High-strength impact-resistant Al-Zn-Mg alloy and preparation method thereof

Abstract

The invention relates to the technical field of aluminum alloy materials, in particular to a high-strength impact-resistant Al-Zn-Mg alloy and a preparation method thereof. The high-strength and impact-resistant Al-Zn-Mg alloy is prepared from the following components in percentage by mass: 5.2 to 7.2 percent by weight of Zn, 1.8 to 2.4 percent by weight of Mg, 0.3 to 0.5 percent by weight of Cu, 0.08 to 0.15 percent by weight of Sc, 0.08 to 0.15 percent by weight of Zr, 0.3 to 0.5 percent by weight of Mn, 0.03 to 0.10 percent by weight of Ti and the balance of Al, and Zn / Mg is 2.4. The preparation method comprises the following steps: taking various raw materials according to the designed component proportion, smelting and casting to obtain an aluminum alloy cast ingot, and then carrying out two-stage homogenizing annealing, rolling, solid solution quenching and aging treatment. The tensile strength of the product obtained after optimization is 560 MPa or above, the yield strength is 520 MPa or above, and the impact toughness is larger than 30 J / cm < 2 >. The composition is reasonable in design, the process is simple and controllable, and the obtained product is excellent in performance and convenient for industrial application.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy materials technology, specifically to a high-strength, impact-resistant Al-Zn-Mg alloy and its preparation method. Background Technology

[0002] Al-Zn-Mg alloys are widely used in aerospace, weapon manufacturing, and high-speed rail fields due to their low density, high strength and toughness, good impact resistance, and excellent corrosion resistance. The performance of this series of aluminum alloys is closely related to the composition and content of alloying elements and the size, type, and distribution of precipitates.

[0003] Currently, the most commonly used impact-resistant Al-Zn-Mg alloys internationally are 7N01, 7039, and 7A48 aluminum alloys. The composition ranges for these three alloys are as follows: 7N01: Zn content 4.4~5.0%, Mg content 1.1~1.7%, Cu content not exceeding 0.2%, Zr content 0.10~0.25%, Fe, Si and other elements content not exceeding 0.25%, Ti content 0.02~0.06%; 7039: Zn content 3.5~4.5%, Mg content 2.3~3.3%, Mn content 0.1~0.4%. For 7A48: Cu content not exceeding 0.1%, Ti content not exceeding 0.1%, Fe content not exceeding 0.4%, Si content not exceeding 0.3%, and Cr content 0.15~0.25%; For 7A48: Zn content 5.2~7.2%, Mg content 1.2~2.2%, Cu content 0.25~0.45%, Zr content 0.07~0.15%, Fe content not exceeding 0.2%, Si content not exceeding 0.1%, Ti content 0.02~0.06%, and Sc content 0.1~0.35%.

[0004] The 7N01 and 7039 aluminum alloys have low Zn and Mg content, and their strength of approximately 350-450 MPa cannot meet the requirements of high load environments. In order to further improve the strength of the alloy, the Zn and Mg content of 7A48 aluminum alloy is increased, which improves the tensile strength and yield strength of the alloy to a certain extent. In particular, after aging treatment, the precipitated phases significantly improve the strength of the alloy, but reduce the impact toughness of the alloy. Therefore, how to coordinate the alloy strength and impact toughness to obtain a high-strength and impact-resistant Al-Zn-Mg alloy is the focus of this invention. Summary of the Invention

[0005] The purpose of this invention is to provide a high-strength impact-resistant aluminum alloy and its manufacturing method. After solution aging treatment, the alloy has a low recrystallization fraction and a very fine grain structure. The grains contain fine and dispersed strengthening precipitates, and the alloy has high strength and good impact resistance.

[0006] This invention selects the composition range of Al-Zn-Mg alloy through composition design and optimization, then prepares the required alloy plates through ingot metallurgy and rolling processes, studies the cold-rolled state and the aged state, and finally determines the composition of Al-Zn-Mg alloy in the aged state after rolling deformation.

[0007] To achieve the above objectives, the present invention employs the following technical solution:

[0008] A high-strength, impact-resistant aluminum alloy has the following chemical composition by mass percentage: Zn 5.2~7.2 wt.%, Mg 1.8~2.4 wt.%, Cu 0.3~0.5 wt.%, Sc 0.08~0.15 wt.%, Zr 0.08~0.15 wt.%, Mn 0.3~0.5 wt.%, Ti 0.03~0.10 wt.%, with the balance being Al, and the Zn / Mg ratio is [not specified]. 2.4.

[0009] The aluminum alloy contains nano-sized η' (Zn2Mg) and T-Mg. 32 (Al, Zn) 49 Dual-structured diffuse-reinforced phase, L12-structured Al3(Sc, Zr) particles and fibrous tissue.

