A high-speed impact-resistant 7xxx series medium-high strength weldable aluminum alloy and a preparation method thereof

Abstract

The invention discloses a high-speed impact resistant 7xxx series medium-high strength weldable aluminum alloy and a preparation method thereof, characterized in that the aluminum alloy is composed of Zn: 4.0-7.0wt%, Mg: 2.0-3.0wt%, Cu: 0.05-0.40wt%, Mn: 0.10-0.40wt%, Cr≤0.25wt%, Ti: 0.03-0.09wt%, Zr: 0.05-0.15wt%, Y: 0.05-0.15wt%, V: 0.03-0.06wt%, Fe≤0.25wt%, Si≤0.20wt%, and the rest is Al and unavoidable impurities. The preparation method includes melting and casting, large structural parts integrally formed or planar structural parts hot rolling formed. The present invention relates to 7xxx series aluminum alloys, which are dealloyed and purified by adding a small amount of elements such as Cu, Mn, Cr, Zr, Ti, Y, and V, thereby enhancing the matrix solid solution bond energy and improving the viscoplasticity of the alloy, thereby achieving large deformation plastic processing and high-speed impact plastic deformation.

Description

Technical Field

[0001] The present invention belongs to the technical field of aluminum alloys, and in particular relates to a high-speed impact resistant 7xxx series medium-high strength weldable aluminum alloy and a preparation method thereof. Background Art

[0002] With the development of modern aluminum equipment technology, the all-round protection and high mobility of special vehicles have become increasingly prominent, and they must be able to deal with threats from various bullets as well as mines and other explosives. On the premise of ensuring a certain degree of protection, the body of a special vehicle places more emphasis on the stability and durability of the structural function. The existing aluminum special vehicle bodies in my country are all manufactured using wire-filled MIG welding connections. The body structure prepared by one-piece molding is more reliable and safer than the welded structure body in the process of long-term service and protection against mine explosion threats. The development of an aluminum alloy for one-piece forgings or homogeneous plates for body structures that is medium-high strength, weldable, resistant to high-speed impact, and has excellent processability has emerged.

[0003] Previous studies have shown that 7xxx series deformed aluminum alloys are prone to adiabatic shearing and shear coordination deformation bands during quasi-static large deformation plastic processing and dynamic high-speed impact processes, and the damage mode forms microcracks along the ends of the deformation bands. Therefore, it is crucial to ensure the performance of the alloy and improve the plastic deformation processing ability of the alloy matrix through micro-element alloying.

[0004] The present invention uses a new principle of micro-element alloying to achieve a new type of 7xxx series medium-high strength weldable aluminum alloy with a single-pass deformation of more than 65% during high-speed impact at room temperature. Through dynamic recrystallization and fine grain coordination, the matrix organization deformation energy absorption is greatly reduced, and the microcrack failure formed at the end of the shear band is improved. The plastic deformation processing capability of the alloy matrix is ​​improved. The researched single-pass large deformation integrated molding preparation technology is used to solve the problem of large-walled thick structure uniformity of special vehicle body structures. Summary of the invention

[0005] The first technical problem to be solved by the present invention is to provide a high-speed impact resistant 7xxx series medium-high strength weldable aluminum alloy which can improve the plastic deformation processing capability of its matrix while ensuring a certain strength.

[0006] The second technical problem to be solved by the present invention is to provide a method for preparing a high-speed impact resistant 7xxx series medium-high strength weldable aluminum alloy.

[0007] The technical solution adopted by the present invention to solve the first technical problem is: a high-speed impact resistant 7xxx series medium-high strength weldable aluminum alloy, characterized in that the mass percentage composition of the aluminum alloy is Zn: 4.0~7.0 wt%, Mg: 2.0~3.0wt%, Cu: 0.05~0.40 wt%, Mn: 0.10~0.40 wt%, Cr≤0.25 wt%, Ti: 0.03~0.09 wt%, Zr: 0.05~0.15 wt%, Fe≤0.25 wt%, Si≤0.20 wt%, inevitable impurities, single impurity content ≤0.05wt%, impurities total ≤0.15wt%, and the rest is Al.

