the other hand, a lower Si content is designed, and Si mainly exists in the form of Mg2Si phase and α-Al(MnFe)Si phase, because higher Si will promote the transformation of Al6(FeMn) phase to α-Al(MnFe)Si phase, and the morphology of the iron-rich phase changes from granular and short rod-like to coarse Chinese character-like, which is not conducive to improving the deformation processing ability and mechanical properties of the alloy. Therefore, the Si content is an important element for regulating the type and morphology of the iron-rich phase. In addition, the Mg2Si phase is the main strengthening phase of the alloy, and a higher Mg content is beneficial to increase the formation kinetics of the Mg2Si phase, so that higher strength can be obtained;

[0041] 2) In terms of morphology control of the iron-rich phase, the present invention adopts Al-Sr-RE composite modification, utilizing the highly active phases of Sr and RE doped mutually in the composite modifier, including Al4 (SrRE) phase and Al 11 (SrRE)3 phase. A trace amount of composite modifier is added, Sr and RE mainly exist in the form of mutually doped atomic clusters. The highly active atomic clusters are easily adsorbed on the surface of the solid phase (for example: iron-rich phase and its nucleation particles) in the melt, which is beneficial to inhibit the nucleation and growth of the iron-rich phase, promote the refinement and modification of the iron-rich phase, and can greatly improve the distribution uniformity of the iron-rich phase in the cast rod. At the same time, the grain boundary and intracrystalline microsegregation of elements such as Fe, Mn, and Si can also be improved. In the selection of rare earths, the present invention selects La and Ce, which are abundant in reserves and low in price, and the addition ratio is controlled at 0.01% to 0.05%, which reduces the production cost of the alloy;

[0042] 3) In order to improve the deformation ability of the alloy, the present invention adds Al-Ti-B refiner to refine the grains;

[0043] In summary, the present invention greatly reduces the harm of the iron-rich phase, increases the tolerance of the alloy to impurity elements, and promotes the grade-preserving utilization of waste cans through component optimization design and Al-Sr-RE composite modification treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is the SEM image of the high-strength and high-toughness recycled Al-Mn-Mg aluminum alloy in Example 1.

[0045] Figure 2 This is the SEM image of the regenerated Al-Mn-Mg aluminum alloy in Comparative Example 2. DETAILED DESCRIPTION

[0046] The present invention will be further explained and illustrated below in conjunction with specific embodiments.

[0047] Embodiment 1:

[0048] A high-strength and high-toughness recycled Al-Mn-Mg aluminum alloy is composed of the following components in mass percentage: Mn: 0.75%; Si: 0.25%; Mg: 1.25%; Fe: 0.5%; Ce: 0.02%; Sr: 0.015%; Ti: 0.01%; B: 0.002%; the remainder is inevitable impurity elements (≤0.15%) and Al.

[0049] The preparation method of the above-mentioned high-strength and high-toughness recycled Al-Mn-Mg aluminum alloy is as follows:

[0050] 1) Melting: pre-processed (including crushing, impurity removal and drying) waste aluminum cans, 3XXX series waste aluminum and 5XXX series waste aluminum are added into the aluminum liquid in the double-chamber furnace through the side well feeding method (to promote the waste aluminum to be drawn into the aluminum liquid to reduce burning loss) for melting to obtain a melt;

[0051] 2) First refining: The melt is transferred to an alloying furnace, and then heated to 730°C, and then 0.15% of a commercially available aluminum alloy refining agent (halide) is introduced with 99.9% purity nitrogen as a carrier, and allowed to stand for 20 minutes (to purify the melt);

[0052] 3) Adjust alloy composition: Take samples to test alloy composition, and start electromagnetic stirring device for 5 minutes after adding raw materials according to the designed composition (to accelerate raw material dissolution and composition homogenization), and then take samples to test to ensure that the alloy composition is qualified;

[0053] 4) Second refining: using nitrogen with a purity of 99.9% as a carrier, introduce 0.1% by mass of a commercially available aluminum alloy refining agent (halide) into the melt and let it stand for 10 minutes (to purify the melt);

[0054] 5) Composite modification: remove the scum on the surface of the melt, add 0.3% Al-8Sr-8Ce composite modifier by mass, start the electromagnetic stirring device for 2 minutes, add 0.01% of commercially available aluminum alloy covering agent (chloride), and let it stand for 30 minutes;

[0055] 6) Casting: The melt is introduced into a flow channel provided with 0.02% Al-5Ti-1B refiner, and then flows into a casting plate after passing through a graphite rotor degassing box and a two-stage ceramic filter plate / box to obtain a high-strength and high-toughness recycled Al-Mn-Mg aluminum alloy (aluminum alloy round bar).

