Aluminum alloy and preparation method thereof, box body for packaging battery, battery and electric device

Abstract

The invention relates to an aluminum alloy and a preparation method thereof, a box body for packaging a battery, the battery and an electric device. The aluminum alloy comprises the following components in percentage by mass: 0.51-0.59% of Si; 0.20% or less of Fe; 0.16 to 0.23 part of Cu; mn < = 0.03; 0.52 to 0.59 parts of Mg; cr < = 0.03; zn < = 0.03; ti < = 0.05; 0.11 to 0.15 of a rare earth element; 0.10% or less of other inevitable impurities; and the balance of Al. By controlling the contents of Si, Mg and Cu in the range, the aluminum alloy has relatively high strength and extrusion performance; and meanwhile, 0.11-0.15 wt% of rare earth elements are added to refine and improve the alloy structure, so that the toughening of the alloy is facilitated, and the extrusion performance of the aluminum alloy is further facilitated.

Description

Technical Field

[0001] The present application relates to an aluminum alloy and a preparation method thereof, a box for packaging batteries, a battery, and an electrical device. Background Art

[0002] In recent years, with the development of lithium-ion secondary battery technology, lithium-ion secondary batteries are widely used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields. As lithium-ion secondary batteries have made great progress, higher requirements are also placed on the extrusion performance of the box used to package the battery. Summary of the invention

[0003] The purpose of the present application is to provide an aluminum alloy and a preparation method thereof, a box for packaging batteries, a battery, and an electrical device.

[0004] The embodiment of the present application is implemented as follows:

[0005] In a first aspect, an embodiment of the present application provides an aluminum alloy, wherein the aluminum alloy comprises the following components in terms of mass percentage:

[0006] Si 0.51-0.59; Fe≤0.20; Cu 0.16-0.23; Mn≤0.03; Mg 0.52-0.59; Cr≤0.03; Zn≤0.03; Ti≤0.05; rare earth elements 0.11-0.15; other unavoidable impurities≤0.10; the balance is Al.

[0007] The aluminum alloy formula of this application, at the same time, in the formula, strictly control the Si content at 0.51wt.%-0.59wt.% and the Mg content at 0.52wt.%-0.59wt.%, in order to improve the precipitation strengthening effect of the alloy, thereby improving the basic mechanical properties of the alloy, and obtaining high strength and high extrusion performance; at the same time, under this formula system, the Cu content is controlled to be 0.16wt.%-0.23wt.%, which is beneficial to improve the solid solution strengthening and precipitation strengthening effects of the alloy, and further improve the mechanical properties of the product. In addition, under this formula system, 0.11wt.%-0.15wt.% of rare earth elements are added to refine and improve the alloy structure, which is beneficial to the toughening of the alloy, and then to the extrusion performance of the aluminum alloy. Therefore, the above-mentioned aluminum alloy can achieve both high strength and high extrusion performance; applying it to the production of boxes for packaging batteries can improve extrusion performance, reduce extrusion difficulty, and improve extrusion efficiency.

[0008] Furthermore, the above aluminum alloy formula strictly controls the Mn and Cr contents below 0.03wt.%, so as to greatly reduce the formation of supersaturated solid solution in the alloy, thereby reducing the quenching sensitivity of the aluminum alloy. Applying it to the production of boxes for packaging batteries can reduce the difficulty of the quenching process, reduce the uneven distribution of residual stress caused by quenching, reduce profile deformation, and improve the qualified rate.

[0009] In some optional embodiments, Si 0.52-0.58; Fe≤0.20; Cu 0.17-0.22; Mn≤0.03; Mg0.53-0.54; Cr≤0.03; Zn≤0.03; Ti≤0.05; rare earth elements 0.12-0.14; other unavoidable impurities≤0.10; and the balance is Al.

[0010] The above aluminum alloy formula further strictly controls the addition amount of Mg and Si elements to further improve the strength and extrusion performance of the alloy, further controls the addition amount of Cu element to further improve the strength of the alloy, and further controls the addition amount of rare earth elements to improve the extrusion performance of the alloy, thereby achieving an alloy with both high strength and low quenching sensitivity and excellent extrusion performance, and has the highest value for industrial application.

[0011] In some optional embodiments, the mass ratio of Mg to Si is 0.881-1.157.

[0012] Controlling the Mg / Si mass ratio between 0.881 and 1.157 can enable the aluminum alloy to obtain excellent extrusion performance and strength.

[0013] In some optional embodiments, the rare earth element includes at least one of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc, or Y.

[0014] In some alternative embodiments, the rare earth element is La.

[0015] Rare earth La has the lowest price among the 17 rare earth elements, and can be economical and practical while improving material performance.

[0016] In some optional embodiments, when other unavoidable impurities include multiple elements, the content of a single element is ≤0.03 by mass percentage.

[0017] Controlling the content of a single impurity element to ≤0.03 is beneficial to avoiding the aggregation of a single element and is beneficial to the comprehensive performance of the aluminum alloy.

[0018] In some optional implementation schemes, the aluminum alloy meets the following conditions under air-cooling quenching conditions, and the cooling intensity of the air-cooling quenching is 5°C / s:

[0019] (a) The tensile strength of aluminum alloy is ≥290Mpa;

[0020] (b) The yield strength of aluminum alloy is ≥260MPa;

[0021] (c) The elongation after fracture of the aluminum alloy is ≥9%.

[0022] In the above technical solution, the cooling intensity of air-cooled quenching is 5°C / s. The higher the quenching cooling intensity, the higher the above performances.

[0023] The present application scheme can achieve the above-mentioned objectives under the condition that the cooling intensity of air-cooled quenching is 5°C / s.

