A manufacturing process for low-stress aluminum-lithium alloy

Abstract

The present invention provides a manufacturing process for a low-stress aluminum-lithium alloy, comprising the following steps: S1) homogenizing an aluminum-lithium alloy ingot; S2) deforming the aluminum-lithium alloy ingot obtained in step S1), followed by solution treatment and aging treatment to obtain the aluminum-lithium alloy; the solution treatment temperature is 500-600°C, the aging treatment temperature is 200-300°C, and the aging treatment cooling method is furnace cooling or furnace cooling plus air cooling. The present invention provides a manufacturing process for an aluminum-lithium alloy. By varying the aging cooling method during heat treatment, the process controls the residual stress in the aluminum-lithium alloy, achieving a good balance between strength and ductility. This process has positive guiding significance for the performance improvement and industrial application of new aluminum-lithium alloys.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum-lithium alloys, and in particular to a manufacturing process of a low-stress aluminum-lithium alloy. Background Art

[0002] Against the backdrop of rapid technological advancement, the requirements for material performance in various fields are becoming increasingly stringent. In particular, in industries such as aerospace and automotive manufacturing, which are highly dependent on material performance, lightweight and high-strength materials have become a research focus. As an emerging member of the aluminum alloy family, aluminum-lithium alloys exhibit a range of outstanding properties thanks to the unique role of lithium. Compared to traditional aluminum alloys, aluminum-lithium alloys have a lower density and high specific strength, high specific stiffness, and good fatigue resistance. Therefore, they are considered to be ideal structural materials for 21st-century aerospace applications, and they also have potential applications in the shipbuilding and weapons industries.

[0003] The primary heat treatment method for aluminum-lithium alloys is solution-assisted aging. During the solution stage, the primary secondary phase in the aluminum-lithium alloy fully dissolves into the matrix, forming a saturated solid solution. Subsequently, during the aging stage, the nanoscale secondary phase gradually precipitates from the matrix. During this process, the precipitation behavior of the precipitated phase can be adjusted by controlling the temperature and time of the aging treatment, thereby optimizing the strengthening effect. Appropriate aging treatment can achieve the optimal size and distribution of the precipitated phase, achieving the best strengthening effect.

[0004] Residual stress is widely present in aluminum-lithium alloy products, which has a very negative impact on the processing and performance of the plate. This is manifested in two aspects: First, after the plate is quenched or during subsequent machining, the presence of residual stress can easily cause the plate to deform, such as bending and warping; second, residual stress can greatly interfere with the performance of the alloy plate during actual service. Stress relief annealing is generally used to reduce the residual stress in aluminum-lithium alloys, but during the stress relief annealing process, the temperature changes significantly, which can have a significant impact on the mechanical properties and microstructure of the material, and thus affect the performance of the components during actual service.

[0005] Professor Wang Junqiang and others proposed using cryogenic treatment to improve the effect of residual stress in 2195 aluminum-lithium alloy on its mechanical properties. Specifically, the 2195 aluminum-lithium alloy was kept at 520°C for 60 minutes, then water quenched. After cooling to room temperature, the 2195 aluminum-lithium alloy was placed in liquid nitrogen for cryogenic treatment. The residual stress in the material was tested using the layer-cutting residual stress test technique. The results showed that compared with the quenched state, the compressive true strain on the surface and core of the material decreased after cryogenic treatment, the difference in plastic strain between the surface and core decreased, the peak compressive stress on the surface decreased by 5.9%, and the peak tensile stress on the core decreased by 13.1%. It can be seen that cryogenic treatment can reduce the residual stress level of 2195 aluminum-lithium alloy.

[0006] However, there are the following problems with cryogenic treatment of the above-mentioned aluminum-lithium alloy: 1) When the 2195 aluminum-lithium alloy is cryogenically treated, the equipment needs to have good low-temperature thermal insulation performance, precise temperature control and monitoring systems to ensure the stability and accuracy of the treatment process; 2) Cryogenic treatment will cause the 2195 aluminum-lithium alloy to shrink, and this dimensional change may exceed the allowable tolerance range. In the aerospace industry, which requires extremely high fitting accuracy, this dimensional change beyond the tolerance range will undoubtedly have an adverse effect on the performance of the aluminum-lithium alloy; 3) The cryogenic treatment process of 2195 aluminum-lithium alloy usually takes a long time to complete. From cooling, insulation to heating of the material, each stage requires strict control of time and temperature. Compared with some traditional heat treatment methods, the efficiency of cryogenic treatment is relatively low; 4) The preparation and use of liquid nitrogen will consume a considerable amount of energy and may also emit a certain amount of greenhouse gases. In addition, if the waste after cryogenic treatment is not handled properly, it may also cause a certain degree of pollution to the environment.

