Preparation method of tough A356 regenerated aluminum alloy with high iron content and regenerated aluminum alloy

Abstract

The invention relates to a preparation method of a tough A356 regenerated aluminum alloy with high iron content and the regenerated aluminum alloy. Belongs to the technical field of aluminum alloy regeneration. According to the method, regenerated A356 aluminum alloy with the iron content being 0.15-0.25 wt% serves as a raw material, Al-Mn mother alloy and Al-Cr mother alloy are sequentially added in the aluminum liquid melt homogenizing stage, and then rare earth mother alloy and Al-Sc mother alloy continue to be added; then, refined particles are added; and finally, controlling the cooling speed to be greater than or equal to 15 DEG C / s during casting. According to the method, many problems in preparation of the high-iron-content regenerated aluminum alloy are effectively solved, and unification of high iron content and good obdurability performance is achieved.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method of a high-iron-content strong-tough A356 recycled aluminum alloy of an aluminum alloy and the recycled aluminum alloy. BACKGROUND

[0002] Casting aluminum alloys are widely used in the fields of automobiles, aerospace, ships and general machinery due to their low density, high specific strength and excellent casting performance. Among them, A356 alloy, as a typical Al-Si-Mg series casting aluminum alloy, is mainly composed of Al-Si eutectic matrix and Mg2Si strengthening phase, and cooperates with appropriate amounts of Si (about 6.5% to 7.5%) and Mg (about 0.3% to 0.5%), and has good casting fluidity, mechanical properties and corrosion resistance, and is often used to manufacture engine blocks, hubs, supports and other complex structure castings. With the increasing demand for lightweight materials in industrial production, the production of A356 alloy continues to increase, and the waste generated in the production and processing process (such as sprues, flash, unqualified castings, etc.) also forms a large-scale recyclable resource.

[0003] Recycled aluminum is a metal material prepared by recycling waste aluminum alloy and re-melting, and its raw material is mainly derived from waste generated in the processing and use of various aluminum alloys. Due to the wide application of A356 alloy in the casting industry, recycled A356 aluminum alloy becomes an important part of aluminum resources. The use of recycled aluminum can significantly reduce energy consumption (the energy consumption of primary aluminum is about 14000-16000 kWh per ton, while the energy consumption of recycled aluminum is only 5%-10%) and carbon emissions. In actual production, recycled A356 aluminum alloy is usually obtained by mixing and melting waste A356 alloy waste with other aluminum alloy waste and adjusting the composition to be close to the standard range of A356 alloy (such as Si and Mg content control), which can effectively alleviate the shortage of primary aluminum resources and reduce the manufacturing cost.

[0004] However, recycled aluminum has the problem of enrichment of impurity elements, especially iron. Because the melting point of iron is very high, it is most likely to be enriched. In the recycling system of aluminum alloy, iron mainly comes from waste. Because the solubility of iron in aluminum alloy melt is very low, excess iron cannot exist in the form of elemental or solid solution, but preferentially forms intermetallic compound phases with aluminum and other elements (such as silicon). In the A356 alloy system, these iron-based compounds mainly include needle-shaped or flaky β-Fe phases and part of blocky or short rod-shaped α-Fe phases, and their formation process is closely related to the cooling rate of the melt, the composition ratio and the solidification conditions.

[0005] From the perspective of material properties, the morphology and distribution of iron-based compounds have a significant impact on the mechanical properties of aluminum alloys. The β-Fe phase usually grows along a specific crystal direction with a high aspect ratio, which can easily serve as a path for crack initiation and propagation in the matrix, leading to a significant decrease in the elongation of the material. Although the α-Fe phase has a lower aspect ratio, its hardness is higher and its interface with the matrix has a weaker bonding strength, which can easily cause stress concentration under external force. When the iron content in recycled A356 aluminum alloy exceeds a certain threshold, the number and size of iron-based compounds increase, which intensifies the damage to the continuity of the matrix, resulting in a significant decrease in the elongation of the casting (when the iron content in the conventional A356 alloy is less than 0.15%, the elongation can reach 10-15%; when the iron content increases to more than 0.25%, the elongation is usually less than 3%), and the impact toughness and fatigue performance of the material are also adversely affected.

