High-strength and high-toughness aluminum-lithium alloy plate and preparation method thereof

Abstract

The invention provides a high-strength and high-toughness aluminum-lithium alloy plate and a preparation method thereof, and belongs to the technical field of metal materials and metallurgy. According to the method, an aluminum-lithium alloy cast ingot with excellent casting performance is cast through alloy elements in scientific proportion and a precise smelting process, most casting defects are eliminated through hot rolling deformation, sufficient machining strengthening is obtained through cold rolling deformation, then two-section pre-deformation is conducted on an aluminum-lithium alloy plate subjected to solution treatment, the dislocation density is increased, and the machining strength of the aluminum-lithium alloy plate is improved. The aging precipitation power of the alloy is remarkably improved, a large number of fine and dispersed T1 (Al2CuLi) phases and theta '(Al2Cu) phase strengthening phases are precipitated in the aging process, the strength, toughness and plasticity of the aluminum-lithium alloy are effectively improved, a destressed high-strength and high-toughness aluminum-lithium alloy plate with the flat appearance is obtained, the yield strength can reach 520-560 MPa, the tensile strength can reach 580-630 MPa, the ductility is 8-12%, and the tensile strength can reach 580-630 MPa. And the use requirements of high-standard aerospace structural materials can be met.

Description

Technical Field

[0001] This invention relates to the fields of metallic materials and metallurgical technology, and in particular to a high-strength and high-toughness aluminum-lithium alloy plate and its preparation method. Background Technology

[0002] Aluminum-lithium alloys are a class of alloys in which metallic lithium is added to the lightweight metal material aluminum or aluminum alloys. Lithium (Li) is the lightest existing metallic element, and adding lithium to aluminum alloys makes them even lighter. Current reports show that replacing conventional aluminum alloys with aluminum-lithium alloys can reduce the weight of components by 10-15% and increase stiffness by 15-20%, while maintaining similar strength, corrosion resistance, fatigue resistance, and ductility as conventional aluminum alloys. This has led to the rapid development of aluminum-lithium alloys, which are gradually replacing traditional 2xxx and 7xxx series aluminum alloys and are widely used in structural materials in the aerospace field.

[0003] The development of aluminum-lithium alloys has gone through three eras, corresponding to three generations of aluminum-lithium alloy products. Compared with the low strength of the first-generation alloys and the poor toughness and plasticity of the second-generation alloys, the third-generation aluminum-lithium alloys have achieved superior comprehensive mechanical properties. The third-generation aluminum-lithium alloys are Al-Cu-Li alloys, a type of age-hardening alloy. Strengthening is mainly achieved through the precipitation of a second phase during artificial aging. The main age-hardening phases include T1 phase (Al2CuLi), θ′ phase (Al2Cu), and δ′ phase (Al3Li). Among these, the T1 phase has the strongest strengthening effect, and its contribution to alloy strength is positively correlated with its volume fraction and diameter. Alloying, work hardening, and age hardening are effective methods to change the types and distribution of precipitated phases in aluminum-lithium alloys, and are also the main means to achieve the strengthening and toughening of aluminum-lithium alloys. However, existing technologies, such as patents with publication numbers CN108823519 A and CN108330360 A, disclose alloy processing methods involving extrusion deformation. However, the sheet metal most commonly used in aerospace structural materials is limited by the deformation method, making it difficult to achieve the strength of extruded alloys. With the continuous development of the aerospace industry, higher requirements are being placed on the strength and toughness of aluminum-lithium alloys, especially aluminum-lithium alloy sheets. Limitations in alloy composition, manufacturing processes, and deformation amounts hinder their further application in related fields. Summary of the Invention

[0004] The purpose of this invention is to provide a high-strength and high-toughness aluminum-lithium alloy sheet and its preparation method. Through scientifically proportioned alloying elements and smelting processes, high-performance aluminum-lithium alloy ingots are smelted. Most casting defects are eliminated by hot rolling deformation, followed by cold rolling deformation to obtain sufficient processing strengthening. The aluminum-lithium alloy sheet after solution treatment is then pre-deformed to increase dislocation density and significantly improve the aging precipitation kinetics of the alloy. During the aging process, a large number of strengthening phases precipitate, effectively improving the strength and toughness of the aluminum-lithium alloy. This results in a stress-relieved, smooth-shaped high-strength and high-toughness aluminum-lithium alloy sheet.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a high-strength and high-toughness aluminum-lithium alloy sheet, with the following chemical composition by mass percentage: Cu 3.3~3.7%, Li 1.0~1.2%, Mg 0.3~0.5%, Mn 0.2~0.6%, Zn 0.2~0.4%, Ag 0.2~0.4%, Zr 0.08~0.12%, Ti 0.08~0.12%, impurities <0.1%, and the remainder being Al; The method for preparing the high-strength and high-toughness aluminum-lithium alloy plate includes the following steps: The raw materials corresponding to each chemical component are mixed, and then melted and refined in sequence. A covering agent is added to obtain an alloy liquid. The alloy liquid is cast into a shape to obtain an ingot; The ingot is homogenized to obtain an alloy slab. The alloy slab is hot-rolled and deformed, and then annealed to obtain an annealed alloy. The annealed alloy is cold-rolled and then solution-treated to obtain a solution-treated alloy. After pre-deformation treatment of the solid solution alloy, aging treatment is performed to obtain a high-strength and high-toughness aluminum-lithium alloy sheet.

[0006] This invention provides a method for preparing the high-strength and high-toughness aluminum-lithium alloy plate described in the above technical solution, comprising the following steps: The raw materials corresponding to each chemical component are mixed, and then melted and refined in sequence. A covering agent is added to obtain an alloy liquid. The alloy liquid is cast into a shape to obtain an ingot; The ingot is homogenized to obtain an alloy slab. The alloy slab is hot-rolled and deformed, and then annealed to obtain an annealed alloy. The annealed alloy is cold-rolled and then solution-treated to obtain a solution-treated alloy. After pre-deformation treatment of the solid solution alloy, aging treatment is performed to obtain a high-strength and high-toughness aluminum-lithium alloy sheet.

[0007] Preferably, the raw materials include Al, Al-Cu master alloy, Al-Mn master alloy, Al-Zr master alloy, Al-Ti master alloy, Zn, Ag, Mg and Li.

[0008] Preferably, the refining agent used in the refining process is argon or hexachloroethane; the covering agent is any two or three of LiCl, LiF, KCl, and NaCl.

[0009] Preferably, the casting method is casting or continuous casting, the casting temperature is 700~740℃, and the formed shape is a cuboid.

[0010] Preferably, the homogenization process includes a first-stage homogenization and a second-stage homogenization performed sequentially. The temperature of the first-stage homogenization is 460~480℃ and the time is 8~12h. The temperature of the second-stage homogenization is 520~540℃ and the time is 12~16h.

[0011] Preferably, the hot rolling deformation temperature is 440~480℃, and the total deformation is 60~80%; the annealing treatment temperature is 530~545℃, and the time is 30~90min.

