Medium strength 7xxx-series recycled aluminum alloy part with high recycled content and method of making

Abstract

The present application provides a high-recycled-material-ratio medium-strength 7xxx-series recycled aluminum alloy part and a preparation method thereof. The high-recycled-material-ratio medium-strength 7xxx-series recycled aluminum alloy part contains at least 75 wt% of recycled aluminum material, the recycled aluminum material includes at least two different recycled aluminum materials from at least one of 5xxx-series and 6xxx-series aluminum alloys, and the high-recycled-material-ratio medium-strength 7xxx-series recycled aluminum alloy part has a tensile strength of 350-550 MPa, a yield strength of 300-500 MPa, and an elongation of greater than 10% under T6 heat treatment. The present application can effectively overcome the disadvantage that the recycled aluminum material of the conventional medium-strength 7xxx-series recycled aluminum alloy part is not easy to obtain, and can improve the recycled material ratio of the medium-strength 7xxx-series recycled aluminum alloy part.

Description

Technical Field

[0001] This invention relates to a medium-strength recycled aluminum alloy part and its preparation method, and particularly to a medium-strength 7xxx series recycled aluminum alloy part with a high recycled aluminum content and its preparation method. Background Technology

[0002] Aluminum possesses advantages such as low density and high strength. By adding different alloying components, aluminum alloys with varying properties can be obtained, leading to their widespread application in various fields and a continuously increasing demand. For example, 5xxx series aluminum alloys, whose main alloying component is magnesium, have moderate strength and good weldability and corrosion resistance, thus they are commonly used in marine equipment, ships, and automotive components. 6xxx series aluminum alloys, whose main alloying components are magnesium and silicon, have excellent machinability, moderate strength, and corrosion resistance, thus they are commonly used in construction, transportation, electronic products, and consumer goods. 7xxx series aluminum alloys, whose main alloying components are magnesium and zinc, with copper content adjustable according to downstream product requirements, are heat-treatable aluminum alloys. High-strength 7xxx series aluminum alloys are widely used in the aerospace industry, while medium-strength 7xxx series aluminum alloys (generally referring to 7xxx series alloys with UTS < 550MPa under T6 heat treatment and lower copper content) are suitable for automotive structural materials, sporting goods, and consumer electronics.

[0003] Due to the wide range of applications and increasing consumption of aluminum alloys, recycling aluminum alloy waste and reusing it is a goal pursued by researchers in related fields. However, limited by the alloy composition content of recycled aluminum alloy materials, recycled aluminum alloys are usually made from the same series of recycled aluminum materials into the same series of recycled aluminum alloy products. In order to increase the proportion of recycled aluminum materials in recycled aluminum alloys, many recycled aluminum alloy products relax the upper limit of alloy composition to meet the requirement of increasing the amount of recycled materials used, but this method comes with the risk of sacrificing the performance of recycled aluminum alloys.

[0004] Furthermore, the recycling of aluminum alloys also faces varying degrees of difficulty due to their different applications. For example, 5xxx and 6xxx series aluminum alloys have high market demand and abundant sources of recycled aluminum. High-strength 7xxx series aluminum alloys are widely used in the aerospace industry, and it is easy to establish a large-scale recycling system through the integration of upstream and downstream supply chains. However, medium-strength 7xxx series aluminum alloys are less widely used in various industries (automotive structural materials, sporting goods, consumer electronics, etc.), and recycling is less common. It is also difficult to obtain recycled materials with similar alloy compositions, making it difficult to increase the proportion of recycled materials from medium-strength 7xxx series aluminum alloys.

[0005] Therefore, overcoming the problem of insufficient recycled material sources for medium-strength 7xxx series aluminum alloys, which leads to a low proportion of recycled aluminum alloys in recycled products, is the goal that this case aims to actively improve. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing medium-strength 7xxx series recycled aluminum alloy parts with a high proportion of recycled materials.

