A method for producing and processing a cast and rolled 2060 aluminum-lithium alloy sheet

Abstract

The application relates to a preparation method of a cast-rolled 2060 aluminum-lithium alloy plate, which comprises the following steps: preparing raw materials according to target aluminum alloy components; melting, cast-rolling, hot rolling and subsequent heat treatment. The preparation method of the cast-rolled 2060 aluminum-lithium alloy plate provided by the application innovatively uses a double-roller cast-rolling process for efficient preparation of the 2060 aluminum-lithium alloy by controlling and optimizing double-roller cast-rolling process parameters, and successfully prepares the 2060 aluminum-lithium alloy plate with less center segregation, good solidification structure and surface quality and excellent comprehensive performance. The application provides a new method with industrial application prospects for green, environment-friendly, short-process and large-scale efficient preparation of the aluminum-lithium alloy.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method of a 2060 aluminum-lithium alloy plate, and belongs to the technical fields of metal material processing and plate manufacturing. BACKGROUND

[0002] Adding Li as an alloying element into aluminum metal can reduce the specific gravity of the alloy, increase the rigidity, and still keep the alloy with high strength, excellent corrosion resistance and fatigue resistance, and good ductility. Research shows that, with the addition of 1% Li in the aluminum alloy, the alloy density can be reduced by 3%, and the elastic modulus can be increased by 6%.

[0003] Therefore, as a representative of the fourth generation of aluminum-lithium alloy, the 2060 aluminum-lithium alloy has low density, high strength, high elastic modulus and excellent corrosion resistance under the optimization of multiple elements, and forms a synergistic strengthening effect to regulate the microstructure. The 2060 aluminum-lithium alloy has been used in various aircraft fuel tanks, aircraft structural parts, aircraft skin and the like, and has a wide application prospect in aerospace. The 2060 aluminum-lithium alloy can replace the traditional aluminum alloy used on the aircraft without making great changes to the airworthiness regulations, and the aluminum-lithium alloy and the traditional aluminum alloy have a great degree of inheritance in terms of structural design criteria and processing manufacturing process; in addition, the forming and maintenance of the aluminum-lithium alloy are more convenient than those of the composite material, and the cost is far lower than that of the carbon fiber composite material. Therefore, although facing the competition of the composite material, the 2060 aluminum-lithium alloy will still be an important aerospace material with great competitiveness in the future due to its own advantages.

[0004] However, the aluminum-lithium alloy is easy to oxidize in the conventional forming process, and the traditional processing technology has great difficulty, a long process, a complex production line, and high energy consumption and production cost, which seriously restricts the preparation of low-cost and high-quality aluminum-lithium alloy plates.

[0005] In the prior art, the preparation method of the 2060 aluminum-lithium alloy plate mainly includes a semi-continuous casting hot rolling process and a hot extrusion process. The traditional hot rolling blank process has the defects of large equipment investment, long process flow, complex production line, high energy consumption and high production cost, which leads to the limitation in market competition, thereby limiting the development of the hot rolling process; the hot extrusion process is complex, and large internal stress is easy to occur, so that the plate quality is difficult to guarantee, and the production efficiency is not high. In order to eliminate the problems of coarse microstructure, composition segregation, anisotropy and poor processability in the aluminum-lithium alloy, the method of subsequent multiple heat treatment is needed to improve the organization and performance of the alloy, resulting in a long processing cycle and low material utilization.

[0006] Up to now, the problems in the preparation technology of the aluminum-lithium alloy plate have not been well solved, and therefore a new process with simple process, short process flow and commercial application needs to be developed to produce and prepare high-performance aluminum alloy plates. SUMMARY

[0007] (I) Technical problems to be solved

[0008] In order to solve the above problems of the prior art, the present application provides a preparation and processing method of a cast-rolled 2060 aluminum-lithium alloy plate, which solves the problems of wide two-phase region of the aluminum-lithium alloy in the prior art, difficulty in continuous casting and rolling to form a plate, high processing difficulty, high segregation of the plate, and difficulty in quality control.

