A processing technology for high-strength fine-grained aluminum-lithium alloy plate

Abstract

The present invention discloses a processing technology for high-strength and fine-grained aluminum-lithium alloy plates, which belongs to the technical field of aluminum-lithium alloy processing. The present invention selects processes such as step-by-step solution treatment, step-by-step cooling, low-temperature deep freezing, cold rolling deformation, secondary solution treatment, and annealing and aging. By establishing a temperature gradient and selecting a suitable heating rate, the problem of increased stress caused by fine grains is reduced while refining the grains. Compared with the traditional solution + deformation process, strengthening means such as low-temperature deep freezing and secondary solution are introduced. By keeping warm at extremely low temperatures, the crystal structure is changed, the grains are made finer and more uniform, the strength and toughness of the aluminum-lithium alloy plates are enhanced, the structure and mechanical properties are uniform, and the application range of precision electronic parts is expanded.

Description

Technical Field

[0001] The present invention belongs to the technical field of aluminum-lithium alloy processing, and in particular relates to a processing technology for a high-strength and fine-grained aluminum-lithium alloy plate. Background Art

[0002] Aluminum-lithium alloys containing elements such as Cu, Mg, Mn, and Li have been widely used in aerospace and precision instrument manufacturing due to their excellent mechanical properties, electrical conductivity, and corrosion resistance. The microstructure of aluminum-lithium alloys determines their overall performance and is also interrelated with their application areas. Fine grains are beneficial for resisting dislocation movement, thereby improving strength and hardness; small and uniform grains can improve the material's plastic deformation ability, thereby increasing toughness. However, the traditional preheating + rolling process, although it can refine the grains, the uneven microstructure and mechanical properties caused by rolling deformation will also reduce the strength and toughness of the final material.

[0003] Chinese invention patent application CN115418534A discloses an 8090 aluminum-lithium alloy fine-grained plate and its preparation method. The comprehensive performance of the aluminum-lithium alloy is improved by combining hot rolling, heat treatment and cold rolling, effectively solving the problems of coarse plate grains and uneven structure and mechanical properties after rolling during the production of 8090 aluminum-lithium alloy, further improving its industrial application value. Although the patent achieves the purpose of grain refinement, the improvement in mechanical properties is not obvious.

[0004] Chinese invention patent application CN116426853A discloses a heat treatment method for aluminum-lithium alloy die forgings, which includes solution treatment, quenching, cold pressing, and aging. The cold pressing can be carried out in steps, and precision cold pressing can be completed in two or more steps according to the thickness of different parts. The step-by-step cold pressing first completes the compression of the thinner parts, and then completes the cold compression of the entire forging step by step. The die forgings treated by the method of the present invention have the characteristics of high dimensional accuracy, small processing volume, and excellent performance. Although this patent is a traditional method of grain refinement, it itself has the phenomenon of uneven mechanical properties due to asymmetric stress caused by cold rolling. Summary of the Invention

[0005] To address the shortcomings of the aforementioned prior art, the present invention proposes a processing technology for producing high-strength, fine-grained aluminum-lithium alloy sheet. Through a multi-stage solution treatment, step-by-step cooling, cold rolling, a second solution treatment, and annealing, the present invention achieves low internal stress conditions by inducing deep cooling to refine the material matrix grains. This grain refinement is further enhanced through deformation and multi-stage heat treatment, resulting in a more uniform structure and mechanical properties, ultimately yielding a high-strength, fine-grained aluminum-lithium alloy.

[0006] To achieve the above object, the technical solution adopted by the present invention is: a processing technology for high-strength fine-grained aluminum-lithium alloy plate comprises the following steps:

[0007] (1) Preheating the aluminum-lithium alloy ingot;

[0008] (2) performing multi-stage solution treatment on the aluminum-lithium alloy ingot;

[0009] (3) Step-by-step cooling and cryogenic treatment of the sample: first, the sample after multi-stage solution treatment is quenched in water, then transferred to liquid nitrogen for cooling, and then cryogenically treated in liquid nitrogen;

[0010] (4) cold rolling and secondary solution treatment of the cryogenically treated samples;

[0011] (5) The sample is subjected to annealing and aging treatment, and then naturally cooled to obtain a high-strength and fine-grained aluminum-lithium alloy plate.

