An aluminum-manganese alloy, its preparation method and application

Abstract

This invention discloses an aluminum-manganese alloy, its preparation method, and its applications, relating to the field of alloy materials technology. The aluminum-manganese alloy of this invention, by mass percentage, comprises the following components: Mn: 1.22–1.7%, Si: 0.2–0.4%, Cu: 0.2–0.5%, Mg: 0.05–0.2%, Ti: 0.01–0.05%, Fe: 0.32–0.8%, Gd: 0.05–0.3%, Zr: 0.05–0.1%, with unavoidable impurities totaling ≤0.15%, and the balance being Al. This aluminum-manganese alloy possesses excellent yield strength, tensile strength, and elongation. The hollow profiles obtained after extrusion exhibit high strength and toughness, meeting the mechanical performance requirements of battery casings without requiring cold working deformation such as drawing, making it particularly suitable for manufacturing battery casings.

Description

Technical Field

[0001] This invention relates to the field of alloy materials technology, and in particular to an aluminum-manganese alloy, its preparation method, and its applications. Background Technology

[0002] Aluminum-manganese alloys possess excellent deformation processing properties, corrosion resistance, and weldability, making them a key material for manufacturing power battery casings in new energy vehicles. Besides good formability, corrosion resistance, and weldability, aluminum alloy materials used in power battery casings for new energy vehicles also require high strength to withstand the impact of vehicle bumps during driving and ensure battery safety. However, commonly used aluminum-manganese alloys, such as 3003 aluminum alloy, exhibit low strength after extrusion, especially yield strength, generally below 60 MPa, which does not meet the mechanical performance requirements of battery casings. Cold deformation processing, such as drawing, is required to utilize work hardening mechanisms to improve the yield strength. This complicates the manufacturing process of power battery casings and increases production costs. Furthermore, cold deformation processing, such as drawing, easily produces defects on the battery casing surface such as orange peel, pits, pinholes, and aluminum shavings, leading to a higher scrap rate. In view of these problems, developing aluminum-manganese alloys with high yield strength immediately after extrusion is of great significance for shortening the processing steps of power battery casings, reducing production costs, and improving product yield. Summary of the Invention

[0003] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. Therefore, the object of the present invention is to provide an aluminum-manganese alloy that improves the yield strength after extrusion by increasing the content of solid solution elements, adding Gd, Zr, and Ti elements to refine the grains, and combining solid solution strengthening with the control of the recrystallization structure ratio.

[0004] A second aspect of the present invention is to provide a method for preparing an aluminum-manganese alloy.

[0005] A third aspect of the present invention is to provide a hollow aluminum alloy profile.

[0006] A fourth aspect of the present invention is to provide a battery casing.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] The first aspect of the present invention provides an aluminum-manganese alloy, which, by mass percentage, comprises the following components: Mn: 1.22-1.7%, Si: 0.2-0.4%, Cu: 0.2-0.5%, Mg: 0.05-0.2%, Ti: 0.01-0.05%, Fe: 0.32-0.8%, Gd: 0.05-0.3%, Zr: 0.05-0.1%, with unavoidable impurities totaling ≤0.15%, and the balance being Al.

[0009] In this invention, the elements work synergistically to enhance the yield strength of the aluminum-manganese alloy after extrusion, achieving high yield strength and good toughness without the need for cold deformation processes such as drawing. The main functions of each element are as follows:

[0010] Mn primarily functions as a solid solution strengthener and can also increase the recrystallization temperature of the alloy, preventing the formation of coarse recrystallized structures during extrusion. Excessive Mn content leads to severe intragranular segregation, requiring prolonged homogenization heat treatment; otherwise, it easily forms a large amount of brittle Al6Mn compound, causing the alloy to crack easily during extrusion. Conversely, insufficient Mn content tends to form coarse iron-containing compounds during extrusion of profiles, reducing the density of the second phase in the alloy and lowering the strength and plasticity of the aluminum-manganese alloy.

[0011] Fe can alleviate the intragranular segregation of Mn. When the Fe content is too high, coarse Al6(FeMn) compounds will be formed, reducing the toughness of the material. However, when the Fe content is too high, it will affect the high-temperature performance of aluminum-manganese alloys, and the amount of precipitated iron-containing compounds will be small, failing to provide precipitation strengthening.

[0012] Si can improve the fluidity of aluminum-manganese alloy melts, thus enhancing the alloy's casting performance. Simultaneously, Si reacts with other elements to form fine Al(Fe,Mn)Si intermetallic compounds, which act as a self-lubricant during the extrusion of aluminum-manganese alloys into profiles. Excessive Si content leads to the formation of brittle phases such as GdAl2Si2, reducing the material's elongation; conversely, insufficient Si content fails to provide solid solution strengthening.

[0013] Cu can improve the tensile strength and corrosion resistance of aluminum-manganese alloys, but when the Cu content is too high, the deformation resistance of aluminum-manganese alloys increases and the plasticity decreases.