[0010] This invention provides an Al-Zn-Mg alloy, using Zn and Mg as the main strengthening elements, and controlling the composition within the range of this invention, which can obtain nanoscale η' (Zn2Mg) and T-Mg. 32 (Al, Zn) 49 The dual-structure dispersion strengthening phase, due to the addition of trace amounts of Sc and Zr, forms dispersed L12 structure Al3(Sc, Zr) particles during solidification and homogenization. These dispersed phase particles have strong stability and can significantly pin grain boundaries and hinder dislocation movement. Therefore, a solution-aged microstructure with fine grains and low recrystallization can be obtained. After solution aging treatment, a large amount of fibrous microstructure is still maintained. In addition, a small amount of Mn element is added, which can form a skeleton-like AlFeMnSi phase with Fe and Si in the matrix, which can reduce the concentration of impurity elements in the matrix. Furthermore, a trace amount of Ti is added in the form of grain refiner Al-5Ti-B, which can further refine the grains.

[0011] This invention discloses a high-strength, impact-resistant Al-Zn-Mg alloy, which, by mass percentage, comprises the following components: Zn 5.2~6.9 wt.%, Mg 2.0~2.4 wt.%, Cu 0.3~0.4 wt.%, Sc 0.09~0.11 wt.%, Zr 0.09~0.11 wt.%, Mn 0.3~0.4 wt.%, Ti 0.03~0.10 wt.%, with the balance being Al, and the Zn / Mg ratio is [not specified]. 2.4.

[0012] The preferred alloy composition, by mass percentage, consists of the following components: Zn 5.2~6.0 wt.%, Mg 2.0~2.2 wt.%, Cu 0.3~0.4 wt.%, Sc 0.09~0.11 wt.%, Zr 0.09~0.11 wt.%, Mn 0.3~0.4 wt.%, Ti 0.03~0.10 wt.%, with the balance being Al, and the Zn / Mg ratio is [missing value]. 2.4.

[0013] The preferred alloy composition, by mass percentage, consists of the following components: Zn 5.2~5.7 wt.%, Mg 2.0~2.2 wt.%, Cu 0.3~0.4 wt.%, Sc 0.09~0.11 wt.%, Zr 0.09~0.11 wt.%, Mn 0.3~0.4 wt.%, Ti 0.03~0.10 wt.%, with the balance being Al, and the Zn / Mg ratio is [missing value]. 2.4.

[0014] Further preferred alloy compositions, by weight percentage, are as follows:

[0015] The mass percentages of Zn, Mg, Cu, Sc, Zr, Mn, and Ti are 5.7%, 2.0%, 0.34%, 0.1%, 0.11%, 0.35%, and 0.065%, with the balance being Al.

[0016] Within this preferred composition range, the alloy exhibits a tensile strength of ≥560 MPa, a yield strength of ≥520 MPa, and an impact toughness greater than 30 J / cm². 2 .

[0017] This invention discloses a method for preparing a high-strength, impact-resistant Al-Zn-Mg alloy. The raw materials are pure Al, pure Zn, pure Mg, and intermediate alloys such as Al-50%Cu, Al-5%Zr, Al-10%Mn, Al-2%Sc, and Al-5Ti-B, which are heated and melted in an electric resistance furnace to obtain a molten alloy liquid. The alloy is then cast into an aluminum alloy ingot through a water-cooled mold. Subsequently, the ingot undergoes two-stage homogenization annealing, rolling, solution quenching, and aging treatment.

[0018] The preparation method of this invention involves first subjecting the obtained ingot to a two-stage homogenization annealing process to eliminate segregation in the as-cast state, reduce the adverse effects of relative strength of grain boundary precipitation, and simultaneously promote the dispersed precipitation of Al3(Sc, Zr) particles with L12 structure. Subsequently, the homogenized alloy is subjected to rolling deformation to break dendrites and refine grains, giving the alloy a distinct orientation and fibrous structure. At the same time, the Al3(Sc, Zr) particles with L12 structure formed during the homogenization process can regulate the recovery and recrystallization process. Then, a solution aging treatment is performed to precipitate dispersed η' strengthening phases in the alloy, resulting in an Al-Zn-Mg alloy with high strength and a very low recrystallization fraction.

[0019] The preferred alloy is prepared as follows: smelting and casting. First, pure Al is preheated to 600℃ and then melted into aluminum liquid at 830℃. Then, intermediate alloys such as Al-50%Cu, Al-5%Zr, Al-10%Mn, and Al-2%Sc are added. The mixture is held at this temperature for 30-60 minutes, and the aluminum liquid is stirred to observe whether the intermediate alloys have completely melted. Then, the temperature is lowered to 740℃, and then pure Zn and pure Mg wrapped in aluminum foil are added. Pure Mg needs to be pressed to the bottom of the aluminum liquid to prevent excessive burning. After the alloy is added, argon and chlorine are mixed for refining. Argon refining time is 1-2 minutes, and hexachloroethane refining is carried out at 0.5% of the ingot mass. The refining is carried out at least twice. After the refining is completed, Al-5Ti-B grain refiner is added to the aluminum liquid. After holding at this temperature for 10-15 minutes, it is cast using a water-cooled mold.