[0009] (II) Technical solutions

[0010] In order to achieve the above-mentioned purposes, the main technical solutions adopted by the present application include:

[0011] A preparation method of a cast-rolled 2060 aluminum-lithium alloy plate, comprising the following steps:

[0012] S1, batching: preparing raw materials according to the target aluminum alloy composition;

[0013] S2, melting: placing aluminum ingots into an electric resistance furnace with the inner wall of the crucible uniformly coated with boron nitride coating, heating the electric resistance furnace, after the aluminum liquid is completely melted, adding zinc ingots and intermediate alloys into the melt, after the added alloy elements are completely melted, reducing the temperature of the electric resistance furnace by 20-40℃; using a pure titanium pressure cover coated with boron nitride to press the magnesium ingots wrapped with aluminum foil into the melt, after degassing and slagging, adding covering agent into the melt; reducing the temperature of the melt to 690℃ and standing for 1.5h, then quickly pressing lithium ingots into the melt using a pressure cover and slowly rotating the pressure cover for stirring, after the lithium ingots are completely melted, withdrawing the pressure cover, and again adding covering agent;

[0014] S3, casting and rolling: guiding the 2060 aluminum-lithium alloy melt after melting to a runner, and guiding the melt into a double-roller casting and rolling machine through a casting nozzle closely connected with the runner for double-roller casting and rolling; obtaining a raw cast-rolled slab;

[0015] S4, hot rolling: hot rolling the aluminum-lithium alloy billet obtained in step S3 to obtain an aluminum-lithium alloy plate with excellent comprehensive performance;

[0016] S5, heat treatment: performing a suitable heat treatment process on the hot-rolled aluminum-lithium alloy plate to obtain an aluminum-lithium alloy plate meeting the performance requirements.

[0017] As described above, preferably, in step S1, the raw materials are high-purity aluminum ingots (99.99%), high-purity lithium ingots (99.9%), high-purity magnesium ingots (99.9%), high-purity zinc ingots (99.9%), and Al-50% Cu, Al-10% Mn, and Al-5% Zr intermediate alloys.

[0018] As described above, preferably, in step S2, the temperature at which the aluminum liquid is completely melted is 750℃.

[0019] The intermediate alloy is Al-50%Cu, Al-10%Mn, Al-5%Zr; the cooling range is 20-40℃.

[0020] According to the preparation method, preferably, in step S2, the covering agent is LiF:LiCl with a mass ratio of 33:67, the two powders are mixed thoroughly, and then are covered on the surface of the melt, and the amount is appropriate to completely cover the melt.

[0021] According to the preparation method, preferably, in step S2, high-purity argon is introduced during the whole smelting process to protect the atmosphere.

[0022] According to the preparation method, preferably, in step S3, the alloy melt casting temperature is 690-710℃; and the casting speed is 0.5-2.2m / min.

[0023] According to the preparation method, preferably, in step S3, in order to prevent the melt from being polluted, the places where the 2060 aluminum-lithium alloy melt flows through in the whole production process are coated with boron nitride paint and are dried.

[0024] According to the preparation method, preferably, after step S3 and before step S4, the 2060 aluminum-lithium alloy cast slab needs to be subjected to homogenization heat treatment, specifically, the cast slab is kept at 430-500℃ for 16-30h, and then is air-cooled.

[0025] According to the preparation method, preferably, in step S4, after the 2060 aluminum-lithium alloy cast rolling plate is milled, the plate is kept at 470-480℃ in a hot blast furnace for 3-24h, and then is subjected to hot rolling experiment, the rolling angular velocity is 1-2.5rad / s, and after the hot rolling, the plate is annealed at 430℃ in the hot blast furnace for 1-2h; the cast rolling plate is hot-rolled to 1.5-3mm, and the reduction of each pass is 0.5-2mm.

[0026] According to the preparation method, preferably, in step S5, the heat treatment is solid solution at a solid solution temperature of 450-500℃ for 0.5-2h, then cold deformation of 6%, and aging at 130-190℃ for 20-48h.

[0027] (Three) beneficial effects

[0028] The beneficial effects of the present application are:

[0029] The preparation method of the cast-rolled 2060 aluminum lithium alloy plate provided by the application realizes the simplification of procedures, the simplification of equipment, the saving of energy and the reduction of cost; meanwhile, the liquid metal realizes rapid solidification in the double-roller casting process, promotes the formation of metastable phase, improves the solid solubility, refines the structure, and thus greatly improves the performance of the material.