[0012] Preferably, the temperature of the cold rolling treatment is 20~25℃, and the total deformation is 60~84%; the temperature of the solution treatment is 525~545℃, and the time is 30~100min.

[0013] Preferably, the pre-deformation process includes a first stage of cold deformation and a second stage of cold deformation performed sequentially. The first stage of cold deformation is pre-rolling with a deformation amount of 5-25% and a processing temperature of 20-25°C. The second stage of cold deformation is pre-stretching with a deformation amount of 2.5-5% and a processing temperature of 20-25°C.

[0014] Preferably, the aging treatment is performed at a temperature of 150~200℃ for 4~32 hours.

[0015] This invention provides a high-strength and high-toughness aluminum-lithium alloy sheet. The aluminum-lithium alloy sheet of this invention features a rationally proportioned composition. The main alloying elements (Al, Cu, Li) ensure sufficient precipitation of strengthening phases, while the remaining micro-alloying elements significantly promote the precipitation of strengthening phases. Through a scientifically proportioned alloying element and smelting process, a high-performance aluminum-lithium alloy ingot is cast. Hot rolling deformation eliminates most casting defects, followed by cold rolling deformation to obtain sufficient processing strengthening. The solution-treated aluminum-lithium alloy sheet then undergoes two-stage pre-deformation, increasing dislocation density and significantly enhancing the aging precipitation kinetics of the alloy. During artificial aging, a large number of fine and dispersed T1 (Al2CuLi) and θ′ (Al2Cu) phases, among other strengthening phases, precipitate, effectively improving the strength and toughness of the aluminum-lithium alloy. This results in a stress-relieved, smooth-surfaced, high-strength and high-toughness aluminum-lithium alloy sheet that meets the requirements of high-standard aerospace structural materials.

[0016] The processing steps of this invention include smelting, refining, and casting. The deformation and heat treatment methods include homogenization, hot rolling, annealing, cold rolling, and solution treatment. After deformation and heat treatment processes with specific parameters, a work-strengthened aluminum-lithium alloy sheet with good compositional uniformity, dense structure, and excellent plasticity is obtained. The pre-deformation and aging methods include sequentially performing pre-rolling cooling deformation treatment and pre-stretching treatment on the solution-treated aluminum-lithium alloy, and then performing artificial aging treatment on the pre-stretched product. This invention introduces a large number of dislocations through the pre-rolling cooling deformation process, thereby introducing work hardening, increasing dislocation density, and improving the aging precipitation dynamics of the alloy. The pre-stretching treatment eliminates residual stress from the cold deformation process, resulting in a stress-relieved alloy sheet with a smooth shape. The artificial aging treatment precipitates a large number of strengthening phases such as T1 (Al2CuLi) phase and θ′ (Al2Cu) phase, effectively achieving the strengthening and toughening of the aluminum-lithium alloy sheet. The aluminum-lithium alloy sheet manufactured using the method of this invention has a yield strength of 520-560 MPa, a tensile strength of 580-630 MPa, and an elongation of 8-12%, which can meet the requirements of high-standard aerospace structural materials.

[0017] The process design of this invention is ingenious, has low equipment requirements, is highly operable, is conducive to engineering practice, and has a good prospect for promotion and application. Attached Figure Description

[0018] Figure 1 The image shows the metallographic structure of the alloy obtained after solution heat treatment in Example 1. Figure 2 The transmission electron microscopy (TEM) diffraction spots, bright-field image, and dark-field image of the aluminum-lithium alloy plate obtained after aging heat treatment in Example 1 are shown; wherein, (a) electron beam along <110> α Dark field diagram of the incident electron beam, (b) electron beam along <112> α Dark field diagram of the incident light; Figure 3Tensile stress-strain curves of the aluminum-lithium alloy plates prepared in Examples 1-4; Figure 4 The graph shows a comparison of the mechanical properties of the aluminum-lithium alloy plates prepared in Examples 1-4. Detailed Implementation

[0019] In this invention, unless otherwise specified, the raw materials or reagents required for preparation are all commercially available products well known to those skilled in the art.

[0020] This invention provides a high-strength and high-toughness aluminum-lithium alloy sheet, with the following chemical composition by mass percentage: Cu 3.3~3.7%, Li 1.0~1.2%, Mg 0.3~0.5%, Mn 0.2~0.6%, Zn 0.2~0.4%, Ag 0.2~0.4%, Zr 0.08~0.12%, Ti 0.08~0.12%, impurities <0.1%, and the remainder being Al; The method for preparing the high-strength and high-toughness aluminum-lithium alloy plate includes the following steps: The raw materials corresponding to each chemical component are mixed, and then melted and refined in sequence. A covering agent is added to obtain an alloy liquid. The alloy liquid is cast into a shape to obtain an ingot; The ingot is homogenized to obtain an alloy slab. The alloy slab is hot-rolled and deformed, and then annealed to obtain an annealed alloy. The annealed alloy is cold-rolled and then solution-treated to obtain a solution-treated alloy. After pre-deformation treatment of the solid solution alloy, aging treatment is performed to obtain a high-strength and high-toughness aluminum-lithium alloy sheet.

[0021] In the high-strength and high-toughness aluminum-lithium alloy sheet of this invention, the main alloying elements (Al, Cu, Li) ensure sufficient precipitation of strengthening phases, while the remaining microalloying elements significantly promote the precipitation of strengthening phases. Specifically, the main alloying elements (Al, Cu, Li) provide the most important strengthening phases, such as the Ti(Al2CuLi) phase and the θ′(Al2Cu) phase; Li can also reduce density and increase stiffness; Mg, Ag, and Zn synergistically promote the precipitation of the Ti phase; Zr and Ti act as grain refiners; and Mn can introduce Al... 20 The Cu2Mn3 phase optimizes recrystallization behavior and reduces the anisotropy of the plate.

[0022] In this invention, the high-strength and high-toughness aluminum-lithium alloy sheet contains 3.3-3.7% Cu, preferably 3.42-3.62%, and more preferably 3.56-3.60%.

[0023] In this invention, the high-strength and high-toughness aluminum-lithium alloy sheet contains 1.0~1.2% Li, preferably 1.01~1.12%, and more preferably 1.05~1.10%.

[0024] In this invention, the high-strength and high-toughness aluminum-lithium alloy sheet contains 0.3-0.5% Mg, preferably 0.35-0.47%, and more preferably 0.39-0.44%.

[0025] In this invention, the high-strength and high-toughness aluminum-lithium alloy sheet contains 0.2-0.6% Mn, preferably 0.21-0.55%, and more preferably 0.36-0.51%.

[0026] In this invention, the high-strength and high-toughness aluminum-lithium alloy sheet contains 0.2-0.4% Zn, preferably 0.25-0.38%, and more preferably 0.34-0.35%.

[0027] In this invention, the high-strength and high-toughness aluminum-lithium alloy sheet contains 0.2-0.4% Ag, preferably 0.25-0.35%, and more preferably 0.26-0.27%.