[0007] Therefore, it is of great significance to provide a heat treatment process for aluminum-lithium alloy to control low residual stress and make it have good mechanical properties. Summary of the Invention

[0008] The technical problem solved by the present invention is to provide a manufacturing process for low-stress aluminum-lithium alloy. The manufacturing process provided in this application can enable the prepared aluminum-lithium alloy to have excellent properties of low residual stress and high strength-plasticity matching.

[0009] In view of this, the present application provides a manufacturing process for a low-stress aluminum-lithium alloy, comprising the following steps:

[0010] S1) homogenizing the aluminum-lithium alloy ingot;

[0011] S2) deforming the aluminum-lithium alloy ingot obtained in step S1), and then performing solution treatment and aging treatment in sequence to obtain an aluminum-lithium alloy;

[0012] The temperature of the solution treatment is 500-600° C., the temperature of the aging treatment is 200-300° C., and the cooling method of the aging treatment is furnace cooling or furnace cooling + air cooling.

[0013] In some specific embodiments, in step S1), the temperature of the homogenization treatment is 400-500°C, and / or the holding time of the homogenization treatment is 10-20 hours, and / or the heating rate of the homogenization treatment is 1-10°C / min, and / or the cooling method of the homogenization treatment is furnace cooling.

[0014] In some specific embodiments, in step S2), the deformation treatment is rolling; the rolling is performed in 2 to 4 passes, and / or the rolling temperature is 400 to 500°C, and / or the rolling is kept warm for 5 to 20 minutes per pass, and / or the total deformation of the rolling is 50 to 70%.

[0015] In some specific embodiments, in step S2), the holding time of the solution treatment is 1 to 5 hours, and / or the cooling method of the solution treatment is water cooling.

[0016] In some specific embodiments, in step S2), the holding time of the aging treatment is 12 to 36 hours.

[0017] In some specific embodiments, in step S2), the cooling method of the aging treatment is furnace cooling + air cooling.

[0018] In some specific embodiments, the aluminum-lithium alloy is a third-generation aluminum-lithium alloy, and the components of the aluminum-lithium alloy, measured in mass percentage, include: Li 1.8~2.6%, Cu 3.8~4.6%, Mg 0.25~0.8%, Ag 0.2~0.6%, Zr 0.08~0.15%, and Al 91.5~93.8%.

[0019] In some specific embodiments, in step S1), the method for manufacturing the aluminum-lithium alloy ingot is specifically as follows:

[0020] Prepare Mg ingots, Al-Ag master alloys, Al-Zr master alloys, Al-Cu master alloys, Al-Li master alloys and Al ingots according to the composition ratio of the aluminum-lithium alloy;

[0021] The Al ingot is added to a vacuum melting furnace and kept at 700-800° C. for 30-90 minutes. The obtained aluminum liquid is cooled to 600-700° C., and then the Mg ingot and the Al-Li master alloy are added and the temperature is raised to 700-800° C., and then the Al-Zr master alloy, the Al-Ag master alloy, and the Al-Cu master alloy are added. The obtained aluminum liquid is kept for 1-3 hours to obtain an aluminum-lithium alloy melt;

[0022] The aluminum-lithium alloy melt is cast to obtain an aluminum-lithium alloy ingot.

[0023] In some specific embodiments, before adding the Al ingot into the vacuum melting furnace, the method further comprises:

[0024] The vacuum melting furnace was evacuated to a vacuum degree of (0.2-0.5) × 10 -2 Pa, then add protective gas, and stop charging when the pressure of the protective gas is 0.10~0.30Pa; repeat the above process 2~5 times.

[0025] In some specific embodiments, the purity of the Al ingot is not less than 99.8%, the purity of the Mg ingot is not less than 99.8%, the purity of the Al-Cu master alloy is not less than 99.9%, the purity of the Al-Li master alloy is not less than 99.9%, the purity of the Al-Ag master alloy is not less than 99.9%, and the purity of the Al-Zr master alloy is not less than 99.8%; and / or the protective gas is argon with a purity ≥99.5%.

