Large-sized complex thin-walled part made of 7-series aluminum alloy and hot-stamping forming method therefor

Abstract

The present application belongs to a stamping forming method, and addresses the technical problem of the degradation in mechanical properties of high-strength aluminum alloys prepared through current aluminum alloy stamping forming processes under natural conditions, and provides a large-sized complex thin-walled part made of a 7-series aluminum alloy, and a hot-stamping forming method therefor. The method includes: performing primary aging treatment on a supersaturated solid-solution state 7-series aluminum alloy to obtain a 7-series aluminum alloy after undergoing the primary aging treatment; performing secondary aging treatment on a primary aging treatment result to obtain a 7-series aluminum alloy after undergoing the secondary aging treatment; heating the 7-series aluminum alloy after undergoing the secondary aging treatment to a temperature greater than a critical temperature at which a precipitate phase dissolves to obtain a heated 7-series aluminum alloy; and stamping and simultaneously quenching the heated 7-series aluminum alloy to obtain a formed part.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The application claims priority to Chinese patent application No. 2025104847227, filed on Apr. 17, 2025, the entire contents of which are incorporated herein by reference.TECHNICAL FIELD

[0002] The present application belongs to a stamping forming method, and particularly relates to a large-sized complex thin-walled part made of a 7-series aluminum alloy and a hot-stamping forming method therefor.BACKGROUND

[0003] In strategic emerging industries such as low-altitude aircrafts and new energy vehicles, the large-sized application of high-strength lightweight materials plays a highly supportive role, effectively enhancing load-carrying performance and efficiency, while improving safety, stability, and functional integration.

[0004] High-strength aluminum alloys have emerged as an ideal material due to their superior specific strength, corrosion resistance, and oxidation resistance. However, the low plasticity of high-strength aluminum alloys at room temperature makes it difficult to meet the high-precision dimensional requirements for large-sized, complex thin-walled components. The hot-stamping forming process enables the integrated forming of large-sized, complex thin-walled components by utilizing key technologies such as solid-solution treatment and deformation within cold dies. Nevertheless, the traditional stamping forming process for aluminum alloys involves a lengthy preparation cycle of several hours and is subject to a natural aging effect, which weakens mechanical properties and makes it challenging to achieve large-sized and low-cost industrial production.SUMMARY

[0005] The present application addresses the technical problem of the degradation in mechanical properties of high-strength aluminum alloys prepared through current aluminum alloy stamping forming processes under natural conditions, and provides a large-sized complex thin-walled part made of a 7-series aluminum alloy, and a hot-stamping forming method therefor.

[0006] In order to achieve the above objective, the present application adopts the following technical solutions:

[0007] in a first aspect, the present application provides a hot-stamping forming method for a large-sized complex thin-walled part made of a 7-series aluminum alloy, including:

[0008] performing primary aging treatment on a supersaturated solid-solution state 7-series aluminum alloy to obtain a 7-series aluminum alloy after undergoing the primary aging treatment;

[0009] performing secondary aging treatment on a primary aging treatment result to obtain a 7-series aluminum alloy after undergoing the secondary aging treatment; wherein, a temperature of the primary aging treatment is lower than a temperature of the secondary aging treatment, and a duration of the primary aging treatment is longer than a duration of the secondary aging treatment;

[0010] heating the 7-series aluminum alloy after undergoing the secondary aging treatment to a temperature greater than a critical temperature at which a precipitate phase dissolves to obtain a heated 7-series aluminum alloy; and

[0011] stamping and simultaneously quenching the heated 7-series aluminum alloy to obtain a formed part.

[0012] Further, after obtaining the formed part, the method further includes: performing tertiary aging treatment on the formed part.

[0013] Further, a temperature for the tertiary aging treatment is in the range of 140-180 °C and the duration is in the rage of 20-40 min.

[0014] Further, the temperature of the primary aging treatment is in the range of 70-120 °C and the temperature of the secondary aging treatment is in the range of 140-180 °C.

[0015] Further, the duration of the primary aging treatment is in the rage of 40-60 min, and the duration of the secondary aging treatment is in the rage of 20-40 min.

