A 7-series aluminum alloy material and a method of manufacturing the same

Abstract

The application discloses a 7-series aluminum alloy material and a preparation method thereof, and belongs to the field of aluminum alloy preparation. On the basis of optimizing the composition of the 7-series aluminum alloy, the proportion of the components and the process are properly adjusted, so that the tensile strength, yield strength and elongation can be guaranteed to meet the use requirements, and the corrosion resistance can be further improved. The addition of Zn elements and Mg elements can significantly improve the strength and hardness of the 7-series aluminum alloy. The proper proportion of Cu or Cr can reduce residual phases (T phase-Al2Mg3Zn3 phase, AlZnMgCu phase or AlZnMgCr), but the residual phases gradually disappear after solid solution treatment, the alloying elements can be solid-solved in the matrix, the AlFe phase is reduced, and the corrosion sites are reduced. In combination with the synergistic effect of the Mn element and the V-containing refiner, the crystal phase of the 7-series aluminum alloy is refined, the mechanical properties of the 7-series aluminum alloy are significantly improved, and the corrosion resistance of the 7-series aluminum alloy is obviously improved.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy preparation technology, and more specifically, to a 7-series aluminum alloy material and its preparation method. Background Technology

[0002] 7xxx series aluminum alloys can be divided into Al-Zn-Mg series and Al-Zn-Mg-Cu series aluminum alloys. These alloys are widely used and have become important structural materials due to their high strength, high modulus, good electrical and thermal conductivity, low density, good plasticity, and machinability. Among the many elements in 7xxx series aluminum alloys, Zn and Mg play the main strengthening roles. Within the solid solution limit of the alloy, increasing the Zn content increases the volume fraction of metastable phases, improving both tensile and yield strength. However, Zn has low solid solubility in the alloy at room temperature and cannot form intermetallic compounds with Al. Therefore, the addition of Zn has limitations in improving the alloy's strength and may increase its susceptibility to corrosion cracking. The addition of Mg provides a moderate increase in strength; however, increasing Mg within the solid solution limit also affects the alloy's corrosion resistance. The addition of Cu can alter the precipitation of intragranular and grain boundary phases, improving the strength, plasticity, and corrosion resistance of alloys. However, excessive Cu addition can easily lead to the formation of coarse residual phases at grain boundaries, deteriorating the alloy's resistance to intergranular corrosion and becoming a starting point for pitting corrosion, thus increasing the alloy's susceptibility to pitting corrosion. Therefore, the performance effects of 7xxx series aluminum alloys need to be considered in conjunction with other elements. Controlling the content and proportion of these elements is crucial for the overall performance of 7xxx series aluminum alloys. For example, existing technologies use Zr to suppress recrystallization in 7xxx series aluminum alloys, forming fine, insoluble Al3Zr particles. These particles have two structures and morphologies: one is tetragonal Al3Zr particles precipitated directly from the melt, which can significantly refine the grains of the as-cast alloy; the other is metastable spherical particles with an L12 structure precipitated during ingot homogenization, coherent with the matrix, which can suppress recrystallization during hot working. However, when the Zr content is too high or the smelting is improper, the alloy is prone to segregation due to uneven Zr distribution, leading to an uneven distribution of the Al3Zr phase. This results in significant differences in recrystallization between Zr-rich and Zr-poor regions. Simultaneously, the Al3Zr phase has poor thermal stability and will transition to an equilibrium state after prolonged high-temperature treatment. This causes the coherent relationship between the Al3Zr phase and the matrix to disappear, and the region near the dispersed phase becomes a coarse phase nucleation zone. This, to some extent, consumes Zn and Mg elements that form strengthening phases, increasing the alloy's quenching sensitivity.