[0026] The present application provides a manufacturing process for a low-stress aluminum-lithium alloy, which first homogenizes an aluminum-lithium alloy ingot, then deforms the homogenized aluminum-lithium alloy ingot, and finally sequentially performs a solid solution treatment and an aging treatment. In the manufacturing method for the aluminum-lithium alloy, the aluminum-lithium alloy after the deformation treatment is sequentially subjected to a solid solution treatment and an aging treatment. After the solid solution treatment and the aging treatment, the strengthening precipitation phases of the aluminum-lithium alloy include δ′, θ′ and β′ phases. The θ′ phase is uniformly dissolved in the matrix after the solid solution treatment, and then precipitates and enriches in large quantities during the aging treatment. The δ′ phase remains almost unchanged after the solid solution treatment, but precipitates in small quantities after the aging treatment. By regulating the cooling method of the aging treatment, the residual stress in the aluminum-lithium alloy can be further controlled, so that a good strength-plasticity match is obtained, and ultimately the obtained aluminum-lithium alloy has excellent properties of low residual stress and strong-plasticity match. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The residual stress and elongation curves of the aluminum-lithium alloy plates manufactured in Examples 1 to 4 are shown;

[0028] Figure 2 The tensile strength curves of the aluminum-lithium alloy plates manufactured in Examples 1 to 4 are as follows;

[0029] Figure 3 This is a microstructure characterization photograph of the aluminum-lithium alloy plate manufactured in Example 1;

[0030] Figure 4 This is a microstructure characterization photograph of the aluminum-lithium alloy plate manufactured in Example 2;

[0031] Figure 5 This is a microstructure characterization photograph of the aluminum-lithium alloy plate manufactured in Example 3;

[0032] Figure 6 This is a microstructure characterization photograph of the aluminum-lithium alloy plate manufactured in Example 4. DETAILED DESCRIPTION

[0033] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0034] In the field of metal materials, there is a common problem of increasing strength at the expense of plasticity. At the same time, the existence of residual stress will lead to a decrease in alloy stability. Therefore, how to reduce the residual stress while ensuring that the mechanical properties of the alloy material are not negatively affected and achieving a balance between the two is a major difficulty. Therefore, it is necessary to provide a suitable aluminum-lithium alloy manufacturing process so that the alloy can precipitate a large amount of dispersed strengthening phases while reducing the residual stress inside the alloy and having a good strength-plasticity match. In view of this, the present application provides a low-stress aluminum-lithium alloy manufacturing process, which controls the residual stress in the aluminum-lithium alloy by adopting an appropriate cooling method for aging treatment of the aluminum-lithium alloy, so that the obtained aluminum-lithium alloy has low residual stress, high strength-plasticity matching and excellent performance. Specifically, an embodiment of the present invention discloses a low-stress aluminum-lithium alloy manufacturing process, comprising the following steps:

[0035] S1) homogenizing the aluminum-lithium alloy ingot;

[0036] S2) deforming the aluminum-lithium alloy ingot obtained in step S1), and then performing solution treatment and aging treatment in sequence to obtain an aluminum-lithium alloy;

[0037] The temperature of the solution treatment is 500-600° C., the temperature of the aging treatment is 200-300° C., and the cooling method of the aging treatment is furnace cooling or furnace cooling + air cooling.

[0038] In the manufacturing method of aluminum-lithium alloy, the present application first homogenizes the aluminum-lithium alloy ingot; during this process, the aluminum-lithium alloy ingot is prepared according to a method well known to those skilled in the art, that is, the ingredients of the aluminum-lithium alloy ingot are mixed and then smelted, and the molten melt is then cast. The aluminum-lithium alloy described in the present application may specifically be a third-generation aluminum-lithium alloy, which includes, by mass percentage: Li 1.8~2.6%, Cu 3.8~4.6%, Mg 0.25~0.8%, Ag0.2~0.6%, Zr 0.08~0.15%, and Al 91.5~93.5%; in the present application, the Li content is 1.9~2.5%, specifically, the Li content is 2.1~2.3%; the Cu content is 3.9~4.5%, specifically, the Cu content is 4.1~4.3%; the Mg content is 0.3~0.64%, specifically, the Mg content is 0.45~0.55%; the Ag content is 0.25~0.5%, specifically, the Ag content is 0.3~0.4%; the Zr content is 0.09~0.13%, specifically, the Zr content is 0.10~0.11%. Based on the above-mentioned composition of the aluminum-lithium alloy, the preparation method of the aluminum-lithium alloy ingot is specifically as follows:

[0039] Prepare Mg ingots, Al-Ag master alloys, Al-Zr master alloys, Al-Cu master alloys, Al-Li master alloys and Al ingots according to the composition ratio of the aluminum-lithium alloy;

[0040] The Al ingot is added to a vacuum melting furnace and kept at 700-800° C. for 30-90 minutes. The obtained aluminum liquid is cooled to 600-700° C., and then the Mg ingot and the Al-Li master alloy are added and the temperature is raised to 700-800° C., and then the Al-Zr master alloy, the Al-Ag master alloy, and the Al-Cu master alloy are added. The obtained aluminum liquid is kept for 1-3 hours to obtain an aluminum-lithium alloy melt;

[0041] The aluminum-lithium alloy melt is cast to obtain an aluminum-lithium alloy ingot.

[0042] During the preparation of the aluminum-lithium alloy ingot, the purity of the Mg ingot is not less than 99.8%, the purity of the Al ingot is not less than 99.8%, the purity of the Al-Cu master alloy is not less than 99.9%, the purity of the Al-Li master alloy is not less than 99.9%, the purity of the Al-Ag gold alloy is not less than 99.9%, and the purity of the Al-Zr master alloy is not less than 99.8%. After the above raw materials are prepared, vacuum melting is performed. Before vacuum melting, the gas in the vacuum melting furnace is preferably purged. Specifically, the vacuum melting furnace is evacuated to a vacuum degree of (0.2~0.5)×10 -2Pa, then add protective gas, and stop charging when the pressure of the protective gas is 0.10~0.30Pa; repeat the above process 2~5 times. More specifically, the vacuum degree is (0.3~0.4)×10 -2 Pa, the shielding gas pressure is 0.15-0.25 Pa, specifically argon with a purity of 99.9%. During the vacuum melting process, before adding the Mg ingot and Al-Li master alloy, the holding temperature is 750-760°C for 40-60 minutes, the temperature is then lowered to 650-680°C, and the temperature is raised to 750-760°C. The resulting aluminum liquid is specifically held for 1.5-2 hours.

[0043] The present application then performs a homogenization treatment on the obtained aluminum-lithium alloy ingot, wherein the temperature of the homogenization treatment is 400~500°C, the holding time of the homogenization treatment is 10~20h, the heating rate of the homogenization treatment is 1~10°C / min, and the cooling method of the homogenization treatment is furnace cooling; specifically, the temperature of the homogenization treatment is 420~480°C, more specifically, the temperature of the homogenization treatment is 430~460°C; specifically, the holding time of the homogenization treatment is 12~18h, more specifically, the holding time of the homogenization treatment is 15~16h; specifically, the heating rate of the homogenization treatment is 2~7°C / min, more specifically, the heating rate of the homogenization treatment is 5~6°C / min.

[0044] According to the present invention, the homogenized aluminum-lithium alloy is then subjected to a deformation treatment. In this application, the deformation treatment is specifically rolling, and the rolling is specifically 2 to 4 passes of rolling, more specifically, 3 passes of rolling; the rolling temperature is 400 to 500°C, specifically, the rolling temperature is 430 to 460°C; the rolling is kept warm for 5 to 20 minutes per pass, specifically, the rolling is kept warm for 10 to 15 minutes per pass; the total deformation of the rolling is 50 to 70%, specifically, the total deformation of the rolling is 60 to 65%.

