A method for manufacturing an Al-5.8Zn-2.2Mg-0.2Er-0.12Zr aluminum alloy plate

Abstract

The application relates to a preparation method of an Al-5.8Zn-2.2Mg-0.2Er-0.12Zr aluminum alloy plate, and belongs to the field of aluminum alloy plate preparation, in particular to a preparation method of an Al-5.8Zn-2.2Mg-0.2Er-0.12Zr aluminum alloy plate. The purpose of the application is to greatly improve the corrosion performance of the Al-Zn-Mg alloy while the Al-Zn-Mg alloy has high strength. The elements contained are weighed, smelted, refined, filtered, cast, homogenized annealed, milled, hot-rolled, solid-solved, stretched, aged, and sawed into products. According to the composition of the alloy, the homogenization annealing, solid-solution stretching and aging process systems are matched, and two kinds of normal-temperature tensile strength and exfoliation corrosion results are obtained. The user can select according to the use environment, and the application can meet the needs of important engineering fields such as ships, ocean engineering and rail transit.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy sheet preparation, specifically relating to a method for preparing Al-5.8Zn-2.2Mg-0.2Er-0.12Zr aluminum alloy sheet. Background Technology

[0002] In numerous applications of modern industry, the demand for material strength is increasing. For example, in the aerospace field, aircraft structural components need to withstand enormous flight loads, complex stress states, and harsh environmental conditions. Al-Zn-Mg alloys, with their high strength achievable through heat treatment and other processes, have become a candidate material for manufacturing critical components such as aircraft beams and wings. In the transportation sector, the need for lightweighting in automobiles and high-speed trains has driven the use of high-strength alloys to ensure structural safety and reliability while reducing weight, making Al-Zn-Mg alloys a focus of attention.

[0003] However, while traditional Al-Zn-Mg alloys exhibit excellent strength, they suffer from significant shortcomings in corrosion resistance. Their corrosion problems mainly stem from the following aspects:

[0004] Alloy composition and microstructure: Elements such as zinc and magnesium in the alloy can form highly electrochemically active phases under certain environments. These phases are more susceptible to corrosion than the aluminum matrix. Furthermore, microstructural inhomogeneities formed during solidification and processing, such as segregation at grain boundaries, provide preferential pathways for corrosion. The contradiction between corrosion susceptibility and strength is the main reason limiting the development and application of Al-Zn-Mg alloys. The distribution of grain boundary precipitates and the width of the non-precipitated zone are key factors affecting the alloy's corrosion resistance. To obtain discontinuously distributed grain boundary precipitates, aging processes such as T74, RRA, and DRRA have been developed. However, these complex heat treatment processes not only increase the difficulty of industrial production but also cause coarsening of intragranular precipitates, leading to a decrease in strength.

[0005] Service environment impact: In practical applications, Al-Zn-Mg alloys are often exposed to harsh environments such as humidity, salinity (e.g., marine environments), and corrosive gases (e.g., industrial pollution areas). For example, in marine environments, chloride ions in seawater can penetrate the oxide film on the alloy surface, initiating various forms of corrosion such as pitting and intergranular corrosion, severely weakening the structural integrity and service life of the alloy.

[0006] For structural components bearing significant loads, such as critical components in aerospace and transportation, corrosion-induced material performance degradation can lead to structural failure and serious safety accidents. Replacement and repair costs for corrosion-damaged components are also high. In industrial facilities, frequent replacement of corrosion-damaged Al-Zn-Mg alloy components not only increases direct material and labor costs but also incurs indirect economic losses due to equipment downtime.

[0007] Therefore, while maintaining the high strength of Al-Zn-Mg alloys, it is essential to significantly improve their corrosion resistance. This will not only expand the alloy's application range in harsher environments, such as marine engineering and coastal infrastructure construction, but also effectively reduce safety risks and economic losses caused by corrosion, thereby enhancing product reliability and overall benefits.

[0008] In summary, given the demand for high strength and the prominent issue of corrosion, significantly improving the corrosion resistance of Al-Zn-Mg alloys while maintaining high strength has become a crucial technical problem that urgently needs to be solved. Summary of the Invention

[0009] The purpose of this invention is to significantly improve the corrosion resistance of Al-Zn-Mg alloys while maintaining high strength, and to provide a method for preparing Al-5.8Zn-2.2Mg-0.2Er-0.12Zr aluminum alloy plates.