[0007] The preparation method of the present invention includes the steps of raw material selection and composition design, purification and refining, melting, and alloy composition conditioning.

[0008] The raw material selection and composition design steps provide at least two types of recycled aluminum materials, and the recycled aluminum materials are at least from one of the 5xxx series aluminum alloys and the 6xxx series aluminum alloys. Based on the content specifications of the target alloying elements of the medium-strength 7xxx series recycled aluminum alloy parts to be prepared, the addition ratio of the recycled aluminum materials and the original pure aluminum ingots is determined to obtain the initial mixture.

[0009] The purification and refining step, based on the target alloy element content specifications for the desired medium-strength 7xxx series recycled aluminum alloy parts, involves purifying and refining at least one of the recycled aluminum materials in the initial mixture, removing a portion of the content of at least one alloy element in the at least one recycled aluminum material, to obtain an intermediate.

[0010] The melting step melts the different series of recycled aluminum materials, primary pure aluminum ingots, and intermediates obtained after the purification and refining steps of the initial mixture into an aluminum alloy molten soup, and the weight percentage (wt%) of each alloying element in the aluminum alloy molten soup is not greater than the weight percentage (wt%) of the corresponding alloying element of the target alloying element.

[0011] The alloy composition quenching and tempering step adjusts the weight percentage of each alloying element in the aluminum alloy molten metal to the content specification range of each alloying element corresponding to the target alloying element, thereby obtaining a quenched and tempered aluminum alloy molten metal. With the weight of the quenched and tempered aluminum alloy molten metal as 100wt%, the content of the recycled aluminum material is at least 75wt%.

[0012] In the preparation method of the present invention, the source of the recycled aluminum material may also be at least one of the 1xxx series aluminum alloys and the 7xxx series aluminum alloys, wherein the 1xxx series aluminum alloys are selected from at least one of 1050, 1070 and 1100, and the 7xxx series aluminum alloys are selected from at least one of 7050 and 7150.

[0013] In the preparation method of the present invention, the 5xxx series aluminum alloy of the recycled aluminum material is selected from at least one of 5050, 5051 and 5056, and the 6xxx series aluminum alloy is selected from at least one of 6060, 6061 and 6063.

[0014] The preparation method of the present invention further includes a casting step, wherein the quenched and tempered aluminum alloy molten metal is cast and subsequently extruded.

[0015] The preparation method of the present invention includes a purification and refining step of at least one of boron treatment and segregation purification treatment to remove at least a portion of the corresponding alloying elements.

[0016] The preparation method of the present invention comprises the following components in the tempered aluminum alloy molten metal: not more than 0.15 wt% silicon, not more than 0.2 wt% iron, not more than 0.4 wt% copper, not more than 0.30 wt% manganese, 0.5-2.0 wt% magnesium, 4.0-8.0 wt% zinc, not more than 0.2 wt% chromium, not more than 0.06 wt% titanium, not more than 0.25 wt% zirconium, and an equal amount of aluminum.

[0017] Furthermore, another object of the present invention is to provide a medium-strength 7xxx series recycled aluminum alloy part with a high proportion of recycled material. The medium-strength 7xxx series recycled aluminum alloy part with a high proportion of recycled material is prepared by the preparation method described above and contains at least 75 wt% recycled aluminum.

[0018] Among them, the medium-strength 7xxx series recycled aluminum alloy parts with a high proportion of recycled materials, under T6 heat treatment, have a tensile strength between 350-550MPa, a yield strength between 300-500MPa, and an elongation greater than 10%.

[0019] The medium-strength 7xxx series recycled aluminum alloy parts with a high proportion of recycled materials of the present invention are composed of: no more than 0.15 wt% silicon, no more than 0.2 wt% iron, no more than 0.4 wt% copper, no more than 0.30 wt% manganese, 0.5-2.0 wt% magnesium, 4.0-8.0 wt% zinc, no more than 0.2 wt% chromium, no more than 0.06 wt% titanium, no more than 0.25 wt% zirconium, and a balanced amount of aluminum.

