High-strength, large-plasticity, corrosion-resistant Al-Zn-Mn-Cu-Mg aluminum alloy and application thereof

Abstract

The application provides an Al-Zn-Mn-Cu-Mg aluminum alloy with high strength, large plasticity and corrosion resistance and application thereof, and belongs to the technical field of aluminum alloys. The Al-Zn-Mn-Cu-Mg aluminum alloy uses Mn elements as important alloy elements, improves corrosion resistance through Mn elements, and makes the alloy have excellent corrosion resistance. The Al-Zn-Mn-Cu-Mg aluminum alloy reduces the content of Mg and Cu elements, controls the precipitation amount and distribution of eta phase and theta phase, and the prepared alloy has a tensile strength of more than 550 MPa and an elongation of not less than 20%, belongs to an ultrahigh-strength aluminum alloy with high plastic deformation capacity, is suitable for profile machining in the fields of traffic transportation, aerospace and the like, and has good practicability.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy technology, specifically relating to a high-strength, high-plasticity, and corrosion-resistant Al-Zn-Mn-Cu-Mg aluminum alloy and its applications. Background Technology

[0002] As a structural metallic material, aluminum alloys are characterized by abundant resources, environmental friendliness, and easy recycling, and occupy a dominant position in transportation, marine engineering, shipbuilding, and construction engineering. The rapid development of the transportation and aerospace industries has led to a rapid increase in the demand for aluminum alloys, while also placing higher demands on their performance. In particular, the development of ultra-high-strength aluminum alloys, represented by Al-Cu and Al-Zn series, has played an important role in promoting tool lightweighting and reducing energy consumption.

[0003] Al-Zn alloys have been widely used for many years, with common alloy systems including Al-Zn-Mg and Al-Zn-Mg-Cu. The addition of Mg or Cu increases the alloy's strength, but the main strengthening phase in these alloys is the η phase (a precipitate composed of Mg and Zn, typically stoichiometrically MgZn2). With the development of aluminum alloy technology, increasing the content of Mg and Cu, and optimizing the composition of existing alloys with Zr, Sc, or other rare earth elements, has become the main method to further improve the strength of Al-Zn alloys. However, with the increase in alloying degree, the η phase and the θ phase (precipitates composed of Al and Cu, typically stoichiometrically Al2Cu) are added to the aluminum alloy. These phases have a large chemical potential difference with the alloy matrix (α-Al), leading to a decrease in the alloy's corrosion resistance, especially a strong increase in stress corrosion cracking. Furthermore, the continuous distribution of the strengthening phase at the matrix grain boundaries also weakens the alloy's plasticity, making it prone to cracking during the manufacture of thin plates or foils, resulting in an increased scrap rate.

[0004] Currently, the conventional methods to overcome the distribution characteristics of the η and θ phases in Al-Zn alloys are multi-stage aging treatment or deformation heat treatment, which complicates the heat treatment process. From the perspective of overall strength design, element substitution (i.e., alloying) is a common design method in existing alloy systems, but it is difficult to break through the limitations of the original composition range. Composition selection in alloy systems with more than four components is a complex process with multiple variables, and the precipitation process of strengthening phases must also be considered, resulting in a relatively slow development of new Al-Zn alloys, and the corrosion resistance problem of this system is difficult to overcome. Therefore, designing a new aluminum alloy with high strength, high plasticity, and corrosion resistance in alloy systems with more than four components has significant engineering application value. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a high-strength, highly ductile, and corrosion-resistant Al-Zn-Mn-Cu-Mg aluminum alloy and its applications. The Al-Zn-Mn-Cu-Mg aluminum alloy of this invention uses Mn as a key alloying element, and enhances corrosion resistance through manganese (Mn), giving the alloy excellent corrosion resistance. The Al-Zn-Mn-Cu-Mg aluminum alloy reduces the content of Mg and Cu elements, and regulates the precipitation amount and distribution of η and θ phases, resulting in a tensile strength exceeding 550 MPa and an elongation of not less than 20%. This ultra-high-strength aluminum alloy with high plastic deformation capacity is suitable for profile processing in transportation, aerospace, and other fields, demonstrating excellent practicality.

[0006] To achieve the above-mentioned technical objectives, the present invention employs the following technical means.

[0007] This invention first provides a high-strength, highly ductile, and corrosion-resistant Al-Zn-Mn-Cu-Mg aluminum alloy. The composition of the Al-Zn-Mn-Cu-Mg aluminum alloy includes: Zn: 6.5wt.%~9.5wt.%, Mn: 0.6wt.%~1.3wt.%, Cu: 0.4wt.%~1.2wt.%, Mg: 0.4wt.%~1.2wt.%, the total content of other impurities does not exceed 0.15wt.%, and the content of a single impurity component does not exceed 0.02wt.%, with the balance being Al.

[0008] Preferably, in the Al-Zn-Mn-Cu-Mg aluminum alloy, the Mn / Zn mass ratio is 0.09 to 0.16, the Mn / Cu and Mn / Mg mass ratios are ≥1.00, and the Cu / Mg mass ratio is 0.50 to 1.29.

[0009] The present invention also provides the application of the above-mentioned Al-Zn-Mn-Cu-Mg aluminum alloy in the preparation of Al-Zn-Mn-Cu-Mg aluminum alloy plates.

[0010] This invention also provides a method for preparing Al-Zn-Mn-Cu-Mg aluminum alloy plates, specifically including the following steps:

[0011] (1) Calculate and weigh the raw materials of Al-Zn-Mn-Cu-Mg aluminum alloy based on the composition of the above-mentioned high-strength, high-plasticity, and corrosion-resistant Al-Zn-Mn-Cu-Mg aluminum alloy.

