Method for producing aluminum alloy drawing material and use thereof

Abstract

This invention relates to a method for preparing aluminum alloy drawn materials and their applications. The aluminum alloy drawn materials are obtained through processes such as aluminum ingot, alloy mixing, melting, casting, homogenization, extrusion, and drawing. The extrusion process employs segmented heating, with the temperature decreasing sequentially in three stages, and the temperature difference controlled within 10-30℃. After hot stripping, the diameter of the aluminum alloy round ingot is reduced by 2-4mm. Further extrusion is carried out at a degassing pressure of 100-130MPa and an outlet temperature deviation within 10℃. The extrusion rod advance speed is 2-5mm / s, with the advance speed decreasing sequentially in three stages, and the advance speed difference controlled within 0.1-0.8mm / s. This results in ultra-thin aluminum alloy profiles with dimensional accuracy controlled within 0.03mm for the same ingot and within 0.05mm for the same extrusion batch, effectively ensuring the smooth progress of the drawing process and thus producing a power battery casing with no bubbles, pores, impurities, or scratches on the surface.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical materials technology, specifically relating to a method for preparing aluminum alloy drawn materials and its application. Background Technology

[0002] Thinning the walls of aluminum alloy square power battery casings is a crucial way to achieve weight reduction, improve space utilization, and increase charging capacity. Based on the requirements of the application scenarios, the casings must possess good corrosion resistance, excellent thermal conductivity, and laser weldability. The material used is 3003 stainless steel, and it also needs to have certain strength and hardness. The outer diameter of the circumscribed circle must be 100mm or more, the aspect ratio must be 2–5:1, and the thinnest wall thickness for square battery casings with equal or unequal wall thicknesses is 0.3mm, with wall thickness accuracy requirements of ±0.08 or even more stringent.

[0003] Existing manufacturing technologies produce aluminum alloy power battery casings (round or square) in the following ways: The first method uses 3003 alloy or a modified alloy, which is rolled into thin sheets, then cut and deep-drawn. The second method uses 3003 alloy or a modified alloy, which is extruded into sheets, then cut and reverse-extruded. The third method uses 3003 alloy or a modified alloy, which is cold-drawn from hot-extruded blanks. The first and second methods have limitations on the length of the finished product due to the significantly increased friction and difficulty of demolding during deep drawing or reverse extrusion, with a maximum length not exceeding 500mm. The third method has no such limitation on the length of the finished product. Existing technology has advantages in manufacturing circular battery casings with equal wall thickness because the blank used for drawing (i.e., the extruded product) is circular. Based on the principle of concentric circles at the center of the extrusion die, the extrusion difficulty is low. Furthermore, since the extruded blank and the drawing process are both circular, the deformation is uniform throughout, virtually eliminating issues like drawing breakage and wrinkling caused by inconsistent or asynchronous deformation. However, while this technology is feasible for manufacturing battery casings with equal walls on all four sides (with a wall thickness of 0.7mm or more), it is difficult to achieve the same results for square battery casings with equal or unequal walls on all four sides (with a minimum wall thickness <0.7mm). The main problems with this technology are... This includes: 1) The dimensions of the drawn billet (i.e., the hot-extruded finished product) are extremely unstable. As is well known, during the hot extrusion process, due to the influence of the temperature fluctuation of the cast rod and the frictional temperature rise during the extrusion process, the dimensions of the extruded finished product will vary at the same cross-section, and the beginning and end of the extruded finished product will also vary, and there is no regularity. When the wall thickness of the cold-drawn finished product is small (wall thickness < 0.7 mm), the wall thickness of the corresponding drawn billet should also decrease synchronously. At this time, the relative deviation of the wall thickness change of the drawn billet is large, resulting in a large difference in the degree of drawing deformation at different places. Often, wavy lines, wrinkles, or even breakage will appear at the wall thickness difference, making drawing impossible. 2) When extruding thin-walled battery shells, oil stains, foreign matter, and segregated layer structure on the surface of the round cast ingot enter the extruded profile, resulting in defects such as scratches and pores at the thin-walled part. 3) When extruding thin-walled battery shells, insufficient degassing during the extrusion process can easily draw air from the ingot cylinder into the product, resulting in bubbles and pore defects on the surface of the thin-walled extruded profile.Chinese patent CN110983115A discloses an improved 3003 aluminum alloy strip and its preparation method. This patented technology controls the aluminum alloy composition to be Si 0.5–0.7%, Fe 0.6–0.8%, Cu 0.05–0.2%, Mn 1.0–1.5%, Mg 0–0.02%, and Zn. The content is 0-0.02%, with Mg+Zn < 0.03%, the remainder being Al, and unavoidable impurities. Strips with a thickness of 1.8-3.5 mm are obtained through steps such as melting and casting, ingot homogenization, hot rolling, cold rolling, stretching, bending, straightening, and cutting. Therefore, this technical solution cannot produce high-performance thin-walled battery casings in the process of manufacturing power battery casings. Chinese patent CN103100575A discloses an isothermal extrusion method with segmented speed control. This technical solution achieves isothermal extrusion by using a segmented curve of the extrusion bar movement speed of the aluminum extrusion press controlled by PLC logic. However, this patent does not address the technical effect of isothermal extrusion with segmented speed control on the preparation of thin-walled power battery casings. Chinese patent CN112547831A discloses a... A method for producing wide-width aluminum alloy stiffened plates involves three-stage preheating of the cast aluminum alloy ingot: the first stage heating temperature is 460–480℃, the middle stage temperature is controlled at 450–470℃, and the final stage temperature is controlled at 440–460℃. Simultaneously, the extrusion cylinder undergoes three-stage preheating: the first stage temperature is 420–440℃, the middle stage at 400–420℃, and the final stage at 380–400℃. The extrusion speed is 0.2–0.4 mm / s, resulting in aluminum alloy stiffened tubing. However, this method produces tubing with a wall thickness exceeding 3 mm, resulting in high mechanical strength. Therefore, this method cannot be used to prepare thin-walled aluminum alloy materials. Furthermore, its welding effect is poor, making it unsuitable for application in thin-walled power battery casings (equal or unequal wall thickness).