[0003] Therefore, the properties of 7xxx series aluminum alloys are closely related to their microstructure. It is necessary to find particles that are finer, more dispersed, and have better thermal stability than the Al3Zr phase to improve the overall properties of 7xxx series alloys. Furthermore, limitations in the manufacturing process can also affect the properties of 7xxx series aluminum alloys. This application optimizes the composition, component ratios, and manufacturing process to address the limitations of existing 7xxx series aluminum alloys in guaranteeing tensile strength, yield strength, and elongation, while further improving corrosion resistance to meet application requirements. Summary of the Invention

[0004] Based on this, in order to solve the technical problem that existing 7xxx series aluminum alloys cannot guarantee tensile strength, yield strength, and elongation while further improving corrosion resistance, this invention provides a 7 series aluminum alloy material and its preparation method, the specific technical solution of which is as follows:

[0005] A 7-series aluminum alloy material, comprising the following components by mass percentage: Si ≤ 0.10%, Fe ≤ 0.15%, Mn 0.25%–0.30%, Mg 1.7%, Zn 6.6%, V 0.09%–0.12%, Ti 0.03%, Cu 0.2%–0.35% or Cr 0.12%–0.15%, single impurity element ≤ 0.05%, total impurities ≤ 0.15%, and Al balance;

[0006] The 7-series aluminum alloy material has a tensile strength ≥500MPa, a yield strength ≥500MPa, an elongation ≥12%, and a peeling corrosion resistance not lower than EA grade.

[0007] In addition, this application also provides a method for preparing 7-series aluminum alloy materials, the method comprising the following steps:

[0008] According to the mass percentage of the chemical composition of 7-series aluminum alloy materials, pure aluminum is added to a melting furnace. After it is completely melted and the temperature of the melt is 720℃~740℃, raw materials containing Si, Fe, Mn, Mg, Zn, Ti, Cu or Cr elements are added in sequence. After melting and complete melting, the content and ratio of alloy elements are adjusted by online composition detection and analysis to obtain molten metal A.

[0009] Argon gas is introduced into the upper, middle and bottom parts of the molten metal A for 10 min to 15 min for refining. Then, a V-containing refining agent is added, the slag is removed and the mixture is kept at a constant temperature to obtain molten metal B.

[0010] Once the temperature of the molten metal B drops to 700℃±5℃, an aluminum alloy ingot is obtained by casting.

[0011] The aluminum alloy ingot is pretreated, then homogenized, and cooled to room temperature with water mist.

[0012] The homogenized aluminum alloy ingot is preheated to 500℃~550℃, the extrusion die is preheated to 400℃~450℃, the die cylinder is preheated to 400℃~450℃, and then extrusion, solution treatment and aging treatment are performed to obtain 7 series aluminum alloy materials.

[0013] Furthermore, the temperature for static heat preservation is 720℃~740℃, and the time is 30min~35min.

[0014] Furthermore, the pretreatment temperature is 250℃~300℃, and the time is 4h~24h.

[0015] Furthermore, the homogenization process is carried out in two stages. The first stage of homogenization is performed at a temperature of 300℃±5℃ for 8h to 10h; the second stage of homogenization is performed at a temperature of 480℃±5℃ for 20h to 24h.

[0016] Furthermore, the extrusion process has a coefficient of 30 to 45, a speed of 6 m / min to 8 m / min, and an outlet temperature of 500°C to 550°C.

[0017] Furthermore, the solution treatment is performed at 470℃±5℃ for 1h~2h, the cooling medium is water at room temperature, and the quenching transfer time does not exceed 10s.

[0018] Furthermore, the aging process includes one of single-stage aging and two-stage aging, wherein the single-stage aging is 24 hours of treatment at 120℃~125℃; and the two-stage aging is 14 hours of treatment at 100℃ and 10 hours of treatment at 130℃~135℃.

[0019] Furthermore, the preparation method of the V-containing refining agent is as follows: aluminum powder and vanadium pentoxide are ball-milled, then heated to complete melting under a protective gas, held at that temperature for 6 to 8 hours, cast, homogenized and hot-extruded, and then cooled to room temperature to obtain a V-containing phase with a size of 5 μm to 30 μm in the V-containing refining agent.

[0020] Furthermore, the average diameter of the V-containing refining agent is 5 mm to 10 mm.

