Preparation method of aluminum alloy pre-stretched thick plate

Abstract

The invention provides a preparation method of an aluminum alloy pre-stretched thick plate. The preparation method comprises the following steps that a 7-series aluminum alloy cast ingot is sequentially subjected to hot rolling, solution treatment, stretching treatment and aging treatment; the temperature of the hot rolling is 420-470 DEG C, and the maximum pass rolling reduction of the hot rolling is 40 mm. The 7XXXT7451 pre-stretched thick plate with high strength and toughness is prepared by adopting a high-temperature large rolling reduction and two-stage aging process, the high-temperature large rolling reduction means that a cast ingot is heated to the high temperature of 420-470 DEG C before hot rolling so as to ensure smooth hot rolling, a plurality of rolling modes with the maximum rolling reduction pass of 40 mm are adopted in the hot rolling process, and the thickness of the hot rolled thick plate is larger than that of the cast ingot. And a certain recrystallization structure is obtained, so that the mechanical property, fracture toughness and other properties of the pre-stretched thick plate are improved.

Description

Technical Field

[0001] This invention relates to the field of alloy materials technology, and in particular to a method for preparing a pre-stretched thick aluminum alloy plate. Background Technology

[0002] Lightweight and high-strength metallic materials have significant advantages such as low density, high strength and toughness, temperature and corrosion resistance, high electrical conductivity, high thermal conductivity, easy processing and forming, and low overall application cost. They are key materials required in many fields such as aerospace, military equipment, and electronic information.

[0003] While the widely used 7050T7451 pre-stretched thick plates exhibit excellent performance in various aspects, they still cannot fully meet the needs of aerospace and other fields for high-strength and tough materials. Therefore, improving the strength of 7-series aluminum alloys is an important goal in the development of advanced aluminum alloys. Summary of the Invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide a method for preparing a pre-stretched aluminum alloy thick plate. The method provided in this application significantly improves the strength of the pre-stretched aluminum alloy thick plate.

[0005] This application provides a method for preparing a pre-stretched aluminum alloy thick plate, comprising the following steps:

[0006] The 7-series aluminum alloy ingots are sequentially subjected to hot rolling, solution treatment, stretching treatment and aging treatment.

[0007] The hot rolling temperature is 420℃~470℃, and the maximum reduction per pass in the hot rolling is 40mm.

[0008] In some specific implementations, the hot rolling is a multi-pass hot rolling process.

[0009] In some specific implementations, the hot rolling reduction in each pass is 10mm to 40mm.

[0010] In some specific implementations, the ingot is heated to 420°C to 470°C before hot rolling.

[0011] In some specific implementations, the solution treatment temperature is 470℃~480℃, and the solution treatment time is 90min~390min.

[0012] In some specific implementations, the deformation rate of the stretching process is 1.5% to 3.0%.

[0013] In some specific implementations, the timeliness processing includes:

[0014] The stretched slab is first kept at 113℃~134℃, and then kept at 144℃~165℃ for a second time.

[0015] In some specific implementations, the first heat preservation time is 300 min to 400 min, and the second heat preservation time is 1200 min to 1740 min.

[0016] In some specific implementations, the 7-series aluminum alloy includes:

[0017] 7.1wt%~8.3wt% Zn; 1.5wt%~1.8wt% Mg; 1.9wt%~2.3wt% Cu and balance Al.

[0018] In some specific implementations, the thickness of the slab obtained after the aging treatment is 20mm~150mm.

[0019] This application provides a method for preparing a pre-stretched aluminum alloy thick plate, comprising the following steps: hot rolling, solution treatment, stretching treatment, and aging treatment of a 7-series aluminum alloy ingot sequentially; the hot rolling temperature is 420℃~470℃, and the maximum reduction per pass is 40mm. This application obtains a high-strength and high-toughness 7XXXT7451 pre-stretched thick plate by employing a high-temperature, high-reduction, and double-stage aging process. The high-temperature, high-reduction process refers to heating the ingot to a high temperature of 420℃~470℃ before hot rolling to ensure smooth hot rolling. During hot rolling, multiple passes with a maximum reduction of 40mm are used to obtain a certain recrystallization structure, thereby improving the mechanical properties and fracture toughness of the pre-stretched thick plate. Results show that the pre-stretched aluminum alloy thick plate prepared by the method provided in this application has a tensile strength of over 517MPa, a specified non-proportional elongation strength of over 476MPa, and an elongation at break of over 9%. Detailed Implementation

[0020] This invention provides a method for preparing pre-stretched thick aluminum alloy plates. Those skilled in the art can refer to the content of this document and appropriately modify the process parameters to achieve the desired result. The method and application of this invention have been described through preferred embodiments. Those skilled in the art can clearly modify or appropriately change and combine the method and application described herein without departing from the content, spirit, and scope of this invention to realize and apply the technology of this invention.