[0024] High strength can be achieved under air-cooled quenching conditions, which can reduce deformation caused by uneven cooling of products under high quenching cooling intensity such as mist cooling and water cooling.

[0025] In addition, some products with relatively symmetrical structures can use mist cooling and water cooling quenching, and the tensile strength, yield strength and elongation of the product will be higher on this basis.

[0026] In a second aspect, an embodiment of the present application provides a method for preparing an aluminum alloy, comprising:

[0027] Smelting and obtaining an aluminum alloy rod according to the composition content of the aluminum alloy provided in the first aspect;

[0028] The aluminum alloy rod is subjected to a homogenization treatment and then a cooling treatment.

[0029] In some optional embodiments, the holding temperature of the homogenization treatment is 555° C. to 575° C., and the holding time is 6 h to 10 h.

[0030] In some optional embodiments, the cooling treatment includes: cooling the aluminum alloy rod to less than 250° C. by strong wind and then cooling it to room temperature by water.

[0031] Due to the excellent extrudability of the above alloy formula, the alloy can obtain higher strength and better extrusion performance under the above homogenization treatment combined with cooling treatment, that is, retain better extrudability while achieving high strength.

[0032] In some optional embodiments, the wind speed of the strong wind is: 180℃ / h~220℃ / h.

[0033] In some optional embodiments, the method for preparing the aluminum alloy further includes processing the aluminum alloy rod after the cooling treatment into an aluminum alloy profile.

[0034] In some optional embodiments, the aluminum alloy rod after cooling is processed into an aluminum alloy profile, comprising:

[0035] Aluminum alloy bars are air-quenched and then cut into profiles.

[0036] In some optional embodiments, the air-cooling quenching temperature is 500°C to 530°C.

[0037] By adjusting the aluminum alloy formula, the aluminum alloy has the characteristics of low quenching sensitivity, so it can be quenched under air-cooling conditions, which reduces the quenching difficulty, reduces the uneven distribution of residual stress caused by quenching, reduces profile deformation, and improves the pass rate.

[0038] In a third aspect, an embodiment of the present application provides a box for packaging batteries, wherein the box for packaging batteries comprises the aluminum alloy of the aforementioned second aspect.

[0039] In a fourth aspect, an embodiment of the present application provides a battery, the battery comprising the box for encapsulating the battery provided in the third aspect.

[0040] In a fifth aspect, an embodiment of the present application provides an electrical device, which includes the battery provided in the fourth aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0042] Figure 1 A schematic diagram of the structure of a vehicle provided in some embodiments of the present application;

[0043] Figure 2 An exploded view of a battery provided for some embodiments of the present application;

[0044] Figure 3 for Figure 2 An exploded view of a battery cell is shown;

[0045] Figure 4 A schematic diagram of a partial structure of an electrode assembly provided in some embodiments of the present application;

[0046] Figure 5 Schematic diagram of the structure of the tensile specimen provided for the tensile test of this application;

[0047] Figure 6 Schematic diagram of the structure of the trial mold provided for the extrusion test of this application.

[0048] icon:

[0049] Vehicles 1000;

[0050] Battery 100; Controller 200; Motor 300;

[0051] Box body 10; first part 11; second part 12; accommodating space 13;

[0052] Battery cell 20; housing 21; electrode assembly 22; electrode terminal 23; pressure relief structure 24;

[0053] Shell 211; cover 212; positive electrode sheet 221; negative electrode sheet 222; isolation film 223;

[0054] Positive electrode current collector 2211; Positive electrode active material layer 2212;

[0055] Negative electrode current collector 2221 ; negative electrode active material layer 2222 . DETAILED DESCRIPTION

[0056] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0057] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0058] In the description of the embodiments of the present application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features.

[0059] In the description of the embodiments of the present application, the orientations or positional relationships indicated by the technical terms "inside" and "outside" are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0060] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0061] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0062] In the embodiments of the present application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the heights, lengths, widths, and other dimensions of the various components in the embodiments of the present application shown in the drawings, as well as the overall heights, lengths, widths, and other dimensions of the integrated device are only exemplary descriptions and should not constitute any limitation to the present application.

[0063] At present, the material used to produce the box body of the packaged battery is usually 6061 aluminum alloy or 6082 aluminum alloy, but this material often has the following problems:

[0064] 1. The extrusion performance is relatively poor, the extrusion is difficult, the extrusion speed is slow, the extrusion production efficiency is low, and the mold life is short;

[0065] 2. The alloy is highly sensitive to quenching and requires water cooling or mist cooling to ensure quenching strength, which will lead to uneven distribution of residual stress generated during quenching and deformation of the profile, such as flatness, bending and twisting in the length direction, and cannot meet the higher use requirements of the product.

[0066] The present application provides an aluminum alloy, which includes the following components by mass percentage:

[0067] Si 0.51-0.59; Fe≤0.20; Cu 0.16-0.23; Mn≤0.03; Mg 0.52-0.59; Cr≤0.03; Zn≤0.03; Ti≤0.05; rare earth elements 0.11-0.15; other unavoidable impurities≤0.10; the balance is Al.

[0068] The aluminum alloy formula of the present application strictly controls the Mn and Cr contents below 0.03wt.%, so as to greatly reduce the formation of supersaturated solid solution in the alloy, thereby reducing the quenching sensitivity of the aluminum alloy; at the same time, in the formula, the Si content is strictly controlled at 0.51wt.%-0.59wt.% and the Mg content is strictly controlled at 0.52wt.%-0.59wt.%, so as to improve the precipitation strengthening effect of the alloy, thereby improving the basic mechanical properties of the alloy and obtaining high strength and high extrusion performance; at the same time, in the formula, 0.11wt.%-0.15wt.% of rare earth elements are added to refine and improve the alloy structure, which is beneficial to the toughening of the alloy and further beneficial to the extrusion performance of the aluminum alloy.