[0006] To improve the negative impact of high iron content on the properties of recycled A356 aluminum alloy, the existing technology usually uses alloying methods to control the morphology of iron phase. For example, by adding transition elements such as manganese and chromium, the interaction between iron and these elements can promote the transformation of the original needle-like β-Fe phase into blocky or short rod-like α-Fe phase, thereby reducing the aspect ratio of the iron phase. This method is based on the principle of phase transformation of iron-based compounds, and by adjusting the alloy composition to change the crystal structure and growth tendency of the iron phase, the crack sensitivity can be theoretically reduced. However, in practical applications, it is found that although the transformation of β-Fe phase to α-Fe phase can change the morphology of iron phase to some extent, the transformed α-Fe phase usually still maintains a large size, and its blocky structure can still form stress concentration points in the matrix. In addition, the addition amount of manganese and chromium needs to be strictly controlled, and excessive introduction may cause other side effects (such as the formation of new brittle phases or the influence on the main strengthening phase of the alloy).

[0007] In addition to alloying control, melt treatment techniques such as grain refinement and modification treatment have also been tried to improve the distribution and effect of iron phase. For example, the invention patent application with the publication number CN 118814036 A discloses a high-strength heat-treatment-free aluminum alloy and its preparation method; it uses recycled A356 aluminum alloy prepared from waste aluminum as the aluminum source, after refining, it first uses Al-Ti-B for grain refinement, then uses mixed rare earth intermediate alloy for modification treatment, and finally performs vacuum high-pressure casting to obtain a recycled aluminum alloy with high tensile strength, high yield strength, and high elongation. However, this process requires the iron content to be controlled below 0.2%; that is, this method mainly targets the optimization of the matrix structure, and lacks specificity in controlling the size of the iron phase and the stability of the morphology, and it is difficult to effectively suppress the size of the iron phase and improve the overall performance of the material when the iron content is high (such as more than 0.20%).

[0008] Directly reducing the iron content in molten aluminum alloys is technically challenging. Currently, the common approach is to dilute the iron content by adding high-purity electrolytic aluminum, rather than removing it directly. However, electrolytic aluminum is energy-intensive; furthermore, adding high-purity aluminum also dilutes other elements, necessitating the simultaneous addition of other functional elements such as Si and Mg. Therefore, improving the tolerance for iron (e.g., keeping the iron content within the range of 0.15% to 0.35%, especially approaching or exceeding the actual recycled raw material level of 0.25%) is a key area for breakthrough in current recycled aluminum alloy technology. Summary of the Invention

[0009] The present invention aims to solve the above problems and thus provides a method for preparing a high-iron-content, strong and tough recycled A356 aluminum alloy.

[0010] The technical solution of the present invention to solve the above problems is as follows:

[0011] A method for preparing a high-iron-content, high-strength recycled A356 aluminum alloy includes the following steps:

[0012] S1. Using recycled A356 aluminum alloy with an iron content of 0.15~0.25wt% as raw material, after pretreatment, it is smelted at 730~750℃ to form molten aluminum.

[0013] S2. During the homogenization stage of the molten aluminum, Al-Mn master alloy and Al-Cr master alloy are added sequentially.

[0014] S3. Continue to add rare earth master alloy and Al-Sc master alloy;

[0015] S4. Add fine particles and disperse them evenly in the molten aluminum at 740~750℃;

[0016] S5. During casting, control the cooling rate to ≥15℃ / s so that the size of the needle-like β-Fe phase is ≤8 μm and the size of the α-Fe phase is ≤10 μm in the microstructure of the solidified aluminum liquid.

[0017] Preferably, in step S2, the Mn content is controlled to be 0.30~0.50 wt%; and the Cr content is controlled to be 0.05~0.15 wt%.

[0018] Preferably, in step S3, the rare earth master alloy is selected from at least one of Al-La, Al-Ce, and Al-Eu, and the total content of rare earth elements is controlled to be 0.05~0.15 wt%.

[0019] Preferably, in step S3, the Sc content is controlled to be 0.05~0.10 wt%.

[0020] Preferably, in step S4, the refined particles are at least one of TiB2, Al2O3, and TiC, and the total content of the refined particles is controlled to be 0.05%~0.15 wt%.

[0021] Preferably, in step S5, the cooling is achieved using a casting process, combined with a high thermal conductivity copper / steel mold that has an internal water cooling system.

[0022] Preferably, after step S5, the elongation of the resulting strong and tough recycled A356 aluminum alloy is ≥8%.

[0023] Preferably, the Fe content of the recycled A356 aluminum alloy waste is 0.20~0.25 wt%, and the iron content is not intentionally reduced through iron removal processes during the preparation process.