[0012] (2) Melt the raw materials weighed in step (1) into Al-Zn-Mn-Cu-Mg alloy melt, then add the Al-Zn-Mn-Cu-Mg alloy melt into a preheated casting mold, and then cool it naturally to obtain an alloy ingot.

[0013] (3) The alloy ingot is preheated and kept at a certain temperature. After the temperature is kept at a certain temperature, it is forged to produce a thick plate. After the forging is completed, a thick plate is obtained. Then the thick plate is cooled to room temperature and cleaned to obtain a thick plate with the surface stains removed.

[0014] (4) The thick plate with the surface stains removed is re-insulated, and the prepared thick plate is obtained after the treatment.

[0015] (5) Use twin-roll rolling to roll the prepared thick plate in multiple passes. After each pass of rolling, heat preservation treatment is performed. After the heat preservation treatment is completed, rolling is performed again until the designed thickness is reached.

[0016] (6) After rolling, a high-strength, high-plasticity, and corrosion-resistant Al-Zn-Mn-Cu-Mg aluminum alloy sheet is obtained.

[0017] Preferably, in step (1), the raw materials include industrial pure aluminum, industrial pure zinc, industrial pure manganese or Al-Mn master alloy, industrial pure copper or Al-Cu master alloy, and industrial pure magnesium or Al-Mg master alloy.

[0018] Preferably, in step (2), the casting mold is preheated to 350°C to 410°C.

[0019] Preferably, in step (3), the preheating and heat preservation conditions are to keep warm at 430℃~480℃ for 45min~70min.

[0020] Preferably, in step (3), the forging conditions are: the pressing rate is 5 mm / s to 15 mm / s, and the forging is continuously performed until 2 / 3 to 1 / 3 of the alloy ingot size in step (2), and the temperature is not controlled during the forging process.

[0021] Preferably, in step (4), the heat preservation treatment is to keep warm at 420℃~460℃ for 30min~60min.

[0022] Preferably, in step (5), the multi-pass rolling process is as follows: the first pass pressing amount is 15% to 30% of the prepared thick plate size, and the pressing amount of each subsequent pass is 10% to 20% of the thickness of the previous pass, until the Al-Zn-Mn-Cu-Mg aluminum alloy plate with the target thickness is obtained.

[0023] After each rolling pass, the material is held at a temperature 5°C to 10°C higher than that described in step (4) for 45 to 60 minutes. Preferably, in step (5), the thickness of the Al-Zn-Mn-Cu-Mg aluminum alloy sheet is 1 mm to 4 mm.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] This invention provides a high-strength, high-toughness, and corrosion-resistant Al-Zn alloy based on the Al-Zn-Mn-Cu-Mg alloy system. Under general production conditions, the designed alloy has a yield strength of over 500 MPa and an elongation of not less than 20%, belonging to the category of ultra-high-strength aluminum alloys with high plastic deformation capacity, and it is superior to the ultra-high-strength aluminum alloys with an elongation of no more than 15% in the prior art.

[0026] The present invention describes a high-strength, highly ductile, and corrosion-resistant Al-Zn-Mn-Cu-Mg aluminum alloy for sheet fabrication, which avoids the use of harsh plastic forming processes such as equal-channel extrusion and high-pressure torsion. Simultaneously, by reducing the content of Mg and Cu elements, the precipitation of η and θ phases is reduced, thereby decreasing their tendency for continuous grain boundary distribution. Furthermore, the presence of Mn element enhances corrosion resistance and mechanical properties, resulting in an alloy with excellent corrosion resistance.

[0027] In this invention, Mn can form an Al-Mn phase (mainly Al6Mn and Al12Mn) in aluminum alloys. This phase has a small potential difference with the aluminum alloy matrix (α-Al phase). Furthermore, under appropriate hot working processes, the precipitated phase size is at the nanoscale, resulting in a significant strengthening effect. Therefore, Mn can improve the corrosion resistance of ultra-high strength aluminum alloys. On the other hand, the Al-Mn phase can also refine recrystallized grains, significantly improving the ductility and toughness of aluminum alloys. Attached Figure Description

[0028] Figure 1 The diagram shows the metallographic structure of the Al-Zn-Mn-Cu-Mg aluminum alloy, where (a) to (j) represent Examples 1 to 10, respectively.

[0029] Figure 2 Electrochemical impedance spectroscopy for Al-Zn-Mn-Cu-Mg aluminum alloy.

[0030] Figure 3 The slow strain rate (1×10⁻⁶) of Al-Zn-Mn-Cu-Mg aluminum alloy in air -6 s -1 ) Stretching curve.

[0031] Figure 4 The slow strain rate (1×10⁻⁶) of Al-Zn-Mn-Cu-Mg aluminum alloy in 0.5M NaCl solution. -6 s -1 ) Stretching curve. Detailed Implementation

[0032] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited thereto. In the following embodiments, Al-Mn master alloys, Al-Cu master alloys, and Al-Mg master alloys are respectively exemplified by Al20Mn alloy, Al20Cu alloy, and Al20Mg alloy. However, the scope of protection of this invention is not limited to these. Any Al-Mn master alloy, Al-Cu master alloy, and Al-Mg master alloy with an alloy composition range of Zn: 6.5wt.% to 9.5wt.%, Mn: 0.6wt.% to 1.3wt.%, Cu: 0.4wt.% to 1.2wt.%, Mg: 0.4wt.% to 1.2wt.%, other impurities totaling no more than 0.15wt.%, and individual impurity components not exceeding 0.02wt.%, with the balance being Al; further, the composition requirements must meet the following conditions: Mn / Zn mass ratio of 0.09 to 0.16, Mn / Cu and Mn / Mg mass ratios ≥ 1.00, and Cu / Mg mass ratio of 0.50 to 1.29. All such Al-Mn master alloys, Al-Cu master alloys, and Al-Mg master alloys can implement the technical solution of this invention.