[0010] A method for preparing an Al-5.8Zn-2.2Mg-0.2Er-0.12Zr aluminum alloy sheet is completed according to the following steps:

[0011] I. Weigh out aluminum ingots, zinc ingots, magnesium ingots, aluminum-manganese master alloys, aluminum-erbium master alloys, aluminum-zirconium master alloys, aluminum-beryllium master alloys, aluminum-titanium wires, and aluminum-titanium-boron grain refiners as raw materials according to the following mass percentages: Si ≤ 0.15%, Fe ≤ 0.15%, Cu ≤ 0.10%, Mn: 0.2%–0.7%, Mg: 1.5%–2.5%, Zr: 0.05%–0.15%, Er: 0.05%–0.30%, Zn: 5.3%–6.3%, Ti: 0.01%–0.05%, single impurity ≤ 0.05%, total impurities ≤ 0.15%, and balance Al.

[0012] 2. Weigh out aluminum ingots, zinc ingots, aluminum-manganese master alloy, aluminum-zirconium master alloy, and aluminum-titanium master alloy for remelting and add them to a melting furnace. The melting temperature is 750-800℃. When the melt temperature is ≥780℃, add aluminum-erbium master alloy and hold for 20 minutes. Then, stir for the first time. When the melt temperature rises again to 780℃ and holds for 20 minutes, stir for the second time. When the melt temperature drops to 750℃ after the second stirring, add magnesium ingots and aluminum-beryllium master alloy. Stir and mix well, then spread No. 2 covering agent and let stand for 20-30 minutes. Then, transfer the melt to a settling furnace and refine it with Ar-Cl2 mixed gas until the hydrogen content in 100 grams of melt is ≤0.15mL to obtain aluminum alloy melt.

[0013] 3. The aluminum alloy melt is filtered through a two-stage ceramic filter with a diameter of 30ppi and a diameter of 50ppi. At the beginning of casting, an aluminum-titanium-boron grain refiner is inserted into the flow channel and the addition rate is controlled. The resulting aluminum alloy melt is poured into a square crystallizer with a diameter of 420×1620mm to obtain an alloy ingot.

[0014] 4. The alloy ingot is homogenized and annealed to obtain a homogenized and annealed ingot, and then milled. The milled ingot is rolled, and after rolling, it is solution quenched and stretched to obtain a solution quenched and stretched plate.

[0015] 5. After solution quenching and stretching, the sheet metal is subjected to aging treatment and then sawn into finished products to obtain Al-5.8Zn-2.2Mg-0.2Er-0.12Zr aluminum alloy sheet metal.

[0016] Beneficial effects of this invention:

[0017] The Al-5.8Zn-2.2Mg-0.2Er-0.12Zr aluminum alloy sheet prepared by this invention can meet the needs of major engineering fields such as ships and rail transit.

[0018] This invention, based on the existing Al-Zn-Mg aluminum alloy composition system, adds rare earth elements such as Er and Zr to further leverage the complex synergistic effects of composite rare earth microalloying elements. It explores a new alloy design model for Er-Zr multi-component composites. Adding Er is one way to improve the corrosion resistance of Al-Zn-Mg alloys. The introduction of Al3(Er,Zr) particles reduces the degree of recrystallization in the alloy, decreasing the number of recrystallization grain boundaries. Grain boundary precipitates tend to preferentially precipitate at high-angle grain boundaries of recrystallized grains with higher energy. Coarse grain boundary precipitates are prone to anodic dissolution, while high-angle grain boundaries with more precipitates provide propagation channels for cracks. The presence of precipitation-free zones near high-angle grain boundaries is also considered to reduce the corrosion resistance of the alloy. Because high-angle grain boundaries have higher interfacial energy, they are conducive to the nucleation of precipitates, thus the precipitation-free zones at high-angle grain boundaries are wider. Due to the potential difference between the non-precipitated zone and the grain boundary precipitates, localized corrosion easily occurs between the two, ultimately leading to intergranular corrosion cracks in the alloy and deteriorating its corrosion resistance. Figure 1 As shown, compared with alloys without Er, alloys with added Er exhibit lower recrystallization, fewer large-angle grain boundaries, and significantly reduced crack propagation paths, thus improving the corrosion resistance of Er-containing alloys. This results in alloys possessing optimal mechanical properties while also enhancing corrosion resistance.