[0021] Compared with the prior art, this application has the following beneficial effects:

[0022] 1. In this invention, by adding a V-containing grain refiner, the as-cast grains of 7-series aluminum alloys can be effectively refined. The V element can form thermally stable Al atoms that are incompatible with the Al matrix. 21The V2-type dispersed phase significantly improves the high-temperature strength of 7-series aluminum alloys, and this dispersed phase also inhibits recrystallization and provides recrystallization temperature. In addition, the addition of V element significantly refines the microstructure, making the internal structure of 7-series aluminum alloys more uniform, and significantly improving the recrystallization resistance after solution treatment. Combined with the process of pretreatment followed by homogenization treatment, the synergistic effect results in smaller subgrain sizes in 7-series aluminum alloys, forming fine dispersed phases that pin dislocations and subgrain boundary migration, exhibiting a significant inhibitory effect on subgrain coarsening, and improving the strength and stress corrosion resistance of the alloy.

[0023] 2. By adding the V-containing grain refiner prepared in this invention, the probability of introducing impurities can be reduced, the uniformity and purity are excellent, the operation is simple and highly controllable, and the absence of oxide surfaces is guaranteed. This can meet the requirements for promoting the uniformity of the microstructure and refining the grains of 7-series aluminum alloys.

[0024] 3. Based on optimizing the composition of 7-series aluminum alloys, this invention appropriately adjusts the component ratio and process to ensure that the tensile strength, yield strength, and elongation meet the application requirements, and further improves corrosion resistance. Among them, the addition of Zn and Mg elements can significantly improve the strength and hardness of 7-series aluminum alloys. A suitable Cu or Cr ratio can reduce residual phases (T phase-Al2Mg3Zn3 phase, AlZnMgCu phase, or AlZnMgCr phase). However, after solution treatment, the residual phases gradually disappear, and all alloying elements can be dissolved in the matrix. The reduction of AlFe phase reduces the number of corrosion sites. Combined with the synergistic effect of Mn element and V-containing refining agent, the crystal phase refinement in 7-series aluminum alloys can not only significantly improve the mechanical properties of 7-series aluminum alloys, but also significantly improve their corrosion resistance. Attached Figure Description

[0025] The invention will be further understood from the following description taken in conjunction with the accompanying drawings. The components in the drawings are not necessarily drawn to scale, but rather the emphasis is on illustrating the principles of the embodiments. In different views, the same reference numerals designate corresponding parts.

[0026] Figure 1 This is a schematic diagram of the as-cast metallographic structure of the 7-series aluminum alloy in Example 1 during its preparation process;

[0027] Figure 2 This is a schematic diagram of the homogeneous metallographic structure of the 7-series aluminum alloy during the preparation process of Example 1;

[0028] Figure 3 This is a schematic diagram of the metallographic structure of the longitudinal section of the extruded aluminum alloy during the preparation process of the 7-series aluminum alloy in Example 1;

[0029] Figure 4 This is a schematic diagram of the metallographic structure of the extruded cross-section of the 7-series aluminum alloy during the preparation process of Example 1. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to its embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the scope of protection of the invention.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0032] An embodiment of the present invention provides a 7-series aluminum alloy material, wherein the 7-series aluminum alloy material comprises the following components by mass percentage: Si ≤ 0.10%, Fe ≤ 0.15%, Mn 0.25%–0.30%, Mg 1.7%, Zn 6.6%, V 0.09%–0.12%, Ti 0.03%, Cu 0.2%–0.35% or Cr 0.12%–0.15%, single impurity element ≤ 0.05%, total impurities ≤ 0.15%, and Al balance;

[0033] The 7-series aluminum alloy material has a tensile strength ≥500MPa, a yield strength ≥500MPa, an elongation ≥12%, and a peeling corrosion resistance not lower than EA grade.

[0034] In addition, this application also provides a method for preparing 7-series aluminum alloy materials, the method comprising the following steps:

[0035] According to the mass percentage of the chemical composition of 7-series aluminum alloy materials, pure aluminum is added to a melting furnace. After it is completely melted and the temperature of the melt is 720℃~740℃, raw materials containing Si, Fe, Mn, Mg, Zn, Ti, Cu or Cr elements are added in sequence. After melting and complete melting, the content and ratio of alloy elements are adjusted by online composition detection and analysis to obtain molten metal A.

[0036] Argon gas is introduced into the upper, middle and bottom parts of the molten metal A for 10 min to 15 min for refining. Then, a V-containing refining agent is added, the slag is removed and the mixture is kept at a constant temperature to obtain molten metal B.