[0028] In this invention, the high-strength and high-toughness aluminum-lithium alloy sheet contains 0.08~0.12% Zr, preferably 0.09~0.11%, and more preferably 0.10%.

[0029] In this invention, the high-strength and high-toughness aluminum-lithium alloy sheet contains 0.08~0.12% Ti, preferably 0.09~0.11%, and more preferably 0.10%.

[0030] In this invention, the content of a single impurity element in the high-strength and high-toughness aluminum-lithium alloy sheet is <0.04%, and the total impurity content is <0.1%. This invention does not limit the specific types of impurity elements; all are known impurities in aluminum-lithium alloys.

[0031] This invention provides a method for preparing the high-strength and high-toughness aluminum-lithium alloy plate described in the above technical solution, comprising the following steps: The raw materials corresponding to each chemical component are mixed, and then melted and refined in sequence. A covering agent is added to obtain an alloy liquid. The alloy liquid is cast into a shape to obtain an ingot; The ingot is homogenized to obtain an alloy slab. The alloy slab is hot-rolled and deformed, and then annealed to obtain an annealed alloy. The annealed alloy is cold-rolled and then solution-treated to obtain a solution-treated alloy. After pre-deformation treatment of the solid solution alloy, aging treatment is performed to obtain a high-strength and high-toughness aluminum-lithium alloy sheet.

[0032] In this invention, the raw materials preferably include Al, Al-Cu master alloy, Al-Mn master alloy, Al-Zr master alloy, Al-Ti master alloy, Zn, Ag, Mg and Li.

[0033] In this invention, each raw material is weighed according to the stated mass percentage, and an argon-protected atmosphere melting furnace is used to add each raw material into the melting furnace in sequence. The preferred order of addition is to first add pure Al, and after Al is completely melted, add Al-Cu master alloy, Al-Mn master alloy, Al-Zr master alloy, Al-Ti master alloy, pure Zn, pure Ag, pure Mg, and pure Li in sequence.

[0034] After all the raw materials are mixed and melted evenly, the resulting melt is refined and then added as a covering agent after standing for 15-30 seconds.

[0035] In this invention, the refining agent used for refining is preferably argon or hexachloroethane; the covering agent is preferably any two or three of LiCl, LiF, KCl, and NaCl; this invention does not have a special limitation on the ratio of different types of covering agents, and any ratio is acceptable. This invention does not have a special limitation on the amount of the refining agent and the covering agent, and can adjust them according to the melt mass and crucible diameter in a manner well known in the art. The smelting process in this invention is designed to provide high-quality ingots for subsequent deformation processing.

[0036] In this invention, the casting method is preferably casting or continuous casting, the casting temperature is preferably 700~740℃, more preferably 710~730℃, and even more preferably 720℃, and the forming shape is preferably cuboid. This invention does not impose any special limitations on the dimensions of the cast body; adjustments can be made according to requirements.

[0037] In this invention, the homogenization process preferably includes a first-stage homogenization and a second-stage homogenization performed sequentially. The temperature of the first-stage homogenization is preferably 460~480℃, more preferably 465~470℃, and the time is preferably 8~12h, more preferably 10h. The temperature of the second-stage homogenization is preferably 520~540℃, more preferably 530℃, and the time is preferably 12~16h, more preferably 13~14h.

[0038] After the homogenization treatment, the present invention preferably removes the surface oxide layer by machining to obtain an alloy slab.

[0039] In this invention, the temperature of the hot rolling deformation is preferably 440~480℃, more preferably 450~465℃, and the total deformation is preferably 60~80%, more preferably 65~75%, and even more preferably 70%; the temperature of the annealing treatment is preferably 530~545℃, more preferably 535~540℃, and the time is preferably 30~90min, more preferably 45~60min.

[0040] In this invention, the temperature of the cold rolling process is preferably 20~25℃, more preferably 25℃, and the total deformation is preferably 60~84%, more preferably 65~75%.

[0041] In this invention, the solution treatment temperature is preferably 525~545℃, more preferably 530~535℃, and the time is preferably 30~100min, more preferably 60~90min.

[0042] After solution treatment, the present invention preferably performs water quenching treatment with a residence time of 1.5 to 2 minutes.

[0043] After rigorous optimization of deformation and heat treatment process parameters, this invention yields an aluminum-lithium alloy sheet with enhanced processing strength, good compositional uniformity, dense structure, and excellent plasticity.

[0044] In this invention, the pre-deformation treatment preferably includes a first stage of cold deformation and a second stage of cold deformation performed sequentially. The first stage of cold deformation is pre-rolling, with a deformation amount preferably of 5-25%, more preferably 10-20%, and even more preferably 15-17.5%, and a processing temperature of 20-25°C, more preferably 25°C. The second stage of cold deformation is pre-stretching, with a deformation amount preferably of 2.5-5%, more preferably 3-4%, and a processing temperature preferably of 20-25°C, more preferably 25°C.

[0045] In this invention, the aging treatment temperature is preferably 150~200℃, more preferably 165~190℃, even more preferably 175~180℃, and the time is preferably 4~32h, more preferably 12~24h, even more preferably 16~18h; the aging treatment is preferably artificial aging treatment.

[0046] This invention introduces a large number of dislocations through a pre-rolling cold deformation process, thereby introducing work hardening, increasing dislocation density, and improving the aging precipitation dynamics of the alloy. The residual stress from the cold deformation process is eliminated through pre-stretching treatment, resulting in a stress-relieved alloy sheet with a smooth shape. Artificial aging treatment precipitates a large number of strengthening phases such as T1(Al2CuLi) and θ′(Al2Cu), resulting in a high-strength and high-toughness aluminum-lithium alloy sheet.

[0047] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0048] Unless otherwise specified, the experimental methods described in the various embodiments of this invention are conventional methods; unless otherwise specified, the reagents and raw materials described below are all commercially available.

[0049] In the following examples, the purity of pure Al is 99.99%, the purity of pure Zn is 99.99%, the purity of pure Ag is 99.9%, the purity of pure Mg is 99.9%, and the purity of pure Li is 99.9%.

[0050] Example 1

[0051] The aluminum-lithium alloy sheet provided in this embodiment has the following alloy composition (wt%) as determined by ICP analysis: Cu 3.56%, Li 1.12%, Mg 0.44%, Mn 0.36%, Zn 0.35%, Ag 0.26%, Zr 0.11%, Ti 0.09%, with the remainder being Al.