[0045] This application finally subjects the deformed aluminum-lithium alloy to solution treatment and aging treatment in sequence; after solution treatment and aging treatment, the strengthening precipitation phases of the aluminum-lithium alloy include δ′, θ′ and β′ phases; the β′ phase is a separate strengthening phase and does not participate in the phase changes and precipitation during solution and aging treatment; the θ′ phase is uniformly dissolved in the matrix after solution treatment, and then precipitates and enriches in large quantities during aging treatment; the δ′ phase is almost unchanged after solution treatment, but will precipitate in small amounts after aging treatment. The temperature of the solution treatment is 500~600℃, and the holding time is 1~5h; specifically, the temperature of the solution treatment is 520~570℃, and the holding time is 2~4h; more specifically, the temperature of the solution treatment is 530~550℃, and the holding time is 2~3h; the cooling method of the solution treatment is water cooling. The temperature of the aging treatment is 200~300℃, and the holding time is 12~36h. Specifically, the temperature of the aging treatment is 210~280℃, and the holding time is 12~24h. More specifically, the temperature of the aging treatment is 250~260℃. The cooling method of the aging treatment is furnace cooling or furnace cooling + air cooling. In the present application, the cooling method of the aging treatment is furnace cooling + air cooling, and the furnace cooling is cooled to 150~180℃ and then air cooled to room temperature. Although the furnace cooling after aging treatment in the present application shows advantages in residual stress and strength-plasticity matching, from the perspective of process stability and performance, furnace cooling + air cooling is a cooling method with performance index requirements and strong process controllability.

[0046] In order to further understand the present invention, the manufacturing process of the low stress aluminum-lithium alloy provided by the present invention is described in detail below in conjunction with the embodiments. The protection scope of the present invention is not limited by the following embodiments.

[0047] Example 1

[0048] (1) Preparation of raw materials The aluminum-lithium alloy manufactured in this embodiment is a third-generation aluminum-lithium alloy, including: Li: 1.9wt%, Cu: 3.9wt%, Mg: 0.3wt%, Ag: 0.25wt%, Zr: 0.09wt%, and the balance is Al; Al ingots, Mg ingots, Al-Cu master alloys, Al-Li master alloys, Al-Ag master alloys, and Al-Zr master alloys are selected as raw materials according to the above elements, and then the ingredients are prepared according to the above proportions, wherein the purity of the Al ingot is not less than 99.8%, the purity of the Mg ingot is not less than 99.8%, the purity of the Al-Cu master alloy is not less than 99.9%, the purity of the Al-Li master alloy is not less than 99.9%, the purity of the Al-Ag master alloy is not less than 99.9%, and the purity of the Al-Zr master alloy is not less than 99.8%;

[0049] (2) Use vacuum resistance furnace for smelting. Pump the vacuum melting furnace into vacuum with a vacuum degree of 0.4×10 -2Pa, adding protective gas argon with a purity of 99.9%. When the protective gas pressure reaches 0.15 Pa, stopping the inflation, and repeating this process 3 times; then adding the Al ingot into the vacuum melting furnace, keeping it warm at 760°C for 60 minutes until it is completely melted, cooling the molten aluminum to 680°C, adding the Mg ingot and the Al-Li master alloy to the cooled molten aluminum and heating it to 760°C, and then adding the Al-Zr master alloy, the Al-Ag master alloy and the Al-Cu master alloy, stirring the molten aluminum continuously to promote the uniform and sufficient dissolution of all alloy elements in the molten aluminum, keeping it warm for 1.5 hours, and obtaining an aluminum alloy molten liquid; slowly and uniformly pouring the aluminum alloy molten liquid into a metal mold, and after the casting is completed, allowing it to cool naturally and form to obtain an aluminum-lithium alloy ingot;

[0050] (3) The aluminum-lithium alloy ingot was homogenized at a heating rate of 5°C / min, a homogenization temperature of 460°C, a holding time of 16 h, and then cooled to room temperature in the furnace;

[0051] (4) The ingot obtained in step (3) was rolled three times at a rolling temperature of 460°C, with each rolling step being kept at this temperature for 10 minutes, and the final total deformation amount reached 60%, thereby obtaining an aluminum-lithium alloy sheet with a thickness of 2.5 mm;

[0052] (5) The hot-rolled aluminum-lithium alloy sheet is subjected to solution treatment (550°C / 2h, water quenching) + aging treatment, the aging temperature is 260°C, the holding time is 24h, and the cooling method is water cooling to obtain an aluminum-lithium alloy sheet;

[0053] The residual stress distribution from the surface to the core of the aluminum-lithium alloy plate obtained by the layer-cutting method (5) was tested, and the room temperature mechanical properties of the sample were tested by room temperature tensile testing.

