Manufacturing process of low-stress aluminum-lithium alloy

Abstract

The invention provides a manufacturing process of a low-stress aluminum-lithium alloy. The manufacturing process comprises the following steps: S1) carrying out homogenization treatment on an aluminum-lithium alloy ingot; and S2) carrying out deformation treatment on the aluminum-lithium alloy ingot obtained in the step S1), and then sequentially carrying out solution treatment and aging treatment to obtain the aluminum-lithium alloy, the temperature of the solution treatment is 500-600 DEG C, the temperature of the aging treatment is 200-300 DEG C, and the cooling mode of the aging treatment is furnace cooling or furnace cooling and air cooling. According to the manufacturing process of the aluminum-lithium alloy, the aging cooling mode of heat treatment is changed, the residual stress in the aluminum-lithium alloy is controlled, the aluminum-lithium alloy obtains good strength and plasticity matching, and the positive guiding significance is achieved for performance improvement and industrial application of the novel aluminum-lithium alloy.

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 development, the requirements for material performance in various fields are becoming increasingly stringent. In particular, in industries such as aerospace and automobile manufacturing that are highly dependent on material performance, lightweight and high-strength materials have become a research focus. As an emerging member of the aluminum alloy material family, aluminum-lithium alloys exhibit a series of outstanding properties thanks to the unique role of lithium. The density of aluminum-lithium alloys is lower than that of traditional aluminum alloys. At the same time, they also have high specific strength, high specific stiffness, and good fatigue resistance. Therefore, they are considered to be very ideal structural materials for aerospace applications in the 21st century, and they also have potential application space in ships and weapons industries.

[0003] The main heat treatment method for aluminum-lithium alloy is solid solution plus aging treatment. In the solid solution stage, the primary second phase in the aluminum-lithium alloy is fully dissolved into the matrix to form a saturated solid solution. Subsequently, in the aging stage, the nano-sized second phase will gradually precipitate from the matrix. In the above process, by controlling the temperature and time of the aging treatment, the precipitation behavior of the precipitated phase can be adjusted to optimize the strengthening effect. Appropriate aging treatment can make the precipitated phase reach the optimal size and distribution, and achieve the best strengthening effect.

[0004] Residual stress is widely present in aluminum-lithium alloy products, which has an extremely adverse effect on the processing and use performance of the plate; it is specifically manifested in two aspects: first, after the plate is quenched or during subsequent machining, the existence of residual stress can easily cause the plate to deform, such as bending and warping; second, residual stress will greatly interfere with the performance of the alloy plate in the actual service process. Generally, stress relief annealing is used to reduce the residual stress inside the aluminum-lithium alloy, but during the stress relief annealing process, the temperature changes significantly, and this temperature change will have a significant impact on the mechanical properties and microstructure of the material, and then affect the performance of the parts in the actual service process.

[0005] Wang Junqiang and other teachers proposed to use cryogenic treatment to improve the influence of internal residual stress of 2195 aluminum-lithium alloy on mechanical properties; specifically: keep 2195 aluminum-lithium alloy at 520℃ for 60min, then quench with water, and after cooling to room temperature, put 2195 aluminum-lithium alloy into liquid nitrogen for cryogenic treatment; the residual stress inside the material was tested by layer cutting residual stress test technology, and the results showed that compared with the quenched state, the compressive true strain of the surface and core of the material after cryogenic treatment decreased, the difference in plastic strain between the surface and core decreased, the peak value of surface compressive stress decreased by 5.9%, and the peak value of tensile stress in 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, the following problems will occur when the above aluminum-lithium alloy is cryogenically treated: 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 matching 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 by the present 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 of a low stress aluminum-lithium alloy, comprising the following steps: S1) homogenizing the aluminum-lithium alloy ingot; S2) subjecting the aluminum-lithium alloy ingot obtained in step S1) to deformation treatment, and then sequentially subjecting the ingot to solid solution treatment and aging treatment to obtain an aluminum-lithium alloy; 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.

[0010] 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 10-20h, 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.

[0011] In some specific embodiments, in step S2), the deformation treatment is rolling; the rolling is 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%.