[0014] Mg primarily functions as a solid solution strengthening element. However, excessive Mg content leads to the formation of too many Mg2Si compounds, reducing the elongation of the aluminum-manganese alloy and affecting its weldability, resulting in decreased weld strength.

[0015] In the melt, Gd can promote the nucleation rate of crystal nuclei, refine the α-Al microstructure, and simultaneously form a surface-active film at the interface between the second phase and α-Al. This film refines hard and brittle phases such as Al(Fe,Mn)Si and Al6(Fe,Mn), causing them to form fine and dispersed precipitates at grain boundaries, reducing the adverse effects of Fe and Si, and significantly improving the strength and plasticity of the material. When the Gd content in the alloy is too high, coarse blocky structures will appear, which is not conducive to grain refinement. In addition, with the addition of Gd, fine and dispersed Gd-containing phases, such as Al2Gd compounds, are formed in aluminum-manganese alloys. These dispersed phases can strongly pin dislocations and subgrain boundaries, inhibiting the formation of recrystallization structures during the extrusion of aluminum-manganese alloys, thereby improving the strength of aluminum-manganese alloys after extrusion.

[0016] Ti forms Al3Ti particles in aluminum-manganese alloys, which helps to refine the α-Al microstructure.

[0017] Zr forms Al3Zr in aluminum-manganese alloys, which improves the weldability of aluminum-manganese alloys and prevents the formation of coarse recrystallization structures during extrusion, thereby increasing the strength after extrusion.

[0018] This invention achieves solid solution strengthening by increasing the content of solid-solution elements such as Fe, Mn, Si, Cu, and Mg. More solid-solution elements also facilitate the formation of more second phases during crystallization, promoting the dispersion strengthening effect of submicron-sized second phases. By adding Gd, Zr, and Ti elements, the grain size of the aluminum-manganese alloy is refined. In particular, Gd significantly increases the recrystallization temperature of the aluminum-manganese alloy during extrusion, inhibits the formation of coarse recrystallized structures, regulates the ratio of recrystallized to deformed structures, and enhances the strength of the extruded alloy.

[0019] In some embodiments of the present invention, the aluminum-manganese alloy comprises, by mass percentage, the following components: Mn: 1.25–1.65%, Si: 0.2–0.4%, Cu: 0.2–0.45%, Mg: 0.05–0.2%, Ti: 0.01–0.05%, Fe: 0.35–0.75%, Gd: 0.05–0.3%, Zr: 0.05–0.1%, with unavoidable impurities totaling ≤0.15%, and the balance being Al.

[0020] In some embodiments of the present invention, the aluminum-manganese alloy comprises, by mass percentage, the following components: Mn: 1.35–1.65%, Si: 0.2–0.35%, Cu: 0.3–0.45%, Mg: 0.08–0.2%, Ti: 0.02–0.05%, Fe: 0.45–0.75%, Gd: 0.1–0.3%, Zr: 0.05–0.1%, unavoidable impurities totaling ≤0.15%, with the balance being Al.

[0021] In some specific embodiments of the present invention, the aluminum-manganese alloy is composed of the following components by mass percentage: Mn: 1.35-1.45%, Si: 0.25-0.35%, Cu: 0.3-0.4%, Mg: 0.08-0.12%, Ti: 0.02-0.03%, Fe: 0.5-0.6%, Gd: 0.1-0.2%, Zr: 0.06-0.08%, unavoidable impurities total ≤0.15%, and the balance is Al.

[0022] In some embodiments of the present invention, the total mass percentage of Fe, Mn and Si in the aluminum-manganese alloy satisfies the following relationship: 1.9% ≤ Fe + Mn + Si ≤ 2.5%.

[0023] In some embodiments of the present invention, the total mass percentage of Fe, Mn and Si in the aluminum-manganese alloy satisfies the following relationship: 1.95% ≤ Fe + Mn + Si ≤ 2.5%.

[0024] The total content of Fe, Mn and Si affects the number of intermetallic compounds formed. When the total content is high, excessive iron and silicon compounds will lead to a decrease in the performance of aluminum-manganese alloys, especially a decrease in toughness. When the total content is low, the yield strength of aluminum-manganese alloys will decrease after extrusion.

[0025] In some embodiments of the present invention, the aluminum-manganese alloy has columnar crystals.

[0026] In some embodiments of the present invention, the grain diameter of the aluminum-manganese alloy is 50-95 μm.

[0027] In some embodiments of the present invention, the grain diameter of the aluminum-manganese alloy is 53-94 μm.

[0028] It should be understood that the grain size of the aluminum-manganese alloy mentioned here refers to the grain size of the aluminum-manganese alloy ingot.

[0029] In some embodiments of the present invention, the aluminum-manganese alloy contains a second phase after homogenization heat treatment, the density of which is (9-15) × 10⁻⁶. 18 m -3 .

[0030] In some embodiments of the present invention, the second phase has (9-14)×10 18 m -3 .