[0052] The preparation method of the above aluminum-lithium alloy plate: Melting and casting: According to the above mass percentages, weigh out pure Al, Al-Cu master alloy, Al-Mn master alloy, Al-Zr master alloy, Al-Ti master alloy, pure Zn, pure Ag, pure Mg, and pure Li raw materials. Add each raw material to the melting furnace in sequence, first adding pure Al. After Al is completely melted, add it to the argon-protected melting furnace in the above order. After all the raw materials are mixed evenly, refine the melt with hexachloroethane. After standing for 20 seconds, sprinkle in LiCl and LiF in a mass ratio of 1:1 as a covering agent. Cast the alloy liquid obtained from melting at 720°C into a rectangular ingot. Homogenization heat treatment and deformation: The above ingot is subjected to a two-stage homogenization treatment of 470℃ / 10h+530℃ / 14h. The surface oxide layer is removed by machining to obtain a regular geometric slab. The slab is hot rolled at 465℃ / 70% and then annealed at 540℃ / 45min. Finally, it is cold rolled at 25℃ with a 75% reduction to obtain a cold-formed aluminum-lithium alloy plate. Solution treatment: The aluminum-lithium alloy plate was subjected to solution heat treatment at 535℃ for 60 min, followed by water quenching for a dwell time of 1.5 min. Pre-deformation and heat treatment: The plate treated above is subjected to pre-rolling cold deformation treatment with a deformation amount of 15% at 25℃, followed by pre-stretching treatment with a deformation amount of 3%, and then artificial aging treatment at 175℃ / 16h to obtain aluminum-lithium alloy plate.

[0053] Tensile mechanical property tests showed that the aluminum-lithium alloy sheet had a yield strength of 521 MPa, a tensile strength of 590 MPa, and an elongation of 10.5%.

[0054] Example 2

[0055] The aluminum-lithium alloy sheet provided in this embodiment has the following alloy composition (wt%) as determined by ICP analysis: Cu 3.56%, Li 1.12%, Mg 0.44%, Mn 0.36%, Zn 0.35%, Ag 0.26%, Zr 0.11%, Ti 0.09%, with the remainder being Al.

[0056] The aluminum-lithium alloy sheet was subjected to the same melting, homogenization heat treatment and deformation process as in Example 1 to obtain a cold-deformed aluminum-lithium alloy sheet.

[0057] The aluminum-lithium alloy plate was subjected to solution heat treatment at 530℃ for 90 min, followed by water quenching for 2 min. The above-treated sheet is subjected to pre-rolling cold deformation treatment with a deformation amount of 15% at 25℃, followed by pre-stretching treatment with a deformation amount of 3%, and then artificial aging treatment at 175℃ for 16h to obtain aluminum-lithium alloy sheet.

[0058] Tensile mechanical property tests showed that the yield strength of the aluminum-lithium alloy sheet was 539 MPa, the tensile strength was 613 MPa, and the elongation was 9.5%.

[0059] Example 3

[0060] The aluminum-lithium alloy sheet provided in this embodiment has the following alloy composition (wt%) as determined by ICP analysis: Cu 3.56%, Li 1.12%, Mg 0.44%, Mn 0.36%, Zn 0.35%, Ag 0.26%, Zr 0.11%, Ti 0.09%, with the remainder being Al.

[0061] The aluminum-lithium alloy sheet was subjected to the same melting, homogenization heat treatment and deformation process as in Example 1 to obtain a cold-deformed aluminum-lithium alloy sheet.

[0062] The aluminum-lithium alloy plate was subjected to solution heat treatment at 535℃ for 60 min, followed by water quenching for 1.5 min. The above-treated sheet is subjected to pre-rolling cold deformation treatment with a deformation amount of 17.5% at 25℃, followed by pre-stretching treatment with a deformation amount of 4%, and then artificial aging treatment at 175℃ for 16h to obtain aluminum-lithium alloy sheet.

[0063] Tensile mechanical property tests showed that the yield strength of the aluminum-lithium alloy sheet was 538 MPa, the tensile strength was 598 MPa, and the elongation was 8.2%.

[0064] Example 4

[0065] The aluminum-lithium alloy sheet provided in this embodiment has the following alloy composition (wt%) as determined by ICP analysis: Cu 3.56%, Li 1.12%, Mg 0.44%, Mn 0.36%, Zn 0.35%, Ag 0.26%, Zr 0.11%, Ti 0.09%, with the remainder being Al.

[0066] The aluminum-lithium alloy sheet was subjected to the same melting, homogenization heat treatment and deformation process as in Example 1 to obtain a cold-deformed aluminum-lithium alloy sheet.

[0067] The aluminum-lithium alloy plate was subjected to solution heat treatment at 535℃ for 60 min, followed by water quenching for 1.5 min. The above-treated sheet is subjected to pre-rolling cold deformation treatment with a deformation amount of 15% at 25℃, followed by pre-stretching treatment with a deformation amount of 3%, and then artificial aging treatment at 180℃ / 12h to obtain aluminum-lithium alloy sheet.

[0068] Tensile mechanical property tests showed that the yield strength of the aluminum-lithium alloy sheet was 529 MPa, the tensile strength was 607 MPa, and the elongation was 9.6%.

[0069] Example 5

[0070] The aluminum-lithium alloy sheet provided in this embodiment has the following alloy composition (wt%) as determined by ICP analysis: Cu 3.62%, Li 1.01%, Mg 0.39%, Mn 0.21%, Zn 0.34%, Ag 0.25%, Zr 0.09%, Ti 0.10%, with the remainder being Al.

[0071] The preparation method of the above aluminum-lithium alloy plate: Melting and casting: According to the above mass percentages, weigh out pure Al, Al-Cu master alloy, Al-Mn master alloy, Al-Zr master alloy, Al-Ti master alloy, pure Zn, pure Ag, pure Mg, and pure Li raw materials and add them to the argon-protected melting furnace in the order of Example 1. After the raw materials are completely mixed evenly, refine the melt with hexachloroethane. After standing for 20 seconds, sprinkle in LiCl, LiF, and KCl in a mass ratio of 1:1:2 as a covering agent. Cast the alloy liquid obtained from melting at 710°C into a rectangular ingot.

[0072] Homogenization heat treatment and deformation: The above-mentioned ingot is subjected to a two-stage homogenization treatment of 470℃ / 10h+530℃ / 14h. The surface oxide layer is removed by machining to obtain a regular geometric slab. The slab is hot rolled at 450℃ / 60% and then annealed at 535℃ / 60min. Finally, it is cold rolled at 84% to obtain a cold-deformed aluminum-lithium alloy plate.

[0073] Solution treatment: The aluminum-lithium alloy plate was subjected to solution heat treatment at 535℃ for 60 min, followed by water quenching for a dwell time of 1.5 min. Pre-deformation and heat treatment: The plate treated above is subjected to pre-rolling cold deformation treatment with a deformation amount of 15% at 25℃, followed by pre-stretching treatment with a deformation amount of 3%, and then artificial aging treatment at 175℃ / 16h to obtain aluminum-lithium alloy plate.

[0074] Tensile mechanical property tests showed that the aluminum-lithium alloy sheet had a yield strength of 528 MPa, a tensile strength of 599 MPa, and an elongation of 10.6%.

[0075] Example 6

[0076] The aluminum-lithium alloy sheet provided in this embodiment has the following alloy composition (wt%) as determined by ICP analysis: Cu 3.62%, Li 1.01%, Mg 0.39%, Mn 0.21%, Zn 0.34%, Ag 0.25%, Zr 0.09%, Ti 0.10%, with the remainder being Al.