[0019] With increasing alloying degree, the strength of Al-Zn-Mg alloys gradually increases, but their corrosion resistance deteriorates significantly, which is the main problem limiting the development of Al-Zn-Mg alloys. This invention optimizes the Zn / Mg ratio and adds microalloying elements Er and Zr, with the main alloying elements Zn+Mg at 7wt%, to study the influence of the Zn / Mg ratio and microalloying elements on the alloy's mechanical and corrosion properties. This maximizes the alloy's strength potential while avoiding the deterioration in corrosion resistance caused by increased alloy content, further promoting the application of Al-Zn-Mg alloys in shipbuilding, rail transportation, and other fields.

[0020] This invention improves the corrosion resistance of Al-Zn-Mg alloy plates. The Al-5.8Zn-2.2Mg-0.2Er-0.12Zr aluminum alloy plates prepared exhibit N-level exfoliation corrosion when the room temperature tensile strength is ≥430MPa, yield strength is ≥350MPa, and elongation is ≥12%; and P-level exfoliation corrosion when the room temperature tensile strength is ≥540MPa, yield strength is ≥520MPa, and elongation is ≥10%, which is 2 to 3 levels higher than that of Al-Zn-Mg alloys of the same level. Attached Figure Description

[0021] Figure 1 This is a photograph of the alloy ingot blank used in Example 2;

[0022] Figure 2 This is a photograph of the hot-rolled alloy sheet used in Example 2;

[0023] Figure 3 This is a photograph of the plate after it peeled off and corroded in Example 2. Detailed Implementation

[0024] The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any combination of the specific embodiments.

[0025] Specific Implementation Method 1: The preparation method of an Al-5.8Zn-2.2Mg-0.2Er-0.12Zr aluminum alloy sheet according to this embodiment is completed according to the following steps:

[0026] I. Weigh out aluminum ingots, zinc ingots, magnesium ingots, aluminum-manganese master alloys, aluminum-erbium master alloys, aluminum-zirconium master alloys, aluminum-beryllium master alloys, aluminum-titanium wires, and aluminum-titanium-boron grain refiners as raw materials according to the following mass percentages: Si ≤ 0.15%, Fe ≤ 0.15%, Cu ≤ 0.10%, Mn: 0.2%–0.7%, Mg: 1.5%–2.5%, Zr: 0.05%–0.15%, Er: 0.05%–0.30%, Zn: 5.3%–6.3%, Ti: 0.01%–0.05%, single impurity ≤ 0.05%, total impurities ≤ 0.15%, and balance Al.

[0027] 2. Weigh out aluminum ingots, zinc ingots, aluminum-manganese master alloy, aluminum-zirconium master alloy, and aluminum-titanium master alloy for remelting and add them to a melting furnace. The melting temperature is 750-800℃. When the melt temperature is ≥780℃, add aluminum-erbium master alloy and hold for 20 minutes. Then, stir for the first time. When the melt temperature rises again to 780℃ and holds for 20 minutes, stir for the second time. When the melt temperature drops to 750℃ after the second stirring, add magnesium ingots and aluminum-beryllium master alloy. Stir and mix well, then spread No. 2 covering agent and let stand for 20-30 minutes. Then, transfer the melt to a settling furnace and refine it with Ar-Cl2 mixed gas until the hydrogen content in 100 grams of melt is ≤0.15mL to obtain aluminum alloy melt.

[0028] 3. The aluminum alloy melt is filtered through a two-stage ceramic filter with a diameter of 30ppi and a diameter of 50ppi. At the beginning of casting, an aluminum-titanium-boron grain refiner is inserted into the flow channel and the addition rate is controlled. The resulting aluminum alloy melt is poured into a square crystallizer with a diameter of 420×1620mm to obtain an alloy ingot.

[0029] 4. The alloy ingot is homogenized and annealed to obtain a homogenized and annealed ingot, and then milled. The milled ingot is rolled, and after rolling, it is solution quenched and stretched to obtain a solution quenched and stretched plate.

[0030] 5. After solution quenching and stretching, the sheet metal is subjected to aging treatment and then sawn into finished products to obtain Al-5.8Zn-2.2Mg-0.2Er-0.12Zr aluminum alloy sheet metal.

[0031] In this embodiment, the amount of aluminum-beryllium master alloy added is 0.005%, which is a very small amount and is intended to prevent ingot cracking.

[0032] In this embodiment, the aluminum-erbium master alloy is stirred twice to ensure its uniform distribution in the aluminum alloy melt.

[0033] In this embodiment, an aluminum-titanium-boron grain refiner is inserted into the casting channel during casting until the casting is completed, with the aim of uniformly melting it into the aluminum alloy melt.