[0033] Example 1:

[0034] The Al-Zn-Mn-Cu-Mg alloy system prepared in this embodiment has the following composition: Zn: 6.5wt%; Mn: 0.6wt%; Cu: 0.4wt%; Mg: 0.4wt%; the total content of other impurities does not exceed 0.15wt.%, and the content of a single impurity component does not exceed 0.02wt.%, with the balance being Al.

[0035] (1) Weigh each raw material that meets the design composition. Based on a total weight of 2kg, weigh the following: industrial pure aluminum: 1.730kg, industrial pure zinc: 0.130kg, Al20Mn alloy: 0.060kg, Al20Cu alloy: 0.040kg, Al20Mg alloy: 0.040kg.

[0036] (2) Then, using general smelting technology, the raw materials weighed in step (1) are sequentially placed into a graphite crucible according to the general smelting technical specifications to prepare Al-Zn-Mn-Cu-Mg alloy ingots. The conventional process includes heating, melting, adding materials (to replenish the element content reduction caused by burning), degassing, refining, and holding to obtain the alloy melt. Then, a cylindrical ingot metal casting mold with an inner cavity of 50 mm diameter is heated to 350°C, and then the alloy melt is poured into the metal casting mold, followed by natural cooling to obtain the alloy ingot.

[0037] (3) The alloy ingot is placed in a muffle furnace for preheating and holding at a temperature of 430℃ for 45 minutes. After holding, the ingot is forged to produce a thick plate. The forging is perpendicular to the radial direction and the pressing rate is 5 mm / s. The plate is continuously forged to 2 / 3 of the diameter of the alloy ingot in step (2). The temperature is not controlled during the forging process. After the forging is completed, a thick plate is obtained. After the thick plate is cooled to room temperature, it is cleaned with a 30 vol.% ethanol aqueous solution to remove surface stains, resulting in a thick plate with the surface stains removed.

[0038] (4) The thick plate with the surface stains removed is put back into the muffle furnace for heat preservation. The temperature range is 420℃ and the heat preservation time is 30 minutes to 60 minutes to obtain a prepared thick plate for rolling.

[0039] (5) Use twin-roll rolling to roll the prepared thick plate in multiple passes. The first pass is 15% of the original size of the prepared thick plate, and the remaining passes are 10% of the thickness of the previous pass. After each pass, the plate needs to be placed in a muffle furnace for heat preservation. The heat preservation temperature is 5°C above the temperature used in step (4), that is, heat preservation at 425°C for 45 minutes.

[0040] (6) After multiple rolling passes, a sheet with a thickness of 1 mm is obtained, and its metallographic structure is shown in the figure below. Figure 1 As shown in (a).

[0041] Example 2:

[0042] The Al-Zn-Mn-Cu-Mg alloy system prepared in this embodiment has the following composition: Zn: 9.5wt%; Mn: 1.3wt%; Cu: 1.2wt%; Mg: 1.2wt%; the total content of other impurities does not exceed 0.15wt.%, and the content of a single impurity component does not exceed 0.02wt.%, with the balance being Al.

[0043] (1) Weigh each raw material that meets the design composition. Based on a total weight of 2kg, weigh the following: industrial pure aluminum: 1.440kg, industrial pure zinc: 0.190kg, Al20Mn alloy: 0.130kg, Al20Cu alloy: 0.120kg, Al20Mg alloy: 0.120kg.

[0044] (2) Then, using general smelting technology, the raw materials weighed in step (1) are sequentially placed into a graphite crucible according to the general smelting technology specifications to prepare Al-Zn-Mn-Cu-Mg alloy ingots. The conventional process includes heating, melting, adding materials (to replenish the element content reduction caused by burning), degassing, refining, and holding to obtain the alloy melt. Then, a cylindrical ingot metal casting mold with an inner cavity of 50 mm diameter is heated to 410°C, and then the alloy melt is poured into the metal casting mold, followed by natural cooling to obtain the alloy ingot.

[0045] (3) The alloy ingot is placed in a muffle furnace for preheating and holding at a temperature of 480℃ for 70 minutes. After holding, the ingot is forged to produce a thick plate. The forging is perpendicular to the radial direction and the pressing rate is 15 mm / s. The plate is continuously forged to 1 / 3 of the diameter of the alloy ingot in step (2). The temperature is not controlled during the forging process. After the forging is completed, a thick plate is obtained. After the thick plate is cooled to room temperature, it is cleaned with a 30 vol.% ethanol aqueous solution to remove surface stains and obtain a thick plate with the surface stains removed.

[0046] (4) The thick plate with the surface stains removed is put back into the muffle furnace for heat preservation. The temperature range is 460℃ and the heat preservation time is 60 minutes to obtain the prepared thick plate for rolling.

[0047] (5) Use twin-roll rolling to roll the prepared thick plate in multiple passes. The first pass is 30% of the original size of the prepared thick plate, and the remaining passes are 20% of the thickness of the previous pass. After each pass, the plate needs to be placed in a muffle furnace for heat preservation. The heat preservation temperature is 10°C above the temperature used in step (4), that is, heat preservation at 470°C for 60 minutes.