[0030] The preparation method of the cast-rolled 2060 aluminum lithium alloy plate provided by the application realizes the simplification of procedures, the simplification of equipment, the saving of energy and the reduction of cost; meanwhile, the liquid metal realizes rapid solidification in the double-roller casting process, promotes the formation of metastable phase, improves the solid solubility, refines the structure, and thus greatly improves the performance of the material. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 The figure a is a cast-rolled equipment schematic diagram, wherein 1 is an upper roller, 2 is a lower roller, 3 is cooling water, 4 is a melt, 5 is a cast-rolled area, and 6 is a plate blank; the figure b is a cast-rolled equipment actual object diagram;

[0032] Figure 2 The figure is a part of the process flow diagram of the application;

[0033] Figure 3 The figure is the cast-rolled plate obtained after the application;

[0034] Figure 4 The figure is the microstructure of the 2060 aluminum lithium alloy plate, wherein (a) and (b) respectively correspond to the microstructure of the 2060 aluminum lithium alloy plate prepared in step S3 in example 1 and example 2;

[0035] Figure 5 The figure is the tensile curve of the plate sample S5 in the state of example 1 and example 2 under the conditions of the cast-rolled speed and the roll gap of 2.2 m / min-3 mm and 1.2 m / min-6 mm.

[0036] Figure 6 The figure is the metal structure of the cast-rolled sample under the state of step S3 in the comparative example and example 2 without and with the protection of the cladding agent, wherein (a) and (b) respectively correspond to the comparative example and example 2. DETAILED DESCRIPTION

[0037] Compared with the complex preparation process of the existing aluminum lithium alloy sheet forming technology, the process flow is greatly shortened, and the manufacturing cost is saved. The double roll casting process technology is that the molten metal is poured into the casting roll through the casting nozzle, and a series of process procedures such as pouring, cooling, crystallization, solidification, rolling and blanking are completed in the roll gap. The characteristics of the present application are that the metal solidification and rolling deformation are carried out at the same time, the liquid metal is subjected to plastic deformation under pressure while crystallizing and solidifying, and the whole process from liquid metal to solid thin strip is completed in a very short time.

[0038] The aluminum lithium alloy has poor fluidity in the molten state, large solidification shrinkage, high tendency of shrinkage cavity and crack, contains lithium element which is chemically active and easy to react, and has a wide liquid-solid two-phase region, so it is difficult to form a sheet in a rapid solidification environment in actual casting and rolling production; the preparation difficulty is high, the yield is low, the cost is high, and the large-scale application is difficult to realize. Therefore, a special casting and rolling process parameter range is adopted in the present application, the casting and rolling speed is reduced and the cooling intensity is increased, the preparation of the cast and rolled 2060 aluminum lithium alloy is realized, and the cast and rolled plate is prevented from existing a large amount of liquid phase or semi-solid phase after leaving the casting and rolling area, thereby causing cracks. At the same time, the present application studies the heat treatment process of the special 2060 aluminum lithium alloy, and the structure is controlled, so that the cast and rolled 2060 aluminum lithium alloy sheet with short process flow, low cost and high strength is realized.

[0039] The preparation method of the present application determines the relatively suitable casting and rolling temperature range and casting and rolling speed range of the 2060 aluminum lithium alloy, and finds that with the increase of the casting and rolling temperature, the macrosegregation degree of the alloy gradually increases, the average secondary dendrite arm spacing of the cast and rolled plate increases, and the solidification structure of the alloy gradually coarsens. And it is found that with the decrease of the casting and rolling speed, the roll gap becomes wider, the casting and rolling stress in the casting and rolling area decreases, and the macroscopic reverse segregation in the cast and rolled plate caused by extrusion is significantly reduced. At a lower casting and rolling speed, the macrosegregation band of the 2060 aluminum lithium alloy becomes wider, which is the main reason for the improvement of the mechanical properties of the alloy. Research finds that the faster the casting and rolling speed in the double roll casting process, the more serious the dendritic segregation of the alloy, and the more the content of the unbalanced eutectic phase in the alloy. In the tensile process, the large-size hard and brittle phase in the microsegregation area and the unbalanced eutectic phase aggregation area of the cast and rolled plate is easy to peel off from the matrix under the action of tensile stress, thereby producing a large number of microcracks, and greatly reducing the ductility of the material. Therefore, the pouring temperature is preferably 690-710 DEG C, and the casting and rolling speed is preferably 0.5-2.2 m / min.