[0037] Once the temperature of the molten metal B drops to 700℃±5℃, an aluminum alloy ingot is obtained by casting.

[0038] The aluminum alloy ingot is pretreated, then homogenized, and cooled to room temperature with water mist.

[0039] The homogenized aluminum alloy ingot is preheated to 500℃~550℃, the extrusion die is preheated to 400℃~450℃, the die cylinder is preheated to 400℃~450℃, and then extrusion, solution treatment and aging treatment are performed to obtain 7 series aluminum alloy materials.

[0040] In one embodiment, the temperature for static heat preservation is 720°C to 740°C, and the time is 30 min to 35 min.

[0041] In one embodiment, the pretreatment temperature is 250°C to 300°C, and the time is 4 hours to 24 hours.

[0042] In one embodiment, the homogenization process is carried out in two stages: the first stage of homogenization is performed at a temperature of 300℃±5℃ for 8h to 10h; the second stage of homogenization is performed at a temperature of 480℃±5℃ for 20h to 24h.

[0043] In one embodiment, the extrusion process has a coefficient of 30 to 45, a speed of 6 m / min to 8 m / min, and an outlet temperature of 500°C to 550°C.

[0044] In one embodiment, the solution treatment is performed at 470℃±5℃ for 1 to 2 hours, the cooling medium is water at room temperature, and the quenching transfer time does not exceed 10 seconds.

[0045] In one embodiment, the aging process includes one of single-stage aging and two-stage aging, wherein the single-stage aging is 24 hours of treatment at 120℃~125℃; and the two-stage aging is 14 hours of treatment at 100℃ and 10 hours of treatment at 130℃~135℃.

[0046] In one embodiment, the preparation method of the V-containing refining agent is as follows: aluminum powder and vanadium pentoxide are ball-milled, then heated to complete melting under a protective gas, held at that temperature for 6 to 8 hours, cast, homogenized and hot-extruded, and then cooled to room temperature to obtain a V-containing phase with a size of 5 μm to 30 μm in the V-containing refining agent.

[0047] In one embodiment, in the preparation method of the V-containing refining agent, the homogenization treatment temperature is 400℃~420℃ and the time is 1h~2h.

[0048] In one embodiment, in the preparation method of the V-containing refining agent, the hot extrusion treatment temperature is 500℃~550℃, and the quenching treatment is performed at a quenching rate of 5℃ / s.

[0049] In one embodiment, the average diameter of the V-containing refining agent is 5 mm to 10 mm.

[0050] The above solution, by optimizing the composition of 7-series aluminum alloys, appropriately adjusting the component ratios and optimizing the process, can guarantee the tensile strength, yield strength, and elongation, and further improve corrosion resistance.

[0051] The implementation schemes of the present invention will now be described in detail with reference to specific embodiments.

[0052] Example 1:

[0053] The 7-series aluminum alloy in Example 1 comprises the following components by mass percentage: Si 0.02%, Fe 0.05%, Mn 0.25%, Mg 1.7%, Zn 6.6%, V 0.10%, Ti 0.03%, Cu 0.25%, individual impurity element ≤0.05%, total impurities ≤0.15%, and Al balance;

[0054] A method for preparing a 7-series aluminum alloy includes the following steps:

[0055] Aluminum powder and vanadium pentoxide were ball-milled, then heated to complete melting under a protective gas, held at that temperature for 6 hours, cast, homogenized at 400℃ for 2 hours, then hot-extruded at 500℃, and quenched at a quenching rate of 5℃ / s. After cooling to room temperature, a V-containing refining agent with an average diameter of 8 mm and a V-phase size of 5 μm to 30 μm was obtained.

[0056] According to the mass percentage of the chemical composition of 7-series aluminum alloy materials, pure aluminum is added to a melting furnace. After it is completely melted and the temperature of the melt is 740℃, raw materials containing Si, Fe, Mn, Mg, Zn, Ti, Cu or Cr elements are added in sequence. After melting and complete melting, the content and ratio of alloy elements are adjusted by online composition detection and analysis to obtain molten metal A.

[0057] Argon gas was introduced into the upper, middle and bottom of the molten metal A for 10 min to 15 min for refining. Then, a V-containing refining agent was added. After removing the slag, the mixture was kept at 720°C for 35 min to obtain molten metal B.