[0034] In this embodiment, the aging treatment adopts two aging systems: single-level and double-level. It matches the corrosion performance of 550MPa and 430MPa strength levels as N-level and P-level, respectively, so that users can choose the appropriate system for their application scenarios.

[0035] In this embodiment, the edge trimming process continues until no cracks are visible to the naked eye on the edge of the wide hot-rolled plate.

[0036] In this embodiment, Zn and Mg are the main components. Variations in their content affect the microstructure, strength, and corrosion resistance of the Al-Zn-Mg alloy, especially the Mg content, which has a significant impact on the alloy's corrosion performance. During the development of industrial Al-Zn-Mg alloys, the Zn content has gradually increased, but the Mg content has been controlled between 1% and 3% to prevent corrosion deterioration caused by excess Mg. Part of the Mg in the alloy participates in the formation of precipitates, playing a role in precipitation strengthening, while another part is dissolved in the matrix; this part is defined as excess Mg. Corrosion tests on Al-Zn-Mg alloys with different compositions revealed the relationship between corrosion crack propagation rate and excess Mg content. When the excess Mg content is between 0.5% and 2%, the corrosion crack propagation rate is the slowest, and the alloy exhibits the best corrosion resistance. However, when the excess Mg content exceeds 2%, the crack propagation rate increases rapidly, and the alloy's corrosion resistance deteriorates significantly. Therefore, optimizing the alloy element content not only ensures the alloy's mechanical properties but also improves its corrosion resistance.

[0037] The Zn / Mg ratio is also a crucial factor affecting the corrosion resistance of alloys. When the Zn / Mg ratio increases from 1 to 2, the crack propagation rate of the Al-Zn-Mg alloy decreases by two orders of magnitude, and the alloy's corrosion resistance improves rapidly. The alloy exhibits optimal corrosion resistance when the Zn / Mg ratio is maintained between 2.7 and 3. With further increases in the Zn / Mg ratio, the crack propagation rate gradually increases, and the alloy's corrosion resistance begins to deteriorate. Therefore, optimizing the Zn / Mg ratio can directly improve the alloy's corrosion resistance. The optimal Zn / Mg ratio range also differs for alloys with different degrees of alloying. However, current research on the correlation between the Zn / Mg ratio and the alloy's microstructure and corrosion resistance is relatively scarce.

[0038] The addition of microalloying elements can reduce the grain size and recrystallization of the alloy, and improve the distribution of grain boundary precipitates, thereby helping to improve the strength and corrosion resistance of the alloy and meeting the comprehensive performance requirements of the alloy in industrial applications.

[0039] The addition of erbium to the aluminum alloy in this embodiment forms fine and stable second-phase particles. These particles act as barriers to dislocation movement, thus helping to improve the alloy's strength. Furthermore, they provide protection on the alloy surface or at grain boundaries, hindering the intrusion of corrosive media and improving corrosion resistance. Compounds formed with other elements segregate at grain boundaries, filling grain boundary defects and reducing the likelihood of grain boundaries acting as preferential corrosion pathways. Simultaneously, zirconium typically forms the Al3Zr phase in aluminum alloys, which exhibits high thermal stability and dispersed distribution. During alloy solidification and subsequent processing, the Al3Zr phase effectively inhibits grain growth and refines the grains. This not only improves the alloy's strength (a grain refinement strengthening mechanism) but also increases the relative area of ​​grain boundaries, making the diffusion path of corrosive media at grain boundaries more tortuous, thereby enhancing the alloy's corrosion resistance.

[0040] In this embodiment, the melting temperature is strictly controlled between 750 and 800°C during the smelting process, and various intermediate alloys are added in a specific order. First, a portion of the intermediate alloy is added and held at a suitable temperature with stirring. This allows for a more uniform distribution of elements in the melt, reducing compositional inhomogeneity caused by localized element enrichment. A uniformly composed alloy exhibits more stable performance during subsequent processing and use, reducing the risk of localized corrosion due to component segregation and improving corrosion resistance. Simultaneously, a uniform compositional distribution is crucial for forming a uniform strengthening phase, thus ensuring the alloy's high strength. When the melt temperature reaches ≥780°C, the aluminum-erbium intermediate alloy is added and held for 20 minutes, followed by stirring. This ensures that erbium is well integrated into the melt and exerts its grain-refining and performance-improving effects.