[0004] In summary, it is currently impossible to obtain an aluminum alloy material that can be used to prepare high-performance thin-walled (equal-walled or unequal-walled) square battery casings with existing technology. Therefore, developing an aluminum alloy and preparation process for preparing thin-walled square power battery casings with equal-walled or unequal-walled structures is of great significance. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention designs aluminum alloy drawn materials by modifying the aluminum alloy composition and the homogenization and extrusion processes during preparation, and further uses the drawing process to prepare the power battery casing.

[0006] In a first aspect, the present invention provides a method for preparing aluminum alloy drawn material, comprising the following steps:

[0007] S1. Mix aluminum ingots and alloys, melt and cast them to obtain aluminum alloy round ingot A;

[0008] S2. The aluminum alloy round ingot A is homogenized and cut into lengths of 300-700 mm to obtain aluminum alloy round ingot B.

[0009] S3. The aluminum alloy round ingot B is heated in stages: the front stage is 490-510℃, the middle stage is 480-500℃, and the tail stage is 460-490℃. The temperature of the front, middle, and tail stages decreases sequentially, and the temperature difference is controlled within 10-30℃. Then, hot peeling is performed. After peeling, the diameter of the aluminum alloy round ingot B is reduced by 2-4mm. Further extrusion degassing is performed. The extrusion degassing pressure is controlled within 100-130MPa, and the temperature deviation at the extrusion outlet is controlled within 10℃. During the extrusion rod advance, the advance speed of the front, middle, and tail stages is 2-5mm / s, and the advance speed of the front, middle, and tail stages decreases sequentially. The difference in advance speed is controlled within 0.1-0.8mm / s. The aluminum alloy extruded profile C is obtained by extrusion.

[0010] S4. The aluminum alloy extruded profile C is drawn to obtain the aluminum alloy drawn material.

[0011] Further, by mass percentage, the aluminum alloy round ingot A in step S1 has the following composition: Cu 0.05-0.18%, Fe≤0.70%, Mn 1.00-1.20%, Si≤0.60%, Mg+Zn+Li≤0.05%, Ti≤0.05%, with the balance being Al and unavoidable impurities.