[0020] As a preferred alloy, the obtained aluminum alloy ingot is subjected to a two-stage homogenization treatment. The specific process is as follows: first, it is heated to the first-stage homogenization temperature and held for 8-16 hours, and then heated to the second-stage homogenization temperature and held for 16-32 hours. The first-stage homogenization temperature is 300-400℃, more preferably 340-360℃, and the second-stage homogenization temperature is 450-480℃, more preferably 470-480℃. The heating rate between the first and second-stage homogenization is not higher than 50℃ / h.

[0021] The preferred alloy is selected for hot rolling followed by cold rolling. The hot rolling temperature is 420~450℃, preferably 435~445℃, and the thickness of the rolled block is hot rolled from 45mm to 10mm. The final rolling temperature is not lower than 380℃. Then, the hot-rolled plate is subjected to intermediate annealing at a temperature of 420~450℃ for 2~4 hours and then cooled in the furnace. The annealed hot-rolled plate is then cold-rolled from 10mm to 6mm, with a single reduction not exceeding 1mm.

[0022] As a preferred alloy, the solution temperature is 430~480℃, the solution treatment time is 2~6h, and after the solution treatment is completed, it is quickly water-cooled to room temperature for quenching.

[0023] As a preferred alloy, the aging treatment adopts a two-stage aging process. The temperature of the first-stage aging treatment is 90~130℃ and the time of the first-stage aging treatment is 4~10h. The temperature of the second-stage aging treatment is 120~180℃ and the time of the second-stage aging treatment is 10~32h. The temperature of the second-stage aging treatment is at least 15℃ higher than the temperature of the first-stage aging treatment.

[0024] The high-strength, impact-resistant Al-Zn-Mg alloy prepared using this process exhibits a tensile strength exceeding 520 MPa, with a preferred strength exceeding 560 MPa, and an impact toughness exceeding 30 J / cm². 2 .

[0025] As a further preferred option, when the alloy composition is expressed as a percentage by mass,

[0026] When the composition is Zn 5.7%, Mg 2.0%, Cu 0.34%, Sc 0.1%, Zr 0.11%, Mn 0.35%, Ti 0.065%, and the balance is Al, the following preparation steps are followed:

[0027] (1) Weigh each component according to the designed aluminum alloy composition ratio, and melt pure Al and Al-Sc, Al-Cu, and Al-Mn master alloys at 830℃ using an electric resistance furnace. Then, cool down to 740℃ and add pure Zn, pure Mg, and Al-Ti-B grain refiner in sequence, and degas and slag remover to obtain molten alloy liquid, which is then cast into ingots; (2) Perform a two-stage homogenization treatment on the ingots obtained in step (1). The first-stage homogenization temperature is 350℃, and the temperature is held for 12 hours. The second-stage homogenization temperature is 475℃, and the temperature is held for 24 hours to obtain homogenized ingots; (3) The homogenized ingot obtained in step (2) is hot rolled at a rolling temperature of 440℃ and the rolling thickness is rolled from 45mm to 10mm; after hot rolling, it is annealed at a temperature of 440℃ for 2 hours and cooled in the furnace, and then cold rolled from 10mm to 6mm; (4) the rolled plate is solution treated at a temperature of 450℃ / 30min+475℃ / 2h; (5) the solution treated plate is subjected to a two-stage aging treatment at a temperature of 120℃ for 6 hours and a temperature of 135℃ for 18~20 hours.

[0028] The resulting product exhibits the following properties: tensile strength of 562~567MPa, yield strength of 515~529MPa, and impact toughness of 30.5~31.5J / cm². 2 .

[0029] The present invention is characterized by providing a high-strength, impact-resistant Al-Zn-Mg alloy, with Zn and Mg as the main strengthening elements, and controlling the composition within the range of the present invention, which can obtain nano-scale η' (Zn2Mg) and T-Mg. 32 (Al, Zn) 49 The dual-structure dispersion strengthening phase, due to the addition of trace amounts of Sc and Zr, forms dispersed L12 structure Al3(Sc, Zr) particles during solidification and homogenization. These dispersed phase particles have strong stability, significantly pinning grain boundaries and hindering dislocation movement. Therefore, a solution-aged microstructure with fine grains and low recrystallization can be obtained. After solution aging treatment, a large amount of fibrous structure is still maintained. In addition, the addition of a small amount of Mn can form a skeletal AlFeMnSi phase with Fe and Si in the matrix, which can reduce the concentration of impurity elements in the matrix. Furthermore, trace amounts of Ti are added in the form of grain refiner Al-5Ti-B to further refine the grains. Under the synergy of the above composition range and processing technology, the preferred alloy has a tensile strength greater than 560 MPa, a yield strength greater than 520 MPa, an elongation greater than 11%, and an impact toughness greater than 30 J / cm. 2 It has excellent overall performance. Attached Figure Description

[0030] Figure 1 This is a characterization diagram of the product obtained in Example 2 of the present invention;

[0031] (a) is the EBSD image of the normal phase surface-rolled surface after solution aging in Example 2, (b) is the bright field image (BF) of the TEM after aging in Example 2, and (c) is the high-resolution image (HRTEM) of Al3(Sc, Zr) particles of the L12 structure and the corresponding diffraction spots of the fast Fourier transform (FFT). Detailed Implementation

[0032] In this invention, the impact toughness of the product is measured in accordance with the GB / T229—2020 standard, and the measurement temperature is room temperature 25℃.