[0008] Preferably, the alloy chemical composition adds a very small amount of elements that form high solid solution bond energy with the Al matrix, with the mass percentages being Y: 0.05-0.15 wt%, and V: 0.03-0.06 wt%.

[0009] The technical solution adopted by the present invention to solve the second technical problem is: a method for preparing a 7xxx series medium-high strength weldable aluminum alloy resistant to high-speed impact, characterized in that it comprises the following preparation steps:

[0010] 1) Melting and casting: the ingredients are prepared according to the required ingredients, the melting temperature is 720℃~780℃, the temperature is kept at 780℃ for a certain time such as 30min~60min, and the ingot is cast at 690℃~720℃;

[0011] 2) One-piece molding of large structural parts (outer dimensions 700-6000mm×200-2000mm×200-600mm):

[0012] (2.1) The aluminum alloy ingot is homogenized by being kept at 470-485°C for 12-36 hours;

[0013] (2.2) The homogenized ingot is widened by forging to obtain a blank; the blank is forged into a basic prototype of a large structural part by free forging, and the edges are trimmed to obtain a conformable blank with a reserved amount of subsequent deformation; the conformable blank is extruded by the upper and lower dies to fill the die cavity by die forging to obtain the final shape of the large structural part, thereby obtaining an integrally formed structural part; the deformation temperature is 400℃~460℃, the final forging temperature is 260℃~400℃, the deformation speed is 10mm / s~30mm / s, and the anvil width ratio is ≥0.4 (preferably 0.4~0.925);

[0014] (2.3) subjecting the molded structural component to overall solid solution treatment at 475-490° C. for 0.5-3 h, room temperature water quenching, two-stage aging heat treatment, with the first stage being at 100-110° C. for 6-8 h, and the second stage being at 135-145° C. for 14 h-18 h, and then being air-cooled after being taken out of the furnace to obtain the required structural strength and protective performance, thereby obtaining the final large-scale aluminum alloy structural component resistant to high-speed impact;

[0015] Or,

[0016] 3) Hot rolling forming of flat structural parts:

[0017] (3.1) Homogenization annealing: The ingot is kept at 470-485°C for 12-36 hours for homogenization treatment;

[0018] (3.2) Hot rolling: the starting rolling temperature is 400℃~460℃, the total processing rate is ≥80%, and the ingot after tempering is processed into plates;

[0019] (3.3) Solution quenching treatment: keep the plate at 475-490℃ for 0.5-3h, and cool it with water at room temperature;

[0020] (3.4) Two-stage aging treatment: Heat the heating furnace to the required temperature, keep it at 100-110℃ for 6-8h in the first stage, keep it at 135-145℃ for 14h-18h in the second stage, and then cool it in air at room temperature to obtain the required structural strength and protective performance, and obtain the final high-speed impact resistant aluminum alloy flat structural parts.

[0021] Preferably, the aluminum alloy billet is subjected to a large deformation of 15% to 35% in 1 to 2 passes during forging and widening or free forging in step 2.2);

[0022] Preferably, in step 3.3), during the hot rolling process, the reduction is 15% to 35% in 1 to 2 passes to achieve large deformation;

[0023] In the aluminum alloy ingot structure of the present invention, in addition to the coarse primary quaternary equilibrium AlZnMg (Cu) phase and MnFeSi phase, the added microalloying effective elements Cu, Mn, Cr, Ti, Zr, Y and V are mainly distributed in the ingot in the form of atoms without forming clusters and precipitated phases.

[0024] The aluminum alloy of the present invention adopts the one-piece molding preparation method of the present invention with 15% to 35% large deformation in the middle 1 to 2 passes to make the large wall thickness section structure of large structural parts or planar structural parts more uniform, even after solid solution at 475 to 490° C., the deformation structure growth of the thickness section is not obvious, the width of the elongated strip grain is about 5 to 20 μm, and the width of the elongated strip subgrain is about 0.5 to 2 μm.