[0012] Preferably, by mass percentage, the aluminum alloy round ingot A in step S1 has the following composition: Cu 0.10-0.18%, Fe 0.36-0.45%, Mn 1.05-1.20%, Si 0.06-0.18%, Mg+Zn+Li≤0.03%, Ti 0.01-0.03%, with the balance being Al and unavoidable impurities.

[0013] Furthermore, by mass percentage, the composition of the round ingot in step S1 includes unavoidable impurities with an individual content of ≤0.05% and a total content of ≤0.15%.

[0014] Furthermore, the melting and casting in step S1 include using an online box degassing device and a ceramic filter plate series tubular filter to treat the purity of the melt.

[0015] Secondly, the present invention also provides an aluminum alloy drawing material.

[0016] Furthermore, the hydrogen content in the aluminum alloy drawn material is ≤0.12ml / 100gAl.

[0017] Thirdly, the present invention also provides an application of aluminum alloy drawn material in the casing of a power battery.

[0018] The deformation at the center point of the long and short sides of the aluminum alloy drawn material is controlled at 15-18%, and the deformation at both sides of the long and short sides is controlled at 13-15%. After drawing, the power battery casing is obtained.

[0019] Furthermore, the shell is circular or square, and the square shell has equal or unequal walls.

[0020] Furthermore, the outer diameter of the square shell is ≥100mm, and the thinnest wall thickness is ≥0.3mm.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] This invention obtains ultra-thin aluminum alloy profiles through homogenization and extrusion processes on round ingots, achieving high dimensional accuracy of the extruded profiles. For the same round ingot, the dimensional accuracy of the extruded profiles (maximum deviation of the nominal wall thickness of the cross-section controlled within 0.03mm; within the same extrusion batch, controlled within 0.05mm) at both ends of the extruded product range effectively ensures the smooth progress of the drawing process. The absence of bubbles, pores, impurities, and scratches on the extruded profiles effectively guarantees the performance of the drawn finished product. Furthermore, this invention utilizes a drawing process on the ultra-thin aluminum alloy profiles to obtain power battery casings with surfaces free of bubbles, pores, impurities, and scratches. Detailed Implementation

[0023] Unless otherwise specified, the experimental methods described in the following embodiments of the present invention are generally performed under conventional conditions or as recommended by the manufacturer. All commonly used chemical reagents used in the embodiments are commercially available products.

[0024] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention.

[0025] The terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, apparatus, product, or device that includes a series of steps is not limited to the steps or modules listed, but may optionally include steps not listed, or may optionally include other steps inherent to such process, method, product, or device.

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of the invention.

[0027] The following embodiments further describe the present invention, but these embodiments are not intended to limit the scope of protection of the present invention.

[0028] Example 1

[0029] The preparation of the aluminum alloy drawn material and the power battery casing in this embodiment specifically includes the following steps:

[0030] S1. According to the mass percentage, aluminum ingots and alloys are mixed, melted and cast, including the use of an online box degassing device and a ceramic filter plate series tubular filter to treat the purity of the melt, to obtain aluminum alloy round ingot A.

[0031] The composition of the round ingot is as follows: Cu 0.12%, Fe 0.44%, Mn 1.18%, Si 0.15%, Mg+Zn+Li: 0.03%, Ti: 0.02%, with the balance being Al and unavoidable impurities (the content of individual unavoidable impurities is ≤0.05%, and the total content is ≤0.15%).

[0032] S2. The aluminum alloy round ingot A is homogenized and cut into 480mm lengths to obtain aluminum alloy round ingot B. The homogenization conditions are: heating to 615℃ within 2.5h, holding for 12h, and then cooling to room temperature by air and mist.