[0033] Comparative Example 1

[0034] Alloy composition and its weight percentage

[0035] Al-5.7Zn-2.0Mg-0.34Cu-0.10Sc-0.11Zr-0.35Mn-0.065Ti. That is, the mass percentage of Zn.

[0036] The mass percentage of the components is 5.7%, the mass percentage of Mg is 2.0%, the mass percentage of Cu is 0.34%, the mass percentage of Sc is 0.1%, the mass percentage of Zr is 0.11%, the mass percentage of Mn is 0.35%, the mass percentage of Ti is 0.065%, and the balance is Al.

[0037] The preparation method is as follows: (1) Weigh each component according to the designed aluminum alloy composition ratio, melt pure Al and Al-Sc, Al-Cu, and Al-Mn master alloys at 830℃ using an electric resistance furnace, then cool down to 740℃ and add pure Zn, pure Mg, and Al-Ti-B grain refiner in sequence, and then degas and slag-refine to obtain molten alloy liquid, and cast it into an ingot; (2) Perform single-stage isothermal homogenization treatment on the ingot obtained in step (1), and heat treat it. (2) The homogenized ingot was obtained after holding at 470℃ for 24 hours; (3) The homogenized ingot obtained in step (2) was hot rolled at 430℃, and the rolling thickness was rolled from 45mm to 10mm; then it was cold rolled from 10mm to 6mm; (4) The rolled plate was solution treated at 470℃ for 2 hours; (5) The solution treated plate was subjected to peak aging treatment at 120℃ for 24 hours. The mechanical property test results are shown in Table 1.

[0038] Comparative Example 2

[0039] Alloy composition and its weight percentage

[0040] Al-6.2Zn-2.0Mg-0.34Cu-0.10Sc-0.11Zr-0.35Mn-0.065Ti. That is, the mass percentages of Zn, Mg, Cu, Sc, Zr, Mn, and Ti are 6.2%, 2.0%, 0.34%, 0.1%, 0.11%, 0.35%, and 0.065%, with the balance being Al.

[0041] The preparation method is as follows: (1) Weigh each component according to the designed aluminum alloy composition ratio, melt pure Al and Al-Sc, Al-Cu, and Al-Mn master alloys at 830℃ using an electric resistance furnace, then cool down to 740℃ and add pure Zn, pure Mg, and Al-Ti-B grain refiner in sequence, and then degas and slag-refine to obtain molten alloy liquid, and cast it into an ingot; (2) Perform single-stage isothermal homogenization treatment on the ingot obtained in step (1), and heat treat it. (2) The homogenized ingot was obtained after holding at 470℃ for 24 hours; (3) The homogenized ingot obtained in step (2) was hot rolled at 430℃, and the rolling thickness was rolled from 45mm to 10mm; then it was cold rolled from 10mm to 6mm; (4) The rolled plate was solution treated at 470℃ for 2 hours; (5) The solution treated plate was subjected to peak aging treatment at 120℃ for 24 hours. The mechanical property test results are shown in Table 1.

[0042] Comparative Example 3

[0043] Alloy composition and its weight percentage

[0044] Al-6.7Zn-2.0Mg-0.34Cu-0.10Sc-0.11Zr-0.35Mn-0.065Ti. That is, the mass percentage of Zn.

[0045] The mass percentage of the component is 6.7%, the mass percentage of Mg is 2.0%, the mass percentage of Cu is 0.34%, the mass percentage of Sc is 0.1%, the mass percentage of Zr is 0.11%, the mass percentage of Mn is 0.35%, the mass percentage of Ti is 0.065%, and the balance is Al.

[0046] The preparation method is as follows: (1) Weigh each component according to the designed aluminum alloy composition ratio, melt pure Al and Al-Sc, Al-Cu, and Al-Mn master alloys at 830℃ using an electric resistance furnace, then cool down to 740℃ and add pure Zn, pure Mg, and Al-Ti-B grain refiner in sequence, and then degas and slag-refine to obtain molten alloy liquid, and cast it into an ingot; (2) Perform single-stage isothermal homogenization treatment on the ingot obtained in step (1), and heat treat it. (2) The homogenized ingot was obtained after holding at 470℃ for 24 hours; (3) The homogenized ingot obtained in step (2) was hot rolled at 430℃, and the rolling thickness was rolled from 45mm to 10mm; then it was cold rolled from 10mm to 6mm; (4) The rolled plate was solution treated at 470℃ for 2 hours; (5) The solution treated plate was subjected to peak aging treatment at 120℃ for 24 hours. The mechanical property test results are shown in Table 1.