[0069] Furthermore, the aluminum alloy provided by the present application, by adjusting the aluminum alloy formula, obtains an extruded aluminum alloy with high strength, low quenching sensitivity and high extrusion performance. The aluminum alloy has high T6 state mechanical properties under air-cooled quenching conditions, reduces the quenching difficulty, reduces the uneven distribution of residual stress caused by quenching, reduces profile deformation, and improves the qualified rate. At the same time, the extrusion performance is good to meet the requirements of industrial production, and improves the extrusion production efficiency and finished product rate, so as to significantly reduce the processing cost.

[0070] The above T6 state represents the heat treatment state, which is the same as the conventional 6061 aluminum alloy T6 state treatment method. This state generally includes medium and thick plate quenching, medium and thick plate slicing, stretching machine, aging treatment, sawing machine, polishing, and packaging. The entire production cycle is about 10 days. After solution heat treatment, cold processing is not required. Straightening and leveling can be performed, but it does not affect the mechanical properties.

[0071] The box for packaging batteries provided in the present application comprises the aforementioned aluminum alloy. The box made of the aluminum alloy has higher strength and higher extrusion performance.

[0072] The battery provided in the present application includes the aforementioned casing, and the battery has higher strength and higher extrusion performance.

[0073] The embodiment of the present application provides an electrical device, comprising the aforementioned battery.

[0074] For the convenience of description, the following embodiments are described by taking a lithium-ion battery according to an embodiment of the present application as an example.

[0075] See also Figure 1 , Figure 1A schematic diagram of the structure of a vehicle 1000 provided for some embodiments of the present application. The vehicle 1000 may be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle 1000, and the battery 100 may be provided at the bottom, head or tail of the vehicle 1000. The battery 100 may be used to power the vehicle 1000, for example, the battery 100 may be used as an operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300, and the controller 200 is used to control the battery 100 to power the motor 300, for example, for starting, navigating and driving the vehicle 1000.

[0076] In some embodiments of the present application, the battery 100 can not only serve as an operating power source for the vehicle 1000, but also serve as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0077] In the present application, the battery 100 may refer to a physical module including a battery cell, or a single physical module including multiple battery cells 20 to provide a higher voltage and capacity. The battery 100 may be in the form of a battery module or a battery pack. The battery 100 may include a housing 10 for encapsulating one or more battery cells 20. The housing 10 may prevent liquid or other foreign matter from affecting the charging or discharging of the battery cells 20.

[0078] See also Figure 2 , Figure 2 An exploded view of a battery 100 provided in some embodiments of the present application, the battery 100 includes a housing 10 and a battery cell 20, and the battery cell 20 is accommodated in the housing 10. In the battery 100, the battery cell 20 may be one or more. If there are multiple battery cells 20, the multiple battery cells 20 may be connected in series, in parallel, or in mixed connection. Mixed connection means that multiple battery cells 20 are both connected in series and in parallel. Multiple battery cells 20 may be directly connected in series, in parallel, or in mixed connection, and then the whole formed by the multiple battery cells 20 is accommodated in the housing 10. Alternatively, multiple battery cells 20 may be first connected in series, in parallel, or in mixed connection to form a module, and the multiple modules may be connected in series, in parallel, or in mixed connection to form a whole, and then accommodated in the housing 10. The battery 100 may also include other structures. For example, multiple battery cells 20 may be electrically connected through a busbar component to achieve parallel, series, or mixed connection of multiple battery cells 20.

[0079] Each battery cell 20 may be a lithium-ion battery, such as a secondary battery or a primary battery; it may also be a lithium-sulfur battery, a sodium-ion battery or a magnesium-ion battery, but is not limited thereto.

[0080] See also Figure 3 , Figure 3 for Figure 2 The exploded view of the battery cell 20 is shown. The battery cell 20 refers to the smallest unit constituting the battery 100. The battery cell 20 may include a housing 21, an electrode assembly 22 and an electrolyte, and the electrode assembly 22 and the electrolyte are both contained in the housing 21.

[0081] The housing 21 may include a shell 211 and a cover 212. The shell 211 is a component used to cooperate with the cover 212 to form an internal sealed space of the battery cell 20, wherein the formed sealed space can be used to accommodate the electrode assembly 22, electrolyte and other components. The cover 212 refers to a component that covers the opening of the shell 211 to isolate the internal environment of the battery cell 20 from the external environment. The shape of the cover 212 can be adapted to the shape of the shell 211 to cooperate with the shell 211, and the cover 212 may also be provided with functional components such as electrode terminals 23 and pressure relief structures 24. A sealing ring may be configured between the opening of the shell 211 and the cover 212 to achieve sealing between the shell 211 and the cover 212.

[0082] The shell 211 and the cover 212 can be of various shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shapes of the shell 211 and the cover 212 can be determined according to the specific shape and size of the electrode assembly 22. The shell 211 and the cover 212 can be made of various materials, such as but not limited to metals such as copper, iron, aluminum, stainless steel, and aluminum alloy. The sealing ring can be made of various materials, such as but not limited to PP (polypropylene), PC (polycarbonate), PET (polyethylene terephthalate) and other materials that are resistant to electrolyte corrosion, high toughness and fatigue resistance. A coating can be formed on the outer surface of the shell 211, and the material of the coating can be various, such as but not limited to corrosion-resistant materials such as Ni and Cr.