[0033] S3. The aluminum alloy round ingot B is heated in stages: 500℃ in the front, 490℃ in the middle, and 475℃ in the rear. Then, hot peeling is performed, reducing the diameter of the aluminum alloy round ingot B by 3mm. Further extrusion is then carried out, with the extrusion degassing pressure controlled at 120MPa and the extrusion outlet temperature deviation controlled within 10℃. During the extrusion rod advance process, the advance speed in the front section is 3.8mm / s, the advance speed in the middle section is 3.3mm / s, and the advance speed in the rear section is 3.0mm / s. Before extrusion, the working zone of the extrusion die is mirror polished, and the die assembly deviation is checked with a stopper rod to be less than 0.01mm. The aluminum alloy extruded profile C is obtained by extrusion. The dimensional accuracy (maximum deviation of the same nominal wall thickness dimension of the cross section) of the aluminum alloy extruded profile C is: 0.030mm at the head and tail of the same round ingot extrusion and 0.048mm in the same extrusion batch.

[0034] S4. The aluminum alloy extruded profile C is drawn to obtain an aluminum alloy drawn material with a hydrogen content of 0.12 ml / 100 g Al.

[0035] The drawing process is as follows: the center point of the long side and the short side are drawn with a deformation amount of 18%, and the two sides of the long side and the short side are drawn with a deformation amount of 15%. After drawing, a power battery shell is obtained. The outer diameter of the battery shell is 120mm, the thinnest wall thickness is 0.3mm, and the surface is free of defects such as bubbles, pores, and scratches.

[0036] Example 2

[0037] The preparation of the aluminum alloy drawn material and the power battery casing in this embodiment specifically includes the following steps:

[0038] S1. According to the mass percentage, aluminum ingots and alloys are mixed, melted and cast, including the use of an online box degassing device and a ceramic filter plate series tubular filter to treat the purity of the melt, to obtain aluminum alloy round ingot A.

[0039] The composition of the round ingot is as follows: Cu 0.12%, Fe 0.44%, Mn 1.18%, Si 0.15%, Mg+Zn+Li: 0.03%, Ti: 0.02%, with the balance being Al and unavoidable impurities (the content of individual unavoidable impurities is ≤0.05%, and the total content is ≤0.15%).

[0040] S2. The aluminum alloy round ingot A is homogenized and cut into 480mm lengths to obtain aluminum alloy round ingot B. The homogenization conditions are: heating to 615℃ within 2.5h, holding for 12h, and then cooling to room temperature by air and mist.

[0041] S3. The aluminum alloy round ingot B is heated in stages: 490℃ for the front stage, 480℃ for the middle stage, and 460℃ for the tail stage. Then, hot peeling is performed, reducing the diameter of the aluminum alloy round ingot B by 3mm. Further extrusion is then carried out, with the extrusion degassing pressure controlled at 130MPa and the extrusion outlet temperature deviation controlled within 10℃. During the extrusion rod advance process, the advance speed is 4.2mm / s for the front stage, 3.8mm / s for the middle stage, and 3.5mm / s for the tail stage. Before extrusion, the working zone of the extrusion die is mirror polished, and the die assembly deviation is checked with a stopper rod to be less than 0.01mm. The aluminum alloy extruded profile C is obtained by extrusion. The dimensional accuracy (maximum deviation of the same nominal wall thickness dimension of the cross section) of the aluminum alloy extruded profile C is: 0.025mm for the head and tail of the same round ingot extrusion and 0.048mm for the same extrusion batch.

[0042] S4. The aluminum alloy extruded profile C is drawn to obtain an aluminum alloy drawn material with a hydrogen content of 0.12 ml / 100 g Al.

[0043] The drawing process is as follows: the center point of the long side and the short side are drawn with a deformation amount of 18%, and the two sides of the long side and the short side are drawn with a deformation amount of 15%. After drawing, a power battery shell is obtained. The outer diameter of the battery shell is 120mm, the thinnest wall thickness is 0.3mm, and the surface is free of defects such as bubbles, pores, and scratches.

[0044] Example 3

[0045] The preparation of the aluminum alloy drawn material and the power battery casing in this embodiment specifically includes the following steps:

[0046] S1. According to the mass percentage, aluminum ingots and alloys are mixed, melted and cast, including the use of an online box degassing device and a ceramic filter plate series tubular filter to treat the purity of the melt, to obtain aluminum alloy round ingot A.

[0047] The composition of the round ingot is as follows: Cu 0.12%, Fe 0.44%, Mn 1.18%, Si 0.15%, Mg+Zn+Li: 0.03%, Ti: 0.02%, with the balance being Al and unavoidable impurities (the content of individual unavoidable impurities is ≤0.05%, and the total content is ≤0.15%).