[0012] 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.

[0013] In some specific embodiments, in step S2), the holding time of the aging treatment is 12 to 36 hours.

[0014] In some specific embodiments, in step S2), the cooling method of the aging treatment is furnace cooling + air cooling.

[0015] In some specific embodiments, the aluminum-lithium alloy is a third-generation aluminum-lithium alloy, and the components of the aluminum-lithium alloy, measured by 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%.

[0016] In some specific embodiments, in step S1), the method for manufacturing the aluminum-lithium alloy ingot is specifically as follows: According to the composition ratio of the aluminum-lithium alloy, a Mg ingot, an Al-Ag master alloy, an Al-Zr master alloy, an Al-Cu master alloy, an Al-Li master alloy and an Al ingot are prepared; The Al ingot is added into a vacuum melting furnace, and kept at 700-800° C. for 30-90 min, 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, and the obtained aluminum liquid is kept for 1-3 h to obtain an aluminum-lithium alloy melt; The aluminum-lithium alloy melt is cast to obtain an aluminum-lithium alloy ingot.

[0017] In some specific embodiments, before adding the Al ingot into the vacuum melting furnace, the process further comprises: The vacuum melting furnace is evacuated to a vacuum degree of (0.2-0.5) × 10 -2 Pa, then add protective gas, and when the pressure of the protective gas is 0.10~0.30Pa, stop charging; the above process is repeated 2~5 times.

[0018] 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%.

[0019] The present application provides a manufacturing process for a low-stress aluminum-lithium alloy, which firstly homogenizes an aluminum-lithium alloy ingot, then deforms the aluminum-lithium alloy ingot after the homogenization treatment, 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, and the strengthening precipitation phases of the aluminum-lithium alloy after the solid solution treatment and the aging treatment 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 is almost unchanged after the solid solution treatment, but will precipitate a small amount after the aging treatment; regulating the cooling method of the aging treatment can further control the residual stress in the aluminum-lithium alloy, so that it obtains a good strength-plasticity match, and finally the obtained aluminum-lithium alloy has the excellent performance of low residual stress and strong-plasticity match. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The residual stress and elongation curves of the aluminum-lithium alloy plates manufactured in Examples 1 to 4; Figure 2 The tensile strength curve of the aluminum-lithium alloy plate manufactured in Examples 1 to 4; Figure 3 This is a microstructure characterization photograph of the aluminum-lithium alloy plate manufactured in Example 1; Figure 4 This is a microstructure characterization photograph of the aluminum-lithium alloy plate manufactured in Example 2; Figure 5 This is a microstructure characterization photograph of the aluminum-lithium alloy plate manufactured in Example 3; Figure 6 This is a microstructure characterization photograph of the aluminum-lithium alloy plate produced in Example 4. DETAILED DESCRIPTION

[0021] 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.

[0022] 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 cause the stability of the alloy to decrease. Therefore, how to reduce the residual stress while ensuring that the mechanical properties of the alloy material are not negatively affected and achieve 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 good strength-plasticity matching. 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 and high strength-plasticity matching excellent performance. Specifically, an embodiment of the present invention discloses a low-stress aluminum-lithium alloy manufacturing process, comprising the following steps: S1) homogenizing the aluminum-lithium alloy ingot; S2) subjecting the aluminum-lithium alloy ingot obtained in step S1) to deformation treatment, and then sequentially subjecting the ingot to solid solution treatment and aging treatment to obtain an aluminum-lithium alloy; 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.

[0023] 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 prepared, mixed and then smelted, and then the smelted molten metal is 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 components of the aluminum-lithium alloy, the preparation method of the aluminum-lithium alloy ingot is specifically as follows: According to the composition ratio of the aluminum-lithium alloy, a Mg ingot, an Al-Ag master alloy, an Al-Zr master alloy, an Al-Cu master alloy, an Al-Li master alloy and an Al ingot are prepared; The Al ingot is added into a vacuum melting furnace, and kept at 700-800° C. for 30-90 min, 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, and the obtained aluminum liquid is kept for 1-3 h to obtain an aluminum-lithium alloy melt; The aluminum-lithium alloy melt is cast to obtain an aluminum-lithium alloy ingot.