[0083] See also Figure 4 The electrode assembly 22 may be composed of a positive electrode sheet 221, a negative electrode sheet 222, and a separator 223. The separator 223 is located between the positive electrode sheet 221 and the negative electrode sheet 222 to play a role of isolation. The electrode assembly 22 may be a winding structure or a laminated structure, but the embodiments of the present application are not limited thereto.

[0084] See also Figure 4 The positive electrode sheet 221 includes a positive electrode current collector 2211 and a positive electrode active material layer 2212. Taking the lithium-ion battery cell 20 as an example, the material of the positive electrode current collector 2211 can be aluminum. The positive electrode active material layer 2212 includes a positive electrode active material.

[0085] Please continue to see Figure 2The box 10 is used to accommodate the battery cell 20, and the box 10 can be of various structures. In some embodiments, the box 10 may include a first part 11 and a second part 12, and the first part 11 and the second part 12 cover each other, and the first part 11 and the second part 12 jointly define a storage space 13 for accommodating the battery cell 20. The second part 12 may be a hollow structure with one end open, and the first part 11 is a plate-like structure, and the first part 11 covers the open side of the second part 12 to form a box 10 with a storage space 13; the first part 11 and the second part 12 may also be hollow structures with one side open, and the open side of the first part 11 covers the open side of the second part 12 to form a box 10 with a storage space 13. Of course, the first part 11 and the second part 12 may be of various shapes, such as a cylinder, a cuboid, etc.

[0086] In some embodiments of the present application, the material of the box body 10 is aluminum alloy.

[0087] Furthermore, in some embodiments of the present application, an aluminum alloy is provided, wherein the aluminum alloy comprises the following components in terms of mass percentage:

[0088] Si 0.51-0.59; Fe≤0.20; Cu 0.16-0.23; Mn≤0.03; Mg 0.52-0.59; Cr≤0.03; Zn≤0.03; Ti≤0.05; rare earth elements 0.11-0.15; other unavoidable impurities≤0.10; the balance is Al.

[0089] The aluminum alloy is obtained by adjusting the aluminum alloy formula to obtain an extruded aluminum alloy with high strength, low quenching sensitivity and high extrusion performance.

[0090] Furthermore, the above aluminum alloy formula strictly controls the Mn and Cr contents below 0.03wt.%, so as to greatly reduce the formation of supersaturated solid solution in the alloy, thereby reducing the quenching sensitivity of the aluminum alloy.

[0091] When the content of Mn and Cr is higher than 0.03wt.%, the alloy quenching sensitivity will be significantly increased. This is because in the solid solution stage, at high temperature, alloy elements such as Mg and Si have high solubility in the Al matrix, forming a solid solution with aluminum as the matrix. Their solubility decreases with decreasing temperature. Therefore, after solid solution and heat preservation, rapid cooling is required to form a metastable supersaturated solid solution.

[0092] The supersaturated solid solution is unstable. When the content of Mn and Cr in the alloy is higher than 0.03wt.%, the particles of the compounds (MnAL6, (FeMn)Al6, CrAl compounds) formed are relatively large. The Mg and Si phases will adhere to the surface of these compounds, which will help the nucleation of the equilibrium phase Mg2Si and provide a shortcut for its diffusion along the boundary, allowing it to precipitate and grow rapidly. The addition of Mn and Cr provides conditions for its precipitation and accelerates its decomposition. Therefore, a higher cooling rate is required to reduce the early precipitation and aggregation of the strengthening phase, that is, to increase the quenching sensitivity of the alloy.

[0093] When the alloy's quenching sensitivity increases, a higher cooling rate and greater cooling intensity are required to ensure quenching strength. However, this will lead to uneven distribution of residual stress generated during quenching, which will cause profile deformation, such as flatness, bending and twisting in the length direction. This aluminum alloy is not suitable for battery boxes, especially the side beam profiles, which are cooled unevenly, resulting in bending and twisting deformation and scrapping, reducing the yield rate.

[0094] Therefore, in the above aluminum alloy formula, the Mn and Cr contents are strictly controlled below 0.03wt.% to obtain an aluminum alloy with low quenching sensitivity.

[0095] Furthermore, in the above aluminum alloy formula, the Si content is strictly controlled at 0.51wt.%-0.59wt.% and the Mg content is 0.52wt.%-0.59wt.% to improve the precipitation strengthening effect of the alloy, thereby improving the basic mechanical properties of the alloy and obtaining high strength and high extrusion performance.

[0096] Si and Mg are basic additive elements in the above-mentioned aluminum alloy formula. The contents of Mg and Si affect the content of the precipitation strengthening phase Mg5Si6 in the alloy, which directly affects the basic strength of the alloy. If the strengthening phase content is too low, the performance cannot meet the requirements. If the strengthening phase content is too high, the strength is too high, which will relatively reduce the extrusion performance of the alloy. In the above-mentioned technical scheme, the Mg5Si6 content is controlled at 0.307%-0.364%. At the same time, the consumption of Si element by Fe (Mn and Cr are not considered when they are below 0.03wt.%) in actual application is comprehensively considered to be 0.4*Fe content (forming AlFeSi phase). Therefore, in the above-mentioned aluminum alloy formula, the Si content is strictly controlled to be 0.51wt.%-0.59wt.% and the Mg content is 0.52wt.%-0.59wt.%, which can improve the precipitation strengthening effect of the alloy, thereby improving the basic mechanical properties of the alloy and obtaining high strength and high extrusion performance.