[0054] The plate manufactured in this embodiment has the problem of cracking around the edges; Figure 3 As shown, Figure 3 This is a microstructure characterization photo of the plate manufactured in this embodiment. Figure 3 It can be seen that the β′ phase has no phase change and precipitation during the solid solution and aging treatments; the θ′ phase is uniformly dissolved in the matrix after solid solution, and then precipitates and enriches in large quantities during aging treatment; the δ′ phase has almost no change after solid solution treatment, but will precipitate a small amount after aging treatment.

[0055] The residual stress of the plate tested by the layer cutting method is 40MPa, the room temperature tensile strength of the plate tested by the room temperature tensile test is 480MPa, and the elongation after fracture is only 6.8%. Figure 1 and Figure 2 shown.

[0056] Example 2

[0057] This embodiment adopts the same manufacturing method as that of embodiment 1 to manufacture aluminum-lithium alloy, with the difference being that the chemical composition and the cooling process after aging are different, as follows:

[0058] The chemical composition of the alloy is: Li: 2.1wt%, Cu: 4.1wt%, Mg: 0.45wt%, Ag: 0.3wt%, Zr: 0.1wt%, and the balance is Al; the cooling process after aging is air cooling.

[0059] The plate manufactured in this embodiment has the phenomenon of bending and warping. Figure 4 As shown, Figure 4 This is a microstructure characterization photo of the plate manufactured in this embodiment. Figure 4 It can be seen that the precipitated phases are mainly θ′ phase and δ′ phase.

[0060] The residual stress of the plate tested by the layer cutting method is 38MPa, the room temperature tensile strength of the plate tested by the room temperature tensile test is 489MPa, and the elongation after fracture is 7.3%. Figure 1 and Figure 2 shown.

[0061] Example 3

[0062] This embodiment adopts the same manufacturing method as that of embodiment 1 to manufacture aluminum-lithium alloy, with the difference being that the chemical composition and the cooling process after aging are different, as follows:

[0063] The chemical composition of the alloy is: Li: 2.3wt%, Cu: 4.3wt%, Mg: 0.55wt%, Ag: 0.4wt%, Zr: 0.11wt%, and the balance is Al; the cooling process after aging is furnace cooling.

[0064] The plate manufactured in this embodiment did not show any bending, warping or even cracking, and the macroscopic appearance of the manufactured plate was straight. Figure 5 As shown, Figure 5 This is a microstructure characterization photo of the plate manufactured in this embodiment. Figure 5 It can be seen that the precipitated phases are mainly θ′ phase and δ′ phase, which are evenly distributed but have significantly increased in size, resulting in aggravated lattice distortion, increased internal stress, and corresponding increase in residual stress.

[0065] The residual stress of the plate tested by the layer cutting method is 27MPa, the room temperature tensile strength of the plate tested by the room temperature tensile test is 523MPa, and the elongation after fracture is 10.2%. Figure 1 and Figure 2 shown.

[0066] Example 4

[0067] This embodiment adopts the same manufacturing method as that of embodiment 1 to manufacture aluminum-lithium alloy, with the difference being that the chemical composition and the cooling process after aging are different, as follows:

[0068] The chemical composition of the alloy is: Li: 2.5wt%, Cu: 4.5wt%, Mg: 0.64wt%, Ag: 0.3wt%, Zr: 0.13wt%, and the balance is Al; the cooling process after aging is furnace cooling to 180°C + air cooling.

[0069] The plate manufactured in this embodiment did not show any bending, warping or cracking, and the macroscopic appearance of the manufactured plate was flat. Figure 6 This is a microstructure characterization photo of the plate manufactured in this embodiment. Figure 6 It can be seen that the precipitated phases are mainly θ′ phase and δ′ phase, and the size and distribution of the precipitated phases have no obvious changes compared with Example 1.

[0070] The residual stress of the plate tested by the layer cutting method is 16MPa, the room temperature tensile strength of the plate tested by the room temperature tensile test is 540MPa, and the elongation after fracture is 12%. Figure 1 and Figure 2 shown.

[0071] Comparing Examples 1, 2, 3, and 4, the aluminum-lithium alloy produced in Example 4 exhibited lower residual stress than that in Examples 1, 2, and 3, and exhibited the highest tensile strength and elongation after fracture. Therefore, considering the alloy's strength-ductility match and cost savings in practical applications, Example 4 was the best choice.