[0048] (6) After multiple rolling passes, a sheet with a thickness of 4 mm is obtained, and its metallographic structure is shown in the figure below. Figure 1 As shown in (b).

[0049] Example 3:

[0050] The Al-Zn-Mn-Cu alloy system prepared in this embodiment has the following composition: Zn: 6.5 wt%; Mn: 1.0 wt%; Cu: 0.7 wt%; Mg: 0.9 wt%; the total content of other impurities does not exceed 0.15 wt.%, and the content of a single impurity component does not exceed 0.02 wt.%, with the balance being Al.

[0051] (1) Weigh each raw material that meets the design composition. Based on a total weight of 2kg, weigh the following: industrial pure aluminum: 1.610kg, industrial pure zinc: 0.130kg, Al20Mn alloy: 0.100kg, Al20Cu alloy: 0.070kg, Al20Mg alloy: 0.090kg.

[0052] (2) Then, using general smelting technology, the raw materials weighed in step (1) are sequentially placed into a graphite crucible according to the general smelting technology specifications to prepare Al-Zn-Mn-Cu-Mg alloy ingots. The conventional process includes heating, melting, adding materials (to replenish the element content reduction caused by burning), degassing, refining, and holding to obtain the alloy melt. Then, a square ingot metal casting mold with an inner cavity of 200mm (length) × 160mm (height) × 20mm (thickness) is heated to 370℃, and then the alloy melt is poured into the metal casting mold, followed by natural cooling to obtain the alloy ingot.

[0053] (3) The alloy ingot is placed in a muffle furnace for preheating and holding at a temperature of 450℃ for 60 minutes. After holding, the ingot is forged to produce a thick plate. The forging is perpendicular to the radial direction and the pressing rate is 10 mm / s. The plate is continuously forged to half the diameter of the alloy ingot in step (2). The temperature is not controlled during the forging process. After the forging is completed, a thick plate is obtained. After the thick plate is cooled to room temperature, it is cleaned with a 30 vol.% ethanol aqueous solution to remove surface stains, resulting in a thick plate with the surface stains removed.

[0054] (4) The thick plate with the surface stains removed is put back into the muffle furnace for heat preservation. The temperature range is 440℃ and the heat preservation time is 45 minutes to obtain the prepared thick plate for rolling.

[0055] (5) Use twin-roll rolling to roll the prepared thick plate in multiple passes. The first pass is 20% of the original size of the prepared thick plate, and the remaining passes are 15% of the thickness of the previous pass. After each pass, the plate needs to be placed in a muffle furnace for heat preservation. The heat preservation temperature is 10°C above the temperature used in step (4), that is, heat preservation at 450°C for 50 minutes.

[0056] (6) After multiple rolling passes, a sheet with a thickness of 2.5 mm is obtained, and its metallographic structure is shown in the figure below. Figure 1 As shown in (c).

[0057] Example 4:

[0058] The Al-Zn-Mn-Cu-Mg alloy system prepared in this embodiment has the following composition: Zn: 7.5wt%; Mn: 0.8wt%; Cu: 0.8wt%; Mg: 0.8wt%; the total content of other impurities does not exceed 0.15wt.%, and the content of a single impurity component does not exceed 0.02wt.%, with the balance being Al.

[0059] (1) Weigh each raw material that meets the design composition. Based on a total weight of 2kg, weigh the following: industrial pure aluminum: 1.610kg, industrial pure zinc: 0.150kg, Al20Mn alloy: 0.080kg, Al20Cu alloy: 0.080kg, Al20Mg alloy: 0.080kg.

[0060] (2) Then, using general smelting technology, the raw materials weighed in step (1) are sequentially placed into a graphite crucible according to the general smelting technology specifications to prepare Al-Zn-Mn-Cu-Mg alloy ingots. The conventional process includes heating, melting, adding materials (to replenish the element content reduction caused by burning), degassing, refining, and holding to obtain the alloy melt. Then, a square ingot metal casting mold with an inner cavity of 200mm (length) × 160mm (height) × 20mm (thickness) is heated to 390℃, and then the alloy melt is poured into the metal casting mold, followed by natural cooling to obtain the alloy ingot.

[0061] (3) The alloy ingot is placed in a muffle furnace for preheating and holding at a temperature of 465℃ for 60 minutes. After holding, the ingot is forged to produce a thick plate. The forging is perpendicular to the radial direction and the pressing rate is 12.5 mm / s. The plate is continuously forged to half the diameter of the alloy ingot in step (2). The temperature is not controlled during the forging process. After the forging is completed, a thick plate is obtained. After the thick plate is cooled to room temperature, it is cleaned with a 30 vol.% ethanol aqueous solution to remove surface stains, resulting in a thick plate with the surface stains removed.

[0062] (4) The thick plate with the surface stains removed is put back into the muffle furnace for heat preservation. The temperature range is 450℃ and the heat preservation time is 40 minutes to obtain the prepared thick plate for rolling.

[0063] (5) Use twin-roll rolling to roll the prepared thick plate in multiple passes. The first pass is 17.5% of the original size of the prepared thick plate, and the remaining passes are 20% of the thickness of the previous pass. After each pass, the plate needs to be placed in a muffle furnace for heat preservation. The heat preservation temperature is 7.5°C above the temperature used in step (4), that is, heat preservation at 457.5°C for 60 minutes.

[0064] (6) After multiple rolling passes, a 3mm thick sheet is obtained, and its metallographic structure is shown in the figure below. Figure 1 As shown in (d).

