Aluminum-manganese alloy and preparation method and application thereof

Abstract

The invention discloses an aluminum-manganese alloy and a preparation method and application thereof, and relates to the technical field of alloy materials. The aluminum-manganese alloy disclosed by the invention is prepared from the following components in percentage by mass: 1.22 to 1.7 percent of Mn, 0.2 to 0.4 percent of Si, 0.2 to 0.5 percent of Cu, 0.05 to 0.2 percent of Mg, 0.01 to 0.05 percent of Ti, 0.32 to 0.8 percent of Fe, 0.05 to 0.3 percent of Gd, 0.05 to 0.1 percent of Zr, less than or equal to 0.15 percent of inevitable impurities and the balance of Al. The aluminum-manganese alloy has excellent yield strength, tensile strength and ductility, a hollow profile obtained after extrusion has high strength and toughness, the mechanical property requirement of the battery shell can be met without cold machining deformation such as drawing, and the aluminum-manganese alloy is particularly suitable for preparing the battery shell.

Description

Technical Field

[0001] The present invention relates to the technical field of alloy materials, and in particular to an aluminum-manganese alloy and a preparation method and application thereof. Background Art

[0002] Aluminum-manganese alloy has good deformation processing performance, corrosion resistance and welding performance, and is a key material for manufacturing power battery shells for new energy vehicles. In addition to having good forming performance, corrosion resistance and welding performance, aluminum alloy materials for power battery shells for new energy vehicles also require high strength to meet the impact requirements of vehicle bumps during driving on the battery and ensure battery safety. However, the commonly used aluminum-manganese alloys, such as 3003 aluminum alloy, have low strength performance after extrusion molding, especially yield strength, which is generally lower than 60MPa, and cannot meet the mechanical performance requirements of the battery shell. It is necessary to use cold deformation processing such as drawing to improve its yield strength by using the work hardening mechanism. This leads to complex preparation procedures for power battery shells and increases production costs. At the same time, cold deformation processing such as drawing is prone to produce defects such as orange peel, pits, pinholes, and aluminum chips pressing on the surface of the battery shell, resulting in an increase in product scrap rate. In view of the above problems, the development of aluminum-manganese alloys with high yield strength after extrusion is of great significance for shortening the processing procedures of power battery shells, reducing production costs, and improving product yields. Summary of the invention

[0003] The present invention aims to solve at least one of the above-mentioned technical problems existing in the prior art. To this end, the purpose of the present invention is to provide an aluminum-manganese alloy, which improves the yield strength of the aluminum-manganese alloy after extrusion by increasing the content of solid solution elements, adding Gd, Zr, and Ti elements to refine the grains, combining solid solution strengthening and regulating the proportion of recrystallized structures.

[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 an aluminum alloy hollow profile.

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

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] The first aspect of the present invention provides an aluminum-manganese alloy, which is composed of the following components, by mass percentage: 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%, the total amount of unavoidable impurities is ≤0.15%, and the balance is Al.

[0009] In the present invention, each element cooperates with each other to improve the yield strength of the aluminum-manganese alloy after extrusion, and can have high yield strength and good toughness without cold deformation processing such as drawing. The main functions of each element are as follows:

[0010] Mn mainly plays a role in solid solution strengthening, and can also increase the recrystallization temperature of the alloy to avoid the formation of coarse recrystallization structure during extrusion. When the Mn content is too high, severe intragranular segregation will occur, requiring a long period of homogenization heat treatment, otherwise a large amount of brittle compound Al6Mn will be easily formed, causing the alloy to crack easily during extrusion; while when the Mn content is too low, coarse iron-containing compounds will be easily formed during extrusion to prepare profiles, reducing the density of the second phase in the alloy and reducing the strength and plasticity of the aluminum-manganese alloy.