[0012] As a preferred embodiment of the present invention, the aluminum-lithium alloy ingot comprises the following atomic percentages: 0.8% to 1.2% Cu, 2.5% to 2.8% Li, 0.6% to 1% Mg, 0.1% to 0.25% Zr, and 0.5% to 0.8% Mn, with the remainder being aluminum and other unavoidable trace impurity elements. Mn can act as a strengthening agent, forming a solid solution to increase strength, and Zr can act as a modifier, refining the grains.

[0013] As a preferred embodiment of the present invention, in step (1), the temperature of the preheating treatment is 150° C. to 160° C., and the holding time is 2 hours.

[0014] As a preferred embodiment of the present invention, the heating rate of the multi-stage solution treatment in step (2) is less than 80°C / min. By slowly heating, the diffusion of solute atoms in the matrix is ​​promoted to obtain a uniform fine-grained structure, while also avoiding the generation of large internal stress in the matrix due to rapid heating.

[0015] As a preferred embodiment of the present invention, in step (4), the heating rate of the secondary solution treatment is less than 80°C / min.

[0016] As a preferred embodiment of the present invention, in step (2), the multi-stage solution treatment is specifically: keeping warm at 380°C for 0.5h, then keeping warm at 450°C for 0.5h, keeping warm at 480°C for 1h, and finally keeping warm at 520°C for 1h.

[0017] As a preferred embodiment of the present invention, in step (3), the quenching time in water is 15 seconds, the sample is transferred to liquid nitrogen for rapid cooling within 10 seconds, and after cooling, it is continued to be cryogenically treated in liquid nitrogen. The cryogenic treatment time is 1 hour and the temperature is 80K~100K.

[0018] As a preferred embodiment of the present invention, in step (4), the total cold rolling pressure is 50%-60%, and the pressure each time is not less than 5%.

[0019] As a preferred embodiment of the present invention, in the step (4), the secondary solution temperature is 540° C. and the time is 2 h.

[0020] As a preferred embodiment of the present invention, in step (5), the annealing treatment is performed at a temperature of 150° C. to 250° C. for a time of 2 h to 3 h.

[0021] Principle of the present invention:

[0022] The present invention improves its mechanical properties based on a uniform fine-grained structure. At the same time, taking into account the problem of increased internal stress caused by the generation of fine-grained structure, the process is improved and the process parameters are optimized in the process of continuous fine-grained strengthening to achieve the reduction of internal stress and reduce the cracking tendency of the material. First, the aluminum-lithium alloy ingot is preheated to eliminate the internal stress and bubbles generated by the casting of the material. Then, a step-by-step solution treatment is carried out to establish a step-by-step solution temperature gradient. By controlling the heating rate, the problem of increased internal stress caused by rapid heating is reduced. In addition, a longer solution treatment time can make the dissolved atoms more evenly distributed in the alloy. Next, the alloy is cooled step by step. Since the aluminum-lithium alloy itself has a large cracking tendency, a two-stage cooling is established to reduce the rapid cooling rate under rapid cooling and avoid cracking of the base material. After liquid nitrogen cooling, it is simultaneously deep-cooled in liquid nitrogen for one hour to promote the grains to become finer. At room temperature, the sample is cold-rolled and deformed, and a larger downward pressure is used to crush and refine the larger grains. Then, a secondary solution treatment is performed on the sample that already has a fine grain structure. After the grains are refined, the grain boundary area of ​​the metal material increases. The small grains and high grain boundary area provide excellent conditions for the secondary solution treatment, which helps to distribute the solute elements more evenly inside the grains, thereby achieving a better secondary solution effect. Finally, the sample is subjected to annealing and aging treatment. By slowly annealing in a heating furnace, the residual stress of the material is reduced. At the same time, slow annealing also has an aging strengthening effect on the sample, and finally a high-strength aluminum-lithium alloy plate with a fine structure is obtained. The association mechanism of the step-by-step cooling treatment and the secondary solution treatment of the present invention greatly improves the comprehensive performance of the aluminum-lithium alloy.