[0040] The present application utilizes a horizontal double roll casting machine, which is disclosed in the published patent (201510970329.5), and the structure is as shown in the figure. Figure 1As shown in the structure of the application, it comprises: 1, upper roller, 2, lower roller, 3, cooling water, 4, melt, 5, casting and rolling area, 6, slab, by controlling and optimizing the process parameters of double-roller casting, innovatively using double-roller casting process for efficient preparation of 2060 aluminum lithium alloy, successfully prepared the center segregation, solidification structure and surface quality of 2060 aluminum lithium alloy plate with good comprehensive performance. Provide a new method with industrial application prospect for the green, short process, large-scale efficient preparation of aluminum lithium alloy.

[0041] The application provides a preparation and processing method of cast and rolled 2060 aluminum lithium alloy plate, and specifically comprises the following steps:

[0042] S1, batching: preparing raw materials according to the target aluminum alloy composition;

[0043] S2, smelting: first evenly smear boron nitride coating on the inner wall of the crucible of the resistance furnace, turn on the resistance furnace, after the coating is dried, put the aluminum ingot into the resistance furnace, heat the resistance furnace, after the aluminum liquid is completely melted, add zinc ingot, Al-50% Cu, Al-10% Mn, Al-5% Zr intermediate alloy into the melt, after the added alloy elements are completely melted, reduce the temperature of the resistance furnace to 720 DEG C; press the magnesium ingot wrapped by aluminum foil into the melt with a pure titanium pressure cover coated with boron nitride, after degassing and slagging, sprinkle the prepared and dried covering agent with a mass ratio of 33% LiF:67% LiCl into the melt; reduce the temperature of the melt to 690 DEG C and stand for 1.5 h, then quickly press the lithium ingot into the melt with the pressure cover and slowly rotate the pressure cover for stirring, after the lithium ingot is completely melted, pull out the pressure cover, and sprinkle the covering agent of 33% LiF-67% LiCl again.

[0044] S3, casting: before starting the double-roller casting experiment, first start the casting mill, then guide the smelted 2060 aluminum lithium alloy melt out of the runner, and guide the melt into the double-roller casting mill through the casting nozzle closely connected with the runner to carry out the double-roller casting experiment. Get the original cast and rolled slab.

[0045] S4, hot rolling: the aluminum lithium alloy billet obtained in step S3 is subjected to hot rolling treatment to obtain an aluminum lithium alloy plate with excellent comprehensive performance;

[0046] S5, heat treatment: the aluminum lithium alloy plate after hot rolling is subjected to a suitable heat treatment process system to obtain an aluminum lithium alloy plate finally meeting the performance.

[0047] The preparation method described above, preferably, in step S1, the raw materials are high-purity aluminum ingot (99.99%), high-purity lithium ingot (99.9%), high-purity magnesium ingot (99.9%), high-purity zinc ingot (99.9%) and Al-50% Cu, Al-10% Mn, Al-5% Zr intermediate alloy.

[0048] The preparation method as described above, preferably, in step S2, high-purity argon is passed through the whole smelting process for atmosphere protection.

[0049] The preparation method as described above, preferably, in step S2, considering the small density and easy volatilization of lithium element and the uniformity of smelting, other alloy elements are first melted in the form of intermediate alloy, and then lithium metal is added in the form of aluminum foil wrapping in the crucible, otherwise, pure lithium block will be oxidized with air, resulting in element deviation and impurity increase, thus deteriorating the performance.

[0050] The preparation method as described above, preferably, in step S3, the alloy melt casting temperature is 690-710℃.

[0051] The preparation method as described above, preferably, in step S3, the casting and rolling speed is 0.5-2.2m / min.

[0052] The preparation method as described above, preferably, in step S3, the smelting furnace is high-silicon steel, and the inner surface of the high-silicon steel smelting furnace is coated with a coating of heat insulating material, and the coating thickness is 100-300μm of boron nitride paint.

[0053] The preparation method as described above, preferably, in step S3, in order to prevent contamination of the melt, the places where the 2060 aluminum-lithium alloy melt flows through during the whole production process are coated with boron nitride paint and dried.

[0054] The preparation method as described above, preferably, after step S3 and before step S4, the 2060 aluminum-lithium alloy cast slab needs to be subjected to homogenization heat treatment, specifically: the cast slab is kept at 430-500℃ for 16-30h, and then air-cooled.