[0011] Fe can reduce the intracrystalline segregation of Mn. When the Fe content is too high, coarse Al6 (FeMn) compounds will be generated, reducing the toughness of the material. When the Fe content is too high, the high-temperature performance of the aluminum-manganese alloy will be affected, and the amount of precipitated iron-containing compounds will be small, which will not play a precipitation strengthening role.

[0012] Si can improve the fluidity of aluminum-manganese alloy melt and improve the casting performance of the alloy. At the same time, Si and other elements form fine Al(Fe,Mn)Si intermetallic compounds, which play a self-lubricating role in the process of extruding aluminum-manganese alloy into profiles. When the Si content is too high, brittle phases such as GdAl2Si2 will be formed, reducing the elongation of the material; while if the Si content is too low, it will not play a role in solid solution strengthening.

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

[0014] Mg element mainly plays a role in solid solution strengthening. When the Mg element content is too high, too many Mg2Si compounds will be generated, which will reduce the elongation of the aluminum-manganese alloy and affect the welding performance of the alloy, resulting in a decrease in weld strength.

[0015] Gd can promote the nucleation rate of crystal nuclei in the melt, refine the α-Al structure, and form a surface active film at the interface between the second phase and α-Al, which can refine hard and brittle phases such as Al(Fe,Mn)Si and Al6(Fe,Mn), so that they form fine dispersed precipitates at the grain boundaries, reduce the adverse effects of Fe and Si, and significantly improve the strength and plasticity of the material. When the Gd content in the alloy is too high, coarse blocky structure will appear, which is not conducive to grain refinement. In addition, with the addition of Gd, fine dispersed phases containing Gd, such as Al2Gd and other compounds, are formed in the aluminum-manganese alloy. These dispersed phases can strongly pin dislocations and subgrain boundaries, inhibit the formation of recrystallized structures when the aluminum-manganese alloy is extruded into profiles, thereby improving the strength of the aluminum-manganese alloy after extrusion.

[0016] Ti forms Al3Ti particles in the aluminum-manganese alloy, which plays a role in refining the α-Al structure.

[0017] Zr forms Al3Zr in the aluminum-manganese alloy, improves the welding performance of the aluminum-manganese alloy, and prevents the aluminum-manganese alloy from forming a coarse recrystallized structure during extrusion, thereby increasing the strength after extrusion.

[0018] The present invention forms a solid solution strengthening effect by increasing the content of solid solution elements such as Fe, Mn, Si, Cu, and Mg. At the same time, more solid solution elements are also conducive to forming more second phases during crystallization, which is conducive to the dispersion strengthening effect of the submicron-level second phase. By adding Gd, Zr, and Ti elements, the grains of the aluminum-manganese alloy are refined, especially the Gd element, which can significantly increase the recrystallization temperature of the aluminum-manganese alloy during extrusion, inhibit the formation of coarse recrystallized structure, regulate the ratio of recrystallized structure to deformed structure, and improve the strength of the extruded alloy.

[0019] In some embodiments of the present invention, the aluminum-manganese alloy is composed of the following components by mass percentage: 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%, the total amount of unavoidable impurities is ≤0.15%, and the balance is Al.

[0020] In some embodiments of the present invention, the aluminum-manganese alloy is composed of the following components by mass percentage: 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%, the total of unavoidable impurities is ≤0.15%, and the balance is 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%, the total of unavoidable impurities is ≤0.15%, and the balance is Al.

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

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

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

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

[0026] In some embodiments of the present invention, the grain diameter of the aluminum-manganese alloy is 50 to 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 grains of the aluminum-manganese alloy mentioned here refer to the grains 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, and the density of the second phase is (9-15)×10 18 m -3 .

