7-series aluminum alloy material and preparation method thereof

Abstract

The invention discloses a 7-series aluminum alloy material and a preparation method thereof, and belongs to the field of aluminum alloy preparation.The 7-series aluminum alloy material and the preparation method thereof have the advantages that on the basis of optimizing components of 7-series aluminum alloy, the proportion and the process of the components are properly adjusted, it can be guaranteed that the tensile strength, the yield strength and the ductility meet the use requirements on the whole, and the corrosion resistance can be further improved; by adding the Zn element and the Mg element, the strength and hardness of the 7-series aluminum alloy can be remarkably improved, a proper Cu or Cr ratio can reduce residual phases (a T-Al2Mg3Zn3 phase, an AlZnMgCu phase or an AlZnMgCr phase), but after solution treatment, the residual phases gradually disappear, all alloy elements can be dissolved in a matrix in a solid mode, an AlFe phase is reduced, then corrosion sites are reduced, and by combining the synergistic effect of the Mn element and the V-containing refiner, the corrosion resistance of the 7-series aluminum alloy is improved. The crystalline phase in the 7-series aluminum alloy is refined, so that the mechanical property of the 7-series aluminum alloy can be obviously improved, and the corrosion resistance of the 7-series aluminum alloy can be obviously improved.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloy preparation, and more particularly, to a 7-series aluminum alloy material and a preparation method thereof. Background Art

[0002] 7xxx series aluminum alloys can be divided into Al-Zn-Mg series and Al-Zn-Mg-Cu series aluminum alloys. This series of alloys has a wide range of applications due to their high strength, high modulus, good electrical and thermal conductivity, low density, good plasticity and processing performance, and has become one of the important structural materials. Among the many elements in 7xxx series aluminum alloys, Zn and Mg elements play a major strengthening role. Without exceeding the solid solution limit of the alloy, an increase in Zn element will increase the volume fraction of metastable phases in the alloy, improving the tensile strength and yield strength of the alloy while increasing its strength. However, at room temperature, the solid solubility of Zn element in the alloy is not high, and it cannot form intermetallic compounds with Al. Therefore, the addition of Zn element has a certain limit in improving the strength of the alloy, and it will also increase the tendency of the alloy to corrode and crack. The addition of Mg element appropriately increases the strength of the alloy. However, within the solid solution limit, increasing the Mg element will also affect the corrosion resistance of the alloy. The addition of Cu element can change the precipitation of intragranular and grain boundary phases to improve the strength, plasticity and corrosion resistance of the alloy. However, if the addition amount of Cu element is too high, it is easy to form coarse residual phases at the grain boundaries, which will deteriorate the intergranular corrosion resistance of the alloy and become the starting point of pitting corrosion, increasing the pitting sensitivity of the alloy. Therefore, for the performance of 7xxx series aluminum alloys, the influence of other elements needs to be considered simultaneously, and the regulation of element content and ratio is of great significance for the comprehensive performance of 7xxx series aluminum alloys. For example, in the prior art, by adding Zr element to 7xxx series aluminum alloys to inhibit recrystallization, fine insoluble particles Al 3 Zr are formed. This particle has two structures and morphologies: one is the tetragonal structure of Al 3 Zr particles directly precipitated from the melt, which can significantly refine the grains of the as-cast alloy; the other is metastable spherical particles with L12 structure precipitated during the homogenization process of the ingot, which are coherent with the matrix and can inhibit recrystallization during hot working. However, when the content of Zr element is too high or the melting is improper, the alloy is prone to segregation due to the uneven distribution of Zr element, resulting in uneven distribution of Al 3 Zr phase. This will lead to significant differences in recrystallization between the Zr-rich region and the Zr-poor region. At the same time, the thermal stability of Al 3 Zr phase is poor, and it will transform to the equilibrium state after long-term high-temperature treatment, resulting in the disappearance of the coherent relationship between Al 3 Zr phase and the matrix. The region near the dispersed phase will become the nucleation region of coarse phases, consuming to a certain extent the Zn and Mg elements that form strengthening phases and increasing the quenching sensitivity of the alloy.