[0021] This application provides a method for preparing a pre-stretched aluminum alloy thick plate, comprising the following steps:

[0022] The 7-series aluminum alloy ingots are sequentially subjected to hot rolling, solution treatment, stretching treatment and aging treatment.

[0023] The hot rolling temperature is 420℃~470℃, and the maximum reduction per pass in the hot rolling is 40mm.

[0024] As a fourth-generation aerospace aluminum alloy urgently needed at present, 7XXX aluminum alloy has higher strength and toughness than 7050 aluminum alloy, and is an important goal in the development of advanced aluminum alloys. During the experiment, the applicant found that although the production of 7XXXT7451 pre-stretched thick plates using a process similar to that of 7050T7451 pre-stretched thick plates was successfully rolled, some mechanical properties and fracture toughness did not meet the requirements. Based on this, this application proposes a process of high temperature, large reduction and two-stage aging.

[0025] This application uses 7-series aluminum alloy ingots as raw materials, preferably 7XXX aluminum alloys, such as 7XXXT7451 aluminum alloy. In some specific implementations, the 7-series aluminum alloy includes: 7.1wt%~8.3wt% Zn; 1.5wt%~1.8wt% Mg; 1.9wt%~2.3wt% Cu and the balance Al.

[0026] This application first involves hot rolling a 7-series aluminum alloy ingot, specifically including heating the ingot to a hot rolling temperature and then hot rolling it. In some specific implementations, the hot rolling temperature is 420℃~470℃, preferably 430℃~450℃; the maximum reduction per pass is 40mm, preferably 10mm~40mm. In some specific implementations, the hot rolling is a multi-pass process, for example, 12~18 passes, preferably 14~16 passes, with each pass having a reduction of 10mm~40mm. Heating the ingot to a high temperature of 420℃~470℃ before hot rolling ensures smooth hot rolling. The use of multiple passes with a maximum reduction of 40mm during hot rolling results in a recrystallized structure, which improves the strength and toughness of the sheet metal.

[0027] After hot rolling, the resulting sheet material undergoes solution treatment, specifically including the following steps: heating the hot-rolled sheet material to the solution temperature and then holding it at that temperature. In some specific implementations, the solution treatment temperature is 470℃~480℃, preferably 472℃~478℃, and the solution treatment time is 90min~390min, preferably 100min~350min.

[0028] After solution treatment, the resulting sheet material is subjected to stretching. This application does not impose any special restrictions on the stretching process, but the deformation rate is 1.5% to 3.0%, preferably 2.0% to 2.5%.

[0029] After stretching, the resulting sheet material undergoes aging treatment. In some specific implementations, the aging treatment includes: holding the stretched sheet at 113℃~134℃ for the first time, and then holding it at 144~165℃ for the second time. In some specific implementations, the temperature of the first holding is preferably 120℃~130℃, and the time is 300min~400min, preferably 320min~380min. In some specific implementations, the temperature of the second holding is preferably 150℃~160℃, and the time is 1200min~1740min, preferably 1200min~1600min. This application employs a two-stage aging process, where after heating to 113~134℃ and holding for a certain time, the sheet is further heated to 144~165℃ and held for a time matching the sheet thickness, resulting in a 7XXXT7451 pre-stretched thick sheet with high strength and toughness.

[0030] In some specific implementations, the thickness of the slab obtained after the aging treatment is 20mm~150mm, preferably 50mm~150mm, and more preferably 100mm~120mm.

[0031] This application provides a method for preparing a pre-stretched aluminum alloy thick plate, comprising the following steps: hot rolling, solution treatment, stretching treatment, and aging treatment of a 7-series aluminum alloy ingot sequentially; the hot rolling temperature is 420℃~470℃, and the maximum reduction per pass is 40mm. This application obtains a high-strength and high-toughness 7XXXT7451 pre-stretched thick plate by employing a high-temperature, high-reduction, and double-stage aging process. The high-temperature, high-reduction process refers to heating the ingot to a high temperature of 420℃~470℃ before hot rolling to ensure smooth hot rolling. During hot rolling, multiple passes with a maximum reduction of 40mm are used to obtain a certain recrystallization structure, thereby improving the mechanical properties and fracture toughness of the pre-stretched thick plate. Results show that the pre-stretched aluminum alloy thick plate prepared by the method provided in this application has a tensile strength of over 517MPa, a specified non-proportional elongation strength of over 476MPa, and an elongation at break of over 9%.