[0023] Compared with the existing technology, the present invention has the following beneficial effects: the present invention selects processes such as step-by-step solution treatment, low-temperature deep cooling, cold rolling deformation, and secondary solution treatment. By establishing a temperature gradient and selecting an appropriate heating rate, the present invention can refine the grains while reducing the stress increase caused by fine grains. Compared with the traditional solution + deformation process, the present invention introduces strengthening measures such as low-temperature deep cooling and secondary solution treatment. Through insulation at extremely low temperatures combined with the cold rolling process, the grains are broken up, making them smaller and more uniform, thereby enhancing the strength and toughness of the aluminum-lithium alloy plate, uniformizing the structure and mechanical properties, and expanding the application range of precision electronic components. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a process flow chart for the processing of high-strength and fine-grained aluminum-lithium alloy plates.

[0025] Figure 2 This is the temperature-time diagram of step-by-step solution treatment, step-by-step cooling, cold rolling, secondary solution treatment and annealing-aging treatment. DETAILED DESCRIPTION

[0026] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0027] Example 1

[0028] A processing technology for high-strength fine-grained aluminum-lithium alloy plate specifically comprises the following steps:

[0029] (1) The chemical composition of the high-strength fine-grained aluminum-lithium alloy plate implemented in the present invention is shown in Table 1.

[0030] Table 1 Chemical composition of the aluminum-lithium alloy plate of this embodiment (wt%)

[0031]

[0032] (2) According to the composition in Table 1, pure aluminum and various elements are first smelted and cast, and the heating furnace is evacuated to a vacuum of less than 10pa for vacuum melting to form an aluminum-lithium alloy ingot with a size of 200mm×100mm×100mm. After completion, the cast aluminum-lithium alloy is heated to 150℃ and kept warm for 2h; the aluminum-lithium alloy ingot is subjected to step-by-step solution treatment, with a heating rate of 80℃ / min, and the solution temperature and solution time are 380℃×0.5h+450℃×0.5h+480℃×1h+520℃×1h; the sample is cooled step by step, first placed in cold water for quenching, kept for 15s, taken out, and quickly transferred to liquid nitrogen within 10s for rapid cooling, and kept in liquid nitrogen for 1h. h of low-temperature deep cooling; the obtained sample is cold rolled with a total reduction of 50%, and the reduction amount each time is not less than 5%; the cold-deformed sample is subjected to secondary solid solution strengthening with a heating rate of 80°C / min, a temperature of 540°C, and a time of 2h; finally, the sample is annealed and aged, and the sample is first air-cooled to 250°C, placed in a heating furnace for furnace cooling, and the annealing and aging time is 3h. After annealing, it is air-cooled to room temperature to obtain a high-strength aluminum-lithium alloy plate with a fine-grained structure.

[0033] Example 2

[0034] A processing technology for high-strength fine-grained aluminum-lithium alloy plate specifically comprises the following steps:

[0035] (1) The chemical composition of the high-strength fine-grained aluminum-lithium alloy plate implemented in the present invention is shown in Table 2.

[0036] Table 2 Chemical composition of the aluminum-lithium alloy plate of this embodiment (wt%)

[0037]

[0038] (2) According to the composition in Table 2, pure aluminum and various elements are first smelted and cast, and the heating furnace is evacuated to a vacuum of less than 10pa for vacuum melting to form an aluminum-lithium alloy ingot with a size of 200mm×100mm×100mm. After completion, the cast aluminum-lithium alloy is heated to 160℃ and kept warm for 2h; the aluminum-lithium alloy ingot is subjected to step-by-step solution treatment, with a heating rate of 60℃ / min, and the solution temperature and solution time are 380℃×0.5h+450℃×0.5h+480℃×1h+520℃×1h; the sample is cooled step by step, first placed in cold water for quenching, kept for 15s, taken out, and quickly transferred to liquid nitrogen within 10s for rapid cooling, and kept in liquid nitrogen for 1h. The obtained samples were cold rolled with a total reduction of 60% and a reduction of not less than 5% each time; the cold-deformed samples were subjected to secondary solid solution strengthening with a heating rate of 50°C / min, a temperature of 540°C, and a solid solution time of 2h; finally, the samples were annealed and aged, firstly the samples were air-cooled to 150°C, then placed in a heating furnace for furnace cooling, the annealing and aging time was 2h, and after annealing, they were air-cooled to room temperature to obtain high-strength aluminum-lithium alloy plates with fine grain structure.

[0039] Example 3

[0040] A processing technology for high-strength fine-grained aluminum-lithium alloy plate specifically comprises the following steps:

[0041] (1) The chemical composition of the high-strength fine-grained aluminum-lithium alloy plate implemented in the present invention is shown in Table 3.