[0056] The scanning electron microscope (SEM) image of the high-strength and high-toughness recycled Al-Mn-Mg aluminum alloy in this embodiment is as follows: Figure 1 shown.

[0057] Depend on Figure 1 It can be seen that the iron-rich phase in the high-strength and high-toughness recycled Al-Mn-Mg aluminum alloy is mainly composed of fine, granular Al6 (FeMn) phase, and the distribution uniformity is good.

[0058] Embodiment 2:

[0059] A high-strength and high-toughness recycled Al-Mn-Mg aluminum alloy is composed of the following components in mass percentage: Mn: 0.5%; Si: 0.4%; Mg: 1.5%; Fe: 1.0%; La: 0.05%; Sr: 0.02%; Ti: 0.015%; B: 0.003%; the remainder is inevitable impurity elements (≤0.15%) and Al.

[0060] The preparation method of the above-mentioned high-strength and high-toughness recycled Al-Mn-Mg aluminum alloy is as follows:

[0061] 1) Melting: adding the pre-treated (including crushing, impurity removal and drying) waste aluminum cans, 3XXX series waste aluminum and 5XXX series waste aluminum into the aluminum liquid in the double-chamber furnace through the side well feeding method to melt and obtain a melt;

[0062] 2) First refining: The melt was transferred to an alloying furnace, and then heated to 750°C, and then 0.2% by mass of a commercially available aluminum alloy refining agent (halide) was introduced with 99.9% purity nitrogen as a carrier, and allowed to stand for 10 minutes;

[0063] 3) Adjust alloy composition: Take samples to test alloy composition, and start electromagnetic stirring device for 3 minutes after replenishing raw materials according to the designed composition, and then take samples to test to ensure that the alloy composition is qualified;

[0064] 4) Second refining: Using 99.9% pure nitrogen as a carrier, 0.05% mass fraction of commercially available aluminum alloy refining agent (halide) is introduced into the melt and allowed to stand for 20 minutes;

[0065] 5) Composite modification: remove the scum on the surface of the melt, add 0.5% Al-6Sr-10La composite modifier by mass, start the electromagnetic stirring device for 1 minute, add 0.008% of commercially available aluminum alloy covering agent (chloride), and let it stand for 10 minutes;

[0066] 6) Casting: The melt is introduced into a flow channel provided with 0.25% Al-4Ti-1B refiner, and then flows into a casting plate after passing through a graphite rotor degassing box and a two-stage ceramic filter plate / box to obtain a high-strength and high-toughness recycled Al-Mn-Mg aluminum alloy (aluminum alloy flat ingot).

[0067] Embodiment 3:

[0068] A high-strength and high-toughness recycled Al-Mn-Mg aluminum alloy, which consists of the following components in mass percentage: Mn: 0.6%; Si: 0.3%; Mg: 1.0%; Fe: 0.8%; Ce: 0.02%; La: 0.01%; Sr: 0.005%; Ti: 0.02%; B: 0.004%; the remainder is inevitable impurity elements (≤0.15%) and Al.

[0069] The preparation method of the above-mentioned high-strength and high-toughness recycled Al-Mn-Mg aluminum alloy is as follows:

[0070] 1) Melting: adding the pre-treated (including crushing, impurity removal and drying) waste aluminum cans, 3XXX series waste aluminum and 5XXX series waste aluminum into the aluminum liquid in the double-chamber furnace through the side well feeding method to melt and obtain a melt;

[0071] 2) First refining: The melt was transferred to an alloying furnace, and then heated to 740°C, and then 0.12% of a commercially available aluminum alloy refining agent (halide) was introduced with 99.9% purity nitrogen as a carrier, and allowed to stand for 15 minutes;

[0072] 3) Adjust alloy composition: Take samples to test alloy composition, and start electromagnetic stirring device for 6 minutes after replenishing raw materials according to the designed composition, and then take samples to test to ensure that the alloy composition is qualified;

[0073] 4) Second refining: Using 99.9% pure nitrogen as a carrier, 0.08% mass fraction of commercially available aluminum alloy refining agent (halide) was introduced into the melt and allowed to stand for 25 minutes;

[0074] 5) Composite modification: remove the scum on the surface of the melt, add 0.2% Al-5Sr-6.7Ce-3.4La composite modifier, start the electromagnetic stirring device for 2 minutes, add 0.005% of commercially available aluminum alloy covering agent (chloride), and let it stand for 15 minutes;

[0075] 6) Casting: The melt is introduced into a flow channel provided with 0.15% Al-5Ti-1B refiner, and then flows into a casting plate after passing through a graphite rotor degassing box and a two-stage ceramic filter plate / box to obtain a high-strength and high-toughness recycled Al-Mn-Mg aluminum alloy (aluminum alloy flat ingot).