[0016] Further, when the 7-series aluminum alloy after undergoing the secondary aging treatment is heated to the temperature greater than the critical temperature at which a precipitate phase dissolves, the 7-series aluminum alloy after undergoing the secondary aging treatment is heated to 200-400 °C at a rate of 50 °C / s or more.

[0017] Further, the stamping of the heated 7-series aluminum alloy is performed by transferring the heated 7-series aluminum alloy into a cold stamping die within 2-5 seconds after obtaining the heated 7-series aluminum alloy.

[0018] Further, when the 7-series aluminum alloy after undergoing the secondary aging treatment is heated to a temperature greater than the critical temperature at which a precipitate phase dissolves, an energy field-assisted method is employed.

[0019] In a second aspect, the present application provides a large-sized complex thin-walled part made of a 7-series aluminum alloy prepared by the hot-stamping forming method for a large-sized complex thin-walled part made of a 7-series aluminum alloy mentioned above.

[0020] Further, the yield strength is greater than or equal to 490 MPa, the tensile strength is greater than or equal to 570 MPa, and the elongation is greater than or equal to 11%.

[0021] Compared with the prior art, the present application has the following beneficial effects: the present application proposes a hot-stamping forming method for a large-sized complex thin-walled part made of a 7-series aluminum alloy. The method involves a two-stage aging treatment on the supersaturated solid-solution state 7-series aluminum alloy, wherein the secondary aging treatment is conducted at a higher temperature and for a shorter duration. Through this two-stage pre-aging treatment, a microstructure dominated by GPII zones can be formed, avoiding the precipitation of GPI zones that are prone to natural aging. The GPII zones are highly stable under natural conditions, ensuring the long-term storage of the raw materials. Consequently, both the raw materials before forming and the large-sized complex thin-walled parts after forming prepared by the present application can be stored for extended periods under natural conditions. Subsequently, the 7-series aluminum alloy after undergoing the secondary aging treatment is heated to a temperature greater than the critical temperature at which a precipitate phase dissolves. This not only enhances the material's formability to enable the integrated forming of complex parts but also prevents the extensive dissolution of GPII zones, maintaining a microstructure predominantly composed of GPII zones after forming, which allows for long-term preservation. The process flow of the forming method in the present application is significantly shortened, the manufacturing costs are substantially reduced, and the performance of the parts is improved, surpassing the peak values of the T6 condition.

[0022] The present application also presents a large-sized complex thin-walled part made of a 7-series aluminum alloy. Through practical verification, its yield strength, tensile strength, and elongation all exceed the peak values of the T6 condition.BRIEF DESCRIPTION OF DRAWINGS

[0023] To illustrate the technical solutions of the embodiments of the application more clearly, the drawings required for use in the embodiments will be briefly described below, it should be understood that the following drawings illustrate only certain embodiments of the present application and therefore should not be regarded as limiting the scope. For those skilled in the art, other related drawings can be obtained from these drawings without making creative labor.

[0024] FIG. 1 is a process schematic diagram of a hot-stamping forming method for a large-sized complex thin-walled part made of a 7-series aluminum alloy according to the present application;

[0025] FIG. 2 is a schematic diagram of a large-sized complex thin-walled part made of a 7-series aluminum alloy prepared according to an embodiment of the present application; and

[0026] FIG. 3 is a schematic diagram of the strength and fracture elongation of a large-sized complex thin-walled part made of a 7-series aluminum alloy prepared in Embodiments 1-6 according to the present application.DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] In order to make the objectives, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present application, and it is obvious that the described embodiments are a part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application as generally described and illustrated in the accompanying drawings herein could be arranged and designed in a wide variety of different configurations.

[0028] Accordingly, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but is merely to represent selected embodiments of the application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0029] It should be noted that like reference numerals and letters refer to like items in the following drawings, and therefore, once an item is defined in one drawing, it is not necessary to be further defined and explained in the following drawings.

[0030] In the description of the embodiments of the present application, it should be noted that if the orientation or positional relationship indicated by the terms “upper”, “lower”, “horizontal”, “inner”, etc. is based on the orientation or positional relationship shown in the drawings, or is the orientation or positional relationship usually placed when the product of the present disclosure is used, it is only for convenience and simplification of the description of the present application, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present application. Furthermore, the terms “first”, “second”, etc. are merely used to distinguish descriptions and cannot be understood as indicating or implying relative importance.