[0024] The present invention provides a method for preparing a high-iron-content, high-toughness recycled A356 aluminum alloy. This method uses recycled A356 aluminum alloy as a raw material and, through a series of process steps and parameter control, the various technical features work together to form an organic whole. This method effectively solves many problems faced in the preparation of high-iron-content recycled aluminum alloys and achieves a balance between high iron content and good strength and toughness.

[0025] First, this invention uses recycled A356 aluminum alloy with an iron content of 0.15~0.25wt% as raw material, which is pretreated and then melted at 730~750℃ to form molten aluminum. This step lays the foundation for the entire scheme. The raw material is directly selected from recycled aluminum alloy waste with a high iron content, breaking through the strict iron content restriction requirements of traditional processes, reducing the cost of raw material pretreatment, and especially eliminating the need for additional iron removal processes or dilution of pure aluminum raw materials, thus avoiding the problems of increased energy consumption and costs. The melting temperature range of 730~750℃ ensures that the molten aluminum has good fluidity, which is conducive to the uniform mixing of various alloying elements and fine particles in the subsequent process, while avoiding the problems of accelerated oxidation and burn-off caused by high temperature and excessive energy consumption. It provides a stable melt environment for the uniform dispersion and reaction of various elements in the subsequent steps, which is a prerequisite for the effective implementation of all subsequent process steps.

[0026] Next, during the homogenization stage of the molten aluminum, Al-Mn and Al-Cr master alloys were added sequentially, controlling the Mn content to be 0.30–0.50 wt% and the Cr content to be 0.05–0.15 wt%. Mn is a key element in regulating the morphology of the iron phase. It can form compounds with iron, preferentially combining with Fe in the acicular β-Fe phase, inhibiting its growth in a single direction, and promoting the gradual transformation of the acicular β-Fe phase into short rod-shaped or granular shapes, thereby initially refining the size of the β-Fe phase. Simultaneously, the appropriate addition of Mn can also provide a certain solid solution strengthening effect on the aluminum matrix without significantly increasing the alloy's brittleness. Although the amount of Cr added is relatively low, it can form complex intermetallic compounds with iron, further inhibiting the coarse growth of the α-Fe phase (blocky / short rod-shaped), and synergistically with Mn to enhance the properties of the aluminum matrix, playing an auxiliary and supplementary role in regulating the iron phase. The synergistic addition of Mn and Cr allows for the control of the morphology and size of the iron phase from the source, creating favorable conditions for further refinement of the iron phase.

[0027] Next, rare earth master alloys and Al-Sc master alloys are added. Rare earth elements (La, Ce, Eu, etc.) can adsorb onto the nuclei of β-Fe and α-Fe phases, altering their crystal growth direction, inhibiting preferential growth of the iron phase along its long axis, and promoting the transformation of the iron phase from needle-like / blocky to more regular short rod-like or granular shapes, further refining the iron phase size. Simultaneously, rare earths can form nanoscale rare earth compounds with aluminum, acting as heterogeneous nucleation cores, indirectly refining primary α-Fe grains and enhancing overall microstructure uniformity. Sc can form Al3Sc nanoscale precipitates with Al. These precipitates possess extremely high thermal stability, preferentially distributing at grain boundaries and iron phase interfaces, hindering iron phase growth and pinning grain boundaries, reducing iron phase segregation at grain boundaries. This not only further refines the iron phase size but also improves the alloy's strength and toughness, complementing and reinforcing the refining effect of rare earth elements. The synergistic addition of rare earth elements and Sc further reduces the size of the iron phase and makes the microstructure more uniform, providing an important microstructural guarantee for obtaining good mechanical properties.

[0028] Then, refined particles are added and uniformly dispersed in the molten aluminum at 740-750℃. These refined particles, such as TiB2, Al2O3, and TiC, possess high melting points and high hardness. After being uniformly dispersed in the molten aluminum, they significantly inhibit the agglomeration and coarse growth of iron phase particles through a physical barrier effect. These particles adsorb at the crystallization front of the iron phase, interrupting its directional growth trend. Combined with the chemical regulation and refinement effects of Mn, Cr, rare earth elements, and Sc on the iron phase, they precisely control the size of the iron phase, ensuring that it remains stable within the target size range during subsequent solidification.