[0024] In the process of preparing the above 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 gold alloy in Al-Ag 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 carried out. Before the vacuum melting, the gas in the vacuum melting furnace is preferably cleaned, specifically: the vacuum melting furnace is evacuated to a vacuum degree of (0.2~0.5)×10 -2Pa, then add protective gas, and when the pressure of the protective gas is 0.10~0.30Pa, stop charging; the above process is repeated 2~5 times. More specifically, the vacuum degree is (0.3~0.4)×10 -2 Pa, the pressure of the protective gas is 0.15~0.25Pa, the protective gas is specifically argon, and the purity of the argon is 99.9%. In the process of vacuum melting, before adding the Mg ingot and the Al-Li master alloy, the insulation temperature is 750~760℃, the insulation time is 40~60min, the temperature is lowered to 650~680℃; the temperature is raised to 750~760℃; the obtained aluminum liquid is specifically kept for 1.5~2h.

[0025] 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.

[0026] According to the present invention, the aluminum-lithium alloy that has been homogenized is then subjected to a deformation treatment. In the present application, the deformation treatment is specifically rolling, and the rolling is specifically 2 to 4 passes of rolling, more specifically, the rolling is 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%.

[0027] Finally, the present application sequentially performs solid solution treatment and aging treatment on the aluminum-lithium alloy after deformation treatment; after solid 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 strengthening phase that exists independently and does not participate in the change and precipitation of the phases during solid solution and aging treatment; the θ′ phase is uniformly dissolved in the matrix after solid solution treatment, 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. The temperature of the solid solution treatment is 500~600℃, and the holding time is 1~5h; specifically, the temperature of the solid solution treatment is 520~570℃, and the holding time is 2~4h; more specifically, the temperature of the solid solution treatment is 530~550℃, and the holding time is 2~3h; the cooling method of the solid 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.

[0028] 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 combination with embodiments, and the protection scope of the present invention is not limited by the following embodiments.

[0029] Example 1 (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%; (2) Use vacuum resistance furnace for smelting. The vacuum melting furnace is evacuated to a vacuum degree of 0.4×10 -2Pa, add protective gas argon with a purity of 99.9%, and stop charging when the protective gas pressure reaches 0.15Pa. This process is repeated 3 times; then add the Al ingot into the vacuum melting furnace, keep it warm at 760°C for 60 minutes until it is completely melted, cool the molten aluminum to 680°C, add Mg ingots and Al-Li master alloy to the cooled molten aluminum and heat it to 760°C, then add Al-Zr master alloy, Al-Ag master alloy and Al-Cu master alloy, stir the molten aluminum continuously to promote all alloy elements to be evenly and fully dissolved in the molten aluminum, keep it warm for 1.5 hours, and obtain an aluminum alloy molten liquid; slowly and uniformly pour the aluminum alloy molten liquid into a metal mold, wait for it to cool naturally after casting, and obtain an aluminum-lithium alloy ingot; (3) The aluminum-lithium alloy ingot is 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; (4) The ingot obtained in step (3) is subjected to three rolling passes at a rolling temperature of 460° C., and each rolling pass is kept at a temperature of 10 min. The final total deformation amount reaches 60%, and an aluminum-lithium alloy sheet with a thickness of 2.5 mm is obtained; (5) subjecting the hot-rolled aluminum-lithium alloy sheet to a 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, thereby obtaining an aluminum-lithium alloy sheet; The residual stress distribution from the surface to the core of the aluminum-lithium alloy plate obtained by the layer-cutting method test step (5) is measured, and the room temperature mechanical properties of the sample are measured by room temperature tensile test.

[0030] The plate manufactured in this embodiment has cracking problems on all sides; Figure 3 As shown, Figure 3 This is a microstructure characterization photograph 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 treatment; 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.

[0031] 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.

[0032] Example 2 This embodiment adopts the same manufacturing method as that of embodiment 1 to manufacture aluminum-lithium alloy, except that the chemical composition and the cooling process after aging are different, as follows: 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.