[0041] The aluminum alloy was refined using an Ar-Cl2 mixed gas until the hydrogen content was ≤0.15mL per 100g of melt. Excessive hydrogen content in aluminum alloys can lead to defects such as pores during solidification, disrupting the alloy's continuity and integrity and becoming initiation points for corrosion. Refining to reduce hydrogen content effectively minimizes these defects, thereby improving the alloy's corrosion resistance. It also helps maintain the alloy's strength, as alloys with fewer defects are less prone to stress concentration and premature failure under load.

[0042] Filtration removes inclusions such as oxides and impurity particles from the melt. These inclusions, if present in the alloy, can become stress concentration points, reducing its strength; they can also disrupt the integrity of the oxide film on the alloy surface or act as channels for corrosive media penetration, exacerbating corrosion. Filtration removes inclusions, improving alloy purity, which helps increase both strength and corrosion resistance. At the start of casting, an aluminum-titanium-boron (ATiB) grain refiner is inserted into the runner at a controlled rate. This ATiB grain refiner further refines the grains, similar to the grain refiner effect of zirconium mentioned earlier; grain refinement strengthens the alloy and increases its strength. Simultaneously, refined grains improve the alloy's corrosion resistance because smaller grains make it more difficult for corrosive media to diffuse at grain boundaries, delaying corrosion.

[0043] Homogenization annealing of alloy ingots can eliminate compositional segregation and microstructure inhomogeneity formed during the solidification process of the ingot. Homogenization annealing makes the alloy's composition and microstructure more uniform, which is beneficial for improving the alloy's corrosion resistance and ensuring its high strength uniformity.

[0044] Rolling can further refine grains, improve the microstructure of the alloy, and increase its strength. At the same time, a suitable rolling process can create a work-hardened layer on the alloy surface, which can, to some extent, improve the alloy's resistance to corrosive media.

[0045] Solution hardening and stretching treatments can better dissolve and precipitate the reinforcing phases in the alloy, forming a uniformly distributed reinforcing phase and improving the alloy's strength. Furthermore, this process optimizes the alloy's microstructure, reducing microstructural defects that easily lead to corrosion, thereby improving its corrosion resistance.

[0046] Aging treatment can further regulate the precipitation state of the strengthening phase in the alloy, so that while maintaining high strength, the alloy can improve its corrosion resistance by optimizing the distribution and morphology of the strengthening phase.

[0047] In summary, this preparation method, through the synergistic effect of multiple aspects such as alloy composition design, melting and refining processes, filtration and grain refinement, and subsequent processing, enables the Al-Zn-Mg alloy to have high strength while significantly improving its corrosion resistance.

[0048] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that: the aluminum-erbium master alloy mentioned in step one is an Al-5%Er master alloy; the aluminum-zirconium master alloy is an Al-5%Zr master alloy; the aluminum-manganese master alloy is an Al-10%Mn master alloy; the aluminum-titanium master alloy is an Al-4%Ti master alloy; the aluminum-beryllium master alloy is an Al-11%Be master alloy; and the aluminum-titanium-boron grain refiner is an Al-5%Ti-1%B alloy. Everything else is the same as in Specific Implementation Method One.

[0049] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 1 in that the first stirring time in step two is 5-10 minutes, and the second stirring time is 5-10 minutes. Everything else is the same as in Specific Implementation Method 1.

[0050] Specific Implementation Method Four: This implementation method differs from Specific Implementation Method One in that the amount of the No. 2 covering agent mentioned in step two accounts for 0.50% to 0.55% of the total mass of the melt in the melting furnace. Everything else is the same as in Specific Implementation Method One.

[0051] Specific Implementation Method Five: This implementation method differs from Specific Implementation Method One in that the volume ratio of argon to chlorine in the Ar-Cl2 mixed gas in step two is (31.5~33):1. Everything else is the same as in Specific Implementation Method One.

[0052] Specific Implementation Method Six: This implementation method differs from Specific Implementation Method One in that the insertion speed of the aluminum-titanium-boron grain refiner into the flow channel in step three is 450–500 mm / min. Everything else is the same as in Specific Implementation Method One.

[0053] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Method One in that the cross-sectional dimensions of the alloy ingot in step three are 420×1620mm, and the length is 4500mm. Everything else is the same as in Specific Implementation Method One.