[0097] Furthermore, in the above aluminum alloy formula, controlling the Cu content to 0.16wt.%-0.23wt.% is beneficial to improving the alloy solid solution strengthening and precipitation strengthening effects, and further improving the mechanical properties of the product.

[0098] When atoms of another element dissolve in solid aluminum, a solid solution is formed. Some individual aluminum atoms are replaced by new atoms on the same lattice. The aluminum is the "solvent" and the new atoms are the "solute" atoms. The solute atoms create a distorted area in the aluminum lattice, which will hinder the plastic flow of aluminum atoms, making deformation difficult and thus increasing strength.

[0099] The diameter of Al atom is 2.84*10- 1 nm, Cu atom diameter 2.52*10- 1 nm, the atomic diameter difference is large, the mismatch degree is -0.32, and Cu atoms have a high solubility in the aluminum matrix at high temperature, with the maximum solubility of 5.67% at 550°C. Therefore, after Cu is added, a tensile stress zone is formed around the Cu atoms, and the aluminum matrix lattice is distorted, making deformation more difficult, thereby improving the solid solution strengthening effect.

[0100] In addition, similar to the mechanism of Mg2Si strengthening phase generated by Mg and Si, an appropriate amount of Cu can generate CuAl2 strengthening phase with the primary α-Al phase in the alloy, and precipitate second phase particles such as GP zone, coherent θ phase", semi-coherent phase θ', incoherent equilibrium phase θ during the aging process to strengthen the matrix.

[0101] The evolution law of the precipitated phase during the aging process is as follows:

[0102] CuAl2 precipitation strengthening:

[0103] Solid solution → GP zone (Cu-rich phase aggregation) → coherent phase θ” → semi-coherent phase θ' → incoherent equilibrium phase θ

[0104] Among them, the θ” phase has the best strengthening effect. After aging, these strengthening phases are dispersed in the aluminum matrix, hindering the movement of dislocations through the dislocation pinning effect, thereby improving the strength.

[0105] On the other hand, Cu has a higher electrode potential and is more sensitive to the corrosion properties of the alloy, which will reduce the corrosion resistance of the material. In addition, the market price of copper-aluminum intermediate alloy is relatively high, and adding too much will affect the economy of the formula.

[0106] Therefore, taking all factors into consideration, in the above aluminum alloy formula, the Cu content is controlled to be 0.16wt.%-0.23wt.%.

[0107] Furthermore, in the above aluminum alloy formula, 0.11wt.%-0.15wt.% of rare earth elements are added to refine and improve the alloy structure, which is beneficial to the toughening of the alloy and further to the extrusion performance of the aluminum alloy.

[0108] In addition to refining and purifying the solution during the metal melting and casting stage, rare earth elements mainly play a role in improving the refinement of the alloy structure and the strong precipitation strengthening effect of dispersed rare earth compounds. The addition of rare earth elements can improve the crack initiation position and propagation path during the alloy fracture process, which is beneficial to the toughening of the alloy and the extrusion performance.

[0109] The above aluminum alloy formula ensures that the alloy has a certain strength and good extrusion performance by strictly controlling the addition amount of Mg and Si elements, further improves the alloy strength by adding an appropriate amount of Cu element, and finally adds an appropriate amount of rare earth elements to improve the alloy's extrusion performance, thereby achieving an alloy with high strength, low quenching sensitivity, and excellent extrusion performance, and has the highest value for industrial application.

[0110] Further optionally, in some embodiments of the present application, the aluminum alloy includes the following components, measured by mass percentage: Si 0.52-0.58; Fe≤0.20; Cu 0.17-0.22; Mn≤0.03; Mg 0.53-0.58; Cr≤0.03; Zn≤0.03; Ti≤0.05; rare earth elements 0.12-0.14; other unavoidable impurities≤0.10; and the balance is Al.

[0111] The above aluminum alloy formula further strictly controls the addition ratio of Mg and Si elements to further improve the strength and extrusion performance of the alloy, further controls the addition amount of Cu element to further improve the strength of the alloy, and further controls the addition amount of rare earth elements to improve the extrusion performance of the alloy, thereby achieving an alloy with both high strength and low quenching sensitivity and excellent extrusion performance, and has the highest value for industrial application.

[0112] For example, in some embodiments of the present application, the aluminum alloy formula is as follows, calculated by mass percentage:

[0113] Si 0.53, Fe≤0.20; Cu 0.18, Mn≤0.03, Mg 0.58, Cr≤0.03, Zn≤0.03; Ti≤0.05; rare earth elements 0.125, other unavoidable impurities ≤0.10; the balance is Al.

[0114] For example, in some embodiments of the present application, the aluminum alloy formula is as follows, calculated by mass percentage:

[0115] Si 0.54, Fe≤0.20; Cu 0.18, Mn≤0.03, Mg 0.57, Cr≤0.03, Zn≤0.03; Ti≤0.05; rare earth elements 0.13, other unavoidable impurities ≤0.10; the balance is Al.

[0116] For example, in some embodiments of the present application, the aluminum alloy formula is as follows, calculated by mass percentage:

[0117] Si 0.55, Fe≤0.20; Cu 0.19, Mn≤0.03, Mg 0.56, Cr≤0.03, Zn≤0.03; Ti≤0.05; rare earth elements 0.14, other unavoidable impurities ≤0.10; the balance is Al.

[0118] For example, in some embodiments of the present application, the aluminum alloy formula is as follows, calculated by mass percentage:

[0119] Si 0.56, Fe≤0.20; Cu 0.20, Mn≤0.03, Mg 0.55, Cr≤0.03, Zn≤0.03; Ti≤0.05; rare earth elements 0.12, other unavoidable impurities ≤0.10; the balance is Al.