[0003] Therefore, there is a close relationship between the properties of 7xxx series aluminum alloys and their microstructures, and it is necessary to find particles that are finer than the Al 3 Zr phase, more dispersed in distribution, and have better thermal stability to improve the comprehensive properties of 7xxx series alloys. In addition, the limitations of the process will also affect the properties of 7xxx series aluminum alloys. This application optimizes the composition, component ratio, and process to solve the problem that 7xxx series aluminum alloys in the prior art cannot ensure tensile strength, yield strength, and elongation while further improving corrosion resistance to meet the usage requirements. Summary of the Invention

[0004] Based on this, in order to solve the technical problem that 7xxx series aluminum alloys in the prior art cannot ensure tensile strength, yield strength, and elongation while further improving corrosion resistance, the present invention provides a 7 series aluminum alloy material and a preparation method thereof. The specific technical solutions are as follows:

[0005] A 7 series aluminum alloy material, the 7 series aluminum alloy material includes 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 the balance is Al;

[0006] The tensile strength of the 7 series aluminum alloy material is ≥ 500 MPa, the yield strength is ≥ 500 Mpa, the elongation is ≥ 12%, and the exfoliation corrosion resistance is not lower than EA level.

[0007] In addition, this application also provides a preparation method of a 7 series aluminum alloy material. The preparation method includes the following steps:

[0008] According to the mass percentage of the chemical components of the 7 series aluminum alloy material, pure aluminum is added to a melting furnace. After it is completely melted and the temperature of the melt is 720°C - 740°C, raw materials containing Si element, Fe element, Mn element, Mg element, Zn element, Ti element, Cu element, or Cr element are added in sequence, and melting treatment is carried out. After it is completely melted, through on-line composition detection and analysis, the alloy element content and ratio are adjusted to obtain molten metal A;

[0009] Argon is introduced into the upper, middle, and bottom of the molten metal A for refining for 10 min - 15 min, and then a V-containing grain refiner is added. After skimming the slag, it is left standing for heat preservation to obtain molten metal B;

[0010] When the temperature of the molten metal B drops to 700°C ± 5°C, an aluminum alloy ingot is cast;

[0011] The aluminum alloy ingot is pre-treated, then homogenized, and water mist cooled to room temperature;

[0012] The homogenized aluminum alloy ingot is preheated to 500 °C - 550 °C, the extrusion die is preheated to 400 °C - 450 °C, and the die barrel is preheated to 400 °C - 450 °C, and then extrusion treatment, solution treatment and aging treatment are carried out to obtain 7-series aluminum alloy materials.

[0013] Further, the temperature for static heat preservation is 720 °C - 740 °C, and the time is 30 min - 35 min.

[0014] Further, the temperature for the pre-treatment is 250 °C - 300 °C, and the time is 4 h - 24 h.

[0015] Further, the homogenization treatment is carried out in two stages. The temperature for the first-stage homogenization is 300 °C ± 5 °C, and the time is 8 h - 10 h; the temperature for the second-stage homogenization is 480 °C ± 5 °C, and the time is 20 h - 24 h.

[0016] Further, the coefficient for the extrusion treatment is 30 - 45, the speed is 6 m / min - 8 m / min, and the outlet temperature of the extruded material is 500 °C - 550 °C.

[0017] Further, the solution treatment is carried out at 470 °C ± 5 °C for 1 h - 2 h, the cooling medium is water at room temperature, and the quenching transfer time does not exceed 10 s.

[0018] Further, the aging treatment includes one of single-stage aging and two-stage aging. The single-stage aging is carried out at 120 °C - 125 °C for 24 h; the two-stage aging is carried out at 100 °C for 14 h and at 130 °C - 135 °C for 10 h.

[0019] Further, the preparation method of the V-containing grain refiner is as follows: Aluminum powder and vanadium pentoxide are subjected to ball milling treatment, and then heated to complete melting under a protective gas, held for 6 h - 8 h, cast, homogenized and hot-extruded, and then cooled to room temperature to obtain a V-containing grain refiner with the size of the V-containing phase being 5 μm - 30 μm.

[0020] Further, the average diameter of the V-containing grain refiner is 5 mm - 10 mm.

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

[0022] 1. In the present invention, by adding a V-containing grain refiner, the as-cast grains of the 7-series aluminum alloy can be effectively refined. The V element can form a thermally stable non-coherent Al 21 V 2The dispersed phase can significantly improve the high-temperature strength of 7xxx series aluminum alloys, and this dispersed phase can also inhibit recrystallization and provide the recrystallization temperature. In addition, the addition of V element significantly refines the microstructure, making the internal structure of 7xxx series aluminum alloys more uniform, significantly improving the recrystallization resistance during solution treatment. Combining with the process of homogenization treatment after pretreatment, the synergistic effect makes the subgrain size of 7xxx series aluminum alloys smaller, forming fine dispersed phases to pin the migration of dislocations and subgrain boundaries, showing an obvious hindering effect on subgrain coarsening and improving the strength and stress corrosion resistance of the alloy.