[0048] S2. The aluminum alloy round ingot A is homogenized and cut into 480mm lengths to obtain aluminum alloy round ingot B. The homogenization conditions are: heating to 615℃ within 2.5h, holding for 12h, and then cooling to room temperature by air and mist.

[0049] S3. The aluminum alloy round ingot B is heated in stages: 510℃ in the front, 495℃ in the middle, and 485℃ in the rear. Then, hot peeling is performed, reducing the diameter of the aluminum alloy round ingot B by 3mm. Further extrusion is then carried out, with the extrusion degassing pressure controlled at 120MPa and the extrusion outlet temperature deviation controlled within 10℃. During the extrusion rod advance process, the advance speed in the front section is 3.5mm / s, the advance speed in the middle section is 3.3mm / s, and the advance speed in the rear section is 3.0mm / s. Before extrusion, the working zone of the extrusion die is mirror polished, and the die assembly deviation is checked with a stopper rod to be less than 0.01mm. The aluminum alloy extruded profile C is obtained by extrusion. The dimensional accuracy (maximum deviation of the same nominal wall thickness dimension of the cross section) of the aluminum alloy extruded profile C is: 0.028mm for the head and tail of the same round ingot extrusion and 0.050mm for the same extrusion batch.

[0050] S4. The aluminum alloy extruded profile C is drawn to obtain an aluminum alloy drawn material with a hydrogen content of 0.12 ml / 100 g Al.

[0051] The drawing process is as follows: the center point of the long side and the short side are drawn with a deformation amount of 18%, and the two sides of the long side and the short side are drawn with a deformation amount of 15%. After drawing, a power battery shell is obtained. The outer diameter of the battery shell is 120mm, the thinnest wall thickness is 0.3mm, and the surface is free of defects such as bubbles, pores, and scratches.

[0052] Example 4

[0053] The preparation of the aluminum alloy drawn material and the power battery casing in this embodiment specifically includes the following steps:

[0054] S1. According to the mass percentage, aluminum ingots and alloys are mixed, melted and cast, including the use of an online box degassing device and a ceramic filter plate series tubular filter to treat the purity of the melt, to obtain aluminum alloy round ingot A.

[0055] The composition of the round ingot is as follows: Cu 0.10%, Fe 0.37%, Mn 1.05%, Si 0.06%, Mg+Zn+Li: 0.03%, Ti: 0.02%, with the balance being Al and unavoidable impurities (the content of individual unavoidable impurities is ≤0.05%, and the total content is ≤0.15%).

[0056] S2. The aluminum alloy round ingot A is homogenized and cut into 320mm lengths to obtain aluminum alloy round ingot B. The homogenization conditions are: heating to 615℃ within 2.5h, holding for 12h, and then cooling to room temperature by air and mist.

[0057] S3. The aluminum alloy round ingot B is heated in stages: 500℃ in the front, 490℃ in the middle, and 475℃ in the rear. Then, hot peeling is performed, reducing the diameter of the aluminum alloy round ingot B by 2mm. Further extrusion is then carried out, with the extrusion degassing pressure controlled at 110MPa and the extrusion outlet temperature deviation controlled within 10℃. During the extrusion rod advance process, the advance speed in the front section is 3.0mm / s, the advance speed in the middle section is 2.6mm / s, and the advance speed in the rear section is 2.2mm / s. Before extrusion, the working zone of the extrusion die is mirror polished, and the die assembly deviation is checked with a stopper rod to be less than 0.01mm. The aluminum alloy extruded profile C is obtained by extrusion. The dimensional accuracy (maximum deviation of the same nominal wall thickness dimension of the cross section) of the aluminum alloy extruded profile C is: 0.025mm for the head and tail of the same round ingot extrusion and 0.045mm for the same extrusion batch.

[0058] S4. The aluminum alloy extruded profile C is drawn to obtain an aluminum alloy drawn material with a hydrogen content of 0.12 ml / 100 g Al.

