A method for preparing 2xxx series aluminum alloy sheet for automobile battery box cover

Abstract

The present invention discloses a method for preparing a 2xxx series aluminum alloy sheet for automotive battery box covers, comprising the following steps: 1) ingot casting; 2) hot rolling; 3) intermediate annealing; 4) cold rolling; 5) solution treatment; 6) room temperature aging; 7) pre-stretching; and 8) room temperature aging to produce the 2xxx series aluminum alloy sheet for automotive battery box covers. This method eliminates the need for homogenization treatment in traditional processing methods. Hot rolling employs alternating vertical and horizontal rolling, significantly increasing the intermediate annealing temperature of the hot-rolled sheet and appropriately extending the annealing hold. This significantly shortens the production process for the 2xxx series aluminum alloy sheet, conserves energy, and significantly reduces production costs. Furthermore, it reduces material anisotropy and improves its formability.

Description

Technical Field

[0001] The present invention belongs to the technical field of aluminum alloy sheets for automobiles, and in particular relates to a method for preparing a 2xxx series aluminum alloy sheet for an automobile battery box cover. Background Art

[0002] Lightweighting vehicles is gaining increasing attention. The range of new energy vehicles is not only related to battery performance but also to the vehicle's weight. Research shows that reducing vehicle weight increases range. Furthermore, lightweighting is a necessary measure to address a range of issues, including environmental pollution and excessive energy consumption. Replacing steel with aluminum alloys in the manufacture of auto bodies and components can reduce vehicle weight by over 50%, significantly reducing the overall vehicle weight. Therefore, replacing steel with aluminum alloy automotive panels is the most effective approach to lightweighting.

[0003] In order to reduce the weight of the battery box, the existing battery box cover is often made very thin. Although this reduces the overall weight of the battery box, it also causes the strength of the battery box cover to decrease, making it easy to deform when subjected to external force collisions. Therefore, the existing battery box cover is either made of steel plate or uses more reinforcing ribs when using 6xxx series aluminum alloy. If high-strength aluminum alloy can be used to prepare the battery box cover, it will be a better choice to meet the strength requirements while reducing the weight. 2xxx series aluminum alloy has high yield strength and high tensile strength. It can be used in parts with strength requirements and can effectively replace steel plates to achieve lightweight effects. However, the production cost of 2xxx series aluminum alloy plates for automobiles prepared using traditional processes is 2 to 4 times that of traditional automotive steel plates. This seriously hinders the large-scale application of 2xxx series aluminum alloy plates in automobiles. Therefore, it is imperative to reduce the production cost of 2xxx series aluminum alloy body plates. Summary of the Invention

[0004] The technical problem addressed by this invention is to provide a method for preparing 2xxx series aluminum alloy sheet material for automotive battery box covers. This method eliminates the homogenization process compared to traditional processing methods. Hot rolling employs alternating vertical and horizontal rolling, significantly increasing the intermediate annealing temperature of the hot-rolled sheet and appropriately extending the annealing hold. This significantly shortens the production process for 2xxx series aluminum alloy sheet material, conserves energy, and significantly reduces production costs. Furthermore, it reduces material anisotropy and improves its formability.

[0005] In order to solve the above technical problems, the invention adopts the following technical solutions :

[0006] A method for preparing a 2xxx series aluminum alloy sheet for an automobile battery box cover comprises the following steps:

[0007] 1) Ingot preparation: 2xxx series aluminum alloy ingots were prepared by direct water-cooled semi-continuous casting method;

[0008] 2) Hot rolling: 2xxx series aluminum alloy is directly hot rolled in a vertical and horizontal direction without homogenization to obtain hot rolled plate;

[0009] 3) Intermediate annealing: The hot-rolled plate is heated, kept warm, and then cooled to room temperature in the furnace to obtain the annealed plate;

[0010] 4) Cold rolling: cold rolling the annealed sheet to obtain a cold rolled sheet;

[0011] 5) Solution treatment: subjecting the cold rolled sheet to solution treatment to obtain a solution treated sheet;

[0012] 6) Place at room temperature: Place the solution treated plate at room temperature;

[0013] 7) Pre-stretching treatment: stretching the solution treated plate after step 6) by 1% to 5%;

[0014] 8) The product is placed at room temperature for more than 14 days to obtain a 2xxx series aluminum alloy sheet for a vehicle battery box cover.

[0015] As an embodiment, in step 1), the aluminum alloy ingot has a thickness of 160-180 mm, and contains the following components and their mass percentages: Si: 0.30-0.50%, Fe: 0.30-0.50%, Cu: 0.30-0.50%, Mn: 0.30-1.00%, Mg: 1.20-1.80%, Zn≤0.25%, Cr≤0.10%, Ti≤0.15%, impurity elements≤0.15%, and the balance is Al.