[0054] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Method One in the following aspects: The process parameters for the homogenization annealing treatment in step four are: heating at 280℃ for 16-20 hours, then raising the temperature to 470℃ and holding for 20-28 hours, followed by air cooling to room temperature; the process parameters for the milling treatment are: milling the ingot to 380mm-400mm; the rolling process involves rolling the milled ingot into a wide hot-rolled plate with a thickness of 8-20mm and a width ≥1500mm, with a maximum reduction of 20mm per pass and a rolling speed controlled at 1.2-1.5m / s; the process parameters for the solution treatment are: first raising the furnace temperature to 470℃, then loading the hot-rolled plate into the furnace, monitoring the metal temperature of the hot-rolled plate until it reaches 470℃, starting the timer and holding for 60 minutes, then removing from the furnace and water quenching to obtain the solution-treated plate; the process parameters for the stretching treatment are: completing the stretching treatment of the solution-treated plate within 2 hours, with the stretching amount controlled at 1.8-2.5%. Everything else is the same as in Specific Implementation Method 1.

[0055] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Method One in that the process parameters for the aging treatment in step five are as follows: After holding the sheet at 120℃ for 6 hours, the furnace temperature is raised to 160℃, and it is held at 160℃ for 20 hours before being removed from the furnace and air-cooled. The sheet is then sawn to obtain Al-5.8Zn-2.2Mg-0.2Er-0.12Zr aluminum alloy sheet with a tensile strength ≥430MPa, yield strength ≥350MPa, elongation ≥12%, and exfoliation corrosion reaching level N. Everything else is the same as in Specific Implementation Method One.

[0056] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Method One in that the aging treatment process parameters in step five are as follows: After the sheet is held at 120℃ for 24 hours, it is removed from the furnace and air-cooled. The sheet is then sawn to obtain an Al-5.8Zn-2.2Mg-0.2Er-0.12Zr aluminum alloy sheet with a tensile strength ≥540MPa, yield strength ≥520MPa, elongation ≥10%, and exfoliation corrosion reaching level P. Everything else is the same as in Specific Implementation Method One.

[0057] The beneficial effects of the present invention are verified by the following embodiments:

[0058] Example 1: A method for preparing an Al-5.8Zn-2.2Mg-0.2Er-0.12Zr aluminum alloy sheet is completed according to the following steps:

[0059] I. Weigh out aluminum ingots, zinc ingots, magnesium ingots, and aluminum ingots for remelting according to the following mass percentages: Si ≤ 0.15%, Fe ≤ 0.15%, Cu ≤ 0.10%, Mn: 0.2%–0.7%, Mg: 1.5%–2.5%, Zr: 0.05%–0.15%, Er: 0.05%–0.30%, Zn: 5.3%–6.3%, Ti: 0.01%–0.05%, single impurity ≤ 0.05%, total impurities ≤ 0.15%, and the balance being Al. The raw materials include manganese master alloy, aluminum-erbium master alloy, aluminum-zirconium master alloy, aluminum-beryllium master alloy, aluminum-titanium wire, and aluminum-titanium-boron grain refiner; the aluminum-erbium master alloy is Al-5%Er master alloy; the aluminum-zirconium master alloy is Al-5%Zr master alloy; the aluminum-manganese master alloy is Al-10%Mn master alloy; the aluminum-titanium master alloy is Al-4%Ti master alloy; the aluminum-beryllium master alloy is Al-11%Be master alloy; and the aluminum-titanium-boron grain refiner is Al-5%Ti-1%B alloy.

[0060] 2. Weigh out the aluminum ingots, zinc ingots, aluminum-manganese master alloy, aluminum-zirconium master alloy, and aluminum-titanium master alloy for remelting and add them to the melting furnace. The melting temperature is 750–800℃. When the melt temperature reaches ≥780℃, add the aluminum-erbium master alloy and hold for 20 minutes. Then, stir for the first time for 5–10 minutes. After the melt temperature rises again to 780℃ and is held for 20 minutes, stir for the second time for 5–10 minutes. When the melt temperature drops to 750℃ after the second stirring, add… Magnesium ingots and aluminum-beryllium master alloys are stirred and mixed thoroughly, then coated with No. 2 covering agent and allowed to stand for 20-30 minutes. The melt is then introduced into a settling furnace and refined using an Ar-Cl2 mixed gas until the hydrogen content in 100 grams of melt is ≤0.15 mL, thus obtaining an aluminum alloy melt. The amount of No. 2 covering agent is 0.50-0.55% of the total mass of the melt in the melting furnace. The volume ratio of argon to chlorine in the Ar-Cl2 mixed gas is (31.5-33):1.