[0047] Comparative Example 4

[0048] Alloy composition and its weight percentage

[0049] Al-6.7Zn-2.0Mg-0.34Cu-0.10Sc-0.11Zr-0.35Mn-0.065Ti. That is, the mass percentage of Zn.

[0050] The mass percentage of the component is 6.7%, the mass percentage of Mg is 2.0%, the mass percentage of Cu is 0.34%, the mass percentage of Sc is 0.1%, the mass percentage of Zr is 0.11%, the mass percentage of Mn is 0.35%, the mass percentage of Ti is 0.065%, and the balance is Al.

[0051] The preparation method is as follows: (1) Weigh each component according to the designed aluminum alloy composition ratio, melt pure Al and Al-Sc, Al-Cu, and Al-Mn master alloys at 830℃ using an electric resistance furnace, then cool down to 740℃ and add pure Zn, pure Mg, and Al-Ti-B grain refiner in sequence, and degas and slag remover to obtain molten alloy liquid, and cast it into an ingot; (2) Perform a two-stage homogenization treatment on the ingot obtained in step (1). The first stage homogenization temperature is 350℃ and the holding time is 12h. The second stage homogenization temperature is 47℃. (2) After holding at 5℃ for 24 hours, a homogenized ingot is obtained; (3) The homogenized ingot obtained in step (2) is hot rolled at a rolling temperature of 440℃, and the rolling thickness is rolled from 45mm to 10mm; then it is cold rolled from 10mm to 6mm; (4) The rolled plate is subjected to solution treatment at a solution treatment regime of 450℃ / 30min + 475℃ / 2h; (5) The solution-treated plate is subjected to a two-stage aging treatment at a first-stage aging temperature of 120℃ and a holding time of 6h, and a second-stage aging temperature of 135℃ and a holding time of 18h. The mechanical property test results are shown in Table 1.

[0052] Comparative Example 5

[0053] Alloy composition and its weight percentage

[0054] Al-6.2Zn-2.0Mg-0.34Cu-0.10Sc-0.11Zr-0.35Mn-0.065Ti. That is, the mass percentage of Zn.

[0055] The mass percentage of the alloy is 6.2%, the mass percentage of Mg is 2.0%, the mass percentage of Cu is 0.34%, the mass percentage of Sc is 0.1%, the mass percentage of Zr is 0.11%, the mass percentage of Mn is 0.35%, the mass percentage of Ti is 0.065%, and the balance is Al.

[0056] The preparation method is as follows: (1) Weigh each component according to the designed aluminum alloy composition ratio, melt pure Al and Al-Sc, Al-Cu, and Al-Mn master alloys at 830℃ using an electric resistance furnace, then cool down to 740℃ and add pure Zn, pure Mg, and Al-Ti-B grain refiner in sequence, and then degas and slag-refine to obtain molten alloy liquid, and cast it into an ingot; (2) Perform single-stage isothermal homogenization treatment on the ingot obtained in step (1), the heat treatment temperature is 470℃, and after holding for 24h, obtain (2) Homogenized ingot; (3) Hot rolling of the homogenized ingot obtained in step (2) at a rolling temperature of 440℃, rolling thickness from 45mm to 10mm; followed by cold rolling from 10mm to 6mm; (4) Solution treatment of the rolled plate at 450℃ / 30min + 475℃ / 2h; (5) Two-stage aging treatment of the solution-treated plate, the first stage aging temperature at 120℃ and the holding time at 6h, and the second stage aging temperature at 135℃ and the holding time at 18h. The mechanical property test results are shown in Table 1.

[0057] Comparative Example 6

[0058] Alloy composition and its weight percentage

[0059] Al-6.7Zn-2.0Mg-0.34Cu-0.10Sc-0.11Zr-0.35Mn-0.065Ti. That is, the mass percentage of Zn.

[0060] The mass percentage of the component is 6.7%, the mass percentage of Mg is 2.0%, the mass percentage of Cu is 0.34%, the mass percentage of Sc is 0.1%, the mass percentage of Zr is 0.11%, the mass percentage of Mn is 0.35%, the mass percentage of Ti is 0.065%, and the balance is Al.

[0061] The preparation method is as follows: (1) Weigh each component according to the designed aluminum alloy composition ratio, melt pure Al and Al-Sc, Al-Cu, and Al-Mn master alloys at 830℃ using an electric resistance furnace, then cool down to 740℃ and add pure Zn, pure Mg, and Al-Ti-B grain refiner in sequence, and then degas and slag-refine to obtain molten alloy liquid, and cast it into an ingot; (2) Perform single-stage isothermal homogenization treatment on the ingot obtained in step (1), the heat treatment temperature is 470℃, and after holding for 24h, obtain (2) Homogenized ingot; (3) Hot rolling of the homogenized ingot obtained in step (2) at a rolling temperature of 440℃, rolling thickness from 45mm to 10mm; followed by cold rolling from 10mm to 6mm; (4) Solution treatment of the rolled plate at 450℃ / 30min + 475℃ / 2h; (5) Two-stage aging treatment of the solution-treated plate, the first stage aging temperature at 120℃ and the holding time at 6h, and the second stage aging temperature at 135℃ and the holding time at 18h. The mechanical property test results are shown in Table 1.