[0016] As an embodiment, in step 2), the holding temperature before hot rolling of the ingot is 480-500° C.; and the holding time is 2-6 hours.

[0017] As an embodiment, in step 2), the 2xxx series aluminum alloy ingot is subjected to head cutting and milling treatment before heating; the hot rolling method is longitudinal and transverse cross rolling, first rolling in the width direction 2-3 times, and then rolling in the length direction 6-9 times to obtain a hot-rolled plate.

[0018] As an embodiment, in step 2), the thickness of the hot-rolled plate is 4-7 mm.

[0019] As an embodiment, in step 3), the heating temperature is 480-500° C.; and the insulation time is 2-6 hours.

[0020] As an embodiment, in step 4), the thickness of the cold-rolled sheet is 1-4 mm.

[0021] As an embodiment, in step 5), the temperature of the solution treatment is 480-500° C., the time is 1-3 hours, and the cooling method is water quenching to room temperature.

[0022] As an embodiment, in step 6), the time of standing at room temperature is 5 to 30 minutes.

[0023] As an embodiment, in step 7), the stretching amplitude of the solution treated plate is 1%-5%.

[0024] Any range described in the present invention includes the end value and any numerical value between the end values ​​and any sub-range formed by the end value or any numerical value between the end values.

[0025] Unless otherwise specified, all raw materials in the present invention can be purchased commercially, and the equipment used in the present invention can adopt conventional equipment in the relevant field or refer to the existing technology in the relevant field.

[0026] Compared with the prior art, the present invention has the following beneficial effects :

[0027] 1) Based on the traditional processing method, the homogenization treatment process is omitted, and the hot rolling adopts vertical and horizontal alternating rolling, which greatly increases the intermediate annealing temperature of the hot-rolled plate and appropriately extends the annealing and heat preservation. It significantly shortens the production process of 2xxx series aluminum alloy plates, saves energy, and greatly reduces production costs. At the same time, the anisotropy of the material is reduced and the material forming performance is improved.

[0028] 2) Based on the traditional processing method, the present invention eliminates the homogenization treatment process and adopts alternating vertical and horizontal rolling for hot rolling, so that the crystalline phase in the ingot is first transformed from a large-sized lamellar phase to a dispersed small-sized lamellar phase after hot rolling, and then through a subsequent improved intermediate annealing process, the crystalline phase in the plate presents a dispersed spherical phase state, and the grain size is smaller than that of the traditional processing method, thereby significantly shortening the production process of 2xxx series aluminum alloy plates, saving energy, and greatly reducing production costs. At the same time, the anisotropy of the material is reduced and the forming performance of the material is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a grain size diagram of the 2xxx series aluminum alloy plate prepared in Example 1 of the present invention;

[0030] Figure 2 This is a crystalline phase distribution diagram of the 2xxx series aluminum alloy plate prepared in Example 1 of the present invention;

[0031] Figure 3 This is a grain size diagram of the aluminum alloy plate prepared in Comparative Example 1 of the present invention;

[0032] Figure 4 This is the crystal phase distribution diagram of the aluminum alloy plate prepared in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0033] In order to explain the present invention more clearly, the present invention is further described below in conjunction with preferred embodiments. Those skilled in the art should understand that the following specific description is illustrative rather than restrictive and should not be used to limit the scope of protection of the present invention.

[0034] It should be noted that when an element is referred to as being “fixed on” or “disposed on” another element, it may be directly on the other element or indirectly on the other element. When an element is referred to as being “connected to” another element, it may be directly connected to the other element or indirectly connected to the other element.

[0035] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0036] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0037] As one aspect of the present invention, a method for preparing a 2xxx series aluminum alloy sheet for an automotive battery box cover comprises the following steps:

[0038] 1) Ingot preparation: 2xxx series aluminum alloy ingots were prepared by direct water-cooled semi-continuous casting method;

[0039] 2) Hot rolling: The 2xxx series aluminum alloy is directly hot-rolled in a longitudinal and transverse direction without homogenization to obtain a hot-rolled plate. The reason why the present invention can eliminate the homogenization process and still maintain excellent performance is that the subsequent heat treatment process of the traditional heat treatment process is heated and extended. The temperature must be at least above 480°C to achieve the effect of melting the crystalline phase. When the temperature is lower than 480°C, the hot-rolled plate is prone to cracks.

[0040] 3) Intermediate annealing: The hot-rolled plate is heated, kept warm, and then cooled to room temperature in the furnace to obtain the annealed plate;

[0041] 4) Cold rolling: cold rolling the annealed sheet to obtain a cold rolled sheet;

[0042] 5) Solution treatment: subjecting the cold rolled sheet to solution treatment to obtain a solution treated sheet;

[0043] 6) Place at room temperature: Place the solution treated plate at room temperature;

[0044] 7) Pre-stretching treatment: stretching the solution treated plate after step 6) by 1% to 5%;

[0045] 8) The product is placed at room temperature for more than 14 days to obtain a 2xxx series aluminum alloy sheet for a vehicle battery box cover.