[0055] The preparation method as described above, preferably, in step S4, after the 2060 aluminum-lithium alloy cast and rolled plate is milled, it is kept at 470℃ in a hot blast furnace for 3h before being subjected to hot rolling experiment, the rolling angular velocity is 1-2.5rad / s, and after hot rolling, it is annealed at 430℃ in a hot blast furnace for 1h.

[0056] The preparation method as described above, preferably, in step S4, the hot rolling process is carried out on a Ф400mm two-roll hot rolling experimental unit, and the alloy plate with an original thickness of 3 / 6mm is hot rolled to 1.5-3mm.

[0057] The preparation method as described above, preferably, in step S5, the ring-rolled plate needs to be subjected to heat treatment, specifically: the solid solution temperature is 450-500℃, the solid solution time is 0.5-2h, then cold deformation is 6%, and aging is carried out at 130-190℃ for 20-48h.

[0058] In order to better explain the present application, in order to facilitate understanding, the following will be combined with the drawings, through the specific implementation, the present application is described in detail.

[0059] Example 1 Preparation of 2060 aluminum lithium alloy cast-rolled medium plate

[0060] The present application proposes a preparation method of 2060 aluminum lithium alloy cast-rolled plate, the equipment used is as shown in Figure 1 The steps are as follows:

[0061] S1, batching: the raw material preparation of 2060 aluminum alloy is carried out according to the proportion of table 1.

[0062] Table 1 Raw material proportion of 2060 aluminum lithium alloy (mass percent)

[0063]

[0064] S2, melt 2060 aluminum lithium alloy by resistance furnace:

[0065] (1) first evenly smear 100-300 μm thick boron nitride coating on the inner wall of the crucible of the resistance furnace, turn on the resistance furnace, after the coating is dried, put the aluminum ingot into the resistance furnace, and the resistance furnace is heated to 750℃.

[0066] (2) after the aluminum liquid is completely melted, add zinc ingot, Al-50% Cu (containing Al Cu alloy with mass percent of 50% Cu), Al-10% Mn (containing Al Mn alloy with mass percent of 10% Mn), Al-5% Zr (containing Al Zr alloy with mass percent of 5% Zr) into the melt, and after the added alloy elements are completely melted, the temperature of the resistance furnace is reduced to 720℃.

[0067] (3) the magnesium ingot wrapped by aluminum foil is pressed into the melt by pure titanium pressure cover coated with boron nitride, after degassing and slagging, the prepared and dried covering agent is poured into the melt. The composition of the covering agent is anhydrous lithium chloride (molecular formula is LiCl) and lithium fluoride (molecular formula is LiF), and the mass ratio of LiCl: LiF is 33:67.

[0068] (4) after the melt temperature is reduced to 690℃ and kept for 1.5h, finally the lithium metal is pressed into the melt in the form of aluminum foil wrapped lithium ingot by pressure cover, and the pressure cover is slowly rotated for stirring, after the lithium ingot is completely melted, the pressure cover is extracted, and the covering agent with mass ratio of 33:67 of LiF: LiCl is poured again to cover the surface of the melt. High-purity argon is introduced throughout the smelting process for atmosphere protection.

[0069] S3, cast-rolled 2060 aluminum lithium alloy, see Figure 2 The operation is shown in

[0070] (1) Before the experiment, graphite should be applied on the surface of the roller to avoid the adhesion of the alloy melt to the roller.

[0071] (2) In order to prevent the contamination of the melt, boron nitride should be applied on the surface of the roller to avoid the adhesion of the alloy melt to the roller.

[0072] (3) Before the experiment, the double roller casting machine should be started, and then the melt of the 2060 aluminum lithium alloy is guided out of the flow tank and into the double roller casting machine through the casting nozzle. The height of the casting nozzle is 3 mm, the casting speed is 2.2 m / min, and the casting temperature is 690℃.

[0073] S4, hot rolling forming:

[0074] (1) The cast slab is subjected to homogenization treatment to reduce internal defects and facilitate subsequent ring rolling deformation. The specific system is: 480℃ for 24h, and then air cooling.

[0075] (2) The homogenized cast slab is subjected to subsequent multi-pass hot rolling treatment to obtain aluminum lithium alloy plate with excellent comprehensive performance. The plate is heated to 430℃ for 2h before ring rolling, and hot rolling starts at a speed of 1.67 rad / s. After two passes, the first pass is from 3mm to 2.5mm, and the second pass is from 2.5mm to 1.5mm.