[0029] Finally, during casting, the cooling rate is controlled at ≥15℃ / s, employing a casting process and utilizing a high-thermal-conductivity copper / steel mold with an internal water-cooling system. Rapid cooling significantly reduces the growth time of the iron phase during solidification, inhibiting its excessive elongation along specific directions and ensuring that the results of controlling the iron phase size in the preceding steps are preserved. The β-Fe phase size is strictly controlled to ≤8μm, and the α-Fe phase size is limited to ≤10μm. Through precise control of this rapid cooling process parameter, the iron phase size and overall microstructure reach their optimal state, providing a direct guarantee for improving the final alloy properties.

[0030] Through the synergistic effect of the above series of steps, the resulting strong and tough recycled A356 aluminum alloy has an elongation of ≥8%. Furthermore, it achieves a balance between high iron content and excellent strength and toughness under conditions where the Fe content is as high as 0.20~0.25 wt% (close to or exceeding the upper limit of iron content in traditional recycled aluminum) and without deliberate iron removal (or dilution). Traditional high-iron-content recycled aluminum typically has an elongation of <3% due to the presence of coarse acicular β-Fe phase. This solution, through the synergistic effect of various technical features, refines the size of the acicular β-Fe phase from >10μm in traditional processes to ≤8μm, and limits the size of the α-Fe phase to ≤10μm. This significantly reduces the cutting effect of the iron phase on the matrix and the stress concentration effect, allowing the alloy to maintain a high iron content while possessing good toughness and a certain strength. This solves the industry problem of poor performance and limited application of recycled aluminum alloys due to high iron content in raw materials, while also reducing raw material pretreatment costs and energy consumption, demonstrating significant technical advantages and economic benefits.

[0031] In summary, the present invention has the following beneficial effects:

[0032] This invention provides a method for preparing a high-iron-content, high-toughness recycled A356 aluminum alloy. By selecting recycled A356 aluminum alloy as raw material and controlling a series of process steps and parameters, the various technical characteristics work together to form an organic whole. This method effectively solves many problems faced in the preparation of high-iron-content recycled aluminum alloys and achieves a balance between high iron content and good strength and toughness. Attached Figure Description

[0033] Figure 1 This is a graph showing the tensile test results of Example 1;

[0034] Figure 2 This is a comparison diagram of the micrograin size of three parts of the original A356.2 and the recycled A356-REC80 aluminum alloy wheel hub of Example 1;

[0035] Figure 3 This is a morphology diagram of the silicon and Fe phases in the core portion of the regenerated A356-REC80 wheel in Example 1;

[0036] Figure 4 These are morphological images of the α-Fe and β-Fe phases in the regenerated A356-REC80 wheel core in Example 1;

[0037] Figure 5 This is a graph showing the tensile test results of Example 2;

[0038] Figure 6 This is a graph showing the tensile test results of Example 3;

[0039] Figure 7 This is a graph showing the tensile test results of Example 4;

[0040] Figure 8 This is a graph showing the tensile test results of Example 5;

[0041] Figure 9 This is a diagram showing the tensile test results for Comparative Example 1;

[0042] Figure 10 This is a diagram showing the tensile test results of Comparative Example 2. Detailed Implementation

[0043] The present invention will be further explained and described below with reference to the accompanying drawings.

[0044] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. Any changes made by those skilled in the art after reading this specification, as long as they fall within the scope of the claims, will be protected by patent law.

[0045] Example 1

[0046] A method for preparing a high-iron-content, high-toughness recycled A356 aluminum alloy, using recycled A356 aluminum alloy scrap with an Fe content of 0.25 wt% as raw material (after pretreatment, other components meet A356 standards: Si 6.8~7.2 wt%, Mg 0.35~0.45 wt%, balance being Al and unavoidable impurities). The method includes the following steps:

[0047] Smelting: After being cleaned by sandblasting and dried, the scrap is placed in a resistance furnace and smelted at 740±5℃ to form a uniform aluminum liquid.

[0048] Mn / Cr addition: During the homogenization stage of the aluminum melt, Al-Mn master alloy and Al-Cr master alloy are added to control the Mn content in the aluminum melt to be 0.40wt% and the Cr content to be 0.10wt%.

[0049] Rare Earth & Sc Addition: Continue to add mixed rare earth master alloy (Al-La+Al-Ce, La to Ce mass ratio of about 1:1) and Al-Sc master alloy, wherein the total content of rare earth elements is 0.10wt% and the content of Sc elements is 0.08wt%.

[0050] Addition of refined particles: Add composite refined particles of TiB2 (80wt%) and Al2O3 (20wt%) (total addition amount 0.10wt%), and uniformly disperse them in the aluminum liquid by mechanical stirring (300rpm, 10min) at 745±5℃.