[0031] In some embodiments of the present invention, the aluminum-manganese alloy contains a second phase after homogenization heat treatment, the average diameter of the second phase being 0.4 to 0.5 μm.

[0032] In some embodiments of the present invention, the recrystallization area ratio of the aluminum-manganese alloy after extrusion is 10-30%.

[0033] In some embodiments of the present invention, the tensile strength of the aluminum-manganese alloy after extrusion is 160-190 MPa.

[0034] In some embodiments of the present invention, the yield strength of the aluminum-manganese alloy after extrusion is 140-160 MPa.

[0035] In some embodiments of the present invention, the yield strength of the aluminum-manganese alloy after extrusion is 140-155 MPa.

[0036] In some embodiments of the present invention, the elongation of the aluminum-manganese alloy after extrusion is 10-15%.

[0037] In some embodiments of the present invention, the elongation of the aluminum-manganese alloy after extrusion is 10-13%.

[0038] A second aspect of the present invention provides a method for preparing the aluminum-manganese alloy described in the first aspect of the present invention, comprising the following steps:

[0039] The components are added according to the formula and mixed. The mixture is then cast using a semi-continuous casting method, followed by homogenization heat treatment to obtain the aluminum-manganese alloy.

[0040] In some embodiments of the present invention, Mn is added as an aluminum-manganese master alloy or a manganese agent; Fe is added as an aluminum-iron master alloy; Cu is added as an aluminum-copper master alloy or copper granules; Mg is added as magnesium ingots; Gd is added as an Al-Gd master alloy; Ti is added as an aluminum-titanium master alloy; and Zr is added as an aluminum-zirconium master alloy.

[0041] Specifically, the Al-Gd master alloy can be Al-10Gd, Al-20Gd, or Al-30Gd.

[0042] In some embodiments of the present invention, during the casting process, the cooling rate during solidification is controlled to be 30-50°C / s.

[0043] In some embodiments of the present invention, during the casting process, the cooling rate during solidification is controlled to be 40-50°C / s.

[0044] In some specific embodiments of the present invention, during the casting process, the cooling rate during solidification is controlled to be 45-50°C / s.

[0045] This invention involves casting ingots with a diameter ≤250mm. The cooling rate is controlled at 30–50℃ / s by adjusting parameters such as casting temperature, casting speed, cooling water volume, cooling water temperature, and cooling water pressure. Due to the high cooling rate, α-Al in the ingot can form columnar crystals with directional solidification characteristics parallel to the cooling direction, with a grain diameter ≤100μm and an average diameter of the second phase at the grain boundaries ≤2μm.

[0046] When the cooling rate is greater than 50℃ / s, it is difficult to achieve under current industrial production conditions, and phenomena such as water backflow and solidification of the gating tube will occur during casting. When the cooling rate is less than 30℃ / s, it is difficult to form columnar crystals with directional solidification characteristics, and the diameter of the second phase at the grain boundary will become coarser, which is not conducive to improving the strength of the alloy.

[0047] Cooling rate refers to the rate at which the aluminum-manganese alloy melt cools from the casting temperature to the solidus line, with the cooling rate at the core of the ingot as the standard.

[0048] In some embodiments of the present invention, the casting process parameters satisfy at least one of the following a) to d):

[0049] a) The casting temperature is 710–750℃;

[0050] b) The casting speed is 180–200 mm / min;

[0051] c) The cooling water temperature is 10–20℃;

[0052] d) Cooling water pressure is 140-155 kPa.

[0053] In some embodiments of the present invention, the casting temperature is 715–745°C.

[0054] In some embodiments of the present invention, the ingot obtained by casting includes a casting rod with a diameter ≤250mm.

[0055] In some embodiments of the present invention, the diameter of the casting rod is 120-130 mm.

[0056] Ingots can be directly cast using a vertical semi-continuous casting method.

[0057] It is understandable that the homogenization heat treatment does not change the shape of the ingot, and the cast rod obtained is also an aluminum-manganese alloy. However, because the diffusion rate of manganese in the aluminum-manganese alloy of this invention is relatively slow, it is dissolved in the matrix in a supersaturated state during solidification. Therefore, further homogenization heat treatment is required to form a uniform and fine second phase at the grain boundaries, further refining the second phase and playing a role in dispersion strengthening, thereby improving the strength and toughness of the aluminum-manganese alloy. When the casting results in a cast rod, the homogenization heat treatment will still produce an aluminum-manganese alloy cast rod.

[0058] In some embodiments of the present invention, the heating rate of the homogenization heat treatment is 10-20 °C / min.

[0059] In some embodiments of the present invention, the heating rate of the homogenization heat treatment is 10-15 °C / min.

[0060] In some embodiments of the present invention, the temperature of the homogenization heat treatment is 570–630°C.

[0061] In some embodiments of the present invention, the temperature of the homogenization heat treatment is 580–625°C.

[0062] In some specific embodiments of the present invention, the temperature of the homogenization heat treatment is 600-610°C.