[0020] The beneficial effects of this invention are as follows: using at least two different recycled aluminum materials as raw materials, and at least one of the recycled aluminum materials being recycled materials of 5xxx series and 6xxx series aluminum alloys with sufficient supply, combined with a purification and refining process, and adjusting the composition content with virgin pure aluminum ingots and alloying elements, a medium-strength 7xxx series recycled aluminum alloy part containing at least 75wt% recycled aluminum material can be obtained. This can effectively overcome the disadvantage that recycled aluminum materials are not easy to obtain in existing medium-strength 7xxx series recycled aluminum alloy parts, and can increase the proportion of recycled material in medium-strength 7xxx series recycled aluminum alloy parts. Attached Figure Description

[0021] Other features and effects of the present invention will be clearly presented in the embodiments with reference to the accompanying drawings, wherein:

[0022] Figure 1 This is a flowchart illustrating one embodiment of the method for preparing medium-strength 7xxx series recycled aluminum alloy parts with a high proportion of recycled materials according to the present invention. Detailed Implementation

[0023] An embodiment of the method for preparing medium-strength 7xxx series recycled aluminum alloy parts with a high proportion of recycled materials according to the present invention is used to prepare medium-strength 7xxx series recycled aluminum alloy parts with a high proportion of recycled materials.

[0024] The high proportion of recycled material in the medium-strength 7xxx series recycled aluminum alloy parts is characterized by the fact that its constituent raw materials contain at least 75 wt% recycled aluminum material, and the recycled aluminum material includes at least two recycled aluminum alloys that are different from the medium-strength 7xxx series recycled aluminum alloy parts.

[0025] Specifically, the recycled aluminum material includes at least one of two types of aluminum alloys, namely, 5xxx series aluminum alloys and 6xxx series aluminum alloys. The 5xxx series aluminum alloys can be selected from at least one of 5050, 5051, and 5056, and the 6xxx series aluminum alloys can be selected from at least one of 6060, 6061, and 6063.

[0026] In some embodiments, the recycled aluminum material may also be sourced from 1xxx series aluminum alloys and 7xxx series aluminum alloys.

[0027] The 1xxx series aluminum alloys of the recycled aluminum material are selected from at least one of 1050, 1070, and 1100, and the 7xxx series aluminum alloys of the recycled aluminum material are selected from at least one of 7050 and 7150.

[0028] The composition of the medium-strength 7xxx series recycled aluminum alloy parts with a high proportion of recycled materials includes: no more than 0.15 wt% silicon, no more than 0.2 wt% iron, no more than 0.4 wt% copper, no more than 0.30 wt% manganese, 0.5-2.0 wt% magnesium, 4.0-8.0 wt% zinc, no more than 0.2 wt% chromium, no more than 0.06 wt% titanium, no more than 0.25 wt% zirconium, and a balanced amount of aluminum. Furthermore, under T6 heat treatment, the medium-strength 7xxx series recycled aluminum alloy parts with a high proportion of recycled materials have a tensile strength between 350-550 MPa, a yield strength between 300-500 MPa, and an elongation greater than 10%.

[0029] In some embodiments, the high-recycled-material-ratio medium-strength 7xxx series recycled aluminum alloy parts contain at least 80 wt% recycled aluminum material, which includes recycled materials mainly composed of 5xxx series aluminum alloys and 6xxx series aluminum alloys, and the total weight percentage of the 5xxx series aluminum alloys and 6xxx series aluminum alloys is not less than 40 wt%, based on the weight percentage of the recycled aluminum material content being 100 wt%.

[0030] In other embodiments, the total weight percentage of the recycled aluminum material in 5xxx series and 6xxx series aluminum alloys is between 40 and 50 wt%.