[0031] Further, if the term “horizontal” appears, it does not mean that the component is required to be absolutely horizontal, but may be slightly inclined. If “horizontal” merely means that its orientation is more horizontal than “vertical”, it does not mean that the structure must be completely horizontal, but may be slightly inclined.

[0032] In the description of the embodiments of the present application, it should also be noted that unless otherwise explicitly specified and limited, if the terms “arranging”, “installation”, “connection”, and “connecting” appear, they should be understood in a broad sense, for example, the connection may be a fixed connection, a detachable connection, or an integral connection; the connection may be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal communication of two elements. Those skilled in the art can understand the specific meanings of the above-mentioned terms in the present application according to the specific circumstances.

[0033] Low-altitude aircrafts and new energy vehicles have been identified as key development directions within strategic emerging industries. In particular, it has been highlighted that the large-sized application of high-strength lightweight materials plays a crucial role in enhancing the core competitiveness of these industries. In response to the demands for lightweight design, functional integration, and improved safety performance in these two types of products, their structural components exhibit characteristics such as large size, thin-walled construction, and complex shapes, as seen in key components like wings, window frames, battery compartments, etc.

[0034] Wherein, the 7-series aluminum alloy stands out as a preferred choice for achieving low-carbon manufacturing and lightweighting due to its excellent specific strength, corrosion resistance, and oxidation resistance characteristics. This 7-series alloy, with Zn and Mg as its main strengthening elements, forms nanoscale η′ (MgZn2) strengthening phases through heat treatment. However, its room-temperature plastic forming capability is limited, making it difficult to meet the high-precision forming requirements for large-sized and complex thin-walled components. Hot-stamping forming technology effectively addresses this challenge by combining solid-solution treatment with in-die quenching processes, enabling the integrated forming of the large-sized complex thin-walled parts. The traditional hot-stamping process consists of three core stages: first, the alloy is heated to the solid-solution temperature to obtain a single-phase supersaturated solid solution; subsequently, rapid forming and quenching are completed in a cold die; finally, tertiary aging treatment promotes the transformation of GP zones into η′ phases, achieving the strengthening effect of the T6 condition. However, this traditional hot-stamping process encounters two major technological bottlenecks:

[0035] (1) Natural aging sensitivity: after quenching, the supersaturated solid solution is prone to natural aging at room temperature, leading to the heterogeneous precipitation of GP zones. This results in fluctuations in the mechanical properties of parts from different batches and a decline in corrosion resistance.

[0036] (2) Mismatch in aging cycles: the tertiary aging treatment can take as long as 20 hours (for example, for a 7075 aluminum alloy), and create a significant time difference with the solution treatment-forming cycle, which is typically completed in minutes. This severely restricts the efficiency of large-sized production and drives up costs.

[0037] In response to the aforementioned problems, while existing improvement solutions can partially alleviate them, a new problem of competitive precipitation of solute atom enrichment forms has emerged. During the pre-aging process, Zn atoms segregate on the {111} crystal plane to form stable GPII zones, while Mg atoms, together with a small amount of Zn atoms, form metastable GPI zones on the {100} crystal plane. The latter continues to evolve subsequently and transforms into the η′ phase eventually, resulting in uneven size distribution of the precipitate phases, and the natural aging effect is generated, which undermines the stability of the material's properties. For instance, the Chinese invention patent CN118147590A proposes an optimized solution for multi-series aluminum alloys. Specifically, for the 7-series aluminum alloys, both forms of solute atom enrichment occur simultaneously, namely, the formation of GPII and GPI zones. The GPI zones continue to grow under natural conditions and may even transform into η′ strengthening phases. Subsequently, the natural aging effect characterized by uneven size and irregular distribution of precipitate phases emerges, leading to a reduction in mechanical properties. This competitive precipitation mechanism imposes stricter requirements on the control of the process window, posing a key challenge that restricts the application of this technology.

[0038] Based on the above current situation, the present application proposes a large-sized complex thin-walled part made of a 7-series aluminum alloy and a hot-stamping forming method therefor, which is described in detail below with reference to the embodiments and the accompanying drawings.