[0061] 3. The aluminum alloy melt is filtered through a two-stage ceramic filter (30ppi + 50ppi). At the start of casting, an aluminum-titanium-boron grain refiner is inserted into the flow channel and the addition rate is controlled. The resulting aluminum alloy melt is poured into a square crystallizer with dimensions of 420×1620mm to obtain an alloy ingot. The insertion rate of the aluminum-titanium-boron grain refiner into the flow channel is 450-500mm / min. The cross-sectional dimensions of the alloy ingot are 420×1620mm and the length is 4500mm.

[0062] IV. The alloy ingot billet undergoes homogenization annealing to obtain a homogenized annealed ingot, which is then milled. The milled ingot billet is rolled, followed by solution quenching and stretching to obtain a solution-quenched and stretched sheet. The process parameters for the homogenization annealing are: heating at 280℃ for 16-20 hours, then raising the temperature to 470℃ and holding for 20-28 hours, followed by air cooling to room temperature. The process parameters for the milling are: milling the ingot to 380mm-400mm. The rolling process involves rolling the milled ingot billet to a thickness of 8mm. Wide hot-rolled plates with a thickness of 20mm and a width ≥1500mm are rolled. The maximum reduction per pass during rolling is 20mm, and the rolling speed is controlled at 1.2~1.5m / s. The process parameters for the solution treatment are as follows: first, the furnace temperature is raised to 470℃, then the hot-rolled plate is loaded into the furnace. When the metal temperature of the hot-rolled plate reaches 470℃, the timer is started and the plate is held at that temperature for 60 minutes. Then, the plate is removed from the furnace and water-quenched to obtain the solution-treated plate. The process parameters for the stretching treatment are as follows: the stretching treatment of the solution-treated plate is completed within 2 hours, and the stretching amount is controlled at 1.8~2.5%.

[0063] 5. After solution quenching and stretching, the sheet metal is subjected to aging treatment, and then sawn into finished products to obtain Al-5.8Zn-2.2Mg-0.2Er-0.12Zr aluminum alloy sheet metal. The process parameters for the aging treatment are as follows: after holding the sheet metal at 120℃ for 6 hours, the furnace temperature is raised to 160℃ and held at 160℃ for 20 hours before being removed from the furnace and air-cooled. The sheet metal is then sawn to obtain Al-5.8Zn-2.2Mg-0.2Er-0.12Zr aluminum alloy sheet metal with tensile strength ≥430MPa, yield strength ≥350MPa, elongation ≥12%, and exfoliation corrosion reaching level N.

[0064] The Al-5.8Zn-2.2Mg-0.2Er-0.12Zr aluminum alloy sheet prepared in this embodiment, after testing, showed that when the room temperature tensile properties were tensile strength ≥430MPa, yield strength ≥350MPa, and elongation ≥12%, the exfoliation corrosion reached level N.

[0065] Example 2: The difference between this example and Example 1 is that the process parameters for the aging treatment in step 5 are as follows: After the plate is kept at 120℃ for 24 hours, it is taken out of the furnace and air-cooled. The plate is then sawn to obtain an Al-5.8Zn-2.2Mg-0.2Er-0.12Zr aluminum alloy plate with tensile strength ≥540MPa, yield strength ≥520MPa, elongation ≥10%, and exfoliation corrosion reaching level P.

[0066] The Al-5.8Zn-2.2Mg-0.2Er-0.12Zr aluminum alloy sheet prepared in this embodiment, after testing, showed that when the room temperature tensile properties were tensile strength ≥540MPa, yield strength ≥520MPa, and elongation ≥10%, the exfoliation corrosion reached level P.

[0067] A photograph of the alloy ingot obtained in this embodiment is shown below. Figure 1 As shown.

[0068] A photograph of the actual alloy sheet obtained in this embodiment is shown below. Figure 2 As shown.

[0069] The photograph of the alloy plate obtained in this embodiment after peeling and corrosion is shown below. Figure 3 As shown, the plate exhibits no delamination or pitting corrosion, and its surface is smooth.