[0042] Table 3 Chemical composition of the aluminum-lithium alloy plate of this embodiment (wt%)

[0043]

[0044] (2) According to the composition in Table 3, pure aluminum and various elements are first smelted and cast, and the heating furnace is evacuated to a vacuum of less than 10pa for vacuum melting to form an aluminum-lithium alloy ingot with a size of 200mm×100mm×100mm. After completion, the cast aluminum-lithium alloy is heated to 155℃ and kept warm for 2h; the aluminum-lithium alloy ingot is subjected to step-by-step solution treatment, with a heating rate of 40℃ / min, and the solution temperature and solution time are 380℃×0.5h+450℃×0.5h+480℃×1h+520℃×1h; the sample is cooled step by step, first placed in cold water for quenching, kept for 15s, taken out, and quickly transferred to liquid nitrogen within 10s for rapid cooling, and then kept in liquid nitrogen for 1h. Low temperature deep cooling; cold rolling the obtained sample with a total pressing amount of 55%, and the pressing amount each time is not less than 5%; the cold deformed sample is subjected to secondary solid solution strengthening, with a heating rate of 30℃ / min, a temperature of 540℃, and a solid solution time of 2h; finally, the sample is annealed and aged, first the sample is air-cooled to 200℃, placed in a heating furnace for furnace cooling, the annealing and aging time is 2.5h, and after annealing, it is air-cooled to room temperature to obtain a high-strength aluminum-lithium alloy plate with fine grain structure.

[0045] Comparative Example 1

[0046] A processing technology for high-strength fine-grained aluminum-lithium alloy plate specifically comprises the following steps:

[0047] (1) The chemical composition of the high-strength fine-grained aluminum-lithium alloy plate implemented in the present invention is shown in Table 4.

[0048] Table 4 Chemical composition of aluminum-lithium alloy of comparative example 1 (wt%)

[0049]

[0050] (2) According to the composition in Table 4, pure aluminum and various elements are first smelted and cast, and the heating furnace is evacuated to a vacuum of less than 10 Pa for vacuum melting to form an aluminum-lithium alloy ingot with a size of 200 mm × 100 mm × 100 mm. After completion, the cast aluminum-lithium alloy is heated to 150 ° C and kept warm for 2 hours; the aluminum-lithium alloy ingot is subjected to step-by-step solid solution treatment, with a solid solution heating rate of 80 ° C / min, and a solid solution temperature and solid solution time of 380 ° C × 0.5 h + 450 ° C × 0.5 h + 480 ° C × 1 h + 520 ° C × 1 h; the sample is placed in cold water for quenching; the obtained sample is cold rolled with a total pressure of 50%, and the pressure each time is not less than 5%; finally, the aluminum-lithium alloy plate is subjected to aging hardening at a temperature of 180 ° C for 3 hours to obtain a traditional high-strength fine-grained aluminum-lithium alloy plate.

[0051] Comparative Example 2

[0052] A processing technology for high-strength fine-grained aluminum-lithium alloy plate specifically comprises the following steps:

[0053] (1) The chemical composition of the high-strength fine-grained aluminum-lithium alloy plate implemented in the present invention is shown in Table 5.

[0054] Table 5 Chemical composition of aluminum-lithium alloy plate of comparative example 2 (wt%)

[0055]

[0056]

[0057] (2) According to the composition in Table 5, pure aluminum and various elements are first smelted and cast, and the heating furnace is evacuated to a vacuum of less than 10 Pa for vacuum melting to form an aluminum-lithium alloy ingot with a size of 200 mm × 100 mm × 100 mm. After completion, the cast aluminum-lithium alloy is heated to 150°C and kept warm for 2 hours; the aluminum-lithium alloy ingot is subjected to step-by-step solution treatment, the solution heating rate is 80°C / min, and the solution temperature and solution time are 380°C×0.5h+450°C×0.5h+480°C×1h+520°C×1h; the sample is cooled step by step, first placed in cold water for quenching, kept for 15 seconds, taken out, and quickly transferred to liquid nitrogen within 10 seconds for rapid cooling, and low-temperature deep cooling is carried out in liquid nitrogen for 1 hour; the obtained sample is cold rolled, with a total pressure of 50%, and the pressure each time is not less than 5%; finally, the aluminum-lithium alloy plate is aged and strengthened at a temperature of 180°C for 3 hours to obtain an aluminum-lithium alloy plate with high strength and fine grain structure after low-temperature deep cooling.