[0065] Example 5:

[0066] The composition of the Al-Zn-Mn-Cu-Mg alloy system prepared in this embodiment is as follows: Zn: 8.5 wt%; Mn: 1.0 wt%; Cu: 0.8 wt%; Mg: 0.4 wt%; the total content of other impurities does not exceed 0.15 wt.%, and the content of a single impurity component does not exceed 0.02 wt.%, with the balance being Al.

[0067] (1) Weigh each raw material that meets the design composition. Based on a total weight of 2kg, weigh the following: industrial pure aluminum: 1.610kg, industrial pure zinc: 0.170kg, Al20Mn alloy: 0.100kg, Al20Cu alloy: 0.080kg, Al20Mg alloy: 0.040kg.

[0068] (2) Then, using general smelting technology, the raw materials weighed in step (1) are sequentially placed into a graphite crucible according to the general smelting technology specifications to prepare Al-Zn-Mn-Cu-Mg alloy ingots. The conventional process includes heating, melting, adding materials (to replenish the element content reduction caused by burning), degassing, refining, and holding to obtain the alloy melt. Then, a square ingot metal casting mold with an inner cavity of 200mm (length) × 160mm (height) × 20mm (thickness) is heated to 400℃, and then the alloy melt is poured into the metal casting mold, followed by natural cooling to obtain the alloy ingot.

[0069] (3) The alloy ingot is placed in a muffle furnace for preheating and holding at a temperature of 475℃ for 65 minutes. After holding, the ingot is forged to produce a thick plate. The forging is perpendicular to the radial direction and the pressing rate is 8 mm / s. The plate is continuously forged to half the diameter of the alloy ingot in step (2). The temperature is not controlled during the forging process. After the forging is completed, a thick plate is obtained. After the thick plate is cooled to room temperature, it is cleaned with a 30 vol.% ethanol aqueous solution to remove surface stains, resulting in a thick plate with the surface stains removed.

[0070] (4) The thick plate with the surface stains removed is put back into the muffle furnace for heat preservation. The temperature range is 430℃ and the heat preservation time is 50 minutes to obtain the prepared thick plate for rolling.

[0071] (5) Use twin-roll rolling to roll the prepared thick plate in multiple passes. The first pass is 25% of the original size of the prepared thick plate, and the remaining passes are 15% of the thickness of the previous pass. After each pass, the plate needs to be placed in a muffle furnace for heat preservation. The heat preservation temperature is 10°C above the temperature used in step (4), that is, heat preservation at 440°C for 50 minutes.

[0072] (6) After multiple rolling passes, a sheet with a thickness of 4 mm is obtained, and its metallographic structure is shown in the figure below. Figure 1 As shown in (e).

[0073] Example 6:

[0074] The composition of the Al-Zn-Mn-Cu-Mg alloy system prepared in this embodiment is as follows: Zn: 7.5 wt%; Mn: 1.2 wt%; Cu: 1.0 wt%; Mg: 1.0 wt%; the total content of other impurities does not exceed 0.15 wt.%, and the content of a single impurity component does not exceed 0.02 wt.%, with the balance being Al.

[0075] (1) Weigh each raw material that meets the design composition. Based on a total weight of 2kg, weigh the following: industrial pure aluminum: 1.530kg, industrial pure zinc: 0.150kg, Al20Mn alloy: 0.120kg, Al20Cu alloy: 0.100kg, Al20Mg alloy: 0.100kg.

[0076] (2) Then, using general smelting technology, the raw materials weighed in step (1) are sequentially placed into a graphite crucible according to the general smelting technology specifications to prepare Al-Zn-Mn-Cu-Mg alloy ingots. The conventional process includes heating, melting, adding materials (to replenish the element content reduction caused by burning), degassing, refining, and holding to obtain the alloy melt. Then, a square ingot metal casting mold with an inner cavity of 200mm (length) × 160mm (height) × 20mm (thickness) is heated to 410℃, and then the alloy melt is poured into the metal casting mold, followed by natural cooling to obtain the alloy ingot.

[0077] (3) The alloy ingot is placed in a muffle furnace for preheating and holding at a temperature of 475℃ for 70 minutes. After holding, the ingot is forged to produce a thick plate. The forging is perpendicular to the radial direction and the pressing rate is 10 mm / s. The plate is continuously forged to 2 / 3 of the diameter of the alloy ingot in step (2). The temperature is not controlled during the forging process. After the forging is completed, a thick plate is obtained. After the thick plate is cooled to room temperature, it is cleaned with a 30 vol.% ethanol aqueous solution to remove surface stains and obtain a thick plate with the surface stains removed.

[0078] (4) The thick plate with the surface stains removed is put back into the muffle furnace for heat preservation. The temperature range is 450℃ and the heat preservation time is 50 minutes to obtain the prepared thick plate for rolling.

[0079] (5) Use twin-roll rolling to roll the prepared thick plate in multiple passes. The first pass is 20% of the original size of the prepared thick plate, and the remaining passes are 20% of the thickness of the previous pass. After each pass, the plate needs to be placed in a muffle furnace for heat preservation. The heat preservation temperature is 5°C above the temperature used in step (4), that is, heat preservation at 455°C for 45 minutes.

[0080] (6) After multiple rolling passes, a sheet with a thickness of 1.5 mm is obtained, and its metallographic structure is shown in the figure below. Figure 1 As shown in (f).

[0081] Example 7:

[0082] The composition of the Al-Zn-Mn-Cu-Mg alloy system prepared in this embodiment is as follows: Zn: 7.5 wt%; Mn: 1.2 wt%; Cu: 0.8 wt%; Mg: 0.7 wt%; the total content of other impurities does not exceed 0.15 wt.%, and the content of a single impurity component does not exceed 0.02 wt.%, with the balance being Al.