[0076] Embodiment 4:

[0077] A high-strength and high-toughness recycled Al-Mn-Mg aluminum alloy, which consists of the following components in mass percentage: Mn: 0.7%; Si: 0.35%; Mg: 1.15%; Fe: 0.7%; Ce: 0.02%; La: 0.02%; Sr: 0.012%; Ti: 0.018%; B: 0.0034%; the remainder is inevitable impurity elements (≤0.15%) and Al.

[0078] The preparation method of the above-mentioned high-strength and high-toughness recycled Al-Mn-Mg aluminum alloy is as follows:

[0079] 1) Melting: adding the pre-treated (including crushing, impurity removal and drying) waste aluminum cans, 3XXX series waste aluminum and 5XXX series waste aluminum into the aluminum liquid in the double-chamber furnace through the side well feeding method to melt and obtain a melt;

[0080] 2) First refining: The melt was transferred to an alloying furnace, and then heated to 735°C, and then 0.18% of a commercially available aluminum alloy refining agent (halide) was introduced with 99.9% purity nitrogen as a carrier, and allowed to stand for 25 minutes;

[0081] 3) Adjust alloy composition: Take samples to test alloy composition, and start electromagnetic stirring device for 4 minutes after replenishing raw materials according to the designed composition, and then take samples to test to ensure that the alloy composition is qualified;

[0082] 4) Second refining: Using 99.9% pure nitrogen as a carrier, 0.06% mass fraction of commercial aluminum alloy refining agent (halide) was introduced into the melt and allowed to stand for 15 minutes;

[0083] 5) Composite modification: remove the scum on the surface of the melt, add 0.4% Al-5Sr-5Ce-5La composite modifier, start the electromagnetic stirring device for 3 minutes, add 0.006% of commercially available aluminum alloy covering agent (chloride), and let it stand for 25 minutes;

[0084] 6) Casting: The melt is introduced into a flow channel provided with 0.1% Al-3Ti-1B refiner, and then flows into a casting plate after passing through a graphite rotor degassing box and a two-stage ceramic filter plate / box to obtain a high-strength and high-toughness recycled Al-Mn-Mg aluminum alloy (aluminum alloy round bar).

[0085] Comparative Example 1:

[0086] A recycled Al-Mn-Mg aluminum alloy (aluminum alloy round bar) is the same as the high-strength and high-toughness recycled Al-Mn-Mg aluminum alloy in Example 1, except that the Si content is adjusted from "0.25%" to "0.5%".

[0087] Comparative Example 2:

[0088] A regenerated Al-Mn-Mg aluminum alloy (aluminum alloy round rod), except that the "Al-8Sr-8Ce composite modifier" in step 5) is replaced by "Al-8Ce modifier" during preparation, the rest is the same as Example 1.

[0089] The SEM image of the recycled Al-Mn-Mg aluminum alloy in this comparative example is as follows: Figure 2 shown.

[0090] Depend on Figure 2 It can be seen that the morphology of the iron-rich phase in the regenerated Al-Mn-Mg aluminum alloy obtained by replacing the Al-8Sr-8Ce composite modifier with the Al-8Ce modifier is changed from Figure 1 The granular shape in the sample is transformed into coarse Chinese character shape, and the density of the recycled Al-Mn-Mg aluminum alloy is significantly reduced.

[0091] Comparative Example 3:

[0092] A regenerated Al-Mn-Mg aluminum alloy (aluminum alloy round rod), except that the "Al-8Sr-8Ce composite modifier" in step 5) is replaced by "Al-8Sr modifier" during preparation, the rest is the same as Example 1.

[0093] Comparative Example 4:

[0094] A regenerated Al-Mn-Mg aluminum alloy (aluminum alloy round rod), except that the "Al-8Sr-8Ce composite modifier" in step 5) is replaced by "Al-8Sr modifier" and "Al-8Ce modifier" during preparation, the rest is the same as Example 1.