[0076] S5, heat treatment: the ring-rolled plate is subjected to appropriate heat treatment to meet the subsequent direct use. The specific system is: solid solution at 490℃ for 1h, water quenching; then tensile deformation of 6% deformation; finally, aging at 170℃ for 36h to obtain the final plate, as shown in Figure 3 (b) and (c) are enlarged views of the box in (a), respectively. The solid solution treatment can dissolve the alloy elements Cu, Mg, etc. in the coarse second phase into the matrix, fully play the role of solid solution strengthening of alloy elements, and re-precipitate fine and uniform second phase in the subsequent aging process, ensuring the performance of the subsequent plate.

[0077] The plate after step S3 is detected, as shown in Figure 4(a) is the microstructure photo of the anode film, to observe the grain size and distribution of the alloy. The specific operation of the anode film is: the test sample is used as the anode, the lead electrode is used as the cathode, and is placed in the Barker reagent (1% HF+1% HBF4+24% C2H5OH+74% H2O) in advance, and the film experiment is carried out at a voltage of 20V, a current of 0.1A and a time of 30s, and a polarizing microscope is used to take pictures. The results show that the obtained plate has good performance, high strength and good plasticity, and is convenient for subsequent processing; the structure is uniform and fine equiaxed crystal structure with less segregation, which is convenient for subsequent processing; and the process is short under the condition of sub-rapid forming, the yield is high, and it is suitable for batch production. It is an ideal forming method of aluminum lithium alloy plate.

[0078] A small part of the plate after step S5 is cut off, and the stretcher leveler is flattened to perform a tensile test. The specific operation is that during the test, the testing machine uniformly stretches the sample at a specified rate, and the testing machine can automatically draw a tensile curve. When the sample is stretched to the yield point, the force measuring pointer has obvious jitter, and the upper and lower yield points can be distinguished. In the calculation, the sample after the test is broken is spliced, and the elongation and cross-section reduction are measured to calculate the elongation rate. The measured tensile curve is shown in Figure 5 (a), and the tensile strength can reach 506MPa, and the elongation rate is appropriate.

[0079] Example 2

[0080] The embodiment provides a preparation method of the preceding cast-rolled 2060 aluminum lithium alloy plate, and the influence of the change of flow field and force field in the cast-rolling process of the 2060 aluminum lithium alloy on the subsequent performance is explored. The difference from example 1 is the change of some parameters, mainly the change of the cast-rolling speed and the nozzle height, and the process parameters are as follows: the pouring temperature is 690 DEG C, the cast-rolling speed is 1.2m / min, the nozzle height is 6mm, and the hot rolling system is five passes of down rolling of 6-5-4-3-2-1.5mm, and the remaining steps are the same as the operation in example 1.

[0081] The results show that the 3 / 6mm cast-rolled plates with different cast-rolling force field and flow field distribution under the influence of different cast-rolling speeds all have high strength after processing and heat treatment, because the process generates fine equiaxed crystals under the condition of sub-rapid solidification, as shown in Figure 4 (b), which shows that a uniform and dense cast-rolled aluminum lithium alloy structure has been obtained. And under the action of cast-rolling shearing, the dendritic crystals are broken to form nucleation points, which promote the refinement of the structure and improve the strength. Although the cast-rolled sample of example 1 has a finer structure under high-speed cast-rolling, the high cast-rolling force and forming speed increase the instability of the semi-solid structure, so the strength is limited. The 6mm cast-rolling after the optimization of the process, that is, example 2, has a tensile curve as shown in Figure 5(b) as shown, the amount of casting strain per unit time is reduced, the extrusion effect is lowered, the turbulent motion of high solubility solute is inhibited, the structure under sub-rapid solidification is more uniform, and the subsequent processing performance is better, Figure 5 The strength in (b) reaches 532 MPa, which is much higher than the required 390 MPa delivery strength of the current industrial-grade 2060 aluminum-lithium alloy plate.

[0082] The present application utilizes the sub-rapid solidification and casting shear effect of the casting process, hot rolling deformation, and a proper T8 heat treatment system (the heat treatment is at a solid solution temperature of 450-500 DEG C for 0.5-2 h, followed by cold deformation of 6% at 130-190 DEG C for aging for 20-48 h), which can effectively control the structure size, realize the high-quality aluminum-lithium alloy plate that can be directly used, shorten the process flow, and broaden the industrial application of the aluminum-lithium alloy plate.