[0063] In some embodiments of the present invention, the homogenization heat treatment time is 8 to 15 hours.

[0064] In some embodiments of the present invention, the homogenization heat treatment time is 8 to 12 hours.

[0065] This invention further employs a rapid heating method for homogenization heat treatment, which is beneficial for controlling the density and diameter of the second phase precipitated in the homogenized aluminum-manganese alloy, ensuring that the density of the second phase is greater than 9.0 × 10⁻⁶. 18 m -3 The average diameter of the second phase is less than 0.5 μm. Its high density and small particle size are beneficial for improving the strength and toughness of aluminum-manganese alloys.

[0066] In some embodiments of the present invention, after the homogenization heat treatment, the furnace is removed and air-cooled.

[0067] A third aspect of the present invention provides an aluminum alloy hollow profile, which is obtained by extrusion molding using an aluminum-manganese alloy as a raw material, as described in the first aspect of the present invention.

[0068] In some embodiments of the present invention, the extrusion step includes forming the aluminum-manganese alloy into an extrusion billet, and extruding it to obtain the aluminum alloy hollow profile; the temperature of the extrusion billet is 450-500°C.

[0069] In some embodiments of the present invention, the temperature of the extruded billet is 470–500°C.

[0070] In some embodiments of the present invention, the extrusion is performed using an extrusion press, and the outlet temperature of the extrusion cylinder of the extrusion press is 500-530°C.

[0071] In some embodiments of the present invention, the outlet temperature of the extrusion cylinder is 500–520°C.

[0072] In some embodiments of the present invention, the wall thickness of the aluminum alloy hollow profile is 0.3 to 1 mm.

[0073] A fourth aspect of the present invention provides a battery casing, the raw materials of which include the aluminum-manganese alloy described in the first aspect of the present invention, or the aluminum alloy hollow profile described in the third aspect of the present invention.

[0074] In some embodiments of the present invention, the battery casing is a power battery casing.

[0075] Specifically, the power battery casing can be the power battery casing for various new energy products, such as new energy vehicles.

[0076] Compared with the prior art, the present invention has at least the following beneficial effects:

[0077] (1) The aluminum-manganese alloy provided by this invention uses Fe and other solid-solution elements as beneficial elements. The alloy employs a high-iron, high-manganese, and high-silicon content ratio to achieve solid-solution strengthening and facilitate the precipitation of the second phase. Simultaneously, micro-alloying with elements such as Gd, Zr, and Ti comprehensively controls the microstructure, preventing the formation of coarse intermetallic compounds, increasing the alloy recrystallization temperature, and suppressing the formation of coarse recrystallized structures after extrusion, thereby improving the mechanical strength of the aluminum-manganese alloy. Furthermore, the addition of elements such as Fe, Mn, and Si reduces the requirements for raw material purity, thus lowering raw material costs.

[0078] (2) The aluminum-manganese alloy preparation method of the present invention is simple. At the same time, by adopting a semi-continuous casting method with a large cooling rate, a microstructure with directional solidification characteristics is formed. The homogenization heat treatment can form a uniform and fine second phase at the grain boundary, thereby achieving the effect of second phase dispersion strengthening and improving the strength and toughness of the aluminum-manganese alloy.

[0079] (3) The hollow profile obtained by extrusion of the aluminum-manganese alloy of the present invention has high strength and toughness, especially high yield strength. It can meet the mechanical performance requirements of battery casing without cold working deformation such as drawing, and is especially suitable for making battery casing. Attached Figure Description

[0080] Figure 1This is a metallographic diagram of the aluminum-manganese alloy in Example 1 of the present invention.

[0081] Figure 2 This is an EBSD image of the aluminum-manganese alloy of Embodiment 1 of the present invention.

[0082] Figure 3 This is a SEM image of the cast rod after casting in Embodiment 1 of the present invention before homogenization heat treatment.

[0083] Figure 4 This is a SEM image of the aluminum-manganese alloy casting rod after homogenization heat treatment in Example 1 of the present invention.

[0084] Figure 5 This is a SEM image of the hollow profile after extrusion in Embodiment 1 of the present invention.

[0085] Figure 6 This is a SEM image of the cast rod after casting in Comparative Example 9 of the present invention before homogenization heat treatment. Detailed Implementation

[0086] The present invention will be further described in detail below through specific embodiments. Unless otherwise specified, the raw materials, reagents, or apparatus used in the embodiments and comparative examples are all available from conventional commercial sources or can be obtained by existing technical methods. Unless otherwise specified, the test or experimental methods are conventional methods in the art.

[0087] The following detailed description is provided in conjunction with specific embodiments and comparative examples.

[0088] Example 1

[0089] An aluminum-manganese alloy, the composition of which is shown in Table 1, Alloy 1.