[0062] Example 1

[0063] Alloy composition and its weight percentage

[0064] Al-5.2Zn-2.0Mg-0.34Cu-0.10Sc-0.11Zr-0.35Mn-0.065Ti. That is, the mass percentages of Zn, Mg, Cu, Sc, Zr, Mn, and Ti are 5.2%, 2.0%, 0.34%, 0.1%, 0.11%, 0.35%, and 0.065%, with the balance being Al.

[0065] The preparation method is as follows: (1) Weigh each component according to the designed aluminum alloy composition ratio, melt pure Al and Al-Sc, Al-Cu, and Al-Mn master alloys at 830℃ using an electric resistance furnace, then cool down to 740℃ and add pure Zn, pure Mg, and Al-Ti-B grain refiner in sequence, and degas and slag remover to obtain molten alloy liquid, and cast it into an ingot; (2) Perform a two-stage homogenization treatment on the ingot obtained in step (1). The first stage homogenization temperature is 350℃ and the holding time is 12h. The second stage homogenization temperature is 475℃ and the holding time is 24h to obtain a homogenized state ingot. (3) The homogenized ingot obtained in step (2) is hot rolled at a rolling temperature of 440℃ and the rolling thickness is rolled from 45mm to 10mm; after hot rolling, it is annealed at a temperature of 440℃ for 2h and cooled in the furnace, and then cold rolled from 10mm to 6mm; (4) The rolled plate is solution treated at a solution treatment regime of 450℃ / 30min+475℃ / 2h; (5) The solution treated plate is subjected to a two-stage aging treatment, with the first stage aging temperature at 120℃ and the holding time at 6h, and the second stage aging temperature at 135℃ and the holding time at 20h. The mechanical property test results are shown in Table 1.

[0066] Example 2

[0067] Alloy composition and its weight percentage

[0068] Al-5.7Zn-2.0Mg-0.34Cu-0.10Sc-0.11Zr-0.35Mn-0.065Ti. That is, the mass percentage of Zn.

[0069] The mass percentage of the components is 5.7%, the mass percentage of Mg is 2.0%, the mass percentage of Cu is 0.34%, the mass percentage of Sc is 0.1%, the mass percentage of Zr is 0.11%, the mass percentage of Mn is 0.35%, the mass percentage of Ti is 0.065%, and the balance is Al.

[0070] The preparation method is as follows: (1) Weigh each component according to the designed aluminum alloy composition ratio, melt pure Al and Al-Sc, Al-Cu, and Al-Mn master alloys at 830℃ using an electric resistance furnace, then cool down to 740℃ and add pure Zn, pure Mg, and Al-Ti-B grain refiner in sequence, and degas and slag remover to obtain molten alloy liquid, and cast it into an ingot; (2) Perform a two-stage homogenization treatment on the ingot obtained in step (1). The first stage homogenization temperature is 350℃ and the holding time is 12h. The second stage homogenization temperature is 475℃ and the holding time is 24h to obtain a homogenized state ingot. (3) The homogenized ingot obtained in step (2) is hot rolled at a rolling temperature of 440℃ and the rolling thickness is rolled from 45mm to 10mm; after hot rolling, it is annealed at a temperature of 440℃ for 2h and cooled in the furnace, and then cold rolled from 10mm to 6mm; (4) The rolled plate is solution treated at a solution treatment regime of 450℃ / 30min+475℃ / 2h; (5) The solution treated plate is subjected to a two-stage aging treatment, with the first stage aging temperature at 120℃ and the holding time at 6h, and the second stage aging temperature at 135℃ and the holding time at 20h. The mechanical property test results are shown in Table 1.

[0071] Example 3

[0072] Alloy composition and its weight percentage

[0073] Al-5.7Zn-2.0Mg-0.34Cu-0.10Sc-0.11Zr-0.35Mn-0.065Ti. That is, the mass percentage of Zn.

[0074] The mass percentage of the components is 5.7%, the mass percentage of Mg is 2.0%, the mass percentage of Cu is 0.34%, the mass percentage of Sc is 0.1%, the mass percentage of Zr is 0.11%, the mass percentage of Mn is 0.35%, the mass percentage of Ti is 0.065%, and the balance is Al.