[0032] Specifically, this application can prepare 7XXXT7451 pre-stretched thick plates according to the following method:

[0033] 7XXXT7451 aluminum alloy ingots are provided, which are composed of 7.1wt%~8.3wt% Zn, 1.5wt%~1.8wt% Mg, 1.9wt%~2.3wt% Cu and the balance Al;

[0034] The ingot is heated to 420℃~470℃ and then hot rolled in 12~18 passes. During the hot rolling process, the reduction in each pass is 10mm~40mm, resulting in a slab with a thickness of 50mm~150mm.

[0035] The slab is heated to 470℃~480℃ and held for 90min~390min for solution treatment.

[0036] The solution-treated slab is then stretched, with a deformation rate of 1.5% to 3.0%.

[0037] The stretched slab is heated to 113℃~134℃ and held for 300min~400min, then heated to 144℃~165℃ and held for 1200min~1740min for two-stage aging treatment to obtain 7XXXT7451 pre-stretched thick plate.

[0038] The 7050T7451 pre-stretched thick plate is prepared according to the following method:

[0039] We provide 7050T7451 aluminum alloy ingots, whose composition is Al-6.2Zn-2.3Mg-2.3Cu;

[0040] The ingot is hot rolled at 420℃~470℃ for 12~18 passes. During the hot rolling process, the reduction in each pass is 10mm~30mm, resulting in a slab with a thickness of 50mm~150mm.

[0041] The slab is heated to 472℃~482℃ and held for 330 minutes for solution treatment.

[0042] The solution-treated slab is then stretched, with a deformation rate of 2.0% to 3.4%.

[0043] The stretched slab is heated to 157℃~168℃ and held for 1500℃ for aging treatment to obtain 7050T7451 pre-stretched thick plate.

[0044] The performance of the 7XXXT7451 pre-stretched thick plate prepared in this application and the 7050T7451 pre-stretched thick plate prepared by the prior art were tested. The results are shown in Table 1, which shows the performance parameters of the pre-stretched thick plate.

[0045] Table 1 Performance parameters of pre-stretched thick plates

[0046]

[0047] As shown in Table 1, the tensile strength of the 7XXXT7451 pre-stretched thick plate provided in this application is higher than 517MPa, the specified non-proportional elongation strength is higher than 476MPa, and the elongation after fracture is greater than 9%. Compared with the 7050T7451 pre-stretched thick plate prepared by the prior art, the performance is significantly improved.

[0048] The following examples further illustrate the preparation method of pre-stretched aluminum alloy thick plates.

[0049] Example 1

[0050] 7XXXT7451 aluminum alloy ingots are provided, which are composed of 7.1wt%~8.3wt% Zn, 1.5wt%~1.8wt% Mg, 1.9wt%~2.3wt% Cu and the balance Al;

[0051] The ingot is heated to 450°C and then hot rolled in 16 passes. During the hot rolling process, the reduction in each pass is 10mm~40mm, resulting in a 120mm thick slab.

[0052] The slab is heated to 475°C and held for 330 minutes for solution treatment.

[0053] The solution-treated slab is then stretched, with a deformation rate of 2.5% to 2.7%.

[0054] The stretched slab was heated to 130℃ and held for 360 minutes, then heated to 160℃ and held for 1260 minutes to obtain 7XXXT7451 pre-stretched thick plate.

[0055] Comparative Example 1

[0056] We provide 050T7451 aluminum alloy ingots, whose composition is: Al-6.2Zn-2.3Mg-2.3Cu;

[0057] The ingot was hot rolled in 18 passes at 450°C. During the hot rolling process, the reduction in each pass was 10mm~30mm, resulting in a 120mm thick slab.

[0058] The slab is heated to 472℃~482℃ and held for 330 minutes for solution treatment.

[0059] The solution-treated slab is then stretched, with a deformation rate of 2.0% to 3.4%.

[0060] The stretched slab was heated to 157℃~168℃ and held for 1500 minutes for aging treatment to obtain 7050T7451 pre-stretched thick plate.

[0061] The performance of the pre-stretched thick plates prepared in Example 1 and Comparative Example 1 was tested, and the results are shown in Table 2. Table 2 shows the performance parameters of the pre-stretched thick plates prepared in this application.