[0083] (1) Weigh each raw material that meets the design composition. Based on a total weight of 2kg, weigh the following: industrial pure aluminum: 1.580kg, industrial pure zinc: 0.150kg, Al20Mn alloy: 0.120kg, Al20Cu alloy: 0.080kg, Al20Mg alloy: 0.070kg.

[0084] (2) Then, using general smelting technology, the raw materials weighed in step (1) are sequentially placed into a graphite crucible according to the general smelting technology specifications to prepare Al-Zn-Mn-Cu-Mg alloy ingots. The conventional process includes heating, melting, adding materials (to replenish the element content reduction caused by burning), degassing, refining, and holding to obtain the alloy melt. Then, a square ingot metal casting mold with an inner cavity of 200mm (length) × 160mm (height) × 20mm (thickness) is heated to 375℃, and then the alloy melt is poured into the metal casting mold, followed by natural cooling to obtain the alloy ingot.

[0085] (3) The alloy ingot is placed in a muffle furnace for preheating and holding at a temperature of 450℃ for 60 minutes. After holding, the ingot is forged to produce a thick plate. The forging is perpendicular to the radial direction and the pressing rate is 12.5 mm / s. The plate is continuously forged to half the diameter of the alloy ingot in step (2). The temperature is not controlled during the forging process. After the forging is completed, a thick plate is obtained. After the thick plate is cooled to room temperature, it is cleaned with a 30 vol.% ethanol aqueous solution to remove surface stains, resulting in a thick plate with the surface stains removed.

[0086] (4) The thick plate with the surface stains removed is put back into the muffle furnace for heat preservation. The temperature range is 430℃ and the heat preservation time is 60 minutes to obtain the prepared thick plate for rolling.

[0087] (5) Use twin-roll rolling to roll the prepared thick plate in multiple passes. The first pass is 30% of the original size of the prepared thick plate, and the remaining passes are 15% of the thickness of the previous pass. After each pass, the plate needs to be placed in a muffle furnace for heat preservation. The heat preservation temperature is 10°C above the temperature used in step (4), that is, heat preservation at 440°C for 45 minutes.

[0088] (6) After multiple rolling passes, a sheet with a thickness of 3.5 mm is obtained, and its metallographic structure is shown in the figure below. Figure 1 As shown in (g).

[0089] Example 8:

[0090] The composition of the Al-Zn-Mn-Cu-Mg alloy system prepared in this embodiment is as follows: Zn: 8.5wt%; Mn: 0.7wt%; Cu: 0.4wt%; Mg: 0.4wt%; the total content of other impurities does not exceed 0.15wt.%, and the content of a single impurity component does not exceed 0.02wt.%, with the balance being Al.

[0091] (1) Weigh each raw material that meets the design composition. Based on a total weight of 2kg, weigh the following: industrial pure aluminum: 1.680kg, industrial pure zinc: 0.170kg, Al20Mn alloy: 0.070kg, Al20Cu alloy: 0.040kg, Al20Mg alloy: 0.040kg.

[0092] (2) Then, using general smelting technology, the raw materials weighed in step (1) are sequentially placed into a graphite crucible according to the general smelting technology specifications to prepare Al-Zn-Mn-Cu-Mg alloy ingots. The conventional process includes heating, melting, adding materials (to replenish the element content reduction caused by burning), degassing, refining, and holding to obtain the alloy melt. Then, a square ingot metal casting mold with an inner cavity of 200mm (length) × 160mm (height) × 20mm (thickness) is heated to 375℃, and then the alloy melt is poured into the metal casting mold, followed by natural cooling to obtain the alloy ingot.

[0093] (3) The alloy ingot is placed in a muffle furnace for preheating and holding at a temperature of 450℃ for 60 minutes. After holding, the ingot is forged to produce a thick plate. The forging is perpendicular to the radial direction and the pressing rate is 12.5 mm / s. The plate is continuously forged to half the diameter of the alloy ingot in step (2). The temperature is not controlled during the forging process. After the forging is completed, a thick plate is obtained. After the thick plate is cooled to room temperature, it is cleaned with a 30 vol.% ethanol aqueous solution to remove surface stains, resulting in a thick plate with the surface stains removed.

[0094] (4) The thick plate with the surface stains removed is put back into the muffle furnace for heat preservation. The temperature range is 440℃ and the heat preservation time is 60 minutes to obtain the prepared thick plate for rolling.

[0095] (5) Use twin-roll rolling to roll the prepared thick plate in multiple passes. The first pass is 30% of the original size of the prepared thick plate, and the remaining passes are 15% of the thickness of the previous pass. After each pass, the plate needs to be placed in a muffle furnace for heat preservation. The heat preservation temperature is 10°C above the temperature used in step (4), that is, heat preservation at 450°C for 45 minutes.

[0096] (6) After multiple rolling passes, a 2mm thick sheet is obtained, and its metallographic structure is shown in the figure below. Figure 1 As shown in (h).

[0097] Example 9:

[0098] The composition of the Al-Zn-Mn-Cu-Mg alloy system prepared in this embodiment is as follows: Zn: 6.5wt%; Mn: 0.9wt%; Cu: 0.6wt%; Mg: 0.5wt%; the total content of other impurities does not exceed 0.15wt.%, and the content of a single impurity component does not exceed 0.02wt.%, with the balance being Al.