[0090] The preparation method of this aluminum-manganese alloy includes the following steps:

[0091] Alloy 1 in Table 1 was cast using a vertical semi-continuous casting method. Mn was added as an aluminum-manganese master alloy, Fe as an aluminum-iron master alloy, Cu as an aluminum-copper master alloy, Mg as a magnesium ingot, Gd as an Al-20Gd master alloy, Ti as an aluminum-titanium master alloy, and Zr as an aluminum-zirconium master alloy. During casting, the core cooling rate of the cast rod was controlled at 49.3℃ / s during melt solidification. The diameter of the cast rod was 127mm. To achieve this cooling rate, the specific casting process parameters were: casting temperature 720℃, casting speed 200mm / min, cooling water temperature 10℃, cooling water pressure 150kPa, and the measured core cooling rate of the cast rod was 49.3℃ / s.

[0092] The cast rods obtained by casting are subjected to homogenization heat treatment in a heat treatment furnace at a heating rate of 15℃ / min, the temperature is raised to 605℃, held for 12h, and then air-cooled to obtain aluminum-manganese alloy cast rods.

[0093] It should be noted that the cooling rate of the core of the casting rod is measured and calculated by embedding thermocouples in the casting rod. The casting temperature, casting speed, cooling water temperature and cooling water pressure are adjusted according to the measurement results. After the required cooling rate is achieved, the casting is prepared according to the corresponding parameters.

[0094] The aluminum-manganese alloy of this embodiment is prepared into a hollow profile by extrusion molding, and the specific method is as follows:

[0095] Aluminum-manganese alloy cast rods are sawn into extrusion billets, which are then heated to 480°C. The extrusion cylinder outlet temperature is 510°C, and the billets are extruded into square hollow aluminum alloy profiles with a wall thickness of 0.52mm.

[0096] Table 1. Composition of aluminum-manganese alloys in the examples and comparative examples (unit: mass percentage / %)

[0097]

[0098] In Table 1, Bal. indicates the balance; Alloy 1 to 18 refers to aluminum-manganese alloy 1 to 18.

[0099] Example 2

[0100] An aluminum-manganese alloy, the composition of which is shown in Alloy 2 of Table 1.

[0101] The preparation method of this aluminum-manganese alloy includes the following steps:

[0102] Alloy 2 in Table 1 was cast using a vertical semi-continuous casting method. Mn was added as an aluminum-manganese master alloy or manganese agent, Fe as an aluminum-iron master alloy, Cu as an aluminum-copper master alloy or copper granules, Mg as magnesium ingots, Gd as an Al-20Gd master alloy, Ti as an aluminum-titanium master alloy, and Zr as an aluminum-zirconium master alloy. The core cooling rate was controlled at 48.6℃ / s during casting, and the diameter of the cast rod was 127mm.

[0103] To achieve the required cooling rate, the specific casting process parameters are as follows: casting temperature 720℃, casting speed 190mm / min, cooling water temperature 12℃, cooling water pressure 145kPa, and the measured cooling rate of the core of the cast rod is 48.6℃ / s.

[0104] The cast rods obtained from casting are subjected to homogenization heat treatment in a heat treatment furnace at a heating rate of 12℃ / min, the temperature is raised to 605℃, held for 12h, and then air-cooled to obtain an aluminum-manganese alloy.

[0105] The aluminum-manganese alloy of this embodiment is prepared into a hollow profile by extrusion molding, and the specific method is as follows:

[0106] Aluminum-manganese alloy cast rods are sawn into extrusion billets, which are then heated to 480°C. The extrusion cylinder outlet temperature is 510°C, and the billets are extruded into square hollow aluminum alloy profiles with a wall thickness of 0.52mm.

[0107] Example 3

[0108] An aluminum-manganese alloy, the composition of which is shown in Table 1, Alloy 3.

[0109] The preparation method of this aluminum-manganese alloy includes the following steps:

[0110] Alloy 3 in Table 1 was cast using a vertical semi-continuous casting method. Mn was added as an aluminum-manganese master alloy or manganese agent, Fe as an aluminum-iron master alloy, Cu as an aluminum-copper master alloy or copper granules, Mg as magnesium ingots, Gd as an Al-20Gd master alloy, Ti as an aluminum-titanium master alloy, and Zr as an aluminum-zirconium master alloy. The core cooling rate of the casting rod was controlled at 47.5℃ / s during the casting process. The diameter of the casting rod was 127mm.

[0111] To achieve the required cooling rate, the specific casting process parameters are as follows: casting temperature 725℃, casting speed 200mm / min, cooling water temperature 15℃, cooling water pressure 150kPa, and the measured cooling rate of the core of the cast rod is 47.5℃ / s.

[0112] The cast rods obtained from casting are subjected to homogenization heat treatment in a heat treatment furnace at a heating rate of 12℃ / min, the temperature is raised to 605℃, held for 12h, and then air-cooled to obtain an aluminum-manganese alloy.