[0058] Once the temperature of the molten metal B drops to 705°C, an aluminum alloy ingot is obtained by casting.

[0059] The aluminum alloy ingot was pretreated at 300°C for 6 hours, and then homogenized. The homogenization process was carried out in two stages: the first stage homogenization was carried out at 305°C for 8 hours; the second stage homogenization was carried out at 485°C for 20 hours, and then cooled to room temperature with water mist.

[0060] The homogenized aluminum alloy ingot is preheated to 500°C, the extrusion die is preheated to 450°C, and the die cylinder is preheated to 400°C. Then, the extrusion process is carried out with a coefficient of 30, a speed of 6 m / min, and an outlet temperature of 500°C for the extruded material. The extruded aluminum alloy ingot is then solution-treated at 475°C for 2 hours with room temperature water as the cooling medium and a quenching transfer time not exceeding 10 seconds.

[0061] The solution-treated aluminum alloy ingot is subjected to a two-stage aging treatment, wherein the two-stage aging is performed at 100℃ for 14 hours and at 135℃ for 10 hours to obtain 7-series aluminum alloy material.

[0062] Example 2:

[0063] The 7-series aluminum alloy in Example 2 comprises the following components by mass percentage: Si 0.03%, Fe 0.03%, Mn 0.30%, Mg 1.7%, Zn 6.6%, V 0.11%, Ti 0.03%, Cu 0.35%, individual impurity element ≤0.05%, total impurities ≤0.15%, and Al balance;

[0064] A method for preparing a 7-series aluminum alloy includes the following steps:

[0065] Aluminum powder and vanadium pentoxide were ball-milled, then heated to complete melting under a protective gas, held for 7 hours, cast, homogenized at 420℃ for 1 hour, then hot-extruded at 550℃, and quenched at a quenching rate of 5℃ / s. After cooling to room temperature, a V-containing refining agent with an average diameter of 10 mm was obtained, and the V-containing phase in the V-containing refining agent had a size of 5μm to 30μm.

[0066] According to the mass percentage of the chemical composition of 7-series aluminum alloy materials, pure aluminum is added to a melting furnace. After it is completely melted and the temperature of the melt is 740℃, raw materials containing Si, Fe, Mn, Mg, Zn, Ti, Cu or Cr elements are added in sequence. After melting and complete melting, the content and ratio of alloy elements are adjusted by online composition detection and analysis to obtain molten metal A.

[0067] Argon gas was introduced into the upper, middle and bottom of the molten metal A for 10 min to 15 min for refining. Then, a V-containing refining agent was added. After removing the slag, the mixture was kept at 730°C for 30 min to obtain molten metal B.

[0068] Once the temperature of the molten metal B drops to 705°C, an aluminum alloy ingot is obtained by casting.

[0069] The aluminum alloy ingot was pretreated at 280°C for 7 hours, and then homogenized. The homogenization process was carried out in two stages: the first stage homogenization was carried out at 305°C for 10 hours; the second stage homogenization was carried out at 485°C for 20 hours, and then cooled to room temperature with water mist.

[0070] The homogenized aluminum alloy ingot is preheated to 550°C, the extrusion die is preheated to 450°C, the die cylinder is preheated to 450°C, and then extrusion is performed. The extrusion coefficient is 35, the speed is 8m / min, and the outlet temperature of the extruded material is 550°C. The extruded aluminum alloy ingot is then solution treated at 475°C for 2 hours, with room temperature water as the cooling medium, and the quenching transfer time does not exceed 10 seconds.

[0071] The solution-treated aluminum alloy ingot is subjected to a two-stage aging treatment, wherein the two-stage aging is 100℃ for 14 hours and 130℃ for 10 hours, to obtain 7-series aluminum alloy material.