[0099] (1) Weigh each raw material that meets the design composition. Based on a total weight of 2kg, weigh the following: industrial pure aluminum: 1.670kg, industrial pure zinc: 0.130kg, Al20Mn alloy: 0.090kg, Al20Cu alloy: 0.060kg, Al20Mg alloy: 0.050kg.

[0100] (2) Then, using general smelting technology, the raw materials weighed in step (1) are sequentially placed into a graphite crucible according to the general smelting technology specifications to prepare Al-Zn-Mn-Cu-Mg alloy ingots. The conventional process includes heating, melting, adding materials (to replenish the element content reduction caused by burning), degassing, refining, and heat preservation to obtain alloy melt. Then, a square ingot metal casting mold with an inner cavity of 200mm (length) × 160mm (height) × 20mm (thickness) is heated to 350℃, and then the alloy melt is poured into the metal casting mold, followed by natural cooling to obtain alloy ingots.

[0101] (3) The alloy ingot is placed in a muffle furnace for preheating and holding at a temperature of 450℃ for 60 minutes. After holding, the ingot is forged to produce a thick plate. The forging is perpendicular to the radial direction and the pressing rate is 12.5 mm / s. The plate is continuously forged to half the diameter of the alloy ingot in step (2). The temperature is not controlled during the forging process. After the forging is completed, a thick plate is obtained. After the thick plate is cooled to room temperature, it is cleaned with a 30 vol.% ethanol aqueous solution to remove surface stains, resulting in a thick plate with the surface stains removed.

[0102] (4) The thick plate with the surface stains removed is put back into the muffle furnace for heat preservation. The temperature range is 445℃ and the heat preservation time is 60 minutes to obtain the prepared thick plate for rolling.

[0103] (5) Use twin-roll rolling to roll the prepared thick plate in multiple passes. The first pass is 30% of the original size of the prepared thick plate, and the remaining passes are 15% of the thickness of the previous pass. After each pass, the plate needs to be placed in a muffle furnace for heat preservation. The heat preservation temperature is 5°C above the temperature used in step (4), that is, heat preservation at 450°C for 45 minutes.

[0104] (6) After multiple rolling passes, a sheet with a thickness of 4 mm is obtained, and its metallographic structure is shown in the figure below. Figure 1 As shown in (j).

[0105] Example 10:

[0106] The composition of the Al-Zn-Mn-Cu-Mg alloy system prepared in this embodiment is as follows: Zn: 8.0 wt%; Mn: 1.1 wt%; Cu: 0.8 wt%; Mg: 0.6 wt%; the total content of other impurities does not exceed 0.15 wt.%, and the content of a single impurity component does not exceed 0.02 wt.%, with the balance being Al.

[0107] (1) Weigh each raw material that meets the design composition. Based on a total weight of 2kg, weigh the following: industrial pure aluminum: 1.590kg, industrial pure zinc: 0.160kg, Al20Mn alloy: 0.110kg, Al20Cu alloy: 0.080kg, Al20Mg alloy: 0.060kg.

[0108] (2) Then, using general smelting technology, the raw materials weighed in step (1) are sequentially placed into a graphite crucible according to the general smelting technology specifications to prepare Al-Zn-Mn-Cu-Mg alloy ingots. The conventional process includes heating, melting, adding materials (to replenish the element content reduction caused by burning), degassing, refining, and holding to obtain the alloy melt. Then, a square ingot metal casting mold with an inner cavity of 200mm (length) × 160mm (height) × 20mm (thickness) is heated to 375℃, and then the alloy melt is poured into the metal casting mold, followed by natural cooling to obtain the alloy ingot.

[0109] (3) The alloy ingot is placed in a muffle furnace for preheating and holding at a temperature of 450℃ for 60 minutes. After holding, the ingot is forged to produce a thick plate. The forging is perpendicular to the radial direction and the pressing rate is 10 mm / s. The plate is continuously forged to half the diameter of the alloy ingot in step (2). The temperature is not controlled during the forging process. After the forging is completed, a thick plate is obtained. After the thick plate is cooled to room temperature, it is cleaned with a 30 vol.% ethanol aqueous solution to remove surface stains, resulting in a thick plate with the surface stains removed.

[0110] (4) The thick plate with the surface stains removed is put back into the muffle furnace for heat preservation. The temperature range is 440℃ and the heat preservation time is 45 minutes to obtain the prepared thick plate for rolling.

[0111] (5) Use twin-roll rolling to roll the prepared thick plate in multiple passes. The first pass is 30% of the original size of the prepared thick plate, and the remaining passes are 20% of the thickness of the previous pass. After each pass, the plate needs to be placed in a muffle furnace for heat preservation. The heat preservation temperature is 10°C above the temperature used in step (4), that is, heat preservation at 450°C for 45 minutes.

[0112] (6) After multiple rolling passes, a 3mm thick sheet is obtained, and its metallographic structure is shown in the figure below. Figure 1As shown in (i).

[0113] In this embodiment, electrochemical impedance spectroscopy was performed on the Al-Zn-Mn-Cu-Mg aluminum alloy materials prepared in Examples 1 to 10, and the detection results were... Figure 2 As shown. A larger semicircle radius of the spectral line indicates better corrosion resistance of the alloy. Therefore, from... Figure 2 As can be seen from this, the corrosion resistance of the alloy described in this invention is significantly better than that of the representative 7075 and 7050 aluminum alloys in the field.

[0114] In this embodiment, the mechanical properties of the Al-Zn-Mn-Cu-Mg aluminum alloys prepared in Examples 1 to 10 were tested according to the room temperature test method described in GB / T 228.1-2021 Metallic Materials, Tensile Testing Part 1. The test results are as follows: Figure 3 As shown in Table 1.