[0058] Comparative Example 3

[0059] A processing technology for high-strength fine-grained aluminum-lithium alloy plate specifically comprises the following steps:

[0060] (1) The chemical composition of the high-strength fine-grained aluminum-lithium alloy plate implemented in the present invention is shown in Table 6.

[0061] Table 6 Chemical composition of aluminum-lithium alloy plate of comparative example 3 (wt%)

[0062]

[0063] (2) According to the composition in Table 6, pure aluminum and various elements are first smelted and cast, and the heating furnace is evacuated to a vacuum of less than 10 Pa for vacuum melting to form an aluminum-lithium alloy ingot with a size of 200 mm × 100 mm × 100 mm. After completion, the cast aluminum-lithium alloy is heated to 150℃ and kept warm for 2h; the aluminum-lithium alloy ingot is subjected to step-by-step solution treatment, with a solution heating rate of 80℃ / min, and the solution temperature and solution time are 380℃×0.5h+450℃×0.5h+480℃×1h+520℃×1h; the sample is rapidly cooled and first placed in cold water for quenching; the obtained sample is cold rolled with a total pressure of 50%, and the pressure each time is not less than 5%; the cold-deformed sample is subjected to secondary solution strengthening with a heating rate of 80℃ / min, a temperature of 540℃, and a solution time of 2h; finally, the sample is annealed and aged, first the sample is air-cooled to 250℃, placed in a heating furnace for furnace cooling, the annealing and aging time is 3h, and after annealing, it is air-cooled to room temperature to obtain a high-strength aluminum-lithium alloy plate with fine grain structure.

[0064] Comparative Example 4

[0065] A processing technology for high-strength fine-grained aluminum-lithium alloy plate specifically comprises the following steps:

[0066] (1) The chemical composition of the high-strength fine-grained aluminum-lithium alloy plate implemented in the present invention is shown in Table 7.

[0067] Table 7 Chemical composition of aluminum-lithium alloy plate of comparative example 4 (wt%)

[0068]

[0069] (2) According to the composition in Table 7, pure aluminum and various elements are first smelted and cast, and the heating furnace is evacuated to a vacuum of less than 10 Pa for vacuum melting to form an aluminum-lithium alloy ingot with a size of 200 mm × 100 mm × 100 mm. After completion, the cast aluminum-lithium alloy is heated to 150℃ and kept warm for 2h; the aluminum-lithium alloy ingot is solution treated with a heating rate of 80℃ / min, and the solution temperature and solution time are 520℃×3h; the sample is cooled step by step, first placed in cold water for quenching, kept for 15s, taken out, and quickly transferred to liquid nitrogen within 10s for rapid cooling, and deep cooled in liquid nitrogen for 1h; the obtained sample is cold rolled with a total pressure of 50%, and the pressure each time is not less than 5%; the cold-deformed sample is subjected to secondary solution strengthening with a heating rate of 80℃ / min, a temperature of 540℃, and a time of 2h; finally, the sample is annealed and aged, first the sample is air-cooled to 250℃, placed in a heating furnace for furnace cooling, the annealing time is 3h, and after annealing, it is air-cooled to room temperature to obtain a high-strength aluminum-lithium alloy plate with fine grain structure.

[0070] The performance of the aluminum-lithium alloy plates prepared according to Examples 1-3 and Comparative Examples 1-4 was tested, and the results are shown in Table 8.

[0071] Table 8

[0072] Sample number Yield strength / MPa Tensile strength / MPa Elongation Example 1 423.1 520.3 7.6％ Example 2 414.8 507.6 7.4％ Example 3 419.5 512.7 7.5％ Comparative Example 1 382.5 471.9 5.8％ Comparative Example 2 390.7 482.7 6.1％ Comparative Example 3 406.2 498.6 6.5％ Comparative Example 4 401.6 495.3 7.1％