[0023] 2. By adding the V-containing refiner prepared by the present invention, the probability of introducing impurities can be reduced, and it has excellent uniformity and purity. Moreover, the operation is simple and the controllability is strong, ensuring no oxidation surface, which can meet the usage requirements of promoting the microstructure uniformity and grain refinement of 7xxx series aluminum alloys.

[0024] 3. On the basis of optimizing the composition of 7xxx series aluminum alloys, the present invention appropriately adjusts the composition ratio and process, which can generally ensure that the tensile strength, yield strength and elongation meet the usage requirements, and can further improve the corrosion resistance. Among them, the addition of Zn element and Mg element can significantly improve the strength and hardness of 7xxx series aluminum alloys. Appropriate ratios of Cu or Cr can reduce the residual phases (T phase - Al 2 Mg 3 Zn 3 phase, AlZnMgCu phase or AlZnMgCr), but after solution treatment, the residual phases gradually disappear, and all alloying elements can be dissolved in the matrix. The AlFe phase decreases, thereby reducing the corrosion sites. Combining with the synergistic effect of Mn element and the V-containing refiner, the crystal phases in 7xxx series aluminum alloys are refined, which can not only significantly improve the mechanical properties of 7xxx series aluminum alloys, but also significantly improve the corrosion resistance of 7xxx series aluminum alloys. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0026] Figure 1 Schematic diagram of the as-cast metallographic structure of 7xxx series aluminum alloy in the preparation process for Example 1;

[0027] Figure 2 Schematic diagram of the homogenized metallographic structure of 7xxx series aluminum alloy in the preparation process for Example 1;

[0028] Figure 3 Schematic diagram of the metallographic structure of the longitudinal section of the extruded state of 7xxx series aluminum alloy in the preparation process for Example 1;

[0029] Figure 4Schematic diagram of the metallographic structure of the cross-section of the extruded 7xxx series aluminum alloy during the preparation process of Example 1. Detailed implementation manners

[0030] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with its embodiments. It should be understood that the specific implementation manners described herein are only used to explain the present invention and do not limit the protection scope of the present invention.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the description of the present invention herein are only for the purpose of describing specific implementation manners and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0032] A 7xxx series aluminum alloy material in an embodiment of the present invention, the 7xxx series aluminum alloy material includes 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 the balance is Al;

[0033] The tensile strength of the 7xxx series aluminum alloy material ≥ 500 MPa, the yield strength ≥ 500 Mpa, the elongation ≥ 12%, and the exfoliation corrosion resistance is not lower than EA level.

[0034] In addition, the present application also provides a preparation method for a 7xxx series aluminum alloy material, and the preparation method includes the following steps:

[0035] According to the mass percentage of the chemical components of the 7xxx series aluminum alloy material, pure aluminum is added to the melting furnace. After it is completely melted and the temperature of the melt is 720°C - 740°C, raw materials containing Si element, Fe element, Mn element, Mg element, Zn element, Ti element, Cu element or Cr element are added in sequence, and melting treatment is carried out. After it is completely melted, through on-line component detection and analysis, the alloy element content and ratio are adjusted to obtain molten metal A;

[0036] Argon is introduced into the upper, middle and bottom of the molten metal A for refining for 10 min - 15 min, and then a V-containing grain refiner is added. After skimming the slag, it is left standing for heat preservation to obtain molten metal B;

[0037] When the temperature of the molten metal B drops to 700°C ± 5°C, an aluminum alloy ingot is cast;

[0038] Pre-treat the aluminum alloy ingot, then perform homogenization treatment, and cool it to room temperature by water mist cooling;

[0039] Preheat the aluminum alloy ingot after homogenization treatment to 500°C - 550°C, preheat the extrusion die to 400°C - 450°C, and preheat the die barrel to 400°C - 450°C, then perform extrusion treatment, solution treatment and aging treatment to obtain 7-series aluminum alloy materials.

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

[0041] In one embodiment, the temperature for the pre-treatment is 250°C - 300°C, and the time is 4 h - 24 h.