[0039] The present application provides a hot-stamping forming method for a large-sized complex thin-walled part made of a 7-series aluminum alloy, including:

[0040] S1, primary aging treatment is performed on a supersaturated solid-solution state 7-series aluminum alloy to obtain a 7-series aluminum alloy after undergoing the primary aging treatment.

[0041] It should be noted that during the primary aging treatment, the ordered segregation of solute atoms (such as Zn and Mg) can be promoted at a relatively low temperature, leading to the formation of stable GPII zones. Additionally, extending the duration of the primary aging treatment ensures the sufficient segregation of Zn atoms on the {111} crystal planes to form the GPII zones. The GPII zones are formed by the ordered arrangement of Zn atoms on the close-packed planes of the aluminum matrix, exhibiting high thermal stability. They can effectively suppress the precipitation of precipitate phases during natural aging, thereby addressing the problem of performance fluctuations caused by long-term storage.

[0042] S2, secondary aging treatment is performed on a primary aging treatment result to obtain a 7-series aluminum alloy after undergoing the secondary aging treatment; wherein, a temperature of the primary aging treatment is lower than a temperature of the secondary aging treatment, and a duration of the primary aging treatment is longer than a duration of the secondary aging treatment.

[0043] It should be noted that the higher temperature during the secondary aging treatment can activate the diffusion of Mg atoms, accelerating the further segregation of Mg and Zn atoms on the {111} crystal planes. These atoms rapidly form the GPII zones centered around the atomic clusters formed during the primary aging treatment. Meanwhile, the segregation of the Mg and Zn atoms on the {100} crystal planes is suppressed, reducing the formation of the GPI zones.

[0044] Through the aforementioned two-stage pre-aging treatment, a microstructure dominated by the GPII zones can be achieved, enabling the manufactured parts to be stored for an extended period under natural conditions.

[0045] S3, the 7-series aluminum alloy after undergoing the secondary aging treatment is heated to a temperature greater than a critical temperature at which a precipitate phase dissolves to obtain a heated 7-series aluminum alloy.

[0046] By employing this heating method, it is possible to not only enhance the material's formability, enabling the integrated forming of complex parts, but also to prevent the extensive dissolution of the GPII zones. As a result, the microstructure after forming remains predominantly composed of the GPII zones, allowing for long-term preservation.

[0047] In practical applications, an energy field-assisted heating method can be adopted to rapidly heat the sheet material to a temperature slightly above the critical temperature at which a significant amount of precipitate phases dissolve, typically within the range of 200-400 °C, without the need for holding at that temperature.

[0048] S4, the heated 7-series aluminum alloy is hot-stamped and simultaneously quenched to obtain a formed part.

[0049] In the present application, after the primary aging treatment of the 7-series aluminum alloy, the Zn atoms precipitate and enrich on the {111} planes of the aluminum lattice, forming a large number of atomic clusters. These clusters provide the foundation for the formation of a substantial number of GPII zones during the secondary pre-aging treatment. Building upon the abundant atomic clusters obtained from the primary aging treatment, the secondary aging treatment rapidly generates a significant quantity of GPII zones. The 7-series aluminum alloy after undergoing the secondary aging treatment serves as the raw material in its microscopic state, exhibiting no changes in microstructure and properties within a 1-year validity period. Energy field-assisted heating can achieve a heating rate of no less than 50 °C / s, rapidly heating the 7-series aluminum alloy after undergoing the secondary aging treatment to a temperature range of 200-400 °C. This minimizes the dissolution of GPII zones during the heating process, ensuring that the proportion of GPII zones in the microstructure after heating is no less than 80%. The microstructure of the formed part consists of GPII zones accounting for no less than 80% of the total. Considering the entire heating process, the duration of the entire forming stage is less than 15 seconds.

[0050] In practical applications, after obtaining the formed part, tertiary aging treatment is also performed on the large-sized complex thin-walled part made of a 7-series aluminum alloy. The temperature for this treatment can range from 140-180 °C, with a duration of 20-40 minutes.

[0051] Traditional aging treatment follows a balance between strength and toughness. However, the tertiary aging treatment proposed in the present application can synergistically enhance both strength and toughness.