[0025] Due to the composite addition of micro-alloying high solid solubility and high bond energy Y and V elements in the aluminum alloy of the present invention, even in the middle of the one-piece molding preparation method, the large-scale aluminum alloy structural parts of the present invention are deformed by a large reduction of 15% to 35% in 1 to 2 passes or in the room temperature high-speed impact deformation process of the alloy plane structural parts of the present invention, the matrix of the aluminum alloy of the present invention locally undergoes streamlined plastic shear deformation, which will form a deformation composed of countless small equiaxed crystals to bring about coordinated shear deformation, enhance the plastic deformation capacity of the matrix and avoid microcrack failure.

[0026] The aluminum alloy of the present invention further improves the thermal stability and corrosion resistance of the matrix aging strengthening phase in the design of the four main elements of Zn, Mg, Cu and Mn. The aging strengthening phase is composed of metastable T'-AlMgZnCu or T'-AlMgZnMn phase and η'-MgZn 2 The phase composition is 2nm~10nm in size, of which the mass fraction of the metastable T' phase is about 7%, and the mass fraction of the metastable η' phase is 1.5%~2.8%.

[0027] Compared with the prior art, the advantages of the present invention are:

[0028] 1) The present invention relates to a 7xxx series Al-Zn-Mg aluminum alloy. The key technical means to solve the technical problems of this application is that the alloy matrix has medium-to-high strength and high visco-plasticity. The total amount of Zn and Mg and the Zn / Mg ratio are controlled to contribute mainly to the matrix strength, and a small amount of Cu, Mn, Cr, Ti, and Zr are added to obtain auxiliary matrix strengthening effects such as solid solution strengthening, fine grain strengthening, and precipitation strengthening; trace composite additions of elements Y and V enhance the matrix solid solution bond energy and improve the alloy's visco-plasticity, thereby achieving large deformation plastic processing and high-speed impact plastic deformation, ensuring the uniformity of thick cross-section organization and performance, and improving performance. The aluminum alloy of the present invention controls the element Cu content, does not form a coarse primary phase of AlCuY, and maximizes the solid solution of element Y in the cast matrix to play a role in solid solution strengthening and toughening.

[0029] 2) The alloy of the present invention has a very wide thermoplastic processing temperature window. When the billet temperature is 266°C, the alloy of the present invention can still achieve 30% to 80% plastic deformation processing. The deformation preparation method of the alloy of the present invention and the microstructure of the grains and precipitated phases regulated by the two-stage heat treatment process have eliminated the adverse effects of coarse grains and precipitation strengthening on the elastic deformation and plastic deformation of the aluminum alloy matrix, and have good filling properties, reducing the number of reheating and deformation processing, and simplifying the processing flow.

[0030] 3) By combining step 1) with step 2) or step 1) with step 3), the mechanical properties of the 7xxx series aluminum alloy of the present invention are achieved: tensile strength R m ≥410 MPa, yield strength R p0.2≥345 MPa, elongation A≥7.0%, Brinell hardness HBW≥120, impact energy KU 2 ≥12 J; Corrosion resistance: no intergranular corrosion, C-ring stress corrosion resistance loading force ≥260 MPa; Welding performance: joint strength of ER5356 MIG welding with wire ≥240 MPa, joint strength of ER5R59 MIG welding with the same process parameters ≥360 MPa; Dynamic impact performance: at 1800 s -1 Under the strain rate, the impact strength can reach 680 MPa, which is 150% higher than the static strength of 450 MPa.