[0095] Mechanical properties test:

[0096] The mechanical properties of the high-strength and high-toughness recycled Al-Mn-Mg aluminum alloys in Examples 1 to 4 and the recycled Al-Mn-Mg aluminum alloys in Comparative Examples 1 to 4 were tested with reference to "GB / T 228.1 Metallic Materials Tensile Test Part 1: Room Temperature Test Methods". The test results are shown in the following table:

[0097] Table 1 Mechanical properties test results of recycled Al-Mn-Mg aluminum alloy

[0098] Test items Tensile strength(MPa) Yield strength (MPa) Elongation(%) Example 1 199±5 106±3 19.0±1.5 Comparative Example 1 205±8 110±5 13.5±2.2 Comparative Example 2 195±6 105±6 14.5±2.5 Comparative Example 3 200±6 105±4 15.0±1.9 Comparative Example 4 201±4 108±5 15.5±2.3 Example 2 210±3 110±3 16.5±1.2 Example 3 195±5 105±4 18.0±1.6 Example 4 201±2 106±3 17.5±1.4

[0099] From Table 1, we can see that:

[0100] 1) Compared with the high-strength and high-toughness recycled Al-Mn-Mg aluminum alloy in Example 1, the strength of the recycled Al-Mn-Mg aluminum alloy in Comparative Example 1 is slightly increased, but the plasticity (elongation) is significantly reduced by 28.9%, indicating that increasing the Si content is not conducive to improving the plasticity of the recycled Al-Mn-Mg aluminum alloy;

[0101] 2) Compared with the high-strength and high-toughness recycled Al-Mn-Mg aluminum alloy in Example 1, the strength of the recycled Al-Mn-Mg aluminum alloy in Comparative Examples 2 and 3 did not change significantly, but the plasticity decreased by 23.7% and 21.1%, respectively, indicating that the effect of the composite addition of Sr and Ce is better than that of adding the same amount of Sr and Ce alone;

[0102] 3) Compared with the high-strength and high-toughness recycled Al-Mn-Mg aluminum alloy in Example 1, the plasticity of the recycled Al-Mn-Mg aluminum alloy in Comparative Example 4 is reduced by 18.4%, indicating that the addition of Sr and Ce in the form of Al-8Sr-8Ce has a better effect on improving the properties of the aluminum alloy than Al-8Sr and Al-8Ce;

[0103] In summary, the present invention can significantly improve the mechanical properties of the alloy by optimizing the composition of the recycled aluminum alloy and modifying the iron-rich phase, which is beneficial to the grade-preserving utilization of waste can materials.

[0104] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A high-strength and high-toughness recycled Al-Mn-Mg aluminum alloy, characterized in that: The following components are present in percentage by weight composition: Mn: 0.50%~0.75%; Si: 0.2%~0.4%; Mg: 1.0%~1.5%; Fe: 0.4%~1.0%; RE: 0.01%~0.05%; Sr：0.005％～0.020％； Ti: 0.01%~0.02%; B：0.002％～0.004％； Unavoidable impurity elements: ≤0.15%; Al: margin; The RE is at least one of La and Ce.

2. The high-strength and high-toughness recycled Al-Mn-Mg aluminum alloy according to claim 1, characterized in that: The RE and Sr are Added in the form of Al-Sr-RE.

3. The high-strength and high-toughness recycled Al-Mn-Mg aluminum alloy according to claim 1 or 2, characterized in that: The Ti and B are added in the form of Al-Ti-B.

4. The high-strength and high-toughness recycled Al-Mn-Mg aluminum alloy according to claim 1 or 2, characterized in that: The Fe content is 1.5 times or more of the Si content.

5. A method for preparing a high-strength and high-toughness recycled Al-Mn-Mg aluminum alloy as claimed in any one of claims 1 to 4, characterized in that: The following steps are involved: 1) Melting: adding discarded aluminum cans, 3XXX series aluminum waste and 5XXX series aluminum waste into aluminum liquid for melting to obtain a melt; 2) First refining: Heat the melt to 730℃~750℃, add refining agent and let stand; 3) Adjust alloy composition: Take samples to test alloy composition, replenish raw materials according to the designed composition, and then take samples to test to ensure that the alloy composition is qualified; 4) Second refining: add refining agent and let stand; 5) Composite modification: remove the scum on the surface of the melt, add Al-Sr-RE composite modifier for modification, add covering agent and let it stand; 6) Casting: Add Al-Ti-B refiner into the melt, and then cast it to obtain high-strength and high-toughness recycled Al-Mn-Mg aluminum alloy.

6. The preparation method according to claim 5, characterized in that: Step 1) The waste aluminum cans are pretreated, and the pretreatment operations include crushing, removing impurities and drying.

7. The preparation method according to claim 5 or 6, characterized in that: The standing time in step 2) is 10 to 30 minutes.

8. The preparation method according to claim 5 or 6, characterized in that: The standing time in step 4) is 10 to 30 minutes.

9. The preparation method according to claim 5 or 6, characterized in that: Step 5) The standing time is 10 min to 30 min.

10. A can, characterized in that: The invention comprises the high-strength and high-toughness recycled Al-Mn-Mg aluminum alloy as described in any one of claims 1 to 4.

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