[0030] In some embodiments of the present invention, the second phase has a (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, and the average diameter of the second phase is 0.4-0.5 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] The second aspect of the present invention provides a method for preparing the aluminum-manganese alloy according to the first aspect of the present invention, comprising the following steps:

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

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

[0041] Specifically, the Al-Gd master alloy may 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 to 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] In the present invention, the ingot diameter is ≤250mm during casting, and the cooling speed is adjusted by adjusting the casting temperature, casting speed, cooling water size, cooling water temperature, cooling water pressure and other parameters to control the cooling speed of the ingot at 30-50℃ / s. Due to the high cooling speed, the α-Al in the ingot can generate columnar crystals with directional solidification characteristics in parallel along the cooling direction, the grain diameter is ≤100μm, and the average diameter of the second phase on the grain boundary is ≤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 pouring tube freezing 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 on the grain boundary will become coarser, which is not conducive to improving the strength of the alloy.

[0047] The cooling rate refers to the cooling rate of the aluminum-manganese alloy melt from the casting temperature to the solidus, based on the cooling rate at the core of the ingot.

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

[0049] a) Casting temperature is 710~750℃;

[0050] b) Casting speed is 180-200 mm / min;

[0051] c) Cooling water temperature is 10-20℃;

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

[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 cast rod, and the diameter of the cast rod is ≤250 mm.

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

[0056] Through vertical semi-continuous casting, cast rods can be directly cast.

[0057] It is understandable that the shape of the ingot is not changed during the homogenization heat treatment process, and the cast rod obtained by casting is also an aluminum-manganese alloy. However, since the diffusion rate of manganese in the aluminum-manganese alloy of the present invention is relatively slow, it is dissolved in the body in a supersaturated state during solidification, so it is necessary to further perform homogenization heat treatment to form a uniform and fine second phase at the grain boundary, so that the second phase is further refined, which plays a role of dispersion strengthening and improves the strength and toughness of the aluminum-manganese alloy. When the casting is a cast rod, it is still an aluminum-manganese alloy cast rod after homogenization heat treatment.

[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 is performed for 8 to 15 hours.

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

[0065] The present invention further adopts a rapid heating method to perform homogenization heat treatment, which is beneficial to control the density and diameter of the second phase precipitated from the aluminum-manganese alloy in the homogenization state, so that the density of the second phase is greater than 9.0×10 18 m -3 The average diameter of the second phase is less than 0.5μm. High density and small particle size are beneficial to improving the strength and toughness of aluminum-manganese alloy.

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

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

[0068] In some embodiments of the present invention, the extrusion step includes forming the aluminum-manganese alloy into an extrusion billet, and obtaining the aluminum alloy hollow profile by extrusion; 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 extruder, and the outlet temperature of the extrusion barrel of the extruder is 500-530°C.

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

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

[0073] A fourth aspect of the present invention provides a battery shell, wherein the raw materials for preparing the battery shell 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 shell is a power battery shell.

[0075] Specifically, the power battery shell may be a power battery shell 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 the present invention uses solid solution elements such as Fe as beneficial elements, adopts a high iron, high manganese and high silicon content ratio in the alloy, forms a solid solution strengthening effect, and is conducive to the precipitation of the second phase, and at the same time, through microalloying with elements such as Gd, Zr, and Ti, the microstructure is comprehensively regulated to avoid the formation of coarse intermetallic compounds, increase the alloy recrystallization temperature, and inhibit the formation of coarse recrystallized structure after extrusion, thereby improving the mechanical strength of the aluminum-manganese alloy. In addition, the addition of elements such as Fe, Mn and Si also reduces the requirements for raw material purity, thereby reducing the cost of raw materials.

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

[0079] (3) The hollow profile obtained after extrusion of the aluminum-manganese alloy of the present invention has high strength and toughness, especially high yield strength, and can meet the mechanical property requirements of the battery shell without cold working deformation such as drawing, and is particularly suitable for preparing battery shells. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

[0083] Figure 4 This is a SEM image of the aluminum-manganese alloy cast 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 Example 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 and before homogenization heat treatment. DETAILED DESCRIPTION

[0086] The present invention is further described in detail below by specific examples. Unless otherwise specified, the raw materials, reagents or devices used in the examples and comparative examples can be obtained from conventional commercial sources or can be obtained by prior art methods. Unless otherwise specified, the experiments or test methods are conventional methods in the art.