[0031] The 7xxx series aluminum alloy of the present invention has the characteristics of meeting the technical requirements of special vehicle protective structures in application, namely, medium-high strength, high fracture toughness, good impact resistance, good corrosion resistance, good weldability, and especially excellent plastic processing performance and significant strain rate strengthening effect, and is suitable for the processing of forgings or plates of large complex cross-section protective structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The three-dimensional atom probe 3DATP distribution of each microalloying element atom in the aluminum alloy ingot matrix of the present invention;

[0033] Figure 2 The EBSD image of the matrix deformed grains after the solid solution treatment of the structural part prepared by the aluminum alloy integral molding of the present invention;

[0034] Figure 3 After the aluminum alloy of the present invention is deformed by 65% ​​by high-speed impact, a shear band is formed locally in the matrix through fine grains;

[0035] Figure 4 TEM images and diffraction spots of alloy matrix subgrains and precipitation strengthening phases after aging treatment of the aluminum alloy of the present invention;

[0036] Figure 5 The stress-strain curve of the high-speed impact of the side wall sample of the aluminum alloy large forging according to Example 2 of the present invention; DETAILED DESCRIPTION

[0037] The present invention is further described in detail below with reference to the embodiments.

[0038] Example 1: Preparation of large one-piece forging body from 7xxx series medium-high strength aluminum alloy

[0039] The mass percentage composition of the aluminum alloy is Zn: 4.08wt%, Mg: 2.03wt%, Cu: 0.125 wt%, Mn: 0.209wt%, Cr: 0.151 wt%, Zr: 0.083 wt%, Ti: 0.066 wt%, Y: 0.145 wt%, V: 0.049 wt%, Fe: 0.138wt%, Si: 0.046wt%, and the rest is Al.

[0040] The preparation steps are as follows:

[0041] 1) Melting and casting: The ingredients are prepared according to the required ingredients, the melting temperature is 750℃~780℃, and the ingot is cast after heat preservation. The specifications are: 100mm×1500mm×2500mm, and the weight is about 1000kg;

[0042] 2) Homogenization annealing: large ingots are kept at 475°C for 24 hours;

[0043] 3) One-piece forging of equal-wall-thickness car bodies: Based on the requirements of the car body structure size of 2m×4m×0.6m and the car body wall thickness of 18mm, the large ingot of 100mm×1500mm×2500mm is heated to 450℃ and kept warm for 10h, and forged into a billet of 1850mm×3500mm×56mm. The required car body structure is forged at 400-450℃ through multiple free forgings + one closed die forging. The free forging and die forging are each subjected to a single-pass reduction of ≥20% deformation, the anvil width ratio is 0.8-0.925, the deformation speed is 10 mm / s-20 mm / s, the final forging temperature is 330℃, and the total deformation is >80%. The forging and bending parts of the car body are subjected to internal quality non-destructive testing using the radiographic method in accordance with the Ministry of Energy standard NB / T 47013.2-2015 "Non-destructive testing of pressure equipment Part 2: Radiographic testing". Subsequent processing and heat treatment can only be carried out after the damage meets level II or above.

[0044] 4) Solution treatment: Internal support of the vehicle body structure, overall solution treatment at 480℃ for 2h, followed by water cooling at room temperature;

[0045] 5) Aging process: The whole car body is subjected to aging treatment: the first stage is 100-110℃ for 6-8h, the second stage is 135-145℃ for 14h-18h and then air-cooled.

[0046] Example 2: Preparation of an integrated V-shaped underbody protection structure using 7xxx series medium- and high-strength aluminum alloy to resist high-speed impact

[0047] The mass percentage composition of the aluminum alloy is Zn: 4.80wt%, Mg: 2.80wt%, Cu: 0.199wt%, Mn: 0.397wt%, Cr: 0.177wt%, Zr: 0.150 wt%, Ti: 0.087wt%, Fe: 0.181 wt%, Si: 0.054 wt%, and the rest is Al.