[0059] The drawing process is as follows: the center point of the long side and the short side are drawn with a deformation amount of 18%, and the two sides of the long side and the short side are drawn with a deformation amount of 15%. After drawing, a power battery shell is obtained. The outer diameter of the battery shell is 120mm, the thinnest wall thickness is 0.3mm, and the surface is free of defects such as bubbles, pores, and scratches.

[0060] Example 5

[0061] The preparation of the aluminum alloy drawn material and the power battery casing in this embodiment specifically includes the following steps:

[0062] S1. According to the mass percentage, aluminum ingots and alloys are mixed, melted and cast, including the use of an online box degassing device and a ceramic filter plate series tubular filter to treat the purity of the melt, to obtain aluminum alloy round ingot A.

[0063] The composition of the round ingot is as follows: Cu 0.10%, Fe 0.37%, Mn 1.05%, Si 0.06%, Mg+Zn+Li: 0.03%, Ti: 0.02%, with the balance being Al and unavoidable impurities (the content of individual unavoidable impurities is ≤0.05%, and the total content is ≤0.15%).

[0064] S2. The aluminum alloy round ingot A is homogenized and cut into 680mm lengths to obtain aluminum alloy round ingot B. The homogenization conditions are: heating to 615℃ within 2.5h, holding for 12h, and then cooling to room temperature by air and mist.

[0065] S3. The aluminum alloy round ingot B is heated in stages: 500℃ in the front, 490℃ in the middle, and 475℃ in the rear. Then, hot peeling is performed, reducing the diameter of the aluminum alloy round ingot B by 4mm. Further extrusion is then carried out, with the extrusion degassing pressure controlled at 110MPa and the extrusion outlet temperature deviation controlled within 10℃. During the extrusion rod advance process, the advance speed in the front section is 3.0mm / s, the advance speed in the middle section is 2.9mm / s, and the advance speed in the rear section is 2.8mm / s. Before extrusion, the working zone of the extrusion die is mirror polished, and the die assembly deviation is checked with a stopper rod to be less than 0.01mm. The aluminum alloy extruded profile C is obtained by extrusion. The dimensional accuracy (maximum deviation of the same nominal wall thickness dimension of the cross section) of the aluminum alloy extruded profile C is: 0.028mm for the head and tail of the same round ingot extrusion and 0.046mm for the same extrusion batch.

[0066] S4. The aluminum alloy extruded profile C is drawn to obtain an aluminum alloy drawn material with a hydrogen content of 0.12 ml / 100 g Al.

[0067] The drawing process is as follows: the center point of the long side and the short side are drawn with a deformation amount of 18%, and the two sides of the long side and the short side are drawn with a deformation amount of 15%. After drawing, a power battery shell is obtained. The outer diameter of the battery shell is 120mm, the thinnest wall thickness is 0.3mm, and the surface is free of defects such as bubbles, pores, and scratches.

[0068] Comparative Examples 1-3

[0069] The difference from Example 1 is that the heating temperature in step S3 of the aluminum alloy drawing process is different, as shown in Table 1.

[0070] Table 1

[0071]

[0072] According to the process parameters in Table 1, the performance of the aluminum alloy extruded profile C and the power battery casing obtained after drawing in Comparative Examples 1-3 is as follows:

[0073] Comparative Example 1: The dimensional accuracy (maximum deviation of the nominal wall thickness of the same section) of the extruded aluminum alloy profile C is as follows: 0.050 mm at the head and tail of the same round ingot extrusion, and 0.100 mm in the same extrusion batch. The extruded aluminum alloy profile C is drawn to obtain a power battery casing. The outer diameter of the battery casing is 120 mm, the thinnest wall thickness is 0.3 mm, and the surface is free of defects such as bubbles, pores, and scratches.

[0074] Comparative Example 2: The dimensional accuracy (maximum deviation of the nominal wall thickness of the same section) of the extruded aluminum alloy profile C is as follows: 0.060 mm at the head and tail of the same round ingot extrusion, and 0.090 mm in the same extrusion batch. The extruded aluminum alloy profile C is drawn to obtain a power battery casing. The outer diameter of the battery casing is 120 mm, the thinnest wall thickness is 0.3 mm, and the surface is free of defects such as bubbles, pores, and scratches.