[0072] Example 3:

[0073] The 7-series aluminum alloy in Example 1 comprises the following components by mass percentage: Si 0.03%, Fe 0.05%, Mn 0.28%, Mg 1.7%, Zn 6.6%, V 0.12%, Ti 0.03%, Cu 0.30%, individual impurity element ≤0.05%, total impurities ≤0.15%, and Al balance;

[0074] A method for preparing a 7-series aluminum alloy includes the following steps:

[0075] Aluminum powder and vanadium pentoxide were ball-milled, then heated to complete melting under a protective gas, held at that temperature for 8 hours, cast, homogenized at 420℃ for 2 hours, then hot-extruded at 550℃, and quenched at a quenching rate of 5℃ / s. After cooling to room temperature, a V-containing refining agent with an average diameter of 10 mm was obtained, and the V-containing phase in the V-containing refining agent had a size of 5μm to 30μm.

[0076] According to the mass percentage of the chemical composition of 7-series aluminum alloy materials, pure aluminum is added to a melting furnace. After it is completely melted and the temperature of the melt is 720℃~740℃, raw materials containing Si, Fe, Mn, Mg, Zn, Ti, Cu or Cr elements are added in sequence. After melting and complete melting, the content and ratio of alloy elements are adjusted by online composition detection and analysis to obtain molten metal A.

[0077] Argon gas was introduced into the upper, middle and bottom of the molten metal A for 15 minutes for refining. Then, a V-containing refining agent was added. After removing the slag, the mixture was kept at 740°C for 30 minutes to obtain molten metal B.

[0078] Once the temperature of the molten metal B drops to 705°C, an aluminum alloy ingot is obtained by casting.

[0079] The aluminum alloy ingot was pretreated at 250°C for 15 hours, and then homogenized. The homogenization process was carried out in two stages: the first stage homogenization was carried out at 305°C for 7 hours; the second stage homogenization was carried out at 485°C for 22 hours, and then cooled to room temperature with water mist.

[0080] The homogenized aluminum alloy ingot is preheated to 550°C, the extrusion die is preheated to 450°C, the die cylinder is preheated to 450°C, and then extrusion is performed. The extrusion coefficient is 45, the speed is 8m / min, and the outlet temperature of the extruded material is 550°C. The extruded aluminum alloy ingot is then solution treated at 475°C for 2 hours, with room temperature water as the cooling medium, and the quenching transfer time does not exceed 10 seconds.

[0081] The solution-treated aluminum alloy ingot is subjected to a two-stage aging treatment, wherein the two-stage aging is performed at 100℃ for 14 hours and at 135℃ for 10 hours to obtain 7-series aluminum alloy material.

[0082] Example 4:

[0083] The difference between Example 4 and Example 3 is that Example 4 uses single-stage aging, which is performed at 120°C for 24 hours, while the rest is the same as Example 3.

[0084] Comparative Example 1:

[0085] The difference between Comparative Example 1 and Example 1 is that the 7-series aluminum alloy in Comparative Example 1 comprises the following components by mass percentage: Si 0.03%, Fe 0.05%, Mn 0.28%, Mg 1.7%, Zn 6.6%, Ti 0.03%, Cu 0.30%, individual impurity element ≤0.05%, total impurities ≤0.15%, and Al balance. Everything else is the same as in Example 1.

[0086] Comparative Example 2:

[0087] The difference between Comparative Example 2 and Example 3 is that in Comparative Example 2, element V and other elements were directly added to the molten aluminum, followed by smelting. After complete melting, the content and ratio of alloying elements were adjusted through online composition analysis to obtain molten metal A. Everything else was the same as in Example 3.

[0088] Comparative Example 3:

[0089] The difference between Comparative Example 3 and Example 3 is that Comparative Example 3 did not undergo solution treatment, but otherwise it was the same as Example 3.

[0090] Comparative Example 4:

[0091] The difference between Comparative Example 4 and Example 3 is that Comparative Example 4 did not undergo pretreatment, but otherwise it was the same as Example 3.

[0092] Comparative Example 5:

[0093] The difference between Comparative Example 5 and Example 3 is that the homogenization process in Comparative Example 5 is a single-stage homogenization, the temperature is 450°C and the time is 24 hours, while the rest is the same as in Example 3.

[0094] Comparative Example 6:

[0095] The difference between Comparative Example 6 and Example 3 is that the aging treatment in Comparative Example 6 is: 120℃ for 10 hours and 200℃ for 6 hours, while the rest is the same as in Example 3.