[0048] The preparation steps are as follows:

[0049] 1) Melting and casting: The ingredients are prepared according to the required ingredients, the melting temperature is 750℃~780℃, and the ingot is cast after heat preservation. The specifications are: 300mm×1200mm×1900mm and the weight is about 1800kg;

[0050] 2) Homogenization annealing: large ingots are kept at 470°C for 24 hours;

[0051] 3) One-piece forging of V-shaped body and bottom components with different wall thicknesses: According to the requirements of body structure size 2m×6m×0.5m, side wall thickness 25mm and body bottom thickness 10mm, the large ingot with specifications of 300mm×1200mm×1900mm is heated to 450℃ and kept warm for 10h, forged into a billet with specifications of 85mm×1800mm×4400mm, and the required body structure is forged at 400-450℃ through multiple free forging + two closed die forging. The free forging and die forging are each subjected to a single-pass reduction of ≥20% deformation, the anvil width ratio is 0.66-0.9, the deformation speed is 10 mm / s-20 mm / s, the final forging temperature is 330-380℃, and the total deformation is >80%. The forging and bending parts of the car body are subjected to internal quality non-destructive testing using the radiographic method in accordance with the Ministry of Energy standard NB / T 47013.2-2015 "Non-destructive testing of pressure equipment Part 2: Radiographic testing". Subsequent processing and heat treatment can only be carried out after the damage meets level II or above.

[0052] 4) Solution treatment: Internal support of the vehicle body structure, overall solution treatment at 480℃ for 2h, followed by water cooling at room temperature;

[0053] 5) Aging process: The whole car body is subjected to aging treatment: the first stage is 100-110℃ for 6-8h, the second stage is 135-145℃ for 14h-18h and then air-cooled.

[0054] Example 3: Preparation of 7xxx series medium-high strength weldable aluminum alloy flat sheet material resistant to high-speed impact

[0055] The aluminum alloy has a mass percentage composition of Zn: 6.97wt%, Mg: 2.88wt%, Cu: 0.388wt%, Mn: 0.400wt%, Cr: 0.102wt%, Zr: 0.058wt%, Ti: 0.031wt%, Y: 0.075wt%, V: 0.060wt%, Fe: 0.175wt%, Si: 0.028wt%, and the rest is Al.

[0056] The preparation steps are as follows:

[0057] 1) Melting and casting: the materials are prepared according to the required ingredients, the melting temperature is 730℃~780℃, and the square ingots are cast after heat preservation, the specifications are: 300 mm×1200 mm×2000 mm;

[0058] 2) Homogenization annealing: the ingot is kept at 485°C for 24 hours;

[0059] 3) Hot rolling: After the ingot is heated to 420℃ and evenly heated, the hot rolling start temperature is 420℃, the final rolling temperature is 300~400℃, the total deformation is 90%, the maximum reduction of a single pass is 20%, the anvil width ratio is 0.8, and a 30mm thick hot-rolled plate is obtained;

[0060] 4) Solution quenching treatment: keep the plate at 475℃ for 1h and cool it with water at room temperature;

[0061] 5) Pre-stretching: straighten and stretch the quenched plate by 1.5% along the rolling direction;

[0062] 6) Aging process: The plate is subjected to aging treatment: the first stage is kept at 100-110℃ for 6-8h, the second stage is kept at 135-145℃ for 14h-18h and then air-cooled.

[0063] Example 4: One-piece Forming Preparation of 7xxx Series Medium-High Strength Weldable Aluminum Alloy Inducer Support Forging Blank

[0064] The mass percentage composition of the aluminum alloy is Zn: 5.99wt%, Mg: 2.43wt%, Cu: 0.09wt%, Mn: 0.374wt%, Cr: 0.006wt%, Zr: 0.095 wt%, Ti: 0.041wt%, Y: 0.055wt%, V: 0.031wt%, Fe: 0.062wt%, Si: 0.022 wt%, and the rest is Al.

[0065] The preparation steps are as follows:

[0066] 1) Melting and casting: the ingredients are prepared according to the required ingredients, the melting temperature is 730℃~780℃, and after heat preservation, round ingots are cast to obtain specifications: φ450 mm×1000 mm;

[0067] 2) Homogenization annealing: the round ingot is kept at 485℃ for 18h;

[0068] 3) Hot die forging of multi-step hollow cylinder: heating temperature of round ingot is 450℃, die temperature is 450℃, deformation temperature is 400℃~450℃, deformation speed is 10 mm / s~20 mm / s, the round ingot is free forged: roughening, square, drawing, chamfering, rolling, roughening to φ700 mm×400 mm, and then forged into multi-step hollow cylinder forging blanks of required finished product specifications after punching, final forging temperature is 260℃~335℃, total deformation is 65%, maximum reduction in single pass is 30%, anvil width ratio is 0.65, outer contour is 700mm, thickness is 200mm;

[0069] 4) Solution treatment: keep the forging blank at 480℃ for 2h and water cool at room temperature;

[0070] 5) Aging process: Aging treatment is then carried out: the first stage is kept at 100-110℃ for 6-8h, the second stage is kept at 135-145℃ for 14h-18h and then air-cooled.