[0120] For example, in some embodiments of the present application, the aluminum alloy formula is as follows, calculated by mass percentage:

[0121] Si 0.57, Fe≤0.20; Cu 0.21, Mn≤0.03, Mg 0.54, Cr≤0.03, Zn≤0.03; Ti≤0.05; rare earth elements 0.125, other unavoidable impurities ≤0.10; the balance is Al.

[0122] Further, in some embodiments of the present application, the mass ratio of Mg to Si is 0.881-1.157.

[0123] During the aging process, Si and Mg interact with each other to precipitate second phase particles such as GP zone (Si-rich, Mg-rich phase aggregation), needle-shaped coherent phase β", rod-shaped semi-coherent phase β', and columnar coherent equilibrium phase β. After aging, these strengthening phases are dispersed in the aluminum matrix, hindering the movement of dislocations through the dislocation pinning effect, thereby improving the strength. The evolution of the precipitated phase during the aging process is as follows:

[0124] Mg2Si precipitation strengthening:

[0125] Solid solution → GP zone (Mg-rich, Si-rich phase aggregation) → Needle-shaped coherent phase B” → Rod-shaped semi-coherent phase β’ → Columnar coherent equilibrium phase β

[0126] Among them, the needle-shaped coherent phase β" has the best strengthening effect and is the most important strengthening precipitation phase in the peak aging alloy. Its chemical composition is Mg5Si6, and the mass ratio of Mg to Si is 0.714:1. If the actual Mg / Si ratio in the alloy is lower than 0.714, Si is excessive, and the excess Si in the matrix is ​​easy to segregate and precipitate on the grain boundary, reducing the grain boundary bonding force. At the same time, it is also easy to cause stress concentration and become the source of crack initiation during deformation, reducing the plasticity of the alloy. Therefore, in the above aluminum alloy formula, the Mg / Si mass ratio is designed to be higher than 0.714, that is, Mg is excessive, and a certain amount of excess Mg helps to improve the thermal stability of the alloy. However, if Mg is too excessive, this part of the excess Mg has no effective Si to combine with it to form a strengthening precipitation phase, which will not only weaken the strengthening effect, but also reduce the extrusion performance of the alloy.

[0127] The content of Mg and Si jointly affects the extrusion performance and strength level of aluminum alloys. As the Mg / Si value of the alloy increases, the strain hardening index of the alloy increases and the extrusion performance of the alloy decreases. After DOE (DESIGN OF EXPERIMENT) test analysis, further optimizing and controlling the Mg / Si mass ratio between 0.881-1.157 can enable aluminum alloys to obtain excellent extrusion performance and strength.

[0128] Furthermore, in some embodiments of the present application, the rare earth element includes at least one of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc, or Y.

[0129] Further optionally, in some embodiments of the present application, the rare earth element is selected as La; the rare earth La has the lowest price among the 17 rare earth elements, and can be economical and practical while improving material performance.

[0130] Furthermore, in some embodiments of the present application, in the aluminum alloy, when other unavoidable impurities include multiple elements, the content of a single element is ≤0.03, measured by mass percentage.

[0131] Controlling the content of a single impurity element to ≤0.03 is beneficial to avoiding the aggregation of a single element and is beneficial to the comprehensive performance of the aluminum alloy.

[0132] Further, in some embodiments of the present application, the aluminum alloy meets the following conditions under air-cooling quenching conditions, and the cooling intensity of the air-cooling quenching is 5°C / s:

[0133] (a) The tensile strength of aluminum alloy is ≥290Mpa;

[0134] (b) The yield strength of aluminum alloy is ≥260MPa;

[0135] (c) The elongation after fracture of the aluminum alloy is ≥9%.

[0136] In the above technical solution, the cooling intensity of air-cooled quenching is 5°C / s. The higher the quenching cooling intensity, the higher the above performances.

[0137] The present application scheme can achieve the above-mentioned objectives under the condition that the cooling intensity of air-cooled quenching is 5°C / s.

[0138] High strength can be achieved under air-cooled quenching conditions, which can reduce deformation caused by uneven cooling of products under high quenching cooling intensity such as mist cooling and water cooling.

[0139] In addition, some products with relatively symmetrical structures can use mist cooling and water cooling quenching, and the tensile strength, yield strength and elongation of the product will be higher on this basis.

[0140] Furthermore, in some embodiments of the present application, a method for preparing an aluminum alloy comprises:

[0141] Smelting and obtaining an aluminum alloy rod by mixing the components and contents of the aluminum alloy provided in any of the above embodiments;

[0142] The aluminum alloy rod is subjected to a homogenization treatment and then a cooling treatment.

[0143] Furthermore, in some embodiments of the present application, the holding temperature of the homogenization treatment is 555° C. to 575° C., and the holding time is 6 h to 10 h.

[0144] Further optionally, in some embodiments of the present application, the holding temperature of the homogenization treatment is 556° C. to 574° C., and the holding time is 7 h to 9 h.

[0145] Illustratively, in some embodiments of the present application, the holding temperature of the homogenization treatment is 557°C, 558°C, 559°C, 560°C, 561°C, 562°C, 563°C, 564°C, 565°C, 566°C, 567°C, 568°C, 569°C, 570°C, 571°C, 572°C, 573°C or 574°C.

[0146] Illustratively, in some embodiments of the present application, the above-mentioned insulation time is 7h, 8h or 9h.

[0147] Furthermore, in some embodiments of the present application, the cooling treatment includes: cooling the aluminum alloy rod to less than 250° C. by strong wind and then cooling it to room temperature by water.