[0042] In one embodiment, the homogenization treatment is carried out in two stages. The temperature for the first-stage homogenization is 300°C ± 5°C, and the time is 8 h - 10 h; the temperature for the second-stage homogenization is 480°C ± 5°C, and the time is 20 h - 24 h.

[0043] In one embodiment, the coefficient for the extrusion treatment is 30 - 45, the speed is 6 m / min - 8 m / min, and the outlet temperature of the extruded material is 500°C - 550°C.

[0044] In one embodiment, the solution treatment is carried out at 470°C ± 5°C for 1 h - 2 h, the cooling medium is water at room temperature, and the quenching transfer time does not exceed 10 s.

[0045] In one embodiment, the aging treatment includes one of single-stage aging and two-stage aging. The single-stage aging is carried out at 120°C - 125°C for 24 h; the two-stage aging is carried out at 100°C for 14 h and 130°C - 135°C for 10 h.

[0046] In one embodiment, the preparation method of the V-containing grain refiner is as follows: Ball-mill aluminum powder and vanadium pentoxide, then heat it to complete melting under a protective gas, keep it warm for 6 h - 8 h, cast, perform homogenization and hot extrusion treatment, and then cool it to room temperature. The size of the V-containing phase in the V-containing grain refiner is 5 μm - 30 μm.

[0047] In one embodiment, in the preparation method of the V-containing grain refiner, the temperature for the homogenization treatment is 400°C - 420°C, and the time is 1 h - 2 h.

[0048] In one embodiment, in the preparation method of the V-containing grain refiner, the temperature for the hot extrusion treatment is 500°C - 550°C, and quenching treatment is carried out at a quenching rate of 5°C / s.

[0049] In one of the embodiments, the average diameter of the V-containing refiner is 5 mm to 10 mm.

[0050] Based on the above solution, by optimizing the composition of the 7-series aluminum alloy, appropriately adjusting the proportion of the components and optimizing the process, the tensile strength, yield strength and elongation can be guaranteed as a whole, and the corrosion resistance can be further improved.

[0051] The following will describe in detail the implementation scheme of the present invention in combination with specific embodiments.

[0052] Example 1:

[0053] The 7-series aluminum alloy in Example 1 includes 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%, single impurity element ≤ 0.05%, total impurities ≤ 0.15%, and the balance is Al;

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

[0055] Perform ball milling on aluminum powder and vanadium pentoxide, then heat to complete melting under a protective gas, keep warm for 6 h, cast, homogenize at 400 °C for 2 h, then perform hot extrusion treatment at 500 °C, and perform quenching treatment at a quenching rate of 5 °C / s, and cool to room temperature to obtain a V-containing refiner with an average diameter of 8 mm, and the size of the V phase in the V-containing refiner is 5 μm to 30 μm;

[0056] Add pure aluminum to the melting furnace according to the mass percentage of the chemical composition of the 7-series aluminum alloy material. After complete melting and the temperature of the melt reaches 740 °C, successively add raw materials containing Si element, Fe element, Mn element, Mg element, Zn element, Ti element, Cu element or Cr element, perform melting treatment, and after complete melting, adjust the alloy element content and ratio through on-line composition detection and analysis to obtain molten metal A;

[0057] Pass argon into the upper, middle and bottom of the molten metal A for refining for 10 min to 15 min, then add the V-containing refiner, skim the slag and keep it static and warm at 720 °C for 35 min to obtain molten metal B;

[0058] Wait for the temperature of the molten metal B to drop to 705 °C and cast to obtain an aluminum alloy ingot;

[0059] The aluminum alloy ingot is pre-treated at 300 °C for 6 h, and then homogenized. The homogenization is carried out in two stages. The temperature of the first-stage homogenization is 305 °C and the time is 8 h; the temperature of the second-stage homogenization is 485 °C and the time is 20 h, and it is cooled to room temperature by water mist.

[0060] The aluminum alloy ingot after homogenization is preheated to 500 °C, the extrusion die is preheated to 450 °C, and the die barrel is preheated to 400 °C, and then extrusion is carried out. The extrusion coefficient is 30, the speed is 6 m / min, and the outlet temperature of the extruded material is 500 °C; the aluminum alloy ingot after extrusion is solution-treated at 475 °C for 2 h, the cooling medium is water at room temperature, and the quenching transfer time does not exceed 10 s;

[0061] The aluminum alloy ingot after solution treatment is subjected to two-stage aging treatment, and the two-stage aging is treatment at 100 °C for 14 h and treatment at 135 °C for 10 h to obtain a 7-series aluminum alloy material.