[0046] The performance index of the 2xxx series aluminum alloy plate is: 0.2 =350-410MPa,σ b =450-510MPa, δ=12-20%.

[0047] The principle of the present invention is that the traditional high-temperature and long-time homogenization process is not only costly, but also causes the lamellar crystal phase in the aluminum alloy ingot to aggregate and spheroidize, forming large-sized unevenly distributed spherical phases, which affects the material consistency and forming performance of the material. The present invention omits the homogenization treatment process on the basis of the traditional processing method, and adopts alternating vertical and horizontal rolling for hot rolling, so that the crystalline phase in the ingot is first transformed from a large-sized lamellar phase to a dispersed small-sized lamellar phase after hot rolling, and then through a subsequent improved intermediate annealing process, the crystalline phase in the plate presents a dispersed spherical phase state, and the grains are refined, thereby significantly shortening the production process of 2xxx series aluminum alloy plates, saving energy, and greatly reducing production costs. At the same time, the anisotropy of the material is reduced and the forming performance of the material is improved.

[0048] In some embodiments, in step 1), the aluminum alloy ingot has a thickness of 160-180 mm and contains the following components and their mass percentages: Si: 0.30-0.50%, Fe: 0.30-0.50%, Cu: 0.30-0.50%, Mn: 0.30-1.00%, Mg: 1.20-1.80%, Zn≤0.25%, Cr≤0.10%, Ti≤0.15%, impurity elements≤0.15%, and the balance is Al.

[0049] In certain embodiments, in step 2), the holding temperature before hot rolling of the ingot is 480-500° C., and the holding time is 2-6 hours.

[0050] In certain embodiments, in step 2), the 2xxx series aluminum alloy ingot is subjected to head and surface milling treatment before heating; the hot rolling method is cross-rolling, first rolling in the width direction 2-3 times, and then rolling in the length direction 6-9 times to obtain a hot-rolled plate.

[0051] In certain embodiments, in step 2), the thickness of the hot-rolled plate is 4-7 mm.

[0052] In certain embodiments, in step 3), the heating temperature is 480-500° C.; and the insulation time is 2-6 hours.

[0053] In some embodiments, in step 4), the thickness of the cold-rolled sheet is 1-4 mm.

[0054] In certain embodiments, in step 5), the solution treatment temperature is 480-500° C., the time is 1-3 h, and the cooling method is water quenching to room temperature.

[0055] In certain embodiments, in step 6), the time of standing at room temperature is 5 to 30 minutes.

[0056] In some embodiments, in step 7), the stretching amplitude of the solution treated plate is 1% to 5%.

[0057] Example 1

[0058] A method for preparing a 2xxx series aluminum alloy sheet for an automobile battery box cover comprises the following steps:

[0059] 1) Ingot preparation: Direct water-cooled semi-continuous casting was used to prepare a 2xxx series aluminum alloy ingot with a thickness of 170 mm. The ingot contained the following components and their mass percentages: Si: 0.30-0.50%, Fe: 0.30-0.50%, Cu: 0.30-0.50%, Mn: 0.30-1.00%, Mg: 1.20-1.80%, Zn≤0.25%, Cr≤0.10%, Ti≤0.15%, impurity elements≤0.15%, and the balance being Al.

[0060] 2) Heating: After the 2xxx series aluminum alloy ingot is cut and milled, it is heated to 495°C in a circulating air furnace and kept at this temperature for 4 hours;

[0061] 3) Hot rolling: The 2xxx series aluminum alloy ingot after holding is hot rolled by first rolling 3 passes along the width direction of the flat ingot and then rolling 8 passes along the length direction of the flat ingot to form a hot rolled plate with a thickness of 4 mm;

[0062] 4) Intermediate annealing: After the hot-rolled plate is cut to length, it is heated to 495°C in a circulating air furnace, kept at this temperature for 2 hours, and then water-cooled to room temperature to obtain the annealed plate;

[0063] 5) Cold rolling: The annealed sheet is cold rolled for 5 passes to obtain a cold rolled sheet with a thickness of 2 mm;

[0064] 6) Solution treatment: The cold rolled plate is solution treated in a circulating air furnace. The heating temperature of the solution treatment is 495°C, the holding time is 140 minutes, and the cooling method is water quenching to room temperature to form a solution treated rolled plate;

[0065] 7) Place at room temperature: Place the rolled plate at room temperature for 20 minutes after solution treatment;

[0066] 8) Pre-stretching treatment: the rolled plate is subjected to pre-stretching treatment after being placed at room temperature, and the pre-stretching is 3% to form a pre-stretched rolled plate;

[0067] 9) Placement at room temperature: The pre-stretched rolled plate is placed at room temperature for more than 14 days to obtain a 2xxx series aluminum alloy plate for the upper cover of the automobile battery box.