[0071] The microalloying effective elements Zn, Mg, Cu, Mn, Cr, Ti, Zr, Y and V added to the aluminum alloy of the present invention are mainly distributed in the ingot in the form of atoms without forming clusters and precipitation phases. Figure 1 As shown, various elements are evenly distributed. The aluminum alloy of the present invention adopts the one-piece forming preparation method of the present invention with a large deformation of 15% to 35% in the middle 1 to 2 passes. The large wall thickness section of large structural parts or planar structural parts has a more uniform structure. Even after solution treatment at 475 to 490°C, the deformation of the thickness section does not grow significantly, and the width of the elongated strip grain is about 5 to 20 μm. See the attached Figure 2 As shown in the figure, the number of recrystallized equiaxed grains is extremely small. Even in the middle of the one-piece forming method, the large aluminum alloy structural parts of the present invention are subjected to 15% to 35% large reduction deformation in 1 to 2 passes or the room temperature high-speed impact deformation process of the alloy flat structural parts of the present invention, the matrix of the aluminum alloy of the present invention undergoes streamlined plastic shear deformation locally, which will form a deformation composed of countless small equiaxed crystals and bring about coordinated shear deformation. See the attached Figure 3 The microstructure of the aluminum alloy of the present invention includes a matrix phase and an aging-strengthening phase. The width of the matrix elongated strip subgrains is about 0.5 to 2 μm, and the length of the subgrains is consistent with the processing direction of the aluminum alloy. The aging-strengthening phase is composed of a metastable T'-AlMgZnCu or T'-AlMgZnMn phase and an η'-MgZn 2 The phase composition is 2nm to 10nm in size, with a mass fraction of about 7% of the metastable T' phase and a mass fraction of 1.5% to 2.8% of the metastable η' phase. Figure 4 As shown, the diffraction spots show that the matrix superlattice Al 3 The (Zr,Y) nanophase will strengthen the alloy matrix.

[0072] The following performance tests were performed on the embodiments:

[0073] According to the national standard GB / T 16865-2013, the specimens for tensile test are processed and tested. According to the national standard GB / T231.1-2009, the specimens for Brinell hardness are processed and tested. According to the national standard GB / T 229-2020, the specimens for KU 2 The impact function specimen processing and testing are carried out according to the national standard GB / T 7998-2005 for intergranular corrosion test specimen processing and testing, according to the national standard GB / T 22640-2008 for C-ring stress corrosion test specimen processing and testing, according to the national standard GB / T 2651-2008 for flat plate welding weld tensile test specimen processing and testing, according to the national standard GB / T 34108-2017 for room temperature high-speed impact test specimen processing and testing. The above test results are shown in Table 2.

[0074] Figure 5 The stress-strain curves of the side wall samples of the large forgings in Example 2 of the present invention after high-speed impact at different strain rates show that the aluminum alloy of the present invention exhibits a positive strain rate strengthening effect, and the impact strength is increased from quasi-static 450MPa to 1800s -1 The strain rate is 680MPa. When the strain rate reaches 3000s -1 When the damage morphology after detonation is measured, the dynamic impact strength can reach more than 1200MPa.