[0062] Example 2:

[0063] The 7-series aluminum alloy in Example 2 includes 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%, single impurity element ≤0.05%, total impurity ≤0.15%, and the balance is Al;

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

[0065] The aluminum powder and vanadium pentoxide are subjected to ball milling treatment, and then heated to complete melting under a protective gas, held for 7 h, cast, homogenized at 420 °C for 1 h, and then hot extruded at 550 °C, and quenched at a quenching rate of 5 °C / s and cooled to room temperature to obtain a V-containing grain refiner with an average diameter of 10 mm, and the size of the V-containing phase in the V-containing grain refiner is 5 μm to 30 μm;

[0066] According to the mass percentage of the chemical components of the 7-series aluminum alloy material, pure aluminum is added to the melting furnace. After complete melting and the temperature of the melt reaches 740 °C, raw materials containing Si element, Fe element, Mn element, Mg element, Zn element, Ti element, Cu element or Cr element are added in sequence, and melting treatment is carried out. After complete melting, the alloy element content and ratio are adjusted through on-line composition detection and analysis to obtain molten metal A;

[0067] Argon is introduced into the upper, middle, and bottom parts of the molten metal A for refining for 10 min to 15 min, and then a V-containing grain refiner is added. After skimming the slag, it is statically heat-insulated at 730 °C for 30 min to obtain molten metal B;

[0068] When the temperature of the molten metal B drops to 705 °C, an aluminum alloy ingot is cast;

[0069] The aluminum alloy ingot is pre-treated at 280 °C for 7 h, and then homogenization treatment is carried out. The homogenization treatment is carried out in two stages. The temperature of the first-stage homogenization is 305 °C and the time is 10 h; the temperature of the second-stage homogenization is 485 °C and the time is 20 h, and it is cooled to room temperature by water mist;

[0070] The aluminum alloy ingot after homogenization treatment is preheated to 550 °C, the extrusion die is preheated to 450 °C, and the die barrel is preheated to 450 °C, and then extrusion treatment is carried out. The coefficient of the extrusion treatment is 35, the speed is 8 m / min, and the outlet temperature of the extruded material is 550 °C; the aluminum alloy ingot after extrusion treatment is solution-treated at 475 °C for 2 h, the cooling medium is water at room temperature, and the quenching transfer time does not exceed 10 s;

[0071] The aluminum alloy ingot after solution treatment is subjected to two-stage aging treatment, and the two-stage aging is treatment at 100 °C for 14 h and treatment at 130 °C for 10 h to obtain a 7-series aluminum alloy material.

[0072] Example 3:

[0073] The 7-series aluminum alloy in Example 1 includes 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%, single impurity element ≤0.05%, total impurities ≤0.15%, and the balance is Al;

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

[0075] Aluminum powder and vanadium pentoxide are subjected to ball milling treatment, and then heated to complete melting under a protective gas, heat-insulated for 8 h, cast, homogenized at 420 °C for 2 h, then subjected to hot extrusion treatment at 550 °C, and quenched at a quenching rate of 5 °C / s, cooled to room temperature to obtain a V-containing grain refiner with an average diameter of 10 mm, and the size of the V phase in the V-containing grain refiner is 5 μm to 30 μm;

[0076] According to the mass percentage of the chemical composition of the 7-series aluminum alloy material, pure aluminum is added to the melting furnace. After it is completely melted and the temperature of the melt is 720°C to 740°C, raw materials containing Si element, Fe element, Mn element, Mg element, Zn element, Ti element, Cu element or Cr element are added in sequence, and smelting treatment is carried out. After complete melting, through on-line composition detection and analysis, the alloy element content and ratio are adjusted to obtain molten metal A;

[0077] Argon is introduced into the upper, middle and bottom of the molten metal A for refining for 15 minutes, then a V-containing grain refiner is added. After skimming the slag, it is statically held at 740°C for 30 minutes to obtain molten metal B;

[0078] When the temperature of the molten metal B drops to 705°C, an aluminum alloy ingot is cast;

[0079] The aluminum alloy ingot is pretreated at 250°C for 15 hours, and then homogenization treatment is carried out. The homogenization treatment is carried out in two stages. The temperature of the first-stage homogenization is 305°C and the time is 7 hours; the temperature of the second-stage homogenization is 485°C and the time is 22 hours, and it is cooled to room temperature by water mist;