[0031] The following is a description of an embodiment of the method for preparing medium-strength 7xxx series recycled aluminum alloy parts with a high proportion of recycled materials according to the present invention.

[0032] See Figure 1 The preparation method of medium-strength 7xxx series recycled aluminum alloy parts with high recycled material ratio of the present invention includes a raw material selection and composition design step 21, a purification and refining step 22, a melting step 23, an alloy composition conditioning step 24, and a casting step 25.

[0033] The raw material selection and composition design step 21 involves providing at least two types of recycled aluminum materials and, based on the target alloy element content specifications for the medium-strength 7xxx series recycled aluminum alloy parts to be prepared, calculating and determining the mixing ratio of the different recycled aluminum materials and the amount of virgin pure aluminum ingots to be added, in order to obtain an initial mixture.

[0034] The recycled aluminum material is derived from at least one of the 5xxx series aluminum alloys and the 6xxx series aluminum alloys. Furthermore, the recycled aluminum material may also originate from at least one of the 1xxx series aluminum alloys and the 7xxx series aluminum alloys.

[0035] Specifically, the 5xxx series aluminum alloys, 6xxx series aluminum alloys, 1xxx series aluminum alloys, and 7xxx series aluminum alloys in the recycled aluminum material can be selected from at least one of 5050, 5051, and 5056; at least one of 6060, 6061, and 6063; at least one of 1050, 1070, and 1100; and at least one of 7050 and 7150.

[0036] It should be noted that, because the sources of recycling are different, the recycled aluminum material can be a specific grade of recycled material or recycled material containing other different components / grades. Therefore, the grade of the recycled aluminum material described in this specification can refer not only to a specific grade of recycled aluminum material, but also to recycled material with the specified grade as the main component (content greater than 50%) but mixed with other different components / grades.

[0037] Next, the purification and refining step 22 is carried out. According to the target alloy element content specifications of the medium-strength 7xxx series recycled aluminum alloy parts to be prepared, at least one of the recycled aluminum materials in the initial mixture is selected for purification and refining to remove part of the content of at least one alloy element in the at least one recycled aluminum material to obtain an intermediate.

[0038] Specifically, the purification and refining step 22 involves calculating the alloy element content of the initial mixture (at least two types of recycled aluminum materials and virgin pure aluminum ingots) based on the proportions of each recycled aluminum material, and comparing it with the target alloy element content of the desired medium-strength 7xxx series recycled aluminum alloy parts. At least one type of recycled aluminum material in the initial mixture is then selected for purification and refining. Alloy elements with excessively large differences, and / or elements that do not require the presence of the target alloy element, are removed to pre-adjust the content of each alloy element in the initial mixture to be no greater than the content of the corresponding target alloy element, or to ensure that the difference between the content of each alloy element and the content of the corresponding target alloy element is within a preset range. The purification and refining process includes at least one of boron treatment and segregation purification treatment.

[0039] The boron treatment involves melting the recycled aluminum material to be purified into an aluminum molten solution, and then adding a boron master alloy to the molten solution. Boron reacts with titanium (Ti), zirconium (Zr), vanadium (V), and chromium (Cr) in the molten aluminum to form borides, which then precipitate. These precipitates are then separated, allowing the removal of titanium (Ti), zirconium (Zr), vanadium (V), and chromium (Cr).

[0040] The segregation purification process involves melting the recycled aluminum material to be purified into a molten aluminum solution, which is then allowed to solidify slowly. During solidification, elements such as silicon (Si), iron (Fe), magnesium (Mg), and copper (Cu) in the molten aluminum solution segregate and diffuse into the liquid phase, thereby obtaining aluminum crystals with relatively high purity and residual aluminum solution containing high concentrations of silicon (Si), iron (Fe), magnesium (Mg), and copper (Cu).

[0041] Since the relevant operating conditions for the boron treatment and the segregation purification treatment are known to those skilled in the art, they will not be described in detail here.