[0096] The samples prepared in Examples 1-4 and the comparative samples prepared in Comparative Examples 1-6 were subjected to performance tests. Specifically, the aluminum alloys underwent low-magnification analysis to observe grain size according to GB / T3264-2000; the mechanical properties of the aluminum alloys were tested according to GB / T228-2010 "Metallic Materials - Tensile Testing - Part 1: Room Temperature Test Method"; and the exfoliation corrosion performance of the aluminum alloys was tested according to GB / T22639-2022 "Aluminum Alloy Products - Exfoliation Corrosion Test Method". The pass rate of the aluminum alloy profiles refers to the percentage of aluminum alloys obtained using the methods of the examples and comparative examples that did not have cracking or other problems. The results are shown in Table 1 below.

[0097] Table 1: Performance Test Results

[0098]

[0099] Analysis of the data in Table 1 shows that after optimizing the composition, component ratio, and process, this application can obtain a 7-series aluminum alloy with uniform microstructure and fine grains. This ensures the tensile strength, yield strength, and elongation of the 7-series aluminum alloy, meeting the mechanical properties required for use. Furthermore, process optimization also promotes the morphology and microstructure of the 7-series aluminum alloy, resulting in superior exfoliation corrosion resistance, a higher yield, and better production efficiency. Specifically, the difference between Comparative Example 1 and Example 1 is that V element was not added in Comparative Example 1, while the method of adding V element in Comparative Example 2 was different. The resulting comparative sample showed poorer overall performance compared to the sample in Example 3, indicating that by adding a specific proportion of V element and using a specific method of addition, this application can help improve the grain refinement effect, thereby enhancing the mechanical properties of the 7-series aluminum alloy. The differences between Comparative Examples 3-6 and Example 3 are all in the process, but they also have a significant impact on mechanical properties and exfoliation corrosion resistance. This shows that after optimizing the compounding of the components and combining it with the optimization of process parameters, this application can obtain a 7-series aluminum alloy with excellent comprehensive performance.

[0100] In addition, metallographic analysis was performed on the 7-series aluminum alloy sample from Example 1. Examples 2-4 were similar to Example 1 and will not be described in detail here. Figure 1 This is a schematic diagram of the as-cast metallographic structure of the 7-series aluminum alloy in Example 1 during its preparation process. Figure 2 This is a schematic diagram of the homogeneous metallographic structure of the 7-series aluminum alloy during the preparation process of Example 1; Figure 3 This is a schematic diagram of the metallographic structure of the longitudinal section of the extruded aluminum alloy during the preparation process of the 7-series aluminum alloy in Example 1; Figure 4 This is a schematic diagram of the metallographic structure of the extruded cross-section of the 7-series aluminum alloy in Example 1 during the preparation process. Figures 1-4 As can be seen from the data, the 7-series aluminum alloy prepared in this application has a uniform microstructure, with no large blocks, and the grains are evenly distributed and relatively fine. The tendency to pit is reduced, and the overall stability is better, which is conducive to obtaining a 7-series aluminum alloy with better comprehensive performance.