[0051] Casting: High thermal conductivity copper molds with internal water cooling system are used for casting, and the cooling rate is controlled to be ≥15℃ / s (the measured average cooling rate is about 18℃ / s).

[0052] Performance Testing: Tensile properties of profiles prepared under different parameters were tested using a Zwick Roell Z050 tensile testing machine. The elongation of the specimens was precisely measured using a fully automated MakroXtens extensometer. Tensile specimens with a thickness of 2.5 mm were prepared along the extrusion direction of the profiles using wire cutting technology. After cutting, the surface of the specimens was polished to ensure a smooth and burr-free surface, guaranteeing the accuracy of the test results.

[0053] Performance results:

[0054] like Figure 1 As shown, the alloy elongation is 13.11% and Rm is 337 MPa.

[0055] like Figure 2 As shown, the microstructure after solidification shows that the size of the needle-like β-Fe phase is ≤10μm and the size of the α-Fe phase is ≤8μm.

[0056] from Figure 3 As can be seen, under a 500μm scale, there is no essential difference in morphology between the original A356 aluminum alloy wheel and the recycled A356-REC80 aluminum alloy wheel of this application in terms of micrograin size comparison in three parts. Figure 3 and Figure 4 It can be seen that, through the optimization process of this invention, many problems faced in the preparation of high iron content recycled aluminum alloys are effectively solved, and the unity of high iron content and good strength and toughness is achieved.

[0057] Example 2

[0058] Compared to Example 1, only the amount of Mn and Cr added in step S2 was adjusted:

[0059] The Mn content was controlled at 0.30 wt%;

[0060] The Cr content is controlled at 0.05 wt%.

[0061] The remaining steps and parameters are exactly the same as in Example 1.

[0062] Performance testing: Same as in Example 1.

[0063] Performance results:

[0064] like Figure 5 As shown, the alloy elongation is 8.19% and Rm is 296 MPa.

[0065] Example 3

[0066] Compared to Example 1, only the amount of rare earth master alloy added in step S3 was adjusted:

[0067] The total content of rare earth elements is controlled at 0.05 wt%.

[0068] The remaining steps and parameters are exactly the same as in Example 1.

[0069] Performance testing: Same as in Example 1.

[0070] Performance results:

[0071] like Figure 6 As shown, the alloy elongation is 7.68% and Rm is 319 MPa.

[0072] Example 4

[0073] Compared to Example 1, only the amount of Al-Sc master alloy added in step S3 was adjusted:

[0074] The total content of Sc element is controlled at 0.05 wt%.

[0075] The remaining steps and parameters are exactly the same as in Example 1.

[0076] Performance testing: Same as in Example 1.

[0077] Performance results:

[0078] like Figure 7 As shown, the alloy elongation is 9.41% and Rm is 313 MPa.

[0079] Example 5

[0080] Compared to Example 1, only the amount of fine particles added in step S4 was adjusted:

[0081] The total amount of fine particles is controlled at 0.05 wt%.

[0082] The remaining steps and parameters are exactly the same as in Example 1.

[0083] Performance testing: Same as in Example 1.

[0084] Performance results:

[0085] like Figure 8As shown, the alloy elongation is 8.48% and Rm is 334 MPa.

[0086] Comparative Example 1

[0087] Raw materials and process: Same as in Example 1, but step S2 is missing.

[0088] Performance testing: Same as in Example 1.

[0089] Performance results:

[0090] like Figure 9 As shown, the alloy elongation is 6.52% and Rm is 333 MPa.

[0091] Comparative Example 2

[0092] Raw materials and process: Same as in Example 1, but step S4 is missing.

[0093] Performance testing: Same as in Example 1.

[0094] Performance results:

[0095] like Figure 10 As shown, the alloy elongation is 6.78% and Rm is 301 MPa.

[0096] Based on the comparison of the embodiments and comparative examples, it can be seen that:

[0097] The key to achieving a balance between high iron content (0.25wt%) and high strength and toughness lies in the synergistic effect of all process parameters: when Mn (0.40wt%), Cr (0.10wt%), rare earth elements (total 0.10wt%), Sc (0.08wt%), and refined particles (total 0.10wt%) are all added within the preferred range, and the cooling rate is ≥15℃ / s, the alloy elongation reaches 13.11% (far exceeding <3% of traditional high iron content recycled aluminum), the tensile strength Rm=337MPa, and the microstructure has β-Fe phase ≤10μm and α-Fe phase ≤8μm, with no essential difference in grain size and morphology from the primary aluminum alloy, thus verifying the effectiveness of the technical solution.