[0073] According to the mechanical property data of the high-strength, fine-grained aluminum-lithium alloy plates prepared by different processes in Table 8, the yield strength, tensile strength, and elongation of Example 1 are superior to those of Comparative Examples 1-4, indicating that low-temperature deep cooling refines the grain size and greatly improves the mechanical properties through secondary solid solution. In addition, due to the establishment of a temperature gradient of step-by-step solid solution treatment and step-by-step cooling, the internal stress is greatly reduced and the toughness of the aluminum-lithium alloy plate is improved. In addition, the mechanism of low-temperature deep cooling and secondary solid solution greatly improves the overall performance of the aluminum-lithium alloy. Compared with Comparative Example 1, which is a traditional preheating + solid solution treatment + cold deformation + aging strengthening process, the comprehensive mechanical properties of the material in Comparative Example 2 are slightly improved, indicating that the strengthening effect is relatively weak under the low-temperature deep cooling process. This is mainly because low-temperature deep cooling causes changes in the crystal structure. Although it has the effect of refining the grains, the aluminum-lithium alloy still has uneven distribution of mechanical properties and microstructure. Comparison between Example 1 and Example 3 shows that the mechanical properties are significantly improved when a secondary solution treatment is performed after cold deformation. The reason is that cold deformation can refine the grains, increase the surface area of ​​the grain boundaries, and provide excellent strengthening conditions for the second solution strengthening. Comparison between Example 1 and Example 4 shows that better mechanical properties are obtained by step-by-step solution treatment than by ordinary solution treatment. The reason may be that step-by-step solution treatment effectively promotes grain refinement and uniform distribution through multiple heating processes, and can reduce residual stress and deformation in the material, resulting in a more stable structure. In summary, low-temperature deep cooling, as an additional supplementary grain refinement treatment after cold deformation, produces a limited number of fine grains, and the problem of uneven tissue distribution still exists. Therefore, both low-temperature deep cooling and cold deformation can play a role in refining grains, and the strengthening effect of the two working together is not significant. However, after the synergistic secondary solid solution strengthening, the solute atoms are more evenly distributed inside the grains, and the slow heating and annealing also reduce the residual stress. Therefore, the coupling of the multiple processes of the present invention produces a higher strength fine-grained aluminum-lithium alloy material, which is suitable for industrial production and provides a feasible solution for the preparation of precision electronic parts.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A processing technology for high-strength fine-grained aluminum-lithium alloy plate, characterized in that: The steps include: (1) Preheating the aluminum-lithium alloy ingot; (2) The aluminum-lithium alloy ingot was kept at 380°C for 0.5 h, then at 450°C for 0.5 h, at 480°C for 1 h, and finally at 520°C for 1 h; (3) The samples were subjected to step-by-step cooling and cryogenic treatment: the samples after multi-stage solution treatment were first placed in water for quenching for 15 seconds, and then transferred to liquid nitrogen for cooling within 10 seconds. After cooling, the samples were cryogenically treated in liquid nitrogen for 1 hour, and the cryogenic treatment temperature was 80K~100K; (4) The samples after cryogenic treatment are subjected to cold rolling and secondary solution treatment in sequence; (5) The sample is subjected to annealing and aging treatment, and then naturally cooled to obtain a high-strength and fine-grained aluminum-lithium alloy plate; The heating rates of the multi-stage solution treatment in step (2) and the secondary solution treatment in step (4) are both less than 80°C / min; The aluminum-lithium alloy ingot includes the following atomic percentage components: 0.8%~1.2% Cu, 2.5%~2.8% Li, 0.6%~1% Mg, 0.1%~0.25% Zr, 0.5%~0.8% Mn, and the rest are aluminum and other inevitable trace impurity elements.

2. The processing technology of the high-strength fine-grained aluminum-lithium alloy plate according to claim 1 is characterized in that: In the step (1), the preheating temperature is 150°C to 160°C, and the holding time is 2 hours.

3. The processing technology of the high-strength fine-grained aluminum-lithium alloy plate according to claim 1 is characterized in that: In the step (4), the total cold rolling pressure is 50%-60%, and the pressure each time is not less than 5%.

4. The processing technology of the high-strength fine-grained aluminum-lithium alloy plate according to claim 1 is characterized in that: In the step (4), the secondary solution temperature is 540°C and the time is 2 hours.

5. The processing technology of the high-strength fine-grained aluminum-lithium alloy plate according to claim 1, characterized in that: In the step (5), the annealing treatment temperature is 150°C-250°C, and the time is 2h-3h.

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