[0077] The aluminum-lithium alloy sheet was subjected to the same melting, homogenization heat treatment and deformation process as in Example 5 to obtain a cold-deformed aluminum-lithium alloy sheet.

[0078] The aluminum-lithium alloy plate was subjected to solution heat treatment at 530℃ for 90 min, followed by water quenching for 2 min. The above-treated sheet is subjected to pre-rolling cold deformation treatment with a deformation amount of 15% at 25℃, followed by pre-stretching treatment with a deformation amount of 3%, and then artificial aging treatment at 175℃ for 16h to obtain aluminum-lithium alloy sheet.

[0079] Tensile mechanical property tests showed that the aluminum-lithium alloy sheet had a yield strength of 541 MPa, a tensile strength of 610 MPa, and an elongation of 9.8%.

[0080] Example 7

[0081] The aluminum-lithium alloy sheet provided in this embodiment has the following alloy composition (wt%) as determined by ICP analysis: Cu 3.62%, Li 1.01%, Mg 0.39%, Mn 0.21%, Zn 0.34%, Ag 0.25%, Zr 0.09%, Ti 0.10%, with the remainder being Al.

[0082] The aluminum-lithium alloy sheet was subjected to the same melting, homogenization heat treatment and deformation process as in Example 5 to obtain a cold-deformed aluminum-lithium alloy sheet.

[0083] The aluminum-lithium alloy sheet was subjected to solution heat treatment at 535℃ for 60 min, followed by water quenching for 1.5 min. The above-treated sheet is subjected to pre-rolling cold deformation treatment with a deformation amount of 17.5% at 25℃, followed by pre-stretching treatment with a deformation amount of 4%, and then artificial aging treatment at 175℃ for 16h to obtain aluminum-lithium alloy sheet.

[0084] Tensile mechanical property tests showed that the aluminum-lithium alloy sheet had a yield strength of 533 MPa, a tensile strength of 618 MPa, and an elongation of 11.2%.

[0085] Example 8

[0086] The aluminum-lithium alloy sheet provided in this embodiment has the following alloy composition (wt%) as determined by ICP analysis: Cu 3.62%, Li 1.01%, Mg 0.39%, Mn 0.21%, Zn 0.34%, Ag 0.25%, Zr 0.09%, Ti 0.10%, with the remainder being Al.

[0087] The aluminum-lithium alloy sheet was subjected to the same melting, homogenization heat treatment, deformation, solution heat treatment and pre-deformation process as in Example 5 to obtain a pre-deformed aluminum-lithium alloy sheet.

[0088] The aluminum-lithium alloy plate was subjected to artificial aging treatment at 180℃ for 12 hours to obtain an aluminum-lithium alloy plate.

[0089] Tensile mechanical property tests showed that the yield strength of the aluminum-lithium alloy sheet was 539 MPa, the tensile strength was 629 MPa, and the elongation was 8.9%.

[0090] Example 9

[0091] The aluminum-lithium alloy plate provided in this embodiment has the following alloy composition (wt%) as determined by ICP analysis: Cu 3.42%, Li 1.05%, Mg 0.47%, Mn 0.51%, Zn 0.35%, Ag 0.27%, Zr 0.08%, Ti 0.11%, with the remainder being Al.

[0092] The preparation method of the above aluminum-lithium alloy plate: According to the above mass percentages, pure Al, Al-Cu master alloy, Al-Mn master alloy, Al-Zr master alloy, Al-Ti master alloy, pure Zn, pure Ag, pure Mg, and pure Li raw materials were weighed and added to the argon-protected melting furnace in the order of Example 1. After all the raw materials were mixed evenly, the melt was refined with argon gas. After standing for 20 seconds, 1:1 LiCl and LiF were sprinkled in as a covering agent. Then the alloy liquid obtained by melting was cast into a rectangular ingot at 730°C. Homogenization heat treatment and deformation process: The ingot is subjected to two-stage homogenization treatment of 460℃ / 12h+540℃ / 13h. The surface oxide layer is removed by machining to obtain a regular geometric slab. The slab is subjected to hot rolling deformation of 465℃ / 70%, annealed at 540℃ / 45min, and then cold rolling deformation of 65% to obtain a cold-deformed aluminum-lithium alloy plate. The aluminum-lithium alloy plate was subjected to the same solution heat treatment, pre-deformation and artificial aging treatment as in Example 7 to obtain the aluminum-lithium alloy plate.

[0093] Tensile mechanical property tests showed that the yield strength of the aluminum-lithium alloy sheet was 548 MPa, the tensile strength was 592 MPa, and the elongation was 8.4%.

[0094] Example 10

[0095] The aluminum-lithium alloy plate provided in this embodiment has the following alloy composition (wt%) as determined by ICP analysis: Cu 3.42%, Li 1.05%, Mg 0.47%, Mn 0.51%, Zn 0.35%, Ag 0.27%, Zr 0.08%, Ti 0.11%, with the remainder being Al.

[0096] The aluminum-lithium alloy sheet was subjected to the same melting, homogenization heat treatment and deformation process as in Example 9 to obtain a cold-deformed aluminum-lithium alloy sheet.

[0097] The aluminum-lithium alloy plate was subjected to solution heat treatment at 535℃ for 60 min, followed by water quenching for 1.5 min. The plate was then subjected to pre-rolling cold deformation treatment at 25℃ with a deformation of 20%, followed by pre-stretching treatment with a deformation of 4%, and finally artificial aging treatment at 175℃ for 16 h to obtain the aluminum-lithium alloy plate.

[0098] Tensile mechanical property tests showed that the aluminum-lithium alloy sheet had a yield strength of 533 MPa, a tensile strength of 603 MPa, and an elongation of 10.8%.

[0099] Example 11

[0100] The aluminum-lithium alloy plate provided in this embodiment has the following alloy composition (wt%) as determined by ICP analysis: Cu 3.42%, Li 1.05%, Mg 0.47%, Mn 0.51%, Zn 0.35%, Ag 0.27%, Zr 0.08%, Ti 0.11%, with the remainder being Al.

[0101] The aluminum-lithium alloy sheet was subjected to the same melting, homogenization heat treatment and deformation process as in Example 9 to obtain a cold-deformed aluminum-lithium alloy sheet.

[0102] The aluminum-lithium alloy plate was subjected to solution heat treatment at 545℃ for 30 min, followed by water quenching for 1.5 min. The plate was then subjected to pre-rolling cold deformation treatment at 25℃ with a deformation of 20%, followed by pre-stretching treatment with a deformation of 4%, and finally artificial aging treatment at 175℃ for 16 h to obtain the aluminum-lithium alloy plate.

[0103] Tensile mechanical property tests showed that the aluminum-lithium alloy sheet had a yield strength of 526 MPa, a tensile strength of 611 MPa, and an elongation of 11.3%.