[0075] Comparative Example 3: The dimensional accuracy (maximum deviation of the nominal wall thickness of the same section) of the extruded aluminum alloy profile C is as follows: 0.080 mm at the head and tail of the same round ingot extrusion, and 0.110 mm in the same extrusion batch. The extruded aluminum alloy profile C is drawn to obtain a power battery casing. The outer diameter of the battery casing is 120 mm, the thinnest wall thickness is 0.3 mm, and the surface is free of defects such as bubbles, pores, and scratches.

[0076] Comparative Examples 4-6

[0077] The difference from Example 1 is that the pushing speed of the extrusion rod in step S3 of the aluminum alloy drawing material preparation is different, as shown in Table 2.

[0078] Table 2

[0079]

[0080] According to the process parameters in Table 2, the performance of the aluminum alloy extruded profile C obtained in Comparative Examples 4-6 and the power battery casing obtained after drawing are as follows:

[0081] Comparative Example 4: The dimensional accuracy (maximum deviation of the same nominal wall thickness dimension of the extruded aluminum alloy profile C) is as follows: 0.070 mm at the head and tail of the same round ingot extrusion, and 0.100 mm in the same extrusion batch. After the extruded aluminum alloy profile C is drawn, a power battery casing is obtained. The outer diameter of the battery casing is 120 mm, the thinnest wall thickness is 0.3 mm, and there are no defects such as bubbles, pores, or scratches on the surface.

[0082] Comparative Example 5: The dimensional accuracy (maximum deviation of the same nominal wall thickness dimension of the extruded aluminum alloy profile C) is as follows: 0.080 mm at the head and tail of the same round ingot extrusion, and 0.110 mm in the same extrusion batch. After the extruded aluminum alloy profile C is drawn, a power battery casing is obtained. The outer diameter of the battery casing is 120 mm, the thinnest wall thickness is 0.3 mm, and the surface is free of defects such as bubbles, pores, and scratches.

[0083] Comparative Example 6: The head and tail of the extruded product from the same round ingot are 0.080 mm, and the same extrusion batch is 0.110 mm. The extruded aluminum alloy profile C is drawn to obtain a power battery casing. The outer diameter of the battery casing is 120 mm, the thinnest wall thickness is 0.3 mm, and the surface is free of defects such as bubbles, pores, and scratches.

[0084] Comparative Examples 7-8

[0085] The difference from Example 1 is that the reduction in diameter of the round ingot after peeling in step S3 of the aluminum alloy drawing process is different, as shown in Table 3.

[0086] Table 3

[0087]

[0088] According to the process parameters in Table 3, the performance of the aluminum alloy extruded profile C obtained in Comparative Examples 7-8 and the power battery casing obtained after drawing are as follows:

[0089] Comparative Example 7: The dimensional accuracy (maximum deviation of the same nominal wall thickness dimension of the extruded aluminum alloy profile C) is as follows: 0.028 mm at the head and tail of the same round ingot extrusion, and 0.048 mm in the same extrusion batch. The extruded aluminum alloy profile C is drawn to obtain a power battery casing. The outer diameter of the battery casing is 120 mm, the thinnest wall thickness is 0.3 mm, the surface is free of bubbles and pores, and the defect rate of impurities and scratches is 1.50%.

[0090] Comparative Example 8: The dimensional accuracy (maximum deviation of the same nominal wall thickness dimension of the extruded aluminum alloy profile C) is as follows: 0.029 mm at the head and tail of the same round ingot extrusion, and 0.048 mm in the same extrusion batch. The extruded aluminum alloy profile C is drawn to obtain a power battery casing. The outer diameter of the battery casing is 120 mm, the thinnest wall thickness is 0.3 mm, the surface is free of bubbles and pores, and the defect rate of impurities and scratches is 5.00%.