[0115] This embodiment, based on GB / T 15970.7-2017 Corrosion of Metals and Alloys—Stress Corrosion Testing—Part 7: Slow Strain Rate Testing, tested the stress corrosion resistance of the Al-Zn-Mn-Cu-Mg aluminum alloys prepared in Examples 1-10 (using the stress corrosion susceptibility factor (I) as the criterion). SSRT (This indicates that) the test results are as follows: Figure 4 As shown in Table 1.

[0116] Among them, stress corrosion sensitivity factor (I SSRT The formula for calculating ) is:

[0117]

[0118] Table 1. Mechanical property parameters and I in air and NaCl solution, Examples 1-10 SSRT value

[0119]

[0120] Combination Figures 3-4 As can be seen from Table 1, the yield strength of the alloys provided by this invention all exceed 500 MPa, meeting the requirements for ultra-high strength aluminum alloys recognized in the art. The yield strength and tensile strength of the alloys provided by this invention are comparable to those of representative alloys in the art (7075 and 7050 aluminum alloys), but the elongation has a significant advantage. Furthermore, as can also be seen from Table 1, the stress corrosion resistance of the provided alloys is superior to that of representative alloys in the art (7075 and 7050 aluminum alloys).

[0121] In summary, the high-strength, high-toughness, and corrosion-resistant Al-Zn alloy based on the Al-Zn-Mn-Cu-Mg alloy system described in this invention, under general production conditions, has a yield strength exceeding 500 MPa and an elongation of not less than 20%. It belongs to the category of ultra-high-strength aluminum alloys with high plastic deformation capacity and is suitable for profile processing in fields such as transportation and aerospace, demonstrating excellent practicality.

[0122] The embodiments described above are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for preparing Al-Zn-Mn-Cu-Mg aluminum alloy sheet, characterized in that, include: (1) Calculate and weigh the raw materials of Al-Zn-Mn-Cu-Mg aluminum alloy according to the composition of high-strength, high-plasticity and corrosion-resistant Al-Zn-Mn-Cu-Mg aluminum alloy; the composition of Al-Zn-Mn-Cu-Mg aluminum alloy includes: Zn: 6.5 wt.% ~ 9.5 wt.%, Mn: 0.6 wt.% ~ 1.3 wt.%, Cu: 0.4 wt.% ~ 1.2 wt.%, Mg: 0.4 wt.% ~ 1.2 wt.%, the total content of other impurities does not exceed 0.15 wt.%, and the content of a single impurity component does not exceed 0.02 wt.%, with the balance being Al; (2) Melt the raw materials weighed in step (1) into an Al-Zn-Mn-Cu-Mg alloy melt, then add the Al-Zn-Mn-Cu-Mg alloy melt into a preheated casting mold, and then let it cool naturally to obtain an alloy ingot; (3) Preheat the alloy ingot and keep it at a certain temperature. After the temperature is maintained, forge the thick plate. After the forging is completed, the thick plate is obtained. Then cool the thick plate to room temperature and clean it to obtain a thick plate with the surface stains removed. The forging conditions are: the pressing rate is 5 mm / s to 15 mm / s, and the forging is continuously pressed to 2 / 3 to 1 / 3 of the alloy ingot size in step (2). The temperature is not controlled during the forging process. (4) The thick plate with the surface stains removed is re-insulated, and the prepared thick plate is obtained after the treatment. The heat preservation treatment is to keep the temperature at 420 ℃~460 ℃ for 30 min~60 min; (5) Use twin-roll rolling to roll the prepared thick plate in multiple passes. After each pass of rolling, heat preservation treatment is performed. After the heat preservation treatment is completed, rolling is performed again until the designed thickness is reached. The multi-pass rolling process is as follows: the first pass has a pressing amount of 15% to 30% of the prepared thick plate size, and the pressing amount of each subsequent pass is 10% to 20% of the thickness of the previous pass, until the Al-Zn-Mn-Cu-Mg aluminum alloy plate of the target thickness is obtained. After each rolling pass, the temperature is kept at 5 ℃~10 ℃ higher than that described in step (4) for 45 min~60 min. (6) After rolling, a high-strength, high-plasticity, and corrosion-resistant Al-Zn-Mn-Cu-Mg aluminum alloy plate is obtained.

2. The method for preparing Al-Zn-Mn-Cu-Mg aluminum alloy sheet according to claim 1, characterized in that, In step (1), the Al-Zn-Mn-Cu-Mg aluminum alloy has a Mn / Zn mass ratio of 0.09~0.16, a Mn / Cu and Mn / Mg mass ratio of ≥1.00, and a Cu / Mg mass ratio of 0.50~1.

29.

3. The method for preparing Al-Zn-Mn-Cu-Mg aluminum alloy sheet according to claim 1, characterized in that, In step (1), the raw materials include industrial pure aluminum, industrial pure zinc, industrial pure manganese or Al-Mn master alloy, industrial pure copper or Al-Cu master alloy, and industrial pure magnesium or Al-Mg master alloy.

4. The method for preparing Al-Zn-Mn-Cu-Mg aluminum alloy sheet according to claim 1, characterized in that, In step (2), the casting mold is preheated to 350℃~410℃.

5. The method for preparing Al-Zn-Mn-Cu-Mg aluminum alloy sheet according to claim 1, characterized in that, In step (3), the preheating and heat preservation conditions are to keep warm at 430 ℃~480 ℃ for 45 min~70 min.

Images