Claims

1. A method for preparing Al-5.8Zn-2.2Mg-0.2Er-0.12Zr aluminum alloy sheet, characterized in that... The preparation method of Al-5.8Zn-2.2Mg-0.2Er-0.12Zr aluminum alloy sheet is completed according to the following steps: I. Weigh out aluminum ingots, zinc ingots, magnesium ingots, and aluminum ingots for remelting according to the following mass percentages: Si ≤ 0.15%, Fe ≤ 0.15%, Cu ≤ 0.10%, Mn: 0.2%~0.7%, Mg: 1.5%~2.5%, Zr: 0.05%~0.15%, Er: 0.05%~0.30%, Zn: 5.3%~6.3%, Ti: 0.01%~0.05%, single impurity ≤ 0.05%, total impurities ≤ 0.15%, and the balance being Al. The raw materials include manganese master alloy, aluminum-erbium master alloy, aluminum-zirconium master alloy, aluminum-beryllium master alloy, aluminum-titanium wire, and aluminum-titanium-boron grain refiner; the aluminum-erbium master alloy is Al-5%Er master alloy; the aluminum-zirconium master alloy is Al-5%Zr master alloy; the aluminum-manganese master alloy is Al-10%Mn master alloy; the aluminum-titanium master alloy is Al-4%Ti master alloy; the aluminum-beryllium master alloy is Al-11%Be master alloy; and the aluminum-titanium-boron grain refiner is Al-5%Ti-1%B alloy.

2. Weigh out the aluminum ingots, zinc ingots, aluminum-manganese master alloy, aluminum-zirconium master alloy, and aluminum-titanium master alloy for remelting and add them to the melting furnace. The melting temperature is 750~800℃. When the melt temperature reaches ≥780℃, add the aluminum-erbium master alloy and hold for 20 minutes. Then, perform the first stirring. After the melt temperature rises again to 780℃ and holds for 20 minutes, perform the second stirring. When the melt temperature drops to 750℃ after the second stirring, add the magnesium ingots and aluminum-beryllium master alloy. Stir and mix thoroughly, then spread No. 2 covering agent, let stand for 20~30 minutes, and then melt... The melt is introduced into a settling furnace and refined using an Ar-Cl2 mixed gas until the hydrogen content in 100 grams of melt is ≤0.15 mL, yielding an aluminum alloy melt. The first stirring time is 5-10 min, and the second stirring time is 5-10 min. The amount of the No. 2 covering agent is 0.50-0.55% of the total mass of the melt in the melting furnace. The volume ratio of argon to chlorine in the Ar-Cl2 mixed gas is (31.5-33):

1. The amount of aluminum-beryllium master alloy added is 0.005% of the total mass of the melt.

3. The aluminum alloy melt is filtered through a two-stage ceramic filter (30ppi + 50ppi). At the start of casting, an aluminum-titanium-boron grain refiner is inserted into the flow channel and the addition rate is controlled. The resulting aluminum alloy melt is poured into a square crystallizer with dimensions of 420×1620mm to obtain an alloy ingot. The insertion rate of the aluminum-titanium-boron grain refiner into the flow channel is 450~500mm / min. The cross-sectional dimensions of the alloy ingot are 420×1620mm and the length is 4500mm. IV. The alloy ingot billet undergoes homogenization annealing to obtain a homogenized annealed ingot, which is then milled. The milled ingot billet is rolled, followed by solution quenching and stretching to obtain a solution-quenched and stretched sheet. The process parameters for homogenization annealing are: heating at 280℃ for 16-20 hours, then raising the temperature to 470℃ and holding for 20-28 hours, followed by air cooling to room temperature. The process parameters for milling are: milling the ingot to 380mm-400mm. The rolling process involves rolling the milled ingot billet to a thickness of 8mm. Wide hot-rolled plates with a thickness of 20mm and a width ≥1500mm are rolled, with a maximum reduction of 20mm per pass and a rolling speed controlled at 1.2~1.5m / s. The solution treatment process parameters are as follows: first, the furnace temperature is raised to 470℃; then, the hot-rolled plate is loaded into the furnace; when the metal temperature of the hot-rolled plate reaches 470℃, the timer is started and the plate is held at that temperature for 60 minutes; then, the plate is removed from the furnace and water-quenched to obtain the solution-treated plate. The stretching process parameters are as follows: the solution-treated plate undergoes stretching within 2 hours, with the stretching amount controlled at 1.8~2.5%.

5. After solution quenching and stretching, the sheet metal is subjected to aging treatment, and then sawn into finished products to obtain Al-5.8Zn-2.2Mg-0.2Er-0.12Zr aluminum alloy sheet metal; the process parameters of the aging treatment are as follows: the sheet metal is held at 120℃ for 24 hours, then air-cooled after being removed from the furnace, and the sheet metal is sawn to obtain Al-5.8Zn-2.2Mg-0.2Er-0.12Zr aluminum alloy sheet metal with tensile strength ≥540MPa, yield strength ≥520MPa, elongation ≥10%, and exfoliation corrosion reaching level P.

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