[0113] The aluminum-manganese alloy of this embodiment is prepared into a hollow profile by extrusion molding, and the specific method is as follows:

[0114] Aluminum-manganese alloy cast rods are sawn into extrusion billets, which are then heated to 480°C. The extrusion cylinder outlet temperature is 510°C, and the billets are extruded into square hollow aluminum alloy profiles with a wall thickness of 0.52mm.

[0115] Example 4

[0116] A method for preparing an aluminum-manganese alloy, wherein alloy 1 in Table 1 is cast using a vertical semi-continuous casting method, differing from Example 1 in that the cooling rate during casting is 32.1℃ / s; otherwise, it is the same as Example 1.

[0117] To achieve the required cooling rate, the specific casting process parameters are as follows: casting temperature 740℃, casting speed 180mm / min, cooling water temperature 18℃, cooling water pressure 140kPa, and the measured cooling rate of the core of the cast rod is 32.1℃ / s.

[0118] The aluminum-manganese alloy of this embodiment was prepared into a hollow profile by extrusion molding, and the method and conditions were the same as in Example 1.

[0119] Example 5

[0120] A method for preparing an aluminum-manganese alloy is described, in which alloy 1 in Table 1 is cast using a vertical semi-continuous casting method. The difference from Example 1 is that the cooling rate during casting is 48.8℃ / s; the holding time during homogenization heat treatment is 8h; and the rest is the same as in Example 1.

[0121] To achieve the required cooling rate, the specific casting process parameters are as follows: casting temperature 720℃, casting speed 195mm / min, cooling water temperature 12℃, cooling water pressure 152kPa, and the measured cooling rate of the core of the cast rod is 48.8℃ / s.

[0122] The aluminum-manganese alloy of this embodiment was prepared into a hollow profile by extrusion molding, and the method and conditions were the same as in Example 1.

[0123] Example 6

[0124] A method for preparing an aluminum-manganese alloy is described, in which alloy 1 in Table 1 is cast using a vertical semi-continuous casting method. The difference from Example 1 is that the cooling rate during casting is 48.2℃ / s; the holding time during homogenization heat treatment is 10h; and the rest is the same as in Example 1.

[0125] To achieve the required cooling rate, the specific casting process parameters are as follows: casting temperature 725℃, casting speed 185mm / min, cooling water temperature 14℃, cooling water pressure 140kPa, and the measured cooling rate of the core of the cast rod is 48.2℃ / s.

[0126] The aluminum-manganese alloy of this embodiment was prepared into a hollow profile by extrusion molding, and the method and conditions were the same as in Example 1.

[0127] Example 7

[0128] A method for preparing an aluminum-manganese alloy is described, in which alloy 1 in Table 1 is cast using a vertical semi-continuous casting method. The difference between this method and Example 1 is that the cooling rate during casting is 49.5℃ / s; otherwise, the method is the same as Example 1.

[0129] To achieve the required cooling rate, the specific casting process parameters are as follows: casting temperature 715℃, casting speed 195mm / min, cooling water temperature 10℃, cooling water pressure 153kPa, and the measured cooling rate of the core of the cast rod is 49.5℃ / s.

[0130] The aluminum-manganese alloy of this embodiment is prepared into a hollow profile by extrusion molding, and the specific method is as follows:

[0131] Aluminum-manganese alloy cast rods are sawn into extrusion billets, which are then heated to 495°C. The extrusion cylinder outlet temperature is 528°C, and the billets are extruded into square hollow aluminum alloy profiles with a wall thickness of 0.52 mm.

[0132] Example 8

[0133] A method for preparing an aluminum-manganese alloy, wherein alloy 1 in Table 1 is cast using a vertical semi-continuous casting method, and the preparation method is the same as in Example 1.

[0134] The aluminum-manganese alloy of this embodiment is prepared into a hollow profile by extrusion molding, and the specific method is as follows:

[0135] Aluminum-manganese alloy cast rods are sawn into extrusion billets, which are then heated to 453°C. The extrusion cylinder outlet temperature is 503°C, and the billets are extruded into hollow profiles with a wall thickness of 0.52 mm by an extrusion press.

[0136] Comparative Examples 1-15

[0137] A method for preparing an aluminum-manganese alloy differs from Example 1 in that the alloys are prepared sequentially according to the composition ratios of alloys 4 to 18 in Table 1 to obtain aluminum-manganese alloys 4 to 18 in Table 1.

[0138] Comparative Example 1 corresponds to Alloy 4 in Table 1, Comparative Example 2 corresponds to Alloy 5, and so on in sequence.

[0139] Hollow profiles were prepared from aluminum-manganese alloys of Comparative Examples 1 to 15 by extrusion molding, using the same method as in Example 1.

[0140] Comparative Example 16

[0141] A method for preparing an aluminum-manganese alloy, wherein alloy 1 in Table 1 is prepared, the difference from Example 1 is that the cooling rate during casting is 25.1℃ / s; the rest is the same as in Example 1.