[0080] The aluminum alloy ingot after homogenization treatment is preheated to 550°C, the extrusion die is preheated to 450°C, and the die barrel is preheated to 450°C, and then extrusion treatment is carried out. The extrusion coefficient is 45, the speed is 8 m / min, and the outlet temperature of the extruded material is 550°C; the aluminum alloy ingot after extrusion treatment is solution-treated at 475°C for 2 hours, the cooling medium is water at room temperature, and the quenching transfer time does not exceed 10 s;

[0081] The aluminum alloy ingot after solution treatment is subjected to two-stage aging treatment, and the two-stage aging is treatment at 100°C for 14 hours and treatment at 135°C for 10 hours to obtain the 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, treatment at 120°C for 24 hours, and others are 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 includes 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%, single impurity element ≤0.05%, total impurity ≤0.15%, and the balance is Al. Others are the same as Example 1.

[0086] Comparative Example 2:

[0087] The difference between Comparative Example 2 and Example 3 is that in Comparative Example 2, the V element and other elements are directly added into the molten aluminum, and then smelted. After complete melting, the alloy element content and ratio are adjusted through on-line composition detection and analysis to obtain molten metal A. Others are the same as in Example 3.

[0088] Comparative Example 3:

[0089] The difference between Comparative Example 3 and Example 3 is that in Comparative Example 3, solution treatment is not carried out, and others are the same as in Example 3.

[0090] Comparative Example 4:

[0091] The difference between Comparative Example 4 and Example 3 is that in Comparative Example 4, pretreatment is not carried out, and others are the same as in Example 3.

[0092] Comparative Example 5:

[0093] The difference between Comparative Example 5 and Example 3 is that in Comparative Example 5, the homogenization treatment is the first-level homogenization, the temperature is 450 °C, and the time is 24 h. Others are the same as in Example 3.

[0094] Comparative Example 6:

[0095] The difference between Comparative Example 6 and Example 3 is that in Comparative Example 6, the aging treatment is: treating at 120 °C for 10 h and treating at 200 °C for 6 h. Others are the same as in Example 3.

[0096] The samples prepared in Examples 1 to 4 and the comparative samples prepared in Comparative Examples 1 to 6 were subjected to performance tests. Among them, the macrostructure detection and analysis of the aluminum alloy were carried out by referring to the method of GB / T 3264-2000 to observe the grain size; the mechanical properties of the aluminum alloy were tested by referring to GB / T 228-2010 "Metallic materials - Tensile testing - Part 1: Method of test at room temperature"; the exfoliation corrosion performance of the aluminum alloy was tested by referring to GB / T 22639-2022 "Test method for exfoliation corrosion of aluminum alloy products"; the qualification rate of the aluminum alloy profiles refers to the proportion of the number of aluminum alloys without problems such as cracking obtained by using the methods of the examples and comparative examples. The results are shown in Table 1 below.

[0097] Table 1: Performance test results

[0098]

[0099] From the data analysis in Table 1, it can be seen that after the components, component ratios and process optimization of this application, a 7-series aluminum alloy with uniform structure and fine grains can be obtained, ensuring the tensile strength, yield strength and elongation rate of the 7-series aluminum alloy, meeting the mechanical properties required for use. In addition, through process optimization, it can also promote the morphological structure of the 7-series aluminum alloy, endowing it with more excellent exfoliation corrosion resistance, a higher qualified rate and better production efficiency. Specifically, the difference between Comparative Example 1 and Example 1 is that V element is not added in Comparative Example 1, and the addition method of V element is different in Comparative Example 2. As a result, the overall performance of the obtained comparative samples is worse than that of the samples in Example 3, indicating that in this application, by adding a specific proportion of V element and a specific addition method of V element, it can help to improve the effect of promoting grain refinement and achieve the purpose of 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 obvious effects on the mechanical properties and exfoliation corrosion resistance, indicating that after the compound optimization of the components in this application and combined with the optimization of process parameters, a 7-series aluminum alloy with excellent comprehensive performance can be obtained.