[0098] Mn / Cr content directly affects the iron phase refinement effect: when Mn and Cr are reduced to the lower limit, the elongation (8.19%) and Rm (296MPa) are significantly lower than the optimal group, but still within the effective range.

[0099] The addition of rare earth elements (REEs) and Sc significantly enhances performance: when the total REE content is reduced to the lower limit of 0.05 wt%, the elongation and Rm decrease; when the Sc content is reduced to the lower limit, the elongation is lower than that of the optimal group, but still within the effective range, indicating that the synergistic effect of rare earth elements and Sc in refining grains and pinning grain boundaries is crucial for improving strength and toughness.

[0100] The addition of fine particles refines the iron phase through physical barrier: when the total amount of fine particles is reduced to the lower limit, the elongation and Rm still meet the standards, but are significantly lower than the optimal group, indicating that the fine particles have a key synergistic effect on further inhibiting the coarsening of the iron phase and improving performance.

[0101] The absence of key steps led to a significant deterioration in performance: when Mn / Cr was missing, the elongation was only 6.52% and Rm=333MPa (it is reasonable to assume that the iron phase was not effectively refined); when fine particles were missing (Comparative Example 2), the elongation was 6.78% and Rm=301MPa (it is reasonable to assume that the iron phase size was large), both of which were far lower than the optimal group, directly proving that Mn / Cr and fine particles are the core processes for suppressing the harm of high iron content.

[0102] In summary, this invention, by controlling the synergistic addition of Mn, Cr, rare earth elements, Sc, and refined particles, achieves precise control over the iron phase size (β-Fe≤10μm, α-Fe≤8μm) and strength and toughness (elongation ≥8%, up to 13.11%; Rm≥296MPa, up to 337MPa) in high-iron-content raw materials, thus solving the industry problem of preparing high-iron-content recycled aluminum alloys.

Claims

1. A method for preparing a high-iron-content, high-strength, and tough recycled A356 aluminum alloy, characterized in that, Includes the following steps: S1. Using recycled A356 aluminum alloy with an iron content of 0.15~0.25wt% as raw material, after pretreatment, it is smelted at 730~750℃ to form molten aluminum. S2. During the homogenization stage of the molten aluminum, Al-Mn master alloy and Al-Cr master alloy are added sequentially. S3. Continue to add rare earth master alloy and Al-Sc master alloy; S4. Add fine particles and disperse them evenly in the molten aluminum at 740~750℃; S5. During casting, control the cooling rate to ≥15℃ / s so that the size of the needle-like β-Fe phase is ≤8 μm and the size of the α-Fe phase is ≤10 μm in the microstructure of the solidified aluminum liquid.

2. The method for preparing a high-iron-content, high-toughness recycled A356 aluminum alloy according to claim 1, characterized in that: In step S2, the Mn content is controlled at 0.30~0.50 wt%; the Cr content is controlled at 0.05~0.15 wt%.

3. The method for preparing a high-iron-content, high-strength, and tough recycled A356 aluminum alloy according to claim 1, characterized in that: In step S3, the rare earth master alloy is selected from at least one of Al-La, Al-Ce, and Al-Eu, and the total content of rare earth elements is controlled to be 0.05~0.15 wt%.

4. The method for preparing a high-iron-content, high-strength, and tough recycled A356 aluminum alloy according to claim 1, characterized in that: In step S3, the Sc content is controlled to be 0.05~0.10 wt%.

5. The method for preparing a high-iron-content, high-toughness recycled A356 aluminum alloy according to claim 1, characterized in that: In step S4, the refined particles are at least one of TiB2, Al2O3, and TiC, and the content of refined particles is controlled to be 0.05~0.15 wt%.

6. The method for preparing a high-iron-content, high-toughness recycled A356 aluminum alloy according to claim 1, characterized in that: In step S5, the cooling is achieved using a casting process, combined with a high thermal conductivity copper / steel mold that has an internal water cooling system.

7. The method for preparing a high-iron-content, high-toughness recycled A356 aluminum alloy according to claim 1, characterized in that, The Fe content of the recycled A356 aluminum alloy waste is 0.20~0.25 wt%, and the iron content is not intentionally reduced through iron removal processes during the preparation process.

8. A high-iron-content, high-toughness recycled A356 aluminum alloy prepared by the method according to any one of claims 1 to 7, characterized in that: The elongation of the recycled A356 aluminum alloy is ≥8%.

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