[0062] Table 2 Performance parameters of the pre-stretched thick plate prepared in this application

[0063]

[0064] Therefore, the method provided in this application improves the strength of pre-stretched aluminum alloy plates.

[0065] Example 2

[0066] 7XXXT7451 aluminum alloy ingots are provided, which are composed of 7.1wt%~8.3wt% Zn, 1.5wt%~1.8wt% Mg, 1.9wt%~2.3wt% Cu and the balance Al;

[0067] The ingot is heated to 430°C and then hot rolled in 14 passes. During the hot rolling process, the reduction in each pass is 10~40mm, resulting in a 120mm thick slab.

[0068] The slab is heated to 475°C and held for 330 minutes for solution treatment.

[0069] The solution-treated slab was then stretched, with a deformation rate of 2.7% to 2.8%.

[0070] The stretched slab was heated to 121℃ and held for 360 minutes, then heated to 152℃ and held for 1200 minutes to obtain 7XXXT7451 pre-stretched thick plate.

[0071] The performance of the pre-stretched thick plate prepared in Example 2 was tested, and the results are shown in Table 3. Table 3 shows the performance parameters of the pre-stretched thick plate prepared in Example 2 of this application.

[0072] Table 3 Performance parameters of the pre-stretched thick plate prepared in Example 2

[0073]

[0074] Example 3

[0075] 7XXXT7451 aluminum alloy ingots are provided, which are composed of 7.1wt%~8.3wt% Zn, 1.5wt%~1.8wt% Mg, 1.9wt%~2.3wt% Cu and the balance Al;

[0076] The ingot is heated to 440°C and then hot rolled in 14 passes. During the hot rolling process, the reduction in each pass is 10~40mm, resulting in a 120mm thick slab.

[0077] The slab is heated to 475°C and held for 330 minutes for solution treatment.

[0078] The solution-treated slab is then stretched, with a deformation rate of 2.5% to 2.9%.

[0079] The stretched slab was heated to 121℃ and held for 360 minutes, then heated to 152℃ and held for 1200 minutes to obtain 7XXXT7451 pre-stretched thick plate.

[0080] The performance of the pre-stretched thick plate prepared in Example 3 was tested, and the results are shown in Table 4. Table 4 shows the performance parameters of the pre-stretched thick plate prepared in Example 3 of this application.

[0081] Table 4 Performance parameters of the pre-stretched thick plate prepared in Example 3

[0082]

[0083] As can be seen from the above embodiments, the present invention achieves mass production of high-strength and high-toughness 7XXXT7451 pre-stretched thick plates without adding extra processes, simply by adjusting the hot rolling-aging process. The pre-stretched thick plates exhibit significantly better mechanical properties and fracture toughness than 7050T7451 pre-stretched thick plates, while maintaining the same level in corrosion resistance, anti-exfoliation corrosion, anti-stress corrosion, and fatigue resistance. Therefore, the pre-stretched thick plates prepared in this application have a wider range of applications and are suitable for scenarios requiring higher mechanical properties and fracture toughness.

[0084] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a pre-stretched aluminum alloy thick plate, comprising the following steps: The 7-series aluminum alloy ingots are sequentially subjected to hot rolling, solution treatment, stretching treatment and aging treatment. The hot rolling temperature is 420℃~470℃, and the maximum reduction per pass in the hot rolling is 40mm.

2. The preparation method according to claim 1, characterized in that, The hot rolling process is a multi-pass hot rolling process.

3. The preparation method according to claim 3, characterized in that, The hot rolling reduction for each pass is 10mm to 40mm.

4. The preparation method according to any one of claims 1 to 3, characterized in that, The ingot is heated to 420°C to 470°C before hot rolling.

5. The preparation method according to claim 1, characterized in that, The solution treatment temperature is 470℃~480℃, and the solution treatment time is 90min~390min.

6. The preparation method according to claim 1, characterized in that, The deformation rate of the stretching treatment is 1.5% to 3.0%.

7. The preparation method according to claim 1, characterized in that, The timeliness processing includes: The stretched slab is first kept at 113℃~134℃, and then kept at 144~165℃ for a second time.

8. The preparation method according to claim 6, characterized in that, The first heat preservation time is 300-400 minutes, and the second heat preservation time is 1200-1740 minutes.

9. The preparation method according to claim 1, characterized in that, The 7-series aluminum alloys include: 7.1wt%~8.3wt% Zn; 1.5wt%~1.8wt% Mg; 1.9wt%~2.3wt% Cu and balance Al.

10. The preparation method according to claim 1, characterized in that, The thickness of the slab obtained after the aging treatment is 20mm~150mm.

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