[0091] Comparative Examples 9-10

[0092] The difference from Example 1 is that the extrusion degassing pressure in step S3 is different, as shown in Table 4;

[0093] Table 4

[0094]

[0095] According to the process parameters in Table 4, the performance of the aluminum alloy extruded profile C obtained in Comparative Examples 9-10 and the power battery casing obtained after drawing are as follows:

[0096] Comparative Example 9: The dimensional accuracy (maximum deviation of the same nominal wall thickness dimension of the extruded aluminum alloy profile C) is as follows: 0.030 mm at the head and tail of the same round ingot extrusion, and 0.046 mm in the same extrusion batch. After the extruded aluminum alloy profile C is drawn, a power battery casing is obtained. The outer diameter of the battery casing is 120 mm, the thinnest wall thickness is 0.3 mm, the surface bubble and pore defect rate is 1.50%, and there are no defects such as scratches.

[0097] Comparative Example 10: The dimensional accuracy (maximum deviation of the same nominal wall thickness dimension of the extruded aluminum alloy profile C) is as follows: 0.028 mm at the head and tail of the same round ingot extrusion, and 0.045 mm in the same extrusion batch. After the extruded aluminum alloy profile C is drawn, a power battery casing is obtained. The outer diameter of the battery casing is 120 mm, the thinnest wall thickness is 0.3 mm, the surface bubble and pore defect rate is 1.20%, and there are no defects such as scratches.

[0098] As can be seen from the results of Examples 1-5 and Comparative Examples 1-10 above, the extrusion process has a significant impact on the dimensional accuracy of the aluminum alloy extruded profile C during the preparation of aluminum alloy drawn material and power battery casing, which in turn affects the surface morphology of the power battery casing obtained after drawing.

[0099] It should be noted that the specific features, structures, materials or characteristics described in this specification can be combined in any way. For the sake of brevity, not all possible combinations of the various technical features in the above embodiments have been described. Without contradiction, those skilled in the art can combine and integrate the different embodiments and features described in this specification.

[0100] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing an aluminum alloy drawn material, characterized in that, Includes the following steps: S1. According to the mass percentage, aluminum ingots and alloys are mixed, melted and cast, including the use of an online box degassing device and a ceramic filter plate series tubular filter to treat the purity of the melt, to obtain aluminum alloy round ingot A. The composition of the round ingot is: Cu 0.12%, Fe 0.44%, Mn 1.18%, Si 0.15%, Mg + Zn + Li. 0.03%, Ti: 0.02%, balance Al and unavoidable impurities, with individual unavoidable impurities ≤0.05% and total impurities ≤0.15%; S2. The aluminum alloy round ingot A is homogenized and cut into 480mm lengths to obtain aluminum alloy round ingot B. The homogenization conditions are: heating to 615℃ within 2.5h, holding for 12h, and then cooling to room temperature by air and mist. S3. The aluminum alloy round ingot B is heated in stages: 490℃ in the front, 480℃ in the middle, and 460℃ in the rear. Then, hot peeling is performed, reducing the diameter of the aluminum alloy round ingot B by 3 mm. Further extrusion is then performed, with the extrusion degassing pressure controlled at 130 MPa and the extrusion outlet temperature deviation controlled within 10℃. During the extrusion rod advance, the advance speed is 4.2 mm / s in the front, 3.8 mm / s in the middle, and 3.5 mm / s in the rear. Before extrusion, the working zone of the extrusion die is mirror-polished, and the die assembly deviation is checked with a stopper rod to be less than 0.01 mm. The extrusion yields aluminum alloy extruded profile C. The dimensional accuracy of the aluminum alloy extruded profile C, with the maximum deviation of the same nominal wall thickness dimension for the same cross-section, is: 0.025 mm for the head and tail of the same round ingot extrusion, and 0.048 mm for the same extrusion batch. S4. The aluminum alloy extruded profile C is drawn to obtain an aluminum alloy drawn material with a hydrogen content of 0.12 ml / 100 g Al. The drawing process is as follows: the drawing deformation at the center point of the long side and the short side is 18%, and the deformation at both sides of the long side and the short side is 15%.

2. The aluminum alloy drawn material prepared by the preparation method described in claim 1.

3. The application of the aluminum alloy drawn material as described in claim 2 in the power battery casing.

4. Use according to claim 3, characterized in that, The power battery casing is circular or square, and the square power battery casing has equal or unequal walls.

5. Use according to claim 4, characterized in that, The outer diameter of the square power battery casing is ≥100 mm, and the thinnest wall thickness is ≥0.3 mm.

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