[0052] After verification, by adopting the forming method of the present application, a significant number of GPII zones in the formed parts are transformed into η′ strengthening phases with more concentrated sizes and more uniform distributions during the tertiary aging process. These η′ phases have a size range of 10-15 nm, which can be adjusted as needed, and account for more than 98% of the microstructure. This not only improves strength but also enhances toughness. Additionally, the process flow is significantly shortened, leading to a substantial reduction in manufacturing costs. The performance of the parts surpasses the peak values of the T6 condition.

[0053] Referring to FIG. 1, there is a process schematic diagram of a hot-stamping forming method for a large-sized complex thin-walled part made of a 7-series aluminum alloy according to the present application. Wherein, the temperature of the primary aging treatment is in the range of 70-120 °C, the duration of the primary aging treatment is 40-60 min, the temperature of the secondary aging treatment is in the range of 140-180 °C, and the duration of the secondary aging treatment is 20-40 min. The 7-series aluminum alloy, after undergoing the secondary aging treatment, is heated to a temperature range of 200-400 °C, with a forming cycle of less than 15 seconds. The temperature of the tertiary aging treatment is in the range of 140-180 °C, and the duration is 20-40 minutes.

[0054] The temperature selection for the primary aging treatment is based on the activation energy required for the segregation of Zn and Mg atoms on the {111} crystal planes to form atomic clusters. If the temperature is too low (below 70 °C) , this process cannot be initiated. Conversely, if the temperature is too high (above 120 °C) , it tends to form GPI zones that are detrimental to the process. The primary aging treatment consumes a portion of the free Zn and Mg atoms. Only by appropriately increasing the temperature during the secondary aging treatment can the diffusion of Zn and Mg atoms be enhanced, thereby activating the formation of GPII zones on the {111} crystal planes. A temperature below 140 °C affects the efficiency of GPII zone formation, while a temperature above 180 °C may lead to the premature formation of η′ phases, which is unfavorable for subsequent forming processes.

[0055] The present application is further illustrated by a number of embodiments below:Embodiment One(1) Primary aging treatment is performed on the supersaturated solid-solution state 7-series aluminum alloy at a temperature of 100 °C for a duration of 50 minutes.

[0057] (2) Secondary aging treatment is performed on the 7-series aluminum alloy after undergoing the primary aging treatment at a temperature of 150 °C for 40 minutes.

[0058] (3) For the 7-series aluminum alloy after undergoing the secondary aging treatment, electric field heating is utilized to rapidly heat the sheet material after undergoing the secondary aging treatment to a temperature slightly above the critical temperature at which a significant amount of precipitate phases dissolve. A temperature of 350 °C can be adopted, with no need for holding at that temperature.

[0059] (4) The heated 7-series aluminum alloy is rapidly transferred to a cold die for stamping and simultaneous quenching. The transfer time should be 2 seconds.

[0060] (5) Tertiary aging treatment is performed on the formed large-sized complex thin-walled part made of the 7-series aluminum alloy at a temperature of 150 °C for 20 minutes.Embodiment Two(1) Primary aging treatment is performed on the supersaturated solid-solution state 7-series aluminum alloy at a temperature of 70 °C for a duration of 60 minutes.

[0062] (2) Secondary aging treatment is performed on the 7-series aluminum alloy after undergoing the primary aging treatment at a temperature of 180 °C for 30 minutes.

[0063] (3) For the 7-series aluminum alloy after undergoing the secondary aging treatment, electric field heating is utilized to rapidly heat the sheet material after undergoing the secondary aging treatment to a temperature slightly above the critical temperature at which a significant amount of precipitate phases dissolve. A temperature of 260 °C can be adopted, with no need for holding at that temperature.

[0064] (4) The heated 7-series aluminum alloy is rapidly transferred to a cold die for stamping and simultaneous quenching. The transfer time should be 5 seconds.

[0065] (5) Tertiary aging treatment is performed on the formed large-sized complex thin-walled part made of the 7-series aluminum alloy at a temperature of 180 °C for 30 minutes.Embodiment Three(1) Primary aging treatment is performed on the supersaturated solid-solution state 7-series aluminum alloy at a temperature of 120 °C for a duration of 40 minutes.