[0075] Through the above examples, it is proved that the mechanical properties of the 7xxx series aluminum alloy of the present invention are as follows: tensile strength R m ≥410 MPa, yield strength R p0.2 ≥345 MPa, elongation A≥7.0%, Brinell hardness HBW≥120, impact energy KU 2 ≥12 J; Corrosion resistance: no intergranular corrosion, C-ring stress corrosion resistance loading force ≥260 MPa; Welding performance: joint strength of ER5356 MIG welding with wire ≥240 MPa, joint strength of ER5R59 MIG welding with the same process parameters ≥360 MPa; Dynamic impact performance: at 1800 s -1 Under the strain rate, the impact strength can reach 680 MPa, which is 150% higher than the static strength of 450 MPa.

[0076] Table 1 Composition / wt% of the examples of the present invention

[0077]

[0078] Table 2 Performance of the embodiments of the present invention

[0079]

Claims

1. A high-strength weldable aluminum alloy of the 7xxx series that is resistant to high-speed impact, characterized in that: The aluminum alloy has a mass percentage composition of Zn: 4.0-7.0 wt%, Mg: 2.0-3.0 wt%, Cu: 0.05-0.40 wt%, Mn: 0.10-0.40 wt%, Cr≤0.25 wt%, Ti: 0.03-0.09 wt%, Zr: 0.05-0.15 wt%, Fe≤0.25 wt%, Si≤0.20 wt%, Y: 0.05-0.15 wt%, V: 0.03-0.06 wt%, inevitable impurities, a single impurity content ≤0.05wt%, impurities total ≤0.15wt%, and the rest is Al.

2. A method for preparing a high-speed impact resistant 7xxx series medium-high strength weldable aluminum alloy according to claim 1, characterized in that: The method comprises the following preparation steps: 1) Melting and casting: the ingredients are prepared according to the required ingredients, the melting temperature is 720℃~780℃, the temperature is kept at 780℃ for 30min~60min, and the ingot is cast at 690℃~720℃; 2) One-piece molding of large structural parts: (2.1) The aluminum alloy ingot is homogenized by being kept at 470-485°C for 12-36 hours; (2.2) The homogenized ingot is widened by forging to obtain a blank; the blank is forged into a basic prototype of a large structural part by free forging, and the edges are trimmed to obtain a conformable blank with a reserved amount of subsequent deformation; the conformable blank is extruded by the upper and lower dies to fill the die cavity by die forging to obtain the final shape of the large structural part, thereby obtaining an integrally formed structural part; the deformation temperature is 400℃~460℃, the final forging temperature is 260℃~400℃, the deformation speed is 10mm / s~30mm / s, and the anvil width ratio is ≥0.4; (2.3) subjecting the molded structural component to overall solid solution treatment at 475-490° C. for 0.5-3 h, room temperature water quenching and two-stage aging heat treatment, with the first stage being at 100-110° C. for 6-8 h, and the second stage being at 135-145° C. for 14 h-18 h, and then being air-cooled after being removed from the furnace to obtain the required structural strength and protective performance, thereby obtaining the final large-scale aluminum alloy structural component resistant to high-speed impact; or 3) Hot rolling forming of flat structural parts: (3.1) Homogenization annealing: The ingot is kept at 470-485°C for 12-30 hours for homogenization treatment; (3.2) Hot rolling: the starting rolling temperature is 400℃~460℃, the total processing rate is ≥80%, and the ingot after tempering is processed into plates; (3.3) Solution quenching treatment: keep the plate at 475-490℃ for 0.5-3h, and cool it with water at room temperature; (3.4) Two-stage aging treatment: Heat the heating furnace to the required temperature, keep it at 100-110℃ for 6-8h in the first stage, keep it at 135-145℃ for 14h-18h in the second stage, and then cool it in air at room temperature to obtain the required structural strength and protective performance, and obtain the final high-speed impact resistant aluminum alloy flat structural parts.

3. The preparation method according to claim 2, characterized in that: The aluminum alloy billet is subjected to large deformation during the forging and widening or free forging process in step (2.2), with a reduction of 15% to 35% in 1 to 2 passes.

4. The preparation method according to claim 2, characterized in that: In the hot rolling of step (3.2), the reduction amount in 1 to 2 passes is 15% to 35% to achieve large deformation.

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