[0042] The melting step 23 involves melting different series of recycled aluminum materials, primary pure aluminum ingots, and the intermediate obtained after purification in the purification and refining step 22 into an aluminum alloy molten metal. The weight percentage of each alloying element in the aluminum alloy molten metal is less than the weight percentage of the corresponding alloying element of the target alloying element.

[0043] Next, the alloy composition tempering step 24 is performed to adjust the weight percentage (wt%) of each alloying element in the aluminum alloy molten metal to the range of content specifications corresponding to the target alloying element, thereby obtaining a tempered aluminum alloy molten metal. Specifically, the alloy composition tempering step 24 can be performed by adding at least one of pure magnesium (Mg), pure zinc (Zn), pure copper (Cu), iron (Fe) cake, manganese (Mn) cake, titanium (Ti) cake, chromium (Cr) cake, and zirconium (Zr) master alloy to the aluminum alloy molten metal to adjust the alloying element content of the molten metal, thereby obtaining the tempered aluminum alloy molten metal, and based on the weight of the tempered aluminum alloy molten metal being 100wt%, the content of recycled aluminum is at least 75wt%.

[0044] Then, the casting step 25 can be carried out to cast the tempered aluminum alloy molten metal into an aluminum billet and then extrude it to obtain the medium-strength 7xxx series recycled aluminum alloy parts with a high proportion of recycled material as described in this invention. The total content of recycled aluminum material is at least 75 wt% based on 100 wt% of the weight of the medium-strength 7xxx series recycled aluminum alloy parts.

[0045] Among them, the casting rods or extruded parts made by the preparation method of medium-strength 7xxx series recycled aluminum alloy parts with high recycled material ratio described in this invention can also have the scrap material generated during the production process recycled and added to the initial mixture or the aluminum alloy molten metal for reuse.

[0046] Referring to Table 1, Table 1 shows the range of alloy element content for the medium-strength 7xxx series recycled aluminum alloy parts (represented as HR7xxx) with a high proportion of recycled materials to be obtained in this invention, as well as the alloy element content specifications for different commercially available aluminum alloy grades (AA7005, AA7046, AA7021, AA7030).

[0047] Table 1

[0048]

[0049] As can be seen from the alloy element content in Table 1, the medium-strength 7xxx series recycled aluminum alloy parts with a high proportion of recycled materials described in this invention can generally meet the alloy element content specifications of medium-strength aluminum alloys with low copper content (maximum copper content ≤ 0.4).

[0050] Next, the following comparative examples (AA7005, AA7021, AA7026, AA7046) and specific examples (AA7005, AA7046) illustrate the preparation of different recycled aluminum alloy parts using different proportions of recycled aluminum, and the measurement results of the physical and electrochemical properties of the recycled aluminum alloy parts.

[0051] The comparative examples are recycled aluminum alloy parts that meet the alloy element content specifications of the corresponding grade by melting and tempering recycled aluminum material of a specific grade with different proportions of virgin pure aluminum ingots and alloy elements (e.g., the recycled aluminum material used comes from AA7046 alloy aluminum material, and the recycled aluminum alloy obtained after tempering still meets the alloy element content specifications of AA7046).

[0052] The specific example is a recycled aluminum alloy part prepared by the method described in this invention, which meets the alloy element content specifications of the medium-strength 7xxx series recycled aluminum alloy parts with a high recycled material ratio as described in this invention. AA7005 and AA7046 are recycled aluminum materials from the specific grade aluminum alloys described; the 5xxx series recycled aluminum materials are mainly composed of AA5051 recycled aluminum materials and contain other different components / grades; the 6xxx series recycled aluminum materials are mainly composed of AA6063 recycled aluminum materials and contain other different components / grades; the 7xxx series recycled aluminum materials are mainly composed of AA7050 recycled aluminum materials and contain other different components / grades.