[0104] Example 12

[0105] The aluminum-lithium alloy plate provided in this embodiment has the following alloy composition (wt%) as determined by ICP analysis: Cu 3.42%, Li 1.05%, Mg 0.47%, Mn 0.51%, Zn 0.35%, Ag 0.27%, Zr 0.08%, Ti 0.11%, with the remainder being Al.

[0106] The aluminum-lithium alloy sheet was subjected to the same melting, homogenization heat treatment and deformation process as in Example 9 to obtain a cold-deformed aluminum-lithium alloy sheet.

[0107] The aluminum-lithium alloy plate was subjected to solution heat treatment at 545℃ for 30 min, followed by water quenching for 1.5 min. The plate was then subjected to pre-rolling cold deformation treatment at 25℃ with a deformation of 20%, followed by pre-stretching treatment with a deformation of 4%, and finally artificial aging treatment at 165℃ for 24 h to obtain the aluminum-lithium alloy plate.

[0108] Tensile mechanical property tests showed that the aluminum-lithium alloy sheet had a yield strength of 535 MPa, a tensile strength of 618 MPa, and an elongation of 9.8%.

[0109] Comparative Example 1

[0110] An aluminum-lithium alloy plate, the alloy composition (wt%) of which is as follows according to ICP analysis: Cu 3.56%, Li 1.12%, Mg 0.44%, Mn 0.36%, Zn 0.35%, Ag 0.26%, Zr 0.11%, Ti 0.09%, with the remainder being Al (composition same as in Example 1).

[0111] The preparation method of the above aluminum-lithium alloy plate: Melting and casting: According to the above mass percentages, weigh out pure Al, Al-Cu master alloy, Al-Mn master alloy, Al-Zr master alloy, Al-Ti master alloy, pure Zn, pure Ag, pure Mg, and pure Li raw materials and add them to the argon-protected melting furnace in the order of Example 1. After the raw materials are completely mixed evenly, refine the melt with hexachloroethane. After standing for 20 seconds, sprinkle in LiCl and LiF in a mass ratio of 1:1 as a covering agent. Cast the alloy liquid obtained from melting at 720°C into a rectangular ingot.

[0112] Homogenization heat treatment and deformation: The ingot is subjected to a two-stage homogenization treatment of 470℃ / 10h + 530℃ / 14h. After removing the surface oxide layer by machining, a regular geometric slab is obtained. The slab is hot rolled at 465℃ / 70% and then annealed at 540℃ / 45min. Finally, it is cold rolled at 25℃ with a 90% reduction to obtain a cold-deformed aluminum-lithium alloy plate. The cold-deformed aluminum-lithium alloy plate has severe edge cracking.

[0113] Solution treatment: The aluminum-lithium alloy plate was subjected to solution heat treatment at 535℃ for 60 min, followed by water quenching for a dwell time of 1.5 min. Pre-deformation and heat treatment: The plate treated above is subjected to pre-rolling cold deformation treatment with a deformation amount of 15% at 25℃, followed by pre-stretching treatment with a deformation amount of 3%, and then artificial aging treatment at 175℃ / 16h to obtain aluminum-lithium alloy plate.

[0114] Tensile mechanical property tests showed that the aluminum-lithium alloy sheet had a yield strength of 543 MPa, a tensile strength of 651 MPa, and an elongation of 5.6%.

[0115] Comparative Example 2

[0116] An aluminum-lithium alloy sheet, the alloy composition (wt%) of which is as follows according to ICP analysis: Cu 3.62%, Li 1.01%, Mg 0.39%, Mn 0.21%, Zn 0.34%, Ag 0.25%, Zr 0.09%, Ti 0.10%, with the remainder being Al (composition same as in Example 5).

[0117] The preparation method of the above aluminum-lithium alloy plate: Based on the above mass percentages, weigh out pure Al, Al-Cu master alloy, Al-Mn master alloy, Al-Zr master alloy, Al-Ti master alloy, pure Zn, pure Ag, pure Mg, and pure Li, and add them sequentially into an argon-protected melting furnace. After all the raw materials are mixed evenly, refine the melt with hexachloroethane. After standing for 20 seconds, sprinkle in LiCl, LiF, and KCl in a mass ratio of 1:1:2 as a covering agent. Then, cast the resulting alloy liquid into a rectangular flat ingot at 710°C.

[0118] Homogenization heat treatment and deformation: The ingot is subjected to a two-stage homogenization treatment of 470℃ / 10h + 530℃ / 14h. After machining to remove the surface oxide layer, a regular geometric slab is obtained. The slab is hot rolled at 450℃ / 60% and then annealed at 535℃ / 60min. Finally, it is cold rolled at 25℃ with a 90% reduction to obtain a cold-deformed aluminum-lithium alloy plate. The cold-deformed aluminum-lithium alloy plate has severe edge cracking.

[0119] Solution treatment: The above aluminum-lithium alloy sheet was subjected to solution heat treatment at 535℃ for 60 min, followed by water quenching for a dwell time of 1.5 min. Pre-deformation and heat treatment: The plate treated above is subjected to pre-rolling cold deformation treatment with a deformation amount of 15% at 25℃, followed by pre-stretching treatment with a deformation amount of 3%, and then artificial aging treatment at 175℃ / 16h to obtain aluminum-lithium alloy plate.

[0120] Tensile mechanical property tests showed that the aluminum-lithium alloy sheet had a yield strength of 524 MPa, a tensile strength of 644 MPa, and an elongation of 4.8%.

[0121] Comparative Example 3

[0122] An aluminum-lithium alloy plate, the alloy composition (wt%) of which is as follows according to ICP analysis: Cu 3.42%, Li 1.05%, Mg 0.47%, Mn 0.51%, Zn 0.35%, Ag 0.27%, Zr 0.08%, Ti 0.11%, with the remainder being Al (composition same as in Example 9).

[0123] The preparation method of the above aluminum-lithium alloy plate: Weigh out pure Al, Al-Cu master alloy, Al-Mn master alloy, Al-Zr master alloy, Al-Ti master alloy, pure Zn, pure Ag, pure Mg, and pure Li raw materials according to the above mass percentages, and add them to the argon-protected melting furnace in this order. After all the raw materials are mixed evenly, use argon to refine the melt. After standing for 20 seconds, sprinkle in LiCl and LiF in a mass ratio of 1:1 as a covering agent. Cast the resulting alloy liquid into a rectangular ingot at 730°C.

[0124] Homogenization heat treatment and deformation: The ingot is subjected to a two-stage homogenization treatment of 460℃ / 12h + 540℃ / 13h. After machining to remove the surface oxide layer, a regular geometric slab is obtained. The slab is hot rolled at 465℃ / 70% and then annealed at 540℃ / 45min. Finally, it is cold rolled at 25℃ with a 90% reduction to obtain a cold-deformed aluminum-lithium alloy plate. The cold-deformed aluminum-lithium alloy plate has severe edge cracking.