[0142] To achieve the required cooling rate, the specific casting process parameters are as follows: casting temperature 750℃, casting speed 150mm / min, cooling water temperature 25℃, cooling water pressure 132kPa, and the measured cooling rate of the core of the cast rod is 25.1℃ / s.

[0143] The aluminum-manganese alloy of this comparative example was extruded into a hollow profile using the same method as in Example 1.

[0144] Comparative Example 17

[0145] A method for preparing an aluminum-manganese alloy, wherein alloy 1 in Table 1 is prepared, the difference from Example 1 is that the heating rate of the homogenization heat treatment is 8℃ / min; the rest is the same as in Example 1.

[0146] The aluminum-manganese alloy of this comparative example was extruded into a hollow profile using the same method as in Example 1.

[0147] Comparative Example 18

[0148] A method for preparing an aluminum-manganese alloy, wherein alloy 1 in Table 1 is prepared, the difference from Example 1 is that the heating rate of the homogenization heat treatment is 20.5℃ / min, and the temperature is raised to 560℃; the rest is the same as in Example 1.

[0149] The aluminum-manganese alloy of this comparative example was extruded into a hollow profile using the same method as in Example 1.

[0150] Comparative Example 19

[0151] A method for preparing a hollow profile, using alloy 1, differs from Example 1 in that the extrusion billet is heated to 445°C and the extrusion cylinder outlet temperature is 489°C; the rest is the same as in Example 1.

[0152] Comparative Example 20

[0153] A method for preparing a hollow profile, using alloy 1, differs from Example 1 in that the extrusion billet is heated to 512°C and the extrusion cylinder outlet temperature is 542°C; the rest is the same as in Example 1.

[0154] Result detection

[0155] The square hollow aluminum alloy profiles obtained in Examples 1-8 and Comparative Examples 1-20 were subjected to microstructure and mechanical property testing, and the specific methods are as follows:

[0156] (1) Grain diameter: Samples were taken from the middle of the cast rods (before homogenization heat treatment) obtained from the examples and comparative examples. After the samples were polished, the grain diameter was detected by EBSD.

[0157] (2) Second phase density and average diameter: Scanning electron microscopy (SEM) was used to randomly photograph more than 10 fields of view of the homogenized aluminum-manganese alloy samples of the examples and comparative examples at a magnification of 500x. The images were observed and analyzed, and the maximum length of the second phase was taken as the diameter. More than 5 particles were randomly measured in each field of view, and the average size of all measured particles was then calculated to obtain the average diameter of the particles. The number of second phase particles in each field of view was counted, and the area of ​​the photographed field of view and the thickness of the sample were measured to obtain its volume, thereby calculating the distribution density of the homogenized second phase.

[0158] (3) Recrystallization area ratio after extrusion: Samples were taken from the hollow profiles obtained by extrusion of aluminum-manganese alloy in the examples and comparative examples. After the samples were polished, they were etched (Keller reagent etching) and then photographed. The area of ​​recrystallized structure and fibrous deformed structure was statistically analyzed using computer software to obtain the results.

[0159] (4) Tensile strength, yield strength and elongation (elongation after fracture): The test shall be conducted in accordance with the test standard GB / T16865-2023.

[0160] The mechanical properties of commercially available 3003 alloy were tested using the same method. The tensile strength was 95–110 MPa, the yield strength was 40–45 MPa, and the elongation was 30–40%. After drawing (H14 state), the tensile strength was 150–180 MPa, the yield strength was 128–145 MPa, and the elongation was ≥4.1%.

[0161] The test results are shown in Tables 2 and 3.

[0162] Table 2. Results of tissue analysis and mechanical property testing of hollow profiles in the embodiments.

[0163]

[0164] The aluminum-manganese alloys obtained in Examples 1-8 all had columnar crystals.

[0165] Table 3. Comparative examples: microstructure analysis and mechanical property test results of hollow profiles.

[0166]

[0167]

[0168] Of the aluminum-manganese alloys in Comparative Examples 1 to 20, except for Comparative Example 16 which is non-columnar, the rest are columnar. Therefore, no grain diameter data is given for Comparative Example 16.

[0169] As can be seen from Tables 2 and 3 above, the aluminum-manganese alloy ingots of the present invention have columnar grains with a grain diameter of less than 100 μm, an average diameter of the second phase that is consistently less than 0.5 μm, and a second phase density of not less than 10 × 10⁻⁶. 18 m -3 The grain diameter, average diameter of the second phase, density of the second phase, and recrystallization area ratio of aluminum-manganese alloys all affect their post-extrusion properties. Among these, the second phase density and recrystallization area ratio have a greater impact on the properties of aluminum-manganese alloys than other microstructure parameters. Strength decreases when the recrystallization area ratio exceeds 30%, and elongation decreases when it is below 10%. The aluminum-manganese alloy of this invention has a recrystallization area ratio of 10-30% after extrusion into hollow profiles. It exhibits high strength without the need for drawing or other processing deformation after extrusion, with a yield strength of not less than 165 MPa and a maximum of 187 MPa, and a tensile strength of not less than 140 MPa, while maintaining an elongation of 10-13%. Therefore, the aluminum-manganese alloy of this invention can achieve a higher yield strength than conventional 3003 aluminum alloy without drawing.