[0053] To elaborate:

[0054] Comparative Example 1 - AA7021 recycled aluminum alloy (recycled aluminum content: 44.6%): 44.6 wt% 7021 recycled aluminum, with 55.4 wt% added virgin pure aluminum ingots and alloying elements;

[0055] Comparative Example 2 - AA7026 recycled aluminum alloy (recycled aluminum content: 24.1%): 24.1 wt% 7026 recycled aluminum, with 75.9 wt% added virgin pure aluminum ingots and alloying elements;

[0056] Comparative Example 3-AA7046 recycled aluminum alloy (recycled aluminum content: 47.6%): 47.6 wt% 7046 recycled aluminum, with 52.4 wt% added virgin pure aluminum ingots and alloying elements;

[0057] Comparative Example 4-AA7005 Recycled Aluminum Alloy (Recycled Aluminum Ratio: 39.5%): 39.5 wt% 7005 recycled aluminum, with 60.5 wt% virgin pure aluminum ingots and alloying elements added;

[0058] Specific example 1 - AA7005 recycled aluminum alloy (recycled aluminum content: 81.6%): 28.7wt% 7005 recycled aluminum, 14.3wt% 5xxx series recycled aluminum, 29.5wt% purified and refined 6xxx series recycled aluminum, 9.1wt% purified and refined 7xxx series recycled aluminum, and 18.4wt% virgin pure aluminum ingots and alloying elements;

[0059] Specific example 2 - AA7046 recycled aluminum alloy (recycled aluminum content: 94.9%): 29.1wt% 7046 recycled aluminum, 16.3wt% 5xxx series recycled aluminum, 27.0wt% purified and refined 6xxx series recycled aluminum, 22.5wt% purified and refined 7xxx series recycled aluminum, and 5.1wt% virgin pure aluminum ingots and alloying elements.

[0060] The alloy proportions used in Comparative Examples 1 to 4 are summarized in Table 2, and the alloy element content, the alloy element content of the recycled aluminum used in Specific Examples 1 and 2, and the related recycled aluminum proportions are summarized in Tables 3 and 4.

[0061] Table 2

[0062]

[0063]

[0064] Table 3

[0065]

[0066] Table 4

[0067]

[0068]

[0069] As can be seen from Examples 1 and 2 (Tables 3 and 4), medium-strength recycled aluminum alloy parts prepared by mixing different series of recycled aluminum materials in different proportions, followed by purification, refining, and alloy composition tempering, can meet the alloy element content specifications of commercially available medium-strength 7xxx series aluminum alloy grades shown in Table 1 (the medium-strength 7xxx series recycled aluminum alloy parts with a high recycled material ratio prepared in Example 1 meet the alloy element specifications of AA7005; the medium-strength 7xxx series recycled aluminum alloy parts with a high recycled material ratio prepared in Example 2 meet the alloy element specifications of AA7046); and the recycled aluminum material content in Examples 1 and 2 can reach as high as 81.6 wt% and 94.9 wt%, respectively. It can be seen that the medium-strength 7xxx series recycled aluminum alloy parts with a high recycled material ratio prepared using the preparation method of the present invention can overcome the problem that the recycled aluminum material ratio of this series of recycled aluminum alloys cannot be increased due to the difficulty in recycling medium-strength 7xxx series aluminum alloys, and can also significantly increase the amount of recycled material used in the recycled aluminum alloys.

[0070] Next, the cast rods prepared using the comparative and specific examples were then extruded to form extruded parts, and their mechanical and electrochemical properties were tested. The relevant measurement results are summarized in Tables 5 and 6.

[0071] The cast rod has a diameter of 7 inches, and is subsequently homogenized and extruded at an extrusion ratio of 25:1, and finally subjected to T6 heat treatment.