[0072] Comparative Example 1: Yang Shengli et al. used quenched 2195 aluminum-lithium alloy

[0073] The residual stress test experiments were conducted on the aluminum-lithium alloys manufactured in this comparative example and that manufactured in Example 4. The results showed that the absolute value of the residual stress of the aluminum-lithium alloy plate manufactured in Comparative Example 1 after quenching was stable within 25 MPa; while the residual stress of the aluminum-lithium alloy manufactured in the present invention was only 16 MPa, with a better stress reduction effect; and the aluminum-lithium alloy involved in the present invention had an excellent strength-to-plasticity ratio at room temperature and was suitable for use in industrial production.

[0074] The above embodiments are only intended to help understand the method and core concept of the present invention. It should be noted that, without departing from the principles of the present invention, a number of improvements and modifications may be made to the present invention by those skilled in the art, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0075] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A process for manufacturing a low-stress aluminum-lithium alloy, comprising the following steps: S1) homogenizing the aluminum-lithium alloy ingot; The aluminum-lithium alloy is a third-generation aluminum-lithium alloy, and the composition of the aluminum-lithium alloy, in terms of mass percentage, includes: Li 2.1-2.6%, Cu 3.8-4.6%, Mg 0.25-0.8%, Ag 0.2-0.6%, Zr 0.08-0.15%, and Al 91.5-93.8%; S2) deforming the aluminum-lithium alloy ingot obtained in step S1), and then performing solution treatment and aging treatment in sequence to obtain an aluminum-lithium alloy; The temperature of the solution treatment is 500-600°C, the holding time of the solution treatment is 1-5 hours, and the cooling method of the solution treatment is water cooling; the temperature of the aging treatment is 200-300°C, the holding time of the aging treatment is 12-36 hours, and the cooling method of the aging treatment is furnace cooling + air cooling.

2. The manufacturing process according to claim 1, characterized in that In step S1), the temperature of the homogenization treatment is 400-500°C, and / or the holding time of the homogenization treatment is 10-20 hours, and / or the heating rate of the homogenization treatment is 1-10°C / min, and / or the cooling method of the homogenization treatment is furnace cooling.

3. The manufacturing process according to claim 1, characterized in that In step S2), the deformation treatment is rolling; the rolling is performed in 2 to 4 passes, and / or the rolling temperature is 400 to 500° C., and / or the heat preservation time of each rolling pass is 5 to 20 minutes, and / or the total deformation of the rolling is 50 to 70%.

4. The manufacturing process according to claim 1, characterized in that In step S1), the method for manufacturing the aluminum-lithium alloy ingot is specifically as follows: Prepare Mg ingots, Al-Ag master alloys, Al-Zr master alloys, Al-Cu master alloys, Al-Li master alloys and Al ingots according to the composition ratio of the aluminum-lithium alloy; The Al ingot is added to a vacuum melting furnace and kept at 700-800° C. for 30-90 minutes. The obtained aluminum liquid is cooled to 600-700° C., and then the Mg ingot and the Al-Li master alloy are added and the temperature is raised to 700-800° C., and then the Al-Zr master alloy, the Al-Ag master alloy, and the Al-Cu master alloy are added. The obtained aluminum liquid is kept for 1-3 hours to obtain an aluminum-lithium alloy melt; The aluminum-lithium alloy melt is cast to obtain an aluminum-lithium alloy ingot.

5. The manufacturing process according to claim 4, characterized in that: Before adding the Al ingot into the vacuum melting furnace, the following steps are further included: The vacuum melting furnace was evacuated to a vacuum degree of (0.2-0.5) × 10 -2 Pa, then add protective gas, and stop charging when the pressure of the protective gas is 0.10~0.30Pa; repeat the above process 2~5 times.

6. The manufacturing process according to claim 5, characterized in that The purity of the Al ingot is not less than 99.8%, the purity of the Mg ingot is not less than 99.8%, the purity of the Al-Cu master alloy is not less than 99.9%, the purity of the Al-Li master alloy is not less than 99.9%, the purity of the Al-Ag master alloy is not less than 99.9%, and the purity of the Al-Zr master alloy is not less than 99.8%; and / or the protective gas is argon with a purity of ≥99.5%.

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