[0125] Solution treatment: The above aluminum-lithium alloy sheet was subjected to solution heat treatment at 535℃ for 60 min, followed by water quenching for a dwell time of 1.5 min. Pre-deformation and heat treatment: The plate treated above is subjected to pre-rolling cold deformation treatment with a deformation amount of 17.5% at 25℃, followed by pre-stretching treatment with a deformation amount of 4%, and then artificial aging treatment at 175℃ / 16h to obtain aluminum-lithium alloy plate.

[0126] Tensile mechanical property tests showed that the yield strength of the aluminum-lithium alloy sheet was 522 MPa, the tensile strength was 588 MPa, and the elongation was 4.5%.

[0127] Comparative Example 4

[0128] An aluminum-lithium alloy plate, the alloy composition (wt%) of which is as follows according to ICP analysis: Cu 3.56%, Li 1.12%, Mg 0.44%, Mn 0.36%, Zn 0.35%, Ag 0.26%, Zr 0.11%, Ti 0.09%, with the remainder being Al (composition same as in Example 2).

[0129] The preparation method of the above aluminum-lithium alloy: Based on the above mass percentages, weigh out pure Al, Al-Cu master alloy, Al-Mn master alloy, Al-Zr master alloy, Al-Ti master alloy, pure Zn, pure Ag, pure Mg, and pure Li, and add them sequentially into an argon-protected melting furnace. After all the raw materials are mixed evenly, refine the melt with hexachloroethane. After standing for 20 seconds, sprinkle in LiCl and LiF in a mass ratio of 1:1 as a covering agent. Cast the resulting alloy liquid into a rectangular ingot at 720°C.

[0130] Homogenization heat treatment and deformation: The ingot is subjected to a two-stage homogenization treatment of 470℃ / 10h + 530℃ / 14h. The surface oxide layer is removed by machining to obtain a regular geometric slab. The slab is hot rolled at 465℃ / 70% and then annealed at 540℃ / 45min. Finally, it is cold rolled at 25℃ with a 75% reduction to obtain a cold-formed aluminum-lithium alloy plate.

[0131] Solution treatment: The aluminum-lithium alloy plate was subjected to solution heat treatment at 550℃ for 60 min, followed by water quenching for 1.5 min. Metallographic observation of the solution alloy revealed overheating. Pre-deformation and heat treatment: The plate treated above is subjected to pre-rolling cold deformation treatment with a deformation amount of 15% at 25℃, followed by pre-stretching treatment with a deformation amount of 3%, and then artificial aging treatment at 175℃ / 16h to obtain aluminum-lithium alloy plate.

[0132] Tensile mechanical property tests showed that the yield strength of the aluminum-lithium alloy sheet was 303 MPa, the tensile strength was 437 MPa, and the elongation was 10.8%.

[0133] Comparative Example 5

[0134] An aluminum-lithium alloy plate, the alloy composition (wt%) of which is as follows according to ICP analysis: Cu 3.56%, Li 1.12%, Mg 0.44%, Mn 0.36%, Zn 0.35%, Ag 0.26%, Zr 0.11%, Ti 0.09%, with the remainder being Al (composition same as in Example 2).

[0135] The aluminum-lithium alloy was subjected to the same smelting, heat treatment and deformation processes as Comparative Example 4 to obtain a cold-deformed aluminum-lithium alloy plate.

[0136] The aluminum-lithium alloy sheet was subjected to solution heat treatment at 500℃ for 90 min, followed by water quenching for 1.5 min. Metallographic observation of the solution-treated alloy revealed that the second phase was not completely dissolved into the matrix. The treated sheet was then subjected to pre-rolling cold deformation at 25℃ with a deformation of 15%, followed by pre-stretching with a deformation of 3%, and finally artificial aging at 175℃ for 16 h to obtain the aluminum-lithium alloy sheet.

[0137] Tensile mechanical property tests showed that the yield strength of the aluminum-lithium alloy sheet was 488 MPa, the tensile strength was 577 MPa, and the elongation was 7.8%.

[0138] Comparative Example 6

[0139] An aluminum-lithium alloy plate, the alloy composition (wt%) of which is as follows according to ICP analysis: Cu 3.56%, Li 1.12%, Mg 0.44%, Mn 0.36%, Zn 0.35%, Ag 0.26%, Zr 0.11%, Ti 0.09%, with the remainder being Al (composition same as in Example 2).

[0140] The aluminum-lithium alloy was subjected to the same smelting, heat treatment and deformation processes as Comparative Example 4 to obtain a cold-deformed aluminum-lithium alloy plate.

[0141] The aluminum-lithium alloy sheet was subjected to solution heat treatment at 535℃ for 60 min, followed by water quenching for 1.5 min. The treated sheet was then subjected to pre-rolling cold deformation at 25℃ with a deformation of 30%, followed by pre-stretching with a deformation of 5%, and finally artificial aging at 175℃ for 16 h to obtain the aluminum-lithium alloy sheet.

[0142] Tensile mechanical property tests showed that the yield strength of the aluminum-lithium alloy sheet was 381 MPa, the tensile strength was 474 MPa, and the elongation was 5.3%.

[0143] Comparative Example 7

[0144] An aluminum-lithium alloy plate, the alloy composition (wt%) of which is as follows according to ICP analysis: Cu 3.56%, Li 1.12%, Mg 0.44%, Mn 0.36%, Zn 0.35%, Ag 0.26%, Zr 0.11%, Ti 0.09%, with the remainder being Al (composition same as in Example 2).

[0145] The aluminum-lithium alloy was subjected to the same smelting, heat treatment and deformation processes as Comparative Example 4 to obtain a cold-deformed aluminum-lithium alloy plate.

[0146] The aluminum-lithium alloy sheet was subjected to solution heat treatment at 535℃ for 60 min, followed by water quenching for 1.5 min. The treated sheet was then subjected to pre-rolling cold deformation at 25℃ with a deformation of 4%, followed by pre-stretching with a deformation of 2%, and finally artificial aging at 175℃ for 16 h to obtain the aluminum-lithium alloy sheet.

[0147] Tensile mechanical property tests showed that the yield strength of the aluminum-lithium alloy sheet was 441 MPa, the tensile strength was 564 MPa, and the elongation was 12.3%.

[0148] Comparative Example 8

[0149] An aluminum-lithium alloy plate, the alloy composition (wt%) of which is as follows according to ICP analysis: Cu 3.56%, Li 1.12%, Mg 0.44%, Mn 0.36%, Zn 0.35%, Ag 0.26%, Zr 0.11%, Ti 0.09%, with the remainder being Al (composition same as in Example 2).

[0150] The aluminum-lithium alloy was subjected to the same smelting, heat treatment and deformation processes as Comparative Example 4 to obtain a cold-deformed aluminum-lithium alloy plate.

[0151] The aluminum-lithium alloy sheet was subjected to solution heat treatment at 535℃ for 60 min, followed by water quenching for 1.5 min. The treated sheet was then subjected to pre-rolling cold deformation at 25℃ with a deformation of 15%, followed by pre-stretching with a deformation of 3%, and finally artificial aging at 225℃ for 12 h to obtain the aluminum-lithium alloy sheet.