[0100] In addition, the metallographic structure analysis was carried out on the 7-series aluminum alloy sample in Example 1. Examples 2-4 are similar to Example 1 and will not be elaborated here. Among them, Figure 1 is the schematic diagram of the as-cast metallographic structure of the 7-series aluminum alloy in Example 1 during the preparation process, Figure 2 is the schematic diagram of the homogenized metallographic structure of the 7-series aluminum alloy in Example 1 during the preparation process; Figure 3 is the schematic diagram of the metallographic structure of the longitudinal section of the extruded state of the 7-series aluminum alloy in Example 1 during the preparation process; Figure 4 is the schematic diagram of the metallographic structure of the cross section of the extruded state of the 7-series aluminum alloy in Example 1 during the preparation process. It can be seen from Figures 1 to 4 that the 7-series aluminum alloy prepared in this application has a uniform tissue morphology, no large blocks are seen, the grain distribution is uniform and relatively fine, the pitting corrosion tendency is reduced, and the overall stability is better, which is conducive to obtaining a 7-series aluminum alloy with more excellent comprehensive performance.

[0101] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, 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, it should be considered to be within the scope described in this specification.

[0102] The above-described embodiments merely represent several implementation manners of the present invention. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A 7 series aluminum alloy material, characterized in that: The 7 series aluminum alloy material includes the following components in mass percentage: Si≤0.10%, Fe≤0.15%, Mn 0.25%-0.30%, Mg 1.7%, Zn 6.6%, V 0.09%-0.12%, Ti0.03%, Cu 0.2%-0.35% or Cr 0.12%-0.15%, single impurity element≤0.05%, total impurities≤0.15%, Al balance; The 7 series aluminum alloy material has a tensile strength of ≥500 MPa, a yield strength of ≥500 MPa, an elongation of ≥12%, and a peeling corrosion resistance performance not lower than EA grade.

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 according to claim 1, and the preparation method comprises the following steps: According to the mass percentage of the chemical composition of the 7 series aluminum alloy material, pure aluminum is added into a smelting furnace, and after it is completely melted and the temperature of the melt is 720°C to 740°C, raw materials containing Si element, Fe element, Mn element, Mg element, Zn element, Ti element, Cu element or Cr element are added in sequence, and smelting treatment is performed. After it is completely melted, the content and proportion of the alloy elements are adjusted through online component detection and analysis to obtain a molten metal A; Argon is introduced into the upper, middle and bottom of the molten metal A for refining for 10 to 15 minutes, and then a V-containing refiner is added, and the molten metal is allowed to stand and be kept warm after slagging to obtain molten metal B; When the temperature of the molten metal B drops to 700°C±5°C, casting to obtain an aluminum alloy ingot; The aluminum alloy ingot is pretreated, then homogenized, and cooled to room temperature by water mist; The aluminum alloy ingot after homogenization treatment is preheated to 500°C-550°C, the extrusion die is preheated to 400°C-450°C, the die barrel is preheated to 400°C-450°C, and then extrusion treatment, solution treatment and aging treatment are performed to obtain 7 series aluminum alloy material.

3. The preparation method according to claim 2, characterized in that: The temperature of the static insulation is 720° C. to 740° C., and the time is 30 min to 35 min.

4. The preparation method according to claim 2, characterized in that: The pretreatment temperature is 250° C. to 300° C., and the pretreatment time is 4 h to 24 h.

5. The preparation method according to claim 2, characterized in that: The homogenization treatment is carried out in two stages. The temperature of the first stage is 300°C±5°C and the time is 8h~10h; the temperature of the second stage is 480°C±5°C and the time is 20h~24h.

6. The preparation method according to claim 2, characterized in that: The coefficient of the extrusion process is 30-45, the speed is 6m / min-8m / min, and the outlet temperature of the extrudate is 500°C-550°C.

7. The preparation method according to claim 2, characterized in that: The solution treatment is carried out at 470°C ± 5°C for 1 h to 2 h, the cooling medium is water at room temperature, and the quenching transfer time does not exceed 10 s.

8. The preparation method according to claim 2, characterized in that: The aging treatment includes one of single-stage aging and double-stage aging, and the single-stage aging is 120° C. to 125° C. for 24 hours; the double-stage aging is 100° C. for 14 hours and 130° C. to 135° C. for 10 hours.

9. The preparation method according to claim 2, characterized in that: 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 protective gas, kept warm for 6h to 8h, cast, homogenized and hot-extruded, and then cooled to room temperature to obtain a V-containing refining agent with a V-containing phase size of 5μm to 30μm.

10. The preparation method according to claim 9, characterized in that: The average diameter of the V-containing refiner is 5 mm to 10 mm.

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