[0087] The following is a detailed description with reference to specific embodiments and comparative examples.

[0088] Example 1

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

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

[0091] Alloy 1 in Table 1 was cast by vertical semi-continuous casting, wherein Mn was added in the form of aluminum-manganese master alloy, Fe was added in the form of aluminum-iron master alloy, Cu was added in the form of aluminum-copper master alloy, Mg was added in the form of magnesium ingot, Gd was added in the form of Al-20Gd master alloy, Ti was added in the form of aluminum-titanium master alloy, and Zr was added in the form of aluminum-zirconium master alloy; during the casting process, the cooling rate of the core of the cast rod during the solidification of the melt was controlled to be 49.3°C / s; the diameter of the cast rod was 127mm; wherein, in order to achieve the corresponding cooling rate, the specific casting process parameters were: casting temperature 720°C, casting speed 200mm / min, cooling water temperature 10°C, cooling water pressure 150kPa, and the measured cooling rate of the core of the cast rod was 49.3°C / s;

[0092] The cast rods obtained by casting were subjected to homogenization heat treatment in a heat treatment furnace at a heating rate of 15°C / min, the temperature was raised to 605°C, kept at this temperature for 12 hours, and then air-cooled out of the furnace to obtain aluminum-manganese alloy cast rods.

[0093] It should be noted that the cooling rate of the core of the cast rod is measured and calculated by burying a thermocouple in the cast rod. The casting temperature, casting speed, cooling water temperature and cooling water pressure are first adjusted according to the measurement results. After the required cooling rate is reached, preparation is carried out 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] The aluminum-manganese alloy cast rods were sawn into extrusion billets, which were heated to 480°C, with the outlet temperature of the extrusion barrel at 510°C, and then extruded into square aluminum alloy hollow profiles with a wall thickness of 0.52 mm through an extruder.

[0096] Table 1 Aluminum-manganese alloy composition of the embodiment and the comparative example (unit: mass percentage / %)

[0097]

[0098] In Table 1, Bal. represents the balance; alloys 1 to 18 are aluminum-manganese alloys 1 to 18.

[0099] Example 2

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

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

[0102] Alloy 2 in Table 1 was cast by vertical semi-continuous casting, wherein Mn was added in the form of aluminum-manganese master alloy or manganese agent, Fe was added in the form of aluminum-iron master alloy, Cu was added in the form of aluminum-copper master alloy or copper rice, Mg was added in the form of magnesium ingot, Gd was added in the form of Al-20Gd master alloy, Ti was added in the form of aluminum-titanium master alloy, and Zr was added in the form of aluminum-zirconium master alloy; during the casting process, the cooling rate of the core of the cast rod was controlled to be 48.6°C / s; the diameter of the cast rod was 127 mm;

[0103] Among them, in order to achieve the corresponding cooling speed, the specific casting process parameters are: casting temperature 720℃, casting speed 190mm / min, cooling water temperature 12℃, cooling water pressure 145kPa, and the measured cooling speed of the core of the cast rod is 48.6℃ / s;

[0104] The cast rods obtained by casting were subjected to homogenization heat treatment in a heat treatment furnace at a heating rate of 12°C / min, the temperature was raised to 605°C, kept at this temperature for 12 hours, and then air-cooled out of the furnace 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] The aluminum-manganese alloy cast rods were sawn into extrusion billets, which were heated to 480°C, with the outlet temperature of the extrusion barrel at 510°C, and then extruded into square aluminum alloy hollow profiles with a wall thickness of 0.52 mm through an extruder.