[0148] The room temperature may be 10°C-40°C. Alternatively, 20°C-35°C.

[0149] Due to the low quenching sensitivity of the above alloy formula, the alloy can obtain higher strength and better extrusion performance under the above homogenization treatment combined with cooling treatment, that is, retain good extrusion performance while achieving high strength.

[0150] Furthermore, in some embodiments of the present application, the cooling treatment includes: cooling the aluminum alloy rod to room temperature using strong wind.

[0151] Furthermore, in some embodiments of the present application, the wind speed of the strong wind is: 180℃ / h~220℃ / h.

[0152] Exemplarily, the wind speeds of strong winds are: 180°C / h, 190°C / h, 200°C / h, 210°C / h, 220°C / h.

[0153] Furthermore, in some embodiments of the present application, the method for preparing the aluminum alloy further includes processing the aluminum alloy rod after the cooling treatment into an aluminum alloy profile.

[0154] Furthermore, in some embodiments of the present application, the aluminum alloy rod after cooling is processed into an aluminum alloy profile, comprising:

[0155] Aluminum alloy bars are air-quenched and then cut into profiles.

[0156] Furthermore, in some embodiments of the present application, the air-cooling quenching temperature is 500°C-530°C.

[0157] Further optionally, in some embodiments of the present application, the air-cooling quenching temperature is 501°C-529°C.

[0158] Illustratively, in some embodiments of the present application, the air-cooling quenching temperature is 505°C, 510°C, 515°C, 520°C or 525°C.

[0159] Some specific embodiments are listed below to better illustrate the present application.

[0160] Examples 1-9

[0161] An aluminum alloy is provided, and the formula is shown in Table 1.

[0162] Comparative Example 1-Comparative Example 4

[0163] An aluminum alloy is provided, and the formula is shown in Table 1.

[0164] Table 1 Aluminum alloy formula (wt.%)

[0165]

[0166]

[0167]

Preparation of aluminum alloy

[0168] (1) preparing ingredients according to the formula of each embodiment or comparative example to obtain raw materials;

[0169] (2) melting, refining, degassing, deslagging, and casting the raw materials to obtain aluminum alloy rods;

[0170] (3) The aluminum alloy rod is homogenized and then cooled. The homogenization process is kept at a temperature of 565°C for 8 hours. The cooling process is cooled by strong wind to <250°C and then water cooled to room temperature or directly cooled by strong wind to room temperature.

[0171] (4) The aluminum alloy rod is heated, extruded, quenched online by strong wind cooling, stretched and straightened, and sawed to obtain an aluminum profile, and the quenching temperature is 520°C;

[0172] (5) The aluminum profile is artificially aged to obtain a high-strength aluminum profile.

[0173]

Aluminum alloy performance test

[0174] 1. Tensile test

[0175] Test method: Refer to GB / T 16865-2013 "Test specimens and methods for tensile testing of deformed aluminum, magnesium and their alloy products" to process the test specimens of each embodiment or comparative example, and finally process the test specimens into standard tensile specimens. The size and shape of the standard tensile specimens are as follows: Figure 5 shown.

[0176] During the test, a Sansi CMT5504 model 50KN tensile testing machine was used at room temperature. Under the same conditions, five specimens were used to stretch each embodiment or comparative example, and the average value of the five specimens was finally used as the experimental data.

[0177] The yield strength, tensile strength and elongation after fracture are obtained by reading the equipment and calculating the experimental data.

[0178] The test results are shown in Table 2.

[0179] 2. Extrusion test

[0180] (1) Trial machine: 2200T, extrusion barrel diameter

[0181] (2) Trial mold: HP19 project side beam (such as Figure 6 ), cross-sectional area 1440.92mm 2 , extrusion ratio 24.27;

[0182] (3) Test aluminum rod: The samples of each embodiment or comparative example are prepared as follows: Aluminum rods;

[0183] (4) Extrusion process parameters

[0184] ①Pressure remaining length: 30mm

[0185] ②Mold temperature: 485℃, insulation time 5h

[0186] ③Aluminum rod temperature: head 490℃, tail 470℃ (lead rod temperature is increased by 10℃ on this basis)

[0187] ④Extrusion speed: 1.8mm / s

[0188] ⑤Quenching temperature: 500℃

[0189] ⑥Quenching method: strong air cooling (upper and lower 100%, left and right 30% air volume)

[0190] ⑦Quenching temperature: ≤200℃

[0191] ⑧Extrusion length: 15m, elongation: 0.9% (stretching length 130mm)

[0192] ⑨ Sawing head and tail: the guide rod is directly scrapped, the rest of the cutting head ≥ 2m, cutting tail ≥ 2m

[0193] ⑩Aging plan: Samples are aged at 175℃*8h, and fixed-length samples are temporarily retained without aging.

[0194] The extrusion breakthrough pressure of each example or comparative example sample was read by the device.

[0195] The extrusion breakthrough pressure was used to characterize the extrusion performance of each embodiment and comparative example.

[0196] The smaller the extrusion breakthrough pressure, the better the extrusion property.

[0197] The test results are shown in Table 2.

[0198] Table 2

[0199] Tensile strength / Mpa Yield strength / Mpa Elongation after break / % Breakthrough pressure / Bar Example 1 291 264 11.3 216 Example 2 303 273 11.8 212 Example 3 293 262 11.2 209 Example 4 295 261 10.9 211 Example 5 295 258 12.2 211 Example 6 298 266 10.8 212 Example 7 299 269 10.9 215 Example 8 299 270 11 214 Example 9 303 271 10.8 214 Comparative Example 1 292 256 10.5 254 Comparative Example 2 314 280 11 272 Comparative Example 3 257 239 11.3 210 Comparative Example 4 269 246 10.4 229 Comparative Example 5 273 252 8.6 240

[0200] From the test results in Table 2 above, we can see that:

[0201] The aluminum alloy of the embodiment of the present application can simultaneously meet the following objectives:

[0202] (a) The tensile strength of aluminum alloy is ≥290Mpa;

[0203] (b) The yield strength of aluminum alloy is ≥260MPa;

[0204] (c) The elongation after fracture of the aluminum alloy is ≥9%.