[0067] (2) Secondary aging treatment is performed on the 7-series aluminum alloy after undergoing the primary aging treatment at a temperature of 150 °C for 20 minutes.

[0068] (3) For the 7-series aluminum alloy after undergoing the secondary aging treatment, electric field heating is utilized to rapidly heat the sheet material after undergoing the secondary aging treatment to a temperature slightly above the critical temperature at which a significant amount of precipitate phases dissolve. A temperature of 200 °C can be adopted, with no need for holding at that temperature.

[0069] (4) The heated 7-series aluminum alloy is rapidly transferred to a cold die for stamping and simultaneous quenching. The transfer time should be 5 seconds.

[0070] (5) Tertiary aging treatment is performed on the formed large-sized complex thin-walled part made of the 7-series aluminum alloy at a temperature of 140 °C for 30 minutes.Embodiment Four(1) Primary aging treatment is performed on the supersaturated solid-solution state 7-series aluminum alloy at a temperature of 90 °C for a duration of 45 minutes.

[0072] (2) Secondary aging treatment is performed on the 7-series aluminum alloy after undergoing the primary aging treatment at a temperature of 140 °C for 35 minutes.

[0073] (3) For the 7-series aluminum alloy after undergoing the secondary aging treatment, electric field heating is utilized to rapidly heat the sheet material after undergoing the secondary aging treatment to a temperature slightly above the critical temperature at which a significant amount of precipitate phases dissolve. A temperature of 400 °C can be adopted, with no need for holding at that temperature.

[0074] (4) The heated 7-series aluminum alloy is rapidly transferred to a cold die for stamping and simultaneous quenching. The transfer time should be 3 seconds.

[0075] (5) Tertiary aging treatment is performed on the formed large-sized complex thin-walled part made of the 7-series aluminum alloy at a temperature of 150 °C for 40 minutes.Embodiment Five(1) Primary aging treatment is performed on the supersaturated solid-solution state 7-series aluminum alloy at a temperature of 80 °C for a duration of 60 minutes.

[0077] (2) Secondary aging treatment is performed on the 7-series aluminum alloy after undergoing the primary aging treatment at a temperature of 160 °C for 40 minutes.

[0078] (3) For the 7-series aluminum alloy after undergoing the secondary aging treatment, electric field heating is utilized to rapidly heat the sheet material after undergoing the secondary aging treatment to a temperature slightly above the critical temperature at which a significant amount of precipitate phases dissolve. A temperature of 320 °C can be adopted, with no need for holding at that temperature.

[0079] (4) The heated 7-series aluminum alloy is rapidly transferred to a cold die for stamping and simultaneous quenching. The transfer time should be 2 seconds.

[0080] (5) Tertiary aging treatment is performed on the formed large-sized complex thin-walled part made of the 7-series aluminum alloy at a temperature of 160 °C for 35 minutes.Embodiment Six(1) Primary aging treatment is performed on the supersaturated solid-solution state 7-series aluminum alloy at a temperature of 100 °C for a duration of 55 minutes.

[0082] (2) Secondary aging treatment is performed on the 7-series aluminum alloy after undergoing the primary aging treatment at a temperature of 180 °C for 35 minutes.

[0083] (3) For the 7-series aluminum alloy after undergoing the secondary aging treatment, electric field heating is utilized to rapidly heat the sheet material after undergoing the secondary aging treatment to a temperature slightly above the critical temperature at which a significant amount of precipitate phases dissolve. A temperature of 280 °C can be adopted, with no need for holding at that temperature.

[0084] (4) The heated 7-series aluminum alloy is rapidly transferred to a cold die for stamping and simultaneous quenching. The transfer time should be 4 seconds.

[0085] (5) Tertiary aging treatment is performed on the formed large-sized complex thin-walled part made of the 7-series aluminum alloy at a temperature of 150 °C for 40 minutes.