[0170] In Comparative Examples 1-15, aluminum-manganese alloys 4-18 were used compared to the embodiments of the present invention. Due to changes in the content of each element, the performance of the aluminum-manganese alloys decreased. For example, in Comparative Examples 1 and 2, the Mn content in the aluminum-manganese alloys was lower or higher, resulting in an increased recrystallization area ratio after extrusion and a decrease in yield strength and tensile strength. Similarly, in Comparative Examples 3-8, due to changes in Fe, Si, or Gd content, the recrystallization area ratio after extrusion increased, while the yield strength and tensile strength decreased. In Comparative Example 9, the Ti content was higher. Although the recrystallization area ratio of the aluminum-manganese alloy after extrusion was only 12.6%, coarse Ti-containing compounds were formed, and these compounds tended to agglomerate, thus reducing strength. In Comparative Examples 10 and 11, the total content of Mn, Fe, and Si changed, resulting in a decrease in the density of the second phase or an increase in the diameter of the second phase, leading to a decrease in the strength of the hollow profiles obtained after extrusion. In Comparative Examples 12 and 13, the absence of Gd or the substitution of Gd with La resulted in a lack of dispersion strengthening and recrystallization inhibition by the fine, dispersed Gd-containing phase. Consequently, the recrystallization area ratio was higher or the second phase density was lower after extrusion, leading to a decrease in strength. In Comparative Examples 14 and 15, reducing the content of Mg or Ti also resulted in a decrease in the performance of the extruded profiles.

[0171] In summary, the aluminum-manganese alloy provided by this invention has excellent yield strength, tensile strength and elongation. The hollow profile obtained after extrusion has high strength and toughness. It can meet the mechanical performance requirements of battery casing without cold working deformation such as drawing, and is especially suitable for manufacturing battery casing.

[0172] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. An aluminum-manganese alloy, characterized in that, By mass percentage, it consists of the following components: Mn: 1.35–1.65%, Si: 0.2–0.35%, Cu: 0.3–0.45%, Mg: 0.08–0.2%, Ti: 0.02–0.05%, Fe: 0.45–0.75%, Gd: 0.1–0.3%, Zr: 0.06–0.1%, unavoidable impurities ≤ 0.15%, balance Al; The aluminum-manganese alloy is prepared by a method comprising the following steps: The components are added according to the formula and mixed, and then cast using a semi-continuous casting method. After homogenization heat treatment, the aluminum-manganese alloy is obtained. During the casting process, the cooling rate during solidification is controlled to be 30~50℃ / s; The homogenization heat treatment time is 8~15h; The aluminum-manganese alloy contains a second phase after homogenization heat treatment.

2. The aluminum-manganese alloy according to claim 1, characterized in that, In the aluminum-manganese alloy, the total mass percentage of Fe, Mn and Si satisfies the following relationship: 2%≤Fe+Mn+Si≤2.5%.

3. The aluminum-manganese alloy according to claim 1 or 2, characterized in that, The aluminum-manganese alloy has columnar crystals; And / or, the grain diameter of the aluminum-manganese alloy is 50~95μm.

4. The aluminum-manganese alloy according to claim 1 or 2, characterized in that, The density of the second phase is (9~15)×10 18 pcs / m 3 ; And / or, the average diameter of the second phase is 0.4~0.5 μm.

5. The aluminum-manganese alloy according to claim 1 or 2, characterized in that, The recrystallization area ratio of the aluminum-manganese alloy after extrusion is 10-30%.

6. A method for preparing the aluminum-manganese alloy according to any one of claims 1 to 5, characterized in that, Includes the following steps: The components are added according to the formula and mixed. The mixture is then cast using a semi-continuous casting method, followed by homogenization heat treatment to obtain the aluminum-manganese alloy.

7. The preparation method according to claim 6, characterized in that, The heating rate of the homogenization heat treatment is 10~20℃ / min; And / or, the temperature of the homogenization heat treatment is 570~630℃.

8. A hollow aluminum alloy profile, characterized in that, It is obtained by extrusion molding from aluminum-manganese alloy as described in any one of claims 1 to 5.

9. The aluminum alloy hollow profile according to claim 8, characterized in that, The extrusion step includes forming the aluminum-manganese alloy into an extrusion billet, and extruding it to obtain the aluminum alloy hollow profile; the temperature of the extrusion billet is 450~500℃. And / or, the extrusion is performed using an extrusion press, wherein the outlet temperature of the extrusion cylinder of the extrusion press is 500~530℃.

10. A battery casing, characterized in that, The raw materials for preparation include the aluminum-manganese alloy as described in any one of claims 1 to 5, or the aluminum alloy hollow profile as described in any one of claims 8 to 9.

Images