[0107] Example 3

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

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

[0110] Alloy 3 in Table 1 was cast by vertical semi-continuous casting, wherein Mn was added in the form of aluminum-manganese master alloy or manganese agent, Fe was added in the form of aluminum-iron master alloy, Cu was added in the form of aluminum-copper master alloy or copper rice, Mg was added in the form of magnesium ingot, Gd was added in the form of Al-20Gd master alloy, Ti was added in the form of aluminum-titanium master alloy, and Zr was added in the form of aluminum-zirconium master alloy; during the casting process, the cooling rate of the core of the cast rod was controlled to be 47.5°C / s; the diameter of the cast rod was 127 mm;

[0111] Among them, in order to achieve the corresponding cooling speed, the specific casting process parameters are: casting temperature 725℃, casting speed 200mm / min, cooling water temperature 15℃, cooling water pressure 150kPa, and the measured cooling speed of the core of the cast rod is 47.5℃ / s;

[0112] The cast rods obtained by casting were subjected to homogenization heat treatment in a heat treatment furnace at a heating rate of 12°C / min, the temperature was raised to 605°C, kept at this temperature for 12 hours, and then air-cooled out of the furnace 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] The aluminum-manganese alloy cast rods were sawn into extrusion billets, which were heated to 480°C, with the outlet temperature of the extrusion barrel at 510°C, and then extruded into square aluminum alloy hollow profiles with a wall thickness of 0.52 mm through an extruder.

[0115] Example 4

[0116] A method for preparing an aluminum-manganese alloy, wherein the alloy 1 in Table 1 is cast by vertical semi-continuous casting, which is different from Example 1 in that the cooling rate during casting is 32.1°C / s; the rest is the same as Example 1.

[0117] Among them, in order to achieve the corresponding cooling speed, the specific casting process parameters are: casting temperature 740℃, casting speed 180mm / min, cooling water temperature 18℃, cooling water pressure 140kPa, and the measured cooling speed of the cast rod core is 32.1℃ / s.

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

[0119] Example 5

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

[0121] Among them, in order to achieve the corresponding cooling speed, the specific casting process parameters are: casting temperature 720℃, casting speed 195mm / min, cooling water temperature 12℃, cooling water pressure 152kPa, and the measured cooling speed of the cast rod core is 48.8℃ / s.

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

[0123] Example 6

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

[0125] Among them, in order to achieve the corresponding cooling speed, the specific casting process parameters are: casting temperature 725℃, casting speed 185mm / min, cooling water temperature 14℃, cooling water pressure 140kPa, and the measured cooling speed of the cast rod core is 48.2℃ / s.

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

[0127] Example 7

[0128] A method for preparing an aluminum-manganese alloy, wherein the alloy 1 in Table 1 is cast by vertical semi-continuous casting, which is different from Example 1 in that the cooling rate during casting is 49.5°C / s; the rest is the same as Example 1.

[0129] Among them, in order to achieve the corresponding cooling speed, the specific casting process parameters are: casting temperature 715℃, casting speed 195mm / min, cooling water temperature 10℃, cooling water pressure 153kPa, and the measured cooling speed of the cast rod core 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] The aluminum-manganese alloy cast rods were sawn into extrusion billets, which were heated to 495°C, with the outlet temperature of the extrusion barrel at 528°C, and then extruded into square aluminum alloy hollow profiles with a wall thickness of 0.52 mm through an extruder.

[0132] Example 8

[0133] A method for preparing an aluminum-manganese alloy, comprising casting alloy 1 in Table 1 by vertical semi-continuous casting, and the preparation method is the same as that 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] The aluminum-manganese alloy cast rods were sawn into extrusion billets, which were heated to 453°C, with the outlet temperature of the extrusion barrel at 503°C, and extruded into hollow profiles with a wall thickness of 0.52 mm through an extruder.

[0136] Comparative Examples 1 to 15

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

[0139] The aluminum-manganese alloys of Comparative Examples 1 to 15 were prepared into hollow profiles by extrusion molding, and the specific method was the same as that of Example 1.