[0152] Tensile mechanical property tests showed that the yield strength of the aluminum-lithium alloy sheet was 522 MPa, the tensile strength was 613 MPa, and the elongation was 4.6%.

[0153] Comparative Example 9

[0154] An aluminum-lithium alloy plate, the alloy composition (wt%) of which, according to ICP analysis, is Cu 3.56%, Li 1.12%, Mg 0.44%, Mn 0.36%, Zn 0.35%, Ag 0.26%, Zr 0.11%, Ti 0.09%, with the remainder being Al (composition same as in Example 2).

[0155] The aluminum-lithium alloy was subjected to the same smelting, heat treatment and deformation processes as Comparative Example 4 to obtain a cold-deformed aluminum-lithium alloy plate.

[0156] The aluminum-lithium alloy sheet was subjected to solution heat treatment at 535℃ for 60 min, followed by water quenching for 1.5 min. The treated sheet was then subjected to pre-rolling cold deformation treatment at 25℃ with a deformation of 15%, followed by pre-stretching treatment with a deformation of 3%, and finally artificial aging treatment at 125℃ for 24 h to obtain the aluminum-lithium alloy sheet.

[0157] Tensile mechanical property tests showed that the yield strength of the aluminum-lithium alloy sheet was 498 MPa, the tensile strength was 553 MPa, and the elongation was 11.6%.

[0158] Comparative Example 10

[0159] The difference from Example 1 is that its alloy composition (wt%), as determined by ICP analysis, is: Cu 3.48%, Li 1.1%, Mg 0.45%, Zn 0.33%, Ag 0.31%, Zr 0.1%, Ti 0.1%, with the remainder being Al.

[0160] The aluminum-lithium alloy was subjected to the same melting, homogenization heat treatment and deformation, solution treatment, pre-deformation and heat treatment aging process as in Example 1 to obtain aluminum-lithium alloy plates.

[0161] Tensile mechanical property tests showed that the yield strength of the aluminum-lithium alloy sheet was 508 MPa, the tensile strength was 563 MPa, and the elongation was 8.6%, indicating that the mechanical properties would be reduced if Mn were not added.

[0162] Characterization and performance testing

[0163] Figure 1 The image shows the metallographic structure of the alloy obtained after solution heat treatment in Example 1; Figure 1 It is known that the solid solution alloy grains are fibrous, which is the typical state of rolled plates and is the basis for the high strength and toughness of the alloy.

[0164] Figure 2 The transmission electron microscopy (TEM) diffraction spots, bright-field image, and dark-field image of the aluminum-lithium alloy plate obtained after aging heat treatment in Example 1 are shown; wherein, (a) electron beam along <110> α Dark field diagram of the incident electron beam, (b) electron beam along <112> α Incident dark field diagram; by Figure 2 It can be seen that a small amount of Al is visible in the aged alloy. 20 The Cu2Mn3 phase and a large amount of uniformly dispersed T1 phase contribute the most to the precipitation strengthening of the alloy.

[0165] Figure 3 The tensile stress-strain curves of the aluminum-lithium alloy plates prepared in Examples 1-4 are shown below; Figure 3 It can be seen that the aluminum-lithium alloy plates of Examples 1 to 4 all have relatively excellent mechanical properties.

[0166] Figure 4 Comparison of the mechanical properties of aluminum-lithium alloy plates prepared in Examples 1-4; Figure 4 It can be seen that the aluminum-lithium alloy plates of Examples 1 to 4 all have relatively excellent mechanical properties.

[0167] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high-strength and high-toughness aluminum-lithium alloy sheet, characterized in that, The chemical composition, by mass percentage, is as follows: Cu 3.3~3.7%, Li 1.0~1.2%, Mg 0.3~0.5%, Mn 0.2~0.6%, Zn 0.2~0.4%, Ag 0.2~0.4%, Zr 0.08~0.12%, Ti 0.08~0.12%, impurities <0.1%, and the remainder is Al; The method for preparing the high-strength and high-toughness aluminum-lithium alloy plate includes the following steps: The raw materials corresponding to each chemical component are mixed, and then melted and refined in sequence. A covering agent is added to obtain an alloy liquid. The alloy liquid is cast into a shape to obtain an ingot; The ingot is homogenized to obtain an alloy slab. The alloy slab is hot-rolled and deformed, and then annealed to obtain an annealed alloy. The annealed alloy is cold-rolled and then solution-treated to obtain a solution-treated alloy. After pre-deformation treatment, the solid solution alloy is aged to obtain a high-strength and high-toughness aluminum-lithium alloy sheet.

2. The method for preparing the high-strength and high-toughness aluminum-lithium alloy plate according to claim 1, characterized in that, Includes the following steps: The raw materials corresponding to each chemical component are mixed, and then melted and refined in sequence. A covering agent is added to obtain an alloy liquid. The alloy liquid is cast into a shape to obtain an ingot; The ingot is homogenized to obtain an alloy slab. The alloy slab is hot-rolled and deformed, and then annealed to obtain an annealed alloy. The annealed alloy is cold-rolled and then solution-treated to obtain a solution-treated alloy. After pre-deformation treatment, the solid solution alloy is aged to obtain a high-strength and high-toughness aluminum-lithium alloy sheet.

3. The preparation method according to claim 2, characterized in that, The raw materials include Al, Al-Cu master alloy, Al-Mn master alloy, Al-Zr master alloy, Al-Ti master alloy, Zn, Ag, Mg and Li.

4. The preparation method according to claim 2 or 3, characterized in that, The refining agent used in the refining process is argon or hexachloroethane; the covering agent is any two or three of LiCl, LiF, KCl, and NaCl.

5. The preparation method according to claim 2, characterized in that, The casting method is either casting or continuous casting, the casting temperature is 700~740℃, and the formed shape is a cuboid.

6. The preparation method according to claim 2, characterized in that, The homogenization process includes a first-stage homogenization and a second-stage homogenization performed sequentially. The temperature of the first-stage homogenization is 460~480℃ and the time is 8~12h. The temperature of the second-stage homogenization is 520~540℃ and the time is 12~16h.

7. The preparation method according to claim 2, characterized in that, The hot rolling deformation temperature is 440~480℃, and the total deformation is 60~80%; the annealing temperature is 530~545℃, and the time is 30~90min.

8. The preparation method according to claim 2, characterized in that, The cold rolling process is performed at a temperature of 20-25°C, with a total deformation of 60-84%; the solution treatment process is performed at a temperature of 525-545°C for a time of 30-100 minutes.

9. The preparation method according to claim 2, characterized in that, The pre-deformation process includes a first stage of cold deformation and a second stage of cold deformation performed sequentially. The first stage of cold deformation is pre-rolling, with a deformation amount of 5-25% and a processing temperature of 20-25℃. The second stage of cold deformation is pre-stretching, with a deformation amount of 2.5-5% and a processing temperature of 20-25℃.

10. The preparation method according to claim 2, characterized in that, The aging treatment is performed at a temperature of 150~200℃ for a time of 4~32h.

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