[0101] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0102] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A 7-series aluminum alloy material, characterized in that, The 7-series aluminum alloy material comprises the following components by mass percentage: Si≤0.10%, Fe≤0.15%, Mn 0.25%~0.30%, Mg 1.7%, Zn 6.6%, V 0.09%~0.12%, Ti 0.03%, Cu0.2%~0.35% or Cr 0.12%~0.15%, single impurity element≤0.05%, total impurities≤0.15%, and Al balance; The 7-series aluminum alloy material has a tensile strength ≥500MPa, a yield strength ≥500MPa, an elongation ≥12%, and a peeling corrosion resistance not lower than EA grade. The preparation method of the 7-series aluminum alloy material includes the following steps: According to the mass percentage of the chemical composition of 7-series aluminum alloy materials, pure aluminum is added to a melting furnace. After it is completely melted and the temperature of the melt is 720℃~740℃, raw materials containing Si, Fe, Mn, Mg, Zn, Ti, Cu or Cr elements are added in sequence. After melting and complete melting, the content and ratio of alloy elements are adjusted by online composition detection and analysis to obtain molten metal A. Argon gas is introduced into the upper, middle and bottom of the molten metal A for 10 min to 15 min for refining. Then, a V-containing refining agent is added, the slag is removed and the mixture is allowed to stand and be kept warm to obtain molten metal B. The preparation method of the V-containing refining agent is as follows: aluminum powder and vanadium pentoxide are ball-milled, then heated to complete melting under a protective gas, kept at that temperature for 6 h to 8 h, cast, homogenized and hot-extruded, and then cooled to room temperature to obtain a V-containing phase with a size of 5 μm to 30 μm in the V-containing refining agent. Once the temperature of the molten metal B drops to 700℃±5℃, an aluminum alloy ingot is obtained by casting. The aluminum alloy ingot is pretreated at 250℃~300℃ for 4h~24h, and then homogenized in two stages. The first stage of homogenization is carried out at 300℃±5℃ for 8h~10h; the second stage of homogenization is carried out at 480℃±5℃ for 20h~24h, and then cooled to room temperature with water mist. The homogenized aluminum alloy ingot is preheated to 500℃~550℃, the extrusion die is preheated to 400℃~450℃, the die cylinder is preheated to 400℃~450℃, and then extrusion is performed. Solution treatment is performed at 470℃±5℃ for 1h~2h, the cooling medium is water at room temperature, and the quenching transfer time does not exceed 10s. The solution-treated aluminum alloy ingot is subjected to single-stage aging or double-stage aging. The single-stage aging is performed at 120℃~125℃ for 24 hours; the double-stage aging is performed at 100℃ for 14 hours and at 130℃~135℃ for 10 hours to obtain 7-series aluminum alloy materials.

2. A method for preparing a 7-series aluminum alloy material, characterized in that, The preparation method is used to prepare the 7-series aluminum alloy material as described in claim 1, and the preparation method includes the following steps: According to the mass percentage of the chemical composition of 7-series aluminum alloy materials, pure aluminum is added to a melting furnace. After it is completely melted and the temperature of the melt is 720℃~740℃, raw materials containing Si, Fe, Mn, Mg, Zn, Ti, Cu or Cr elements are added in sequence. After melting and complete melting, the content and ratio of alloy elements are adjusted by online composition detection and analysis to obtain molten metal A. Argon gas is introduced into the upper, middle and bottom of the molten metal A for 10 min to 15 min for refining. Then, a V-containing refining agent is added, the slag is removed and the mixture is allowed to stand and be kept warm to obtain molten metal B. The preparation method of the V-containing refining agent is as follows: aluminum powder and vanadium pentoxide are ball-milled, then heated to complete melting under a protective gas, kept at that temperature for 6 h to 8 h, cast, homogenized and hot-extruded, and then cooled to room temperature to obtain a V-containing phase with a size of 5 μm to 30 μm in the V-containing refining agent. Once the temperature of the molten metal B drops to 700℃±5℃, an aluminum alloy ingot is obtained by casting. The aluminum alloy ingot is pretreated at 250℃~300℃ for 4h~24h, and then homogenized in two stages. The first stage of homogenization is carried out at 300℃±5℃ for 8h~10h; the second stage of homogenization is carried out at 480℃±5℃ for 20h~24h, and then cooled to room temperature with water mist. The homogenized aluminum alloy ingot is preheated to 500℃~550℃, the extrusion die is preheated to 400℃~450℃, the die cylinder is preheated to 400℃~450℃, and then extrusion is performed. Solution treatment is performed at 470℃±5℃ for 1h~2h, the cooling medium is water at room temperature, and the quenching transfer time does not exceed 10s. The solution-treated aluminum alloy ingot is subjected to single-stage aging or double-stage aging. The single-stage aging is performed at 120℃~125℃ for 24 hours; the double-stage aging is performed at 100℃ for 14 hours and at 130℃~135℃ for 10 hours to obtain 7-series aluminum alloy materials.

3. The preparation method according to claim 2, characterized in that, The temperature for static heat preservation is 720℃~740℃, and the time is 30min~35min.

4. The preparation method according to claim 2, characterized in that, The extrusion process has a coefficient of 30-45, a speed of 6-8 m / min, and an outlet temperature of 500-550℃.

5. The preparation method according to claim 2, characterized in that, The average diameter of the V-containing refining agent is 5 mm to 10 mm.

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