[0083] The aluminum-lithium alloy plate prepared by the processes of melting, casting, hot rolling, and T8 heat treatment has finer as-cast grains, more uniform structure and performance, and no obvious macrosegregation.

[0084] Comparative Example

[0085] The comparative example is based on Example 2, and the surface of the melt in step S2 is not protected by the cladding agent provided by the application, and the lithium block is not wrapped with aluminum foil paper. Figure 6 (a) as shown, the structure in Comparative Example 2 is as shown in Figure 6 (b), and the results show that the structure without the protection of the cladding agent contains a large amount of oxide inclusions, resulting in large-size composition segregation, which deteriorates the structure and performance.

[0086] The above is only a preferred embodiment of the present application, and is not intended to limit the other forms of the present application, and any person skilled in the art can modify or modify the above disclosed technical content as equivalent embodiments. However, any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present application still belong to the protection scope of the present application.

Claims

1. A method of producing a cast and rolled 2060 aluminum-lithium alloy sheet material, characterized by, It comprises the following steps: S1, batching: preparing raw materials according to the target aluminum alloy composition; S2, smelting: placing aluminum ingots into the inner wall of the crucible evenly coated with boron nitride coating in the resistance furnace, heating the resistance furnace, after the aluminum liquid is completely melted, adding zinc ingots and intermediate alloy into the melt, after the added alloy elements are completely melted, reducing the temperature of the resistance furnace by 20-40℃; using a pure titanium pressure cover coated with boron nitride to press the magnesium ingot wrapped with aluminum foil into the melt, after degassing and slagging, adding covering agent into the melt; reducing the temperature of the melt to 690℃ and standing for 1.5h, then quickly pressing lithium ingots into the melt with the pressure cover and slowly rotating the pressure cover for stirring, after the lithium ingots are completely melted, withdrawing the pressure cover, and again adding covering agent; wherein the covering agent is LiF:LiCl with a mass ratio of 33:67, after the two powders are fully mixed, covering the surface of the melt, and the amount is sufficient to cover the melt; S3, casting and rolling: guiding the smelted 2060 aluminum lithium alloy melt out to the runner, and guiding the melt into the double roll casting and rolling machine through the casting nozzle closely connected with the runner to perform double roll casting and rolling; obtaining the original casting and rolling slab; the casting and rolling temperature of the 2060 aluminum lithium alloy melt is 690℃; the casting and rolling speed of the double roll casting and rolling machine is 1.2m / min; S4, hot rolling: uniformly homogenizing the aluminum lithium alloy blank obtained in step S3, specifically, the aluminum lithium alloy blank is heat treated at 430-500℃ for 16-30h, and then air cooled; after milling the surface of the 2060 aluminum lithium alloy casting and rolling plate, heat treating at 470-480℃ in the hot air furnace for 3-24h, and then performing hot rolling experiment, the rolling angular velocity is 1-2.5rad / s, and after hot rolling, annealing at 430℃ in the hot air furnace for 1-2h; hot rolling the casting and rolling slab to 1.5-3mm, and the reduction per pass is 0.5-2mm; obtaining aluminum lithium alloy plate with excellent comprehensive performance; S5, heat treatment: performing appropriate heat treatment process on the hot rolled aluminum lithium alloy plate to obtain aluminum lithium alloy plate meeting the performance requirements.

2. The production method according to claim 1, wherein In step S1, high-purity aluminum ingots, high-purity lithium ingots, high-purity magnesium ingots, high-purity zinc ingots, and Al-50%Cu, Al-10%Mn, Al-5%Zr intermediate alloy are used as raw materials.

3. The production method according to claim 1, wherein In step S2, the temperature at which the aluminum liquid is completely melted is 750℃; The intermediate alloy is Al-50%Cu, Al-10%Mn, and Al-5%Zr; the temperature reduction range is 20-40℃.

4. The production method according to claim 1, wherein In step S2, high-purity argon is continuously introduced during the smelting process for atmosphere protection.

5. The production method according to claim 1, wherein In step S3, to prevent contamination of the melt, the places where the 2060 aluminum lithium alloy melt flows during the entire production process need to be coated with boron nitride coating and dried.

6. The production method according to claim 1, wherein In step S5, the heat treatment is solid solution at 450-500℃ for 0.5-2h, then cold deformation of 6%, and aging at 130-190℃ for 20-48h.

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