[0072] Tensile test: After heat treatment (T6), the tensile strength (UTS), yield strength (TYS), and elongation (EL) of the test specimens are measured according to ASTM B557M-15 (2023). The specimens are made according to the dimensions shown in FIG 6. Rectangular tension test specimens in ASTM B557M-15 (2023), and the specimens are sampled parallel to the extrusion direction.

[0073] Electrochemical performance testing: The test was conducted using a potentiostat. The surface of the test piece was polished to a mirror finish with a 50nm silica polishing solution. Before testing, the sample was allowed to stand in the detection solution for 30 minutes, and then the voltage was scanned and observed.

[0074] Electrochemical detection solution: 3.5 wt% sodium chloride solution is used;

[0075] Reference electrode: AgCl; Auxiliary electrode: Carbon;

[0076] Scan rate: 1 mV / s.

[0077] Table 5

[0078]

[0079] Table 6

[0080]

[0081] Generally, medium-strength 7xxx series aluminum alloys such as 7003 / 7005 / 7021 / 7046 have a UTS of approximately 350MPa to 550MPa after T6 heat treatment. As shown in Table 5, under the same heat treatment (T6) conditions, the mechanical properties of medium-strength 7xxx series recycled aluminum alloy parts with a high proportion of recycled material (specific examples 1 and 2) prepared by the method of this invention can indeed cover the mechanical properties of general medium-strength 7xxx series aluminum alloys. Moreover, compared with medium-strength 7xxx series recycled aluminum alloy parts conforming to the same composition specifications prepared using a single recycled aluminum material (AA7021, AA7026, AA7046, AA7005) (comparative examples 1 to 4), their mechanical and electrochemical properties are comparable. This shows that the medium-strength 7xxx series recycled aluminum alloy parts with a high proportion of recycled material prepared by the method of this invention can not only have a high proportion of recycled aluminum material, but also maintain mechanical and electrochemical properties comparable to those of medium-strength 7xxx series aluminum alloy parts of the same series specifications.

[0082] In summary, the method for preparing medium-strength 7xxx series recycled aluminum alloy parts with a high proportion of recycled materials according to the present invention utilizes 5xxx series and 6xxx series aluminum alloys, which have high market demand and abundant recycled material sources, as the source of recycled aluminum. A purification and refining step is then used to remove or reduce the content of alloying elements in the recycled aluminum that differ significantly from the desired target aluminum alloy, ensuring that the alloying element content of the initial mixture after purification and refining is no greater than that of the target aluminum alloy. Finally, alloy composition is tempered by adding alloying elements, resulting in medium-strength 7xxx series recycled aluminum alloy parts with a high proportion of recycled materials, containing at least 75 wt% recycled aluminum, and belonging to a different series from the recycled aluminum. This method solves the problem that existing medium-strength 7xxx series aluminum alloys are difficult to improve in terms of recycled material ratio due to the relatively dispersed application industries (automotive structural materials, sporting goods, consumer electronics, etc.), low recycling penetration, and difficulty in obtaining recycled materials with similar alloy compositions. Furthermore, the medium-strength 7xxx series recycled aluminum alloy parts of the present invention with a high proportion of recycled materials can more precisely control alloy elements through purification, alloy composition conditioning and other steps. Therefore, although the medium-strength 7xxx series recycled aluminum alloy parts of the present invention with a high proportion of recycled materials contain more than 75 wt% recycled aluminum, their mechanical properties and electrochemical characteristics are still comparable to those of medium-strength 7xxx series aluminum alloys with low recycled material content, and are not affected by the proportion of recycled aluminum, so the purpose of the present invention can be effectively achieved.