[0140] Comparative Example 16

[0141] A method for preparing an aluminum-manganese alloy is used to prepare alloy 1 in Table 1. The difference from Example 1 is that the cooling rate during casting is 25.1° C. / s; the rest is the same as Example 1.

[0142] Among them, in order to achieve the corresponding cooling speed, the specific casting process parameters are: casting temperature 750℃, casting speed 150mm / min, cooling water temperature 25℃, cooling water pressure 132kPa, and the measured cooling speed 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 in the same manner as in Example 1.

[0144] Comparative Example 17

[0145] A method for preparing an aluminum-manganese alloy is used to prepare alloy 1 in Table 1. The difference from Example 1 is that the heating rate of the homogenization heat treatment is 8° C. / min; the rest is the same as Example 1.

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

[0147] Comparative Example 18

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

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

[0150] Comparative Example 19

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

[0152] Comparative Example 20

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

[0154] Results

[0155] The square aluminum alloy hollow profiles obtained in the above Examples 1 to 8 and Comparative Examples 1 to 20 were subjected to microstructure testing 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 by casting in the examples and comparative examples, and the samples were polished and then subjected to EBSD for grain diameter detection.

[0157] (2) Density and average diameter of the second phase: A scanning electron microscope (SEM) was used to randomly photograph more than 10 fields of view of the aluminum-manganese alloy samples after homogenization treatment in the embodiments and comparative examples, with a magnification of 500 times, and the images were observed and analyzed. The maximum length of the second phase was taken as the diameter. More than 5 particles were randomly measured in the photos of each field of view, and then the sizes of all measured particles were averaged to obtain the average diameter of the particles. The number of second phases was counted in the photos of each field of view, and the field of view area and sample thickness of the photos were measured to obtain their volume, thereby calculating the distribution density of the second phase after homogenization.

[0158] (3) Recrystallization area ratio after extrusion: Samples were taken from the hollow profiles obtained after extrusion of the aluminum-manganese alloy in the embodiments and comparative examples. The samples were polished and then corroded (Keller reagent corrosion). Then, photos were taken. The areas of the recrystallized structure and the fibrous deformation structure were statistically analyzed using computer software to obtain the results.

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

[0160] The mechanical properties of conventional commercially available 3003 alloy were tested using the same method, and its tensile strength was 95-110 MPa, yield strength was 40-45 MPa, and 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 Table 2 and Table 3.

[0162] Table 2: Test results of microstructure detection and hollow profile mechanical properties of the embodiment

[0163]

[0164] The grains of the aluminum-manganese alloys obtained in Examples 1 to 8 are all columnar crystals.

[0165] Table 3 Comparative example of microstructure detection and hollow profile mechanical properties test results

[0166]

[0167]

[0168] The aluminum-manganese alloys of Comparative Examples 1 to 20 are all columnar crystals except Comparative Example 16 which is non-columnar crystals. Therefore, no grain diameter data is given for Comparative Example 16.

[0169] Combining Table 2 and Table 3, it can be seen that the grains of the aluminum-manganese alloy ingot of the present invention are all columnar crystals, the grain diameter is less than 100 μm, the average diameter of the second phase is stably less than 0.5 μm, and the density of the second phase is not less than 10×10 18 m -3 . The grain diameter, average diameter of the second phase, density of the second phase and recrystallization area ratio after extrusion of the aluminum-manganese alloy will affect its performance after extrusion. Among them, the second phase density and recrystallization area ratio have a greater impact on the performance of the aluminum-manganese alloy than other organizational parameters. When the recrystallization area ratio exceeds 30%, the strength decreases, and when it is less than 10%, the elongation decreases. The aluminum-manganese alloy of the present invention has a recrystallization area ratio of 10 to 30% after being extruded into a hollow profile. It has high strength without the need for processing deformation such as drawing after extrusion. The yield strength is not less than 165MPa, and the maximum reaches 187MPa. The tensile strength is not less than 140MPa, and the elongation can be maintained at 10 to 13%. It can be seen that the aluminum-manganese alloy of the present invention can obtain a higher yield strength than conventional 3003 aluminum alloy without drawing.