[0033] The plate manufactured in this embodiment has the phenomenon of bending and warping. Figure 4 As shown, Figure 4 This is a microstructure characterization photograph of the plate manufactured in this embodiment. Figure 4 It can be seen that the precipitated phases are mainly θ′ phase and δ′ phase.

[0034] 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.

[0035] Example 3 This embodiment adopts the same manufacturing method as that of embodiment 1 to manufacture aluminum-lithium alloy, except that the chemical composition and the cooling process after aging are different, as follows: 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.

[0036] The plate manufactured in this embodiment did not show any bending, warping or even cracking, and the macroscopic appearance of the manufactured plate was flat. Figure 5 As shown, Figure 5 This is a microstructure characterization photograph 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 obviously grown in size, resulting in aggravated lattice distortion, increased internal stress, and corresponding increase in residual stress.

[0037] 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.

[0038] Example 4 This embodiment adopts the same manufacturing method as that of embodiment 1 to manufacture aluminum-lithium alloy, except that the chemical composition and the cooling process after aging are different, as follows: 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.

[0039] The plate manufactured in this embodiment does not show any bending, warping or even cracking, and the macroscopic appearance of the manufactured plate is flat. Figure 6 This is a microstructure characterization photograph 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.

[0040] 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.

[0041] Compared with Examples 1, 2, 3, and 4, the residual stress of the aluminum-lithium alloy manufactured in Example 4 is less than that in Examples 1, 2, and 3, and the tensile strength and elongation after fracture are the highest. Therefore, considering the strength-plasticity matching of the alloy and the cost consumption in practical applications, Example 4 is the best.

[0042] Comparative Example 1: Yang Shengli et al. used quenched 2195 aluminum-lithium alloy The residual stress test experiment was conducted to compare the aluminum-lithium alloy manufactured in this comparative example with that manufactured in Example 4. The results show that the absolute value of the residual stress of the aluminum-lithium alloy plate manufactured in Comparative Example 1 after quenching is stable within 25MPa; while the residual stress of the aluminum-lithium alloy manufactured in the present invention is only 16MPa, and the reduction effect is better; and the aluminum-lithium alloy involved in the present invention has an excellent strength-to-plasticity ratio at room temperature, and is suitable for being put into the field of industrial production.

[0043] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0044] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be 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 will not be limited to the embodiments shown herein, but rather 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; S2) subjecting the aluminum-lithium alloy ingot obtained in step S1) to deformation treatment, and then sequentially subjecting the ingot to solid solution treatment and aging treatment to obtain an aluminum-lithium alloy; 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.

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 10-20h, 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 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%.

4. The manufacturing process according to claim 1, characterized in that: 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.

5. The manufacturing process according to claim 1, characterized in that: In step S2), the holding time of the aging treatment is 12 to 36 hours.

6. The manufacturing process according to claim 1, characterized in that: In step S2), the cooling method of the aging treatment is furnace cooling + air cooling.

7. The manufacturing process according to any one of claims 1 to 6, characterized in that: 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%.

8. The manufacturing process according to claim 7, characterized in that: In step S1), the method for manufacturing the aluminum-lithium alloy ingot is specifically as follows: According to the composition ratio of the aluminum-lithium alloy, a Mg ingot, an Al-Ag master alloy, an Al-Zr master alloy, an Al-Cu master alloy, an Al-Li master alloy and an Al ingot are prepared; The Al ingot is added into a vacuum melting furnace, and kept at 700-800° C. for 30-90 min, 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, and the obtained aluminum liquid is kept for 1-3 h to obtain an aluminum-lithium alloy melt; The aluminum-lithium alloy melt is cast to obtain an aluminum-lithium alloy ingot.

9. The manufacturing process according to claim 8, characterized in that: Before adding the Al ingot into the vacuum melting furnace, the following steps are also included: The vacuum melting furnace is evacuated to a vacuum degree of (0.2-0.5) × 10 -2 Pa, then add protective gas, and when the pressure of the protective gas is 0.10~0.30Pa, stop charging; the above process is repeated 2~5 times.

10. The manufacturing process according to claim 9, 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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