[0075] The preparation method is as follows: (1) Weigh each component according to the designed aluminum alloy composition ratio, melt pure Al and Al-Sc, Al-Cu, and Al-Mn master alloys at 830℃ using an electric resistance furnace, then cool down to 740℃ and add pure Zn, pure Mg, and Al-Ti-B grain refiner in sequence, and degas and slag remover to obtain molten alloy liquid, and cast it into an ingot; (2) Perform single-stage isothermal homogenization treatment on the ingot obtained in step (1), the heat treatment temperature is 470℃, and after holding for 24h, obtain a homogenized ingot; (3) Perform step ( 2) The obtained homogenized ingot was hot rolled at a rolling temperature of 440℃, and the rolling thickness was rolled from 45mm to 10mm; it was annealed at a temperature of 440℃ for 2 hours and cooled in the furnace, and then cold rolled from 10mm to 6mm; (4) The rolled plate was solution treated at a temperature of 450℃ / 30min + 475℃ / 2h; (5) The solution treated plate was subjected to a two-stage aging treatment, with the first stage aging temperature at 120℃ and a holding time of 6h, and the second stage aging temperature at 135℃ and a holding time of 18h. The mechanical property test results are shown in Table 1.

[0076] Example 4

[0077] Alloy composition and its weight percentage

[0078] Al-5.2Zn-2.0Mg-0.34Cu-0.10Sc-0.11Zr-0.35Mn-0.065Ti. That is, the mass percentages of Zn, Mg, Cu, Sc, Zr, Mn, and Ti are 5.2%, 2.0%, 0.34%, 0.1%, 0.11%, 0.35%, and 0.065%, with the balance being Al.

[0079] The preparation method is as follows: (1) Weigh each component according to the designed aluminum alloy composition ratio, melt pure Al and Al-Sc, Al-Cu, and Al-Mn master alloys at 830℃ using an electric resistance furnace, then cool down to 740℃ and add pure Zn, pure Mg, and Al-Ti-B grain refiner in sequence, and degas and slag remover to obtain molten alloy liquid, and cast it into an ingot; (2) Perform a two-stage homogenization treatment on the ingot obtained in step (1). The first stage homogenization temperature is 350℃ and the holding time is 12h. The second stage homogenization temperature is 475℃ and the holding time is 24h to obtain a homogenized state ingot. (3) The homogenized ingot obtained in step (2) is hot rolled at a rolling temperature of 440℃ and the rolling thickness is rolled from 45mm to 10mm; after hot rolling, it is annealed at a temperature of 440℃ for 2 hours and then cooled in the furnace, followed by cold rolling from 10mm to 6mm; (4) The rolled plate is solution treated at a temperature of 450℃ / 30min + 475℃ / 2h; (5) The solution treated plate is subjected to a two-stage aging treatment at a temperature of 120℃ for 6 hours and a temperature of 135℃ for 18 hours. The mechanical property test results are shown in Table 1.

[0080] Example 5

[0081] Alloy composition and its weight percentage

[0082] Al-5.7Zn-2.0Mg-0.34Cu-0.10Sc-0.11Zr-0.35Mn-0.065Ti. That is, the mass percentages of Zn, Mg, Cu, Sc, Zr, Mn, and Ti are 5.7%, 2.0%, 0.34%, 0.1%, 0.11%, 0.35%, and 0.065%, with the balance being Al.

[0083] The preparation method is as follows: (1) Weigh each component according to the designed aluminum alloy composition ratio, melt pure Al and Al-Sc, Al-Cu, and Al-Mn master alloys at 830℃ using an electric resistance furnace, then cool down to 740℃ and add pure Zn, pure Mg, and Al-Ti-B grain refiner in sequence, and degas and slag remover to obtain molten alloy liquid, and cast it into an ingot; (2) Perform a two-stage homogenization treatment on the ingot obtained in step (1). The first stage homogenization temperature is 350℃ and the holding time is 12h. The second stage homogenization temperature is 475℃ and the holding time is 24h to obtain a homogenized state ingot. (3) The homogenized ingot obtained in step (2) is hot rolled at a rolling temperature of 440℃ and the rolling thickness is rolled from 45mm to 10mm; after hot rolling, it is annealed at a temperature of 440℃ for 2 hours and then cooled in the furnace, followed by cold rolling from 10mm to 6mm; (4) The rolled plate is solution treated at a temperature of 450℃ / 30min + 475℃ / 2h; (5) The solution treated plate is subjected to a two-stage aging treatment at a temperature of 120℃ for 6 hours and a temperature of 135℃ for 18 hours. The mechanical property test results are shown in Table 1.

[0084] .

Claims

1. A high-strength, impact-resistant Al-Zn-Mg alloy, characterized in that: The composition, by mass percentage, comprises the following components: Zn 5.2–7.2 wt.%, Mg 1.8–2.4 wt.%, Cu 0.3–0.5 wt.%, Sc 0.08–0.15 wt.%, Zr 0.08–0.15 wt.%, Mn 0.3–0.5 wt.%, Ti 0.03–0.10 wt.%, with the balance being Al, and the Zn / Mg ratio is [not specified]. 2.4; The aluminum alloy contains nano-sized η'(Zn2Mg) and T-Mg. 32 (Al, Zn) 49 Al3(Sc, Zr) particles with a dual-structured dispersion-enhanced phase and an L12 structure.