[0170] In Comparative Examples 1 to 15, compared with the embodiments of the present invention, aluminum-manganese alloys 4 to 18 are used respectively. Due to the change in the content of each element, the performance of the aluminum-manganese alloy decreases. For example, the aluminum-manganese alloys of Comparative Examples 1 and 2 have a lower or higher Mn element content, the recrystallization area rate after extrusion increases, and the yield strength and tensile strength decrease. Similarly, in Comparative Examples 3 to 8, due to changes in Fe content, Si content or Gd content, the recrystallization area rate after extrusion increases, and the yield strength and tensile strength decrease. In Comparative Example 9, the Ti content is relatively high. Although the recrystallization area rate of the aluminum-manganese alloy after extrusion is only 12.6%, coarse Ti-containing compounds are formed, and the Ti-containing compounds are easy to agglomerate, so the strength decreases. In Comparative Examples 10 and 11, the total content of Mn, Fe and Si changes, the second phase density decreases or the second phase diameter increases, and the strength of the hollow profile obtained after extrusion decreases. In Comparative Examples 12 and 13, Gd was not added or La was used to replace Gd, and the dispersion strengthening and recrystallization inhibition effect of the fine dispersed phase containing Gd was lacking. After extrusion, the recrystallization area ratio was high or the second phase density was low, and the strength decreased. Comparative Examples 14 and 15 reduced the content of Mg or Ti, and the performance of the extruded profiles also decreased.

[0171] In summary, the aluminum-manganese alloy provided by the present invention has excellent yield strength, tensile strength and elongation. The hollow profile obtained after extrusion has high strength and toughness, and does not require cold working deformation such as drawing to meet the mechanical performance requirements of the battery shell. It is particularly suitable for preparing battery shells.

[0172] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. An aluminum-manganese alloy, characterized in that: In terms of mass percentage, it is composed of 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%, the total amount of unavoidable impurities is ≤0.15%, and the balance is Al.

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: 1.9%≤Fe+Mn+Si≤2.5%.

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

4. The aluminum-manganese alloy according to claim 1 or 2, characterized in that: The aluminum-manganese alloy contains a second phase after homogenization heat treatment, and the density of the second phase is (9-15)×10 18 m -3 ; And / or, the aluminum-manganese alloy contains a second phase after homogenization heat treatment, and 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 rate 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: The following steps are involved: The components are added and mixed according to a proportion, cast by a semi-continuous casting method, and then subjected to a homogenization heat treatment to obtain the aluminum-manganese alloy.

7. The preparation method according to claim 6, characterized in that: During the casting process, the cooling rate during solidification is controlled to be 30 to 50°C / s; And / or, the heating rate of the homogenization heat treatment is 10-20°C / min; And / or, the temperature of the homogenization heat treatment is 570-630°C; And / or, the homogenization heat treatment time is 8 to 15 hours.

8. A hollow aluminum alloy profile, characterized in that: The aluminum-manganese alloy is obtained by extrusion molding using the aluminum-manganese alloy as a raw material.

9. The aluminum alloy hollow profile according to claim 8, characterized in that: The extrusion step includes making the aluminum-manganese alloy into an extrusion blank, and obtaining the aluminum alloy hollow profile by extrusion; the temperature of the extrusion blank is 450-500° C.; And / or, the extrusion is performed using an extruder, and the outlet temperature of the extrusion barrel of the extruder is 500-530°C.

10. A battery case, characterized in that: The raw material comprises the aluminum-manganese alloy described in any one of claims 1 to 5, or the aluminum alloy hollow profile described in any one of claims 8 to 9.

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