[0086] FIG. 2 is a schematic diagram of a large-sized complex thin-walled part made of a 7-series aluminum alloy prepared according to an embodiment of the present application. Upon testing the large-size complex thin-walled part made of the 7-series aluminum alloy fabricated through the present application, it was found that it exhibits a yield strength exceeding 490 MPa, a tensile strength exceeding 570 MPa, and an elongation greater than 11%. Moreover, while the traditional tertiary aging process for the 7-series aluminum alloy typically spans over 20 hours, when integrated with the overall process of the present application, the duration of the tertiary aging cycle can be significantly reduced from the hour range to the minute range. FIG. 3 is a schematic diagram of the strength and fracture elongation of a large-sized complex thin-walled part made of a 7-series aluminum alloy prepared in Embodiments 1-6 according to the present application, as evident from FIG. 3, all parts produced using the present application meet the aforementioned performance criteria.

[0087] The foregoing is only the preferred embodiments of the present application and is not intended to limit the present application, and various modifications and variations of the present application will be apparent to those skilled in the art. It is intended that all such modifications, equivalents, improvements, and the like be included within the spirit and scope of the present application.

Claims

1. A hot-stamping forming method for a large-sized complex thin-walled part made of a 7-series aluminum alloy, comprising:performing primary aging treatment on a supersaturated solid-solution state 7-series aluminum alloy to obtain a 7-series aluminum alloy after undergoing the primary aging treatment;performing secondary aging treatment on a primary aging treatment result to obtain a 7-series aluminum alloy after undergoing the secondary aging treatment; wherein, a temperature of the primary aging treatment is lower than a temperature of the secondary aging treatment, and a duration of the primary aging treatment is longer than a duration of the secondary aging treatment;heating the 7-series aluminum alloy after undergoing the secondary aging treatment to a temperature greater than a critical temperature at which a precipitate phase dissolves to obtain a heated 7-series aluminum alloy; andstamping and simultaneously quenching the heated 7-series aluminum alloy to obtain a formed part.

2. The hot-stamping forming method for a large-sized complex thin-walled part made of a 7-series aluminum alloy according to claim 1, wherein, after obtaining the formed part, the method further comprises:performing tertiary aging treatment on the formed part.

3. The hot-stamping forming method for a large-sized complex thin-walled part made of a 7-series aluminum alloy according to claim 2, wherein a temperature for the tertiary aging treatment is in the range of 140-180 °C and the duration is in the range of 20-40 min.

4. The hot-stamping forming method for a large-sized complex thin-walled part made of a 7-series aluminum alloy according to claim 1, wherein the temperature of the primary aging treatment is in the range of 70-120 °C and the temperature of the secondary aging treatment is in the range of 140-180 °C.

5. The hot-stamping forming method for a large-sized complex thin-walled part made of a 7-series aluminum alloy according to claim 1, wherein the duration of the primary aging treatment is in the range of 40-60 min, and the duration of the secondary aging treatment is in the range of 20-40 min.

6. The hot-stamping forming method for a large-sized complex thin-walled part made of a 7-series aluminum alloy according to claim 1, wherein when the 7-series aluminum alloy after undergoing the secondary aging treatment is heated to the temperature greater than the critical temperature at which a precipitate phase dissolves, the 7-series aluminum alloy after undergoing the secondary aging treatment is heated to 200-400 °C at a rate of 50 °C / s or more.

7. The hot-stamping forming method for a large-sized complex thin-walled part made of a 7-series aluminum alloy according to claim 1, wherein the stamping of the heated 7-series aluminum alloy is performed by transferring the heated 7-series aluminum alloy into a cold stamping die within 2-5 seconds after obtaining the heated 7-series aluminum alloy.

8. The hot-stamping forming method for a large-sized complex thin-walled part made of a 7-series aluminum alloy according to claim 1, wherein when the 7-series aluminum alloy after undergoing the secondary aging treatment is heated to a temperature greater than the critical temperature at which a precipitate phase dissolves, an energy field-assisted method is employed.

9. A large-sized complex thin-walled part made of a 7-series aluminum alloy prepared by the hot-stamping forming method for a large-sized complex thin-walled part made of a 7-series aluminum alloy according to claim 8.

10. The large-sized complex thin-walled part made of a 7-series aluminum alloy according to claim 9, wherein the yield strength is greater than or equal to 490 MPa, the tensile strength is greater than or equal to 570 MPa, and the elongation is greater than or equal to 11%.

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