[0205] (d) The extrusion breakthrough pressure of aluminum alloy is ≤216Bar.

[0206] Comparative Examples 1 to 4 cannot simultaneously meet the objectives that the above embodiments of the present application intend to achieve.

[0207] The formula of Comparative Example 1 is the commonly used 6061 aluminum alloy, which has a relatively low yield strength and an extrusion breakthrough pressure far exceeding the target of this application; it cannot meet the requirements of this application.

[0208] The formula of Comparative Example 2 is the commonly used 6082 aluminum alloy, and its extrusion breakthrough pressure far exceeds the target of this application; it cannot meet the requirements of this application.

[0209] The formula of Comparative Example 3 is the commonly used 6063 aluminum alloy, and its tensile strength and yield strength are far lower than the target of this application; it cannot meet the requirements of this application.

[0210] The formulas of Comparative Examples 4 and 5 are not in the aluminum alloy of the present application, and their tensile strength and yield strength are both lower than the target values ​​of the present application; the elongation after fracture of Comparative Example 5 is also lower than the target of the present application; both Comparative Examples 4 and 5 cannot meet the requirements of the present application; the extrudable breakthrough pressures of Comparative Examples 4 and 5 far exceed the target of the present application; and cannot meet the requirements of the present application.

[0211] The embodiments described above are part of the embodiments of the present application, rather than all of the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the present application for protection, but merely represents the selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

Claims

1. An aluminum alloy, characterized in that: The aluminum alloy comprises the following components in terms of mass percentage: Si 0.51-0.59; Fe≤0.20; Cu 0.16-0.23; Mn≤0.03; Mg 0.52-0.59; Cr≤0.03; Zn≤0.03; Ti≤0.05; rare earth elements 0.11-0.15; other unavoidable impurities≤0.10; the balance is Al.

2. The aluminum alloy according to claim 1, characterized in that The Si is 0.52-0.58; the Fe is ≤0.20; the Cu is 0.17-0.22; the Mn is ≤0.03; the Mg is 0.53-0.58; the Cr is ≤0.03; the Zn is ≤0.03; the Ti is ≤0.05; the rare earth element is 0.12-0.14; Other unavoidable impurities ≤ 0.10; the balance is Al.

3. The aluminum alloy according to claim 1 or 2, characterized in that: The mass ratio of the Mg to the Si is 0.881-1.157; optionally, the mass ratio of the Mg to the Si is 0.897-1.

115.

4. The aluminum alloy according to any one of claims 1 to 3, characterized in that: The rare earth element includes at least one of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc, or Y.

5. The aluminum alloy according to any one of claims 1 to 4, characterized in that: The rare earth element is La.

6. The aluminum alloy according to any one of claims 1 to 5, characterized in that: When the other unavoidable impurities include multiple elements, the content of a single element is ≤0.03 in percentage by mass.

7. The aluminum alloy according to any one of claims 1 to 6, characterized in that: The aluminum alloy meets the following conditions under air-cooling quenching, and the cooling intensity of the air-cooling quenching is 5°C / s: (a) The tensile strength of the aluminum alloy is ≥290Mpa; (b) the yield strength of the aluminum alloy is ≥260MPa; (c) The elongation after fracture of the aluminum alloy is ≥9%.

8. A method for preparing an aluminum alloy, characterized in that: include: Smelting the aluminum alloy rod by mixing the components and contents of the aluminum alloy according to any one of claims 1 to 7; The aluminum alloy rod is subjected to a homogenization treatment and then a cooling treatment.

9. The method for preparing an aluminum alloy according to claim 8, characterized in that: The heat preservation temperature of the homogenization treatment is 555° C. to 575° C., and the heat preservation time is 6 h to 10 h.

10. The method for preparing an aluminum alloy according to claim 8, characterized in that: The cooling treatment comprises: cooling the aluminum alloy rod to less than 250° C. by strong wind and then cooling it to room temperature by water.

11. The method for preparing an aluminum alloy according to claim 8, characterized in that: The cooling treatment includes: cooling the aluminum alloy rod to room temperature by using strong wind.

12. The method for preparing an aluminum alloy according to claim 10 or 11, characterized in that: The wind speed of the strong wind is: 180℃ / h~220℃ / h.

13. The method for preparing an aluminum alloy according to any one of claims 8 to 12, characterized in that: The method for preparing the aluminum alloy further includes processing the aluminum alloy rod after cooling into an aluminum alloy profile.

14. The method for preparing an aluminum alloy according to claim 13, characterized in that: The step of processing the aluminum alloy rod after cooling into an aluminum alloy profile comprises: The aluminum alloy rod is subjected to air cooling and quenching, and then cut into a profile.

15. The method for preparing an aluminum alloy according to claim 14, characterized in that: The air-cooling quenching temperature is 500°C to 530°C.

16. A box for packaging batteries, characterized in that: The box for packaging batteries comprises the aluminum alloy according to any one of claims 1-15.

17. A battery, characterized in that: The battery comprises the case for packaging a battery as claimed in claim 16.

18. An electrical device, characterized in that: The electrical device comprises the battery according to claim 17.

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