[0083] The above description is merely an embodiment of the present invention and should not be construed as limiting the scope of the present invention. Any simple equivalent changes and modifications made in accordance with the claims and description of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing medium-strength 7xxx series recycled aluminum alloy parts with a high proportion of recycled materials, characterized in that: The preparation method includes: The raw material selection and composition design steps involve providing at least two types of recycled aluminum materials, wherein the recycled aluminum materials are derived from at least one of the 5xxx series aluminum alloys and the 6xxx series aluminum alloys; and determining the addition ratio of the recycled aluminum materials and virgin pure aluminum ingots based on the target alloy element content specifications of the medium-strength 7xxx series recycled aluminum alloy parts to be finally prepared, thereby obtaining an initial mixture. The purification and refining step involves purifying and refining at least one of the recycled aluminum materials in the initial mixture according to the target alloy element content specifications of the desired medium-strength 7xxx series recycled aluminum alloy parts, removing a portion of the content of at least one alloy element in the at least one recycled aluminum material to obtain an intermediate. In the melting step, the different series of recycled aluminum materials, primary pure aluminum ingots, and the intermediate obtained after the purification and refining step of the initial mixture are melted into an aluminum alloy molten soup, wherein the weight percentage of each alloying element in the aluminum alloy molten soup is not greater than the weight percentage of the corresponding alloying element of the target alloying element; and The alloy composition tempering step involves adjusting the weight percentage of each alloying element in the aluminum alloy molten metal to the content specification range corresponding to the target alloying element, thereby obtaining a tempered aluminum alloy molten metal. The content of the recycled aluminum material is at least 75 wt%, with the weight of the tempered aluminum alloy molten metal being 100 wt%.

2. The preparation method according to claim 1, characterized in that: The recycled aluminum material may also be sourced from at least one of the 1xxx series aluminum alloys and the 7xxx series aluminum alloys, wherein the 1xxx series aluminum alloys are selected from at least one of 1050, 1070 and 1100, and the 7xxx series aluminum alloys are selected from at least one of 7050 and 7150.

3. The preparation method according to claim 1, characterized in that: The 5xxx series aluminum alloys of the recycled aluminum material are selected from at least one of 5050, 5051 and 5056, and the 6xxx series aluminum alloys are selected from at least one of 6060, 6061 and 6063.

4. The preparation method according to claim 1, characterized in that: The preparation method also includes a casting step, in which the quenched and tempered aluminum alloy molten metal is cast and subsequently extruded.

5. The preparation method according to claim 1, characterized in that: The purification and refining step is at least one of boron treatment and segregation purification treatment to remove at least a portion of the corresponding alloying elements.

6. The preparation method according to claim 1, characterized in that: The composition of the tempered aluminum alloy molten metal includes: no more than 0.15 wt% silicon, no more than 0.2 wt% iron, no more than 0.4 wt% copper, no more than 0.30 wt% manganese, 0.5-2.0 wt% magnesium, 4.0-8.0 wt% zinc, no more than 0.2 wt% chromium, no more than 0.06 wt% titanium, no more than 0.25 wt% zirconium, and an equal amount of aluminum.

7. A medium-strength 7xxx series recycled aluminum alloy part with a high proportion of recycled materials, characterized in that: The medium-strength 7xxx series recycled aluminum alloy parts prepared by the preparation method according to claim 1 contain at least 75 wt% recycled aluminum material, and the medium-strength 7xxx series recycled aluminum alloy parts prepared by the high-recycled material ratio have a tensile strength between 350-550 MPa, a yield strength between 300-500 MPa, and an elongation greater than 10% under T6 heat treatment conditions.

8. The medium-strength 7xxx series recycled aluminum alloy parts with a high proportion of recycled materials according to claim 7, characterized in that: The composition of the medium-strength 7xxx series recycled aluminum alloy parts with a high proportion of recycled materials includes: no more than 0.15 wt% silicon, no more than 0.2 wt% iron, no more than 0.4 wt% copper, no more than 0.30 wt% manganese, 0.5-2.0 wt% magnesium, 4.0-8.0 wt% zinc, no more than 0.2 wt% chromium, no more than 0.06 wt% titanium, no more than 0.25 wt% zirconium, and a balanced amount of aluminum.

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