2. The high-strength, impact-resistant Al-Zn-Mg alloy according to claim 1, characterized in that: The composition, by mass percentage, comprises the following components: Zn 5.2–6.9 wt.%, Mg 2.0–2.4 wt.%, Cu 0.3–0.4 wt.%, Sc 0.09–0.11 wt.%, Zr 0.09–0.11 wt.%, Mn 0.3–0.4 wt.%, Ti 0.03–0.10 wt.%, with the balance being Al, and the Zn / Mg ratio is [not specified]. 2.

4.

3. The high-strength, impact-resistant Al-Zn-Mg alloy according to claim 2, characterized in that: The composition, by mass percentage, comprises the following components: Zn 5.2–6.0 wt.%, Mg 2.0–2.2 wt.%, Cu 0.3–0.4 wt.%, Sc 0.09–0.11 wt.%, Zr 0.09–0.11 wt.%, Mn 0.3–0.4 wt.%, Ti 0.03–0.10 wt.%, with the balance being Al, and the Zn / Mg ratio is [not specified]. 2.

4.

4. The high-strength, impact-resistant Al-Zn-Mg alloy according to claim 1, characterized in that: The high-strength, impact-resistant Al-Zn-Mg alloy contains nano-sized η' (Zn2Mg) and T-Mg. 32 (Al, Zn) 49 The dual-structured diffuse-reinforced phase, along with L12-structured Al3(Sc, Zr) particles and fibrous tissue.

5. A method for preparing a high-strength, impact-resistant Al-Zn-Mg alloy, characterized in that: According to the designed composition ratio, the raw materials are pure Al, pure Zn, pure Mg and intermediate alloys such as Al-50%Cu, Al-5%Zr, Al-10%Mn, Al-2%Sc and Al-5Ti-B. The raw materials are heated and melted in a resistance furnace to obtain molten alloy liquid. The molten alloy liquid is then cast into aluminum alloy ingots through a water-cooled mold. Subsequently, the ingots undergo two-stage homogenization annealing, rolling, solution quenching and aging treatment.

6. The method for preparing a high-strength, impact-resistant Al-Zn-Mg alloy according to claim 5, characterized in that: The smelting and casting process is as follows: First, pure Al is preheated to 600℃ and then melted into molten aluminum at 830℃. Then, intermediate alloys such as Al-50%Cu, Al-5%Zr, Al-10%Mn, and Al-2%Sc are added. The mixture is held at this temperature for 30-60 minutes, and the molten aluminum is stirred to observe whether the intermediate alloys have completely melted. Then, the temperature is lowered to 740℃, and then pure Zn and pure Mg wrapped in aluminum foil are added. Pure Mg needs to be pressed to the bottom of the molten aluminum to prevent excessive burning. After adding the alloys, argon and chlorine are mixed for refining. Argon refining time is 1-2 minutes, and hexachloroethane refining is carried out at 0.5% of the ingot mass. The refining is carried out at least twice. After refining, Al-5Ti-B grain refiner is added to the molten aluminum. After holding at this temperature for 10-15 minutes, the mixture is cast using a water-cooled mold.

7. The method for preparing a high-strength, impact-resistant Al-Zn-Mg alloy according to claim 5, characterized in that: The obtained aluminum alloy ingot is subjected to a two-stage homogenization treatment. The specific process is as follows: first, it is heated to the first-stage homogenization temperature and held for 8~16 hours, and then heated to the second-stage homogenization temperature and held for 16~32 hours. The first-stage homogenization temperature is 300~400℃, the second-stage homogenization temperature is 450~480℃, and the heating rate between the first-stage and second-stage homogenization is not higher than 50℃ / h.

8. The method for preparing a high-strength, impact-resistant Al-Zn-Mg alloy according to claim 5, characterized in that: The alloy is selected for hot rolling followed by cold rolling. The hot rolling temperature is 420~450℃, and the thickness of the rolled block is 10mm from 45mm. The final rolling temperature is not lower than 380℃. Then, the hot-rolled plate is annealed in the intermediate annealing temperature at 420~450℃ for 2~4 hours and then cooled in the furnace. The annealed hot-rolled plate is then cold-rolled from 10mm to 6mm, with a single reduction not exceeding 1mm.

9. The method for preparing a high-strength, impact-resistant Al-Zn-Mg alloy according to claim 5, characterized in that: The solution temperature is 430~480℃, the solution treatment time is 2~6h, and after the solution treatment is completed, it is quickly water-cooled to room temperature for quenching.

10. The method for preparing a high-strength, impact-resistant Al-Zn-Mg alloy according to claim 5, characterized in that: The aging process employs a two-stage aging process. The first-stage aging process is carried out at a temperature of 90–130 °C for 4–10 hours, while the second-stage aging process is carried out at a temperature of 120–180 °C for 10–32 hours.

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