[0068] The grain size of the plate is shown in the figure Figure 1 As shown, the crystal phase distribution diagram is as follows Figure 2 As shown;

[0069] Figure 1 This is a grain size diagram of the 2xxx series aluminum alloy plate prepared in Example 1;

[0070] Figure 2 : is the crystal phase distribution diagram of the 2xxx series aluminum alloy plate prepared in this Example 1;

[0071] The 2xxx series aluminum alloy plate prepared in this Example 1 was subjected to a tensile test, and the relevant performance index data are shown in Table 1 below.

[0072] Example 2

[0073] A method for preparing a 2xxx series aluminum alloy sheet for an automobile battery box cover comprises the following steps:

[0074] 1) Ingot Preparation: A 2xxx series aluminum alloy ingot having a thickness of 170 mm was prepared by direct water-cooled semi-continuous casting, and containing the following components by mass: Si: 0.30%, Fe: 0.30%, Cu: 0.30%, Mn: 0.30%, Mg: 1.20%, Zn: 0.20%, Cr: 0.05%, Ti: 0.10%, impurity elements: 0.10%, and the balance being Al;

[0075] 2) Heating: After the 2xxx series aluminum alloy ingot is cut and milled, it is heated to 485°C in a circulating air furnace and kept at this temperature for 6 hours;

[0076] 3) Hot rolling: The 2xxx series aluminum alloy ingot after holding is hot rolled by first rolling 3 passes along the width direction of the flat ingot and then rolling 8 passes along the length direction of the flat ingot to form a hot rolled plate with a thickness of 5 mm;

[0077] 4) Intermediate annealing: After the hot-rolled plate is cut to length, it is heated to 485°C in a circulating air furnace, kept at this temperature for 4 hours, and then water-cooled to room temperature to obtain the annealed plate;

[0078] 5) Cold rolling: The annealed sheet is cold rolled for 5 passes to obtain a cold rolled sheet with a thickness of 2 mm;

[0079] 6) Solution treatment: The cold rolled plate is solution treated in a circulating air furnace. The heating temperature of the solution treatment is 485°C, the holding time is 110 minutes, and the cooling method is water quenching to room temperature to form a solution treated rolled plate;

[0080] 7) Place at room temperature: Place the rolled plate at room temperature for 5 minutes after solution treatment;

[0081] 8) Pre-stretching treatment: the rolled plate is subjected to pre-stretching treatment after being placed at room temperature, and the pre-stretching is 1% to form a pre-stretched rolled plate;

[0082] 9) Standing at room temperature: The pre-aging-treated rolled plate is placed at room temperature for more than 14 days to produce a 2xxx series aluminum alloy plate for an automotive battery box upper cover.

[0083] Example 3

[0084] A method for preparing a 2xxx series aluminum alloy sheet for an automobile battery box cover comprises the following steps:

[0085] 1) Ingot Preparation: A 2xxx series aluminum alloy ingot having a thickness of 170 mm was prepared by direct water-cooled semi-continuous casting, and containing the following components by mass: Si: 0.50%, Fe: 0.50%, Cu: 0.50%, Mn: 1.00%, Mg: 1.80%, Zn: 0.25%, Cr: 0.10%, Ti: 0.15%, impurity elements: 0.15%, and the balance being Al;

[0086] 2) Heating: After the 2xxx series aluminum alloy ingot is cut and milled, it is heated to 500°C in a circulating air furnace and kept at this temperature for 2 hours;

[0087] 3) Hot rolling: The 2xxx series aluminum alloy ingot after holding is hot rolled by first rolling 3 passes along the width direction of the flat ingot and then rolling 8 passes along the length direction of the flat ingot to form a hot rolled plate with a thickness of 7 mm;

[0088] 4) Intermediate annealing: After the hot-rolled plate is cut to length, it is heated to 500°C in a circulating air furnace, kept at this temperature for 2 hours, and then water-cooled to room temperature to obtain the annealed plate;

[0089] 5) Cold rolling: The annealed sheet is cold rolled for 5 passes to obtain a cold rolled sheet with a thickness of 2 mm;

[0090] 6) Solution treatment: The cold rolled plate is solution treated in a circulating air furnace. The heating temperature of the solution treatment is 500°C, the holding time is 180 minutes, and the cooling method is water quenching to room temperature to form a solution treated rolled plate;

[0091] 7) Place at room temperature: Place the rolled plate at room temperature for 30 minutes after solution treatment;

[0092] 8) Pre-stretching treatment: the rolled plate is subjected to pre-stretching treatment after being placed at room temperature, and the pre-stretching is 5% to form a pre-stretched rolled plate;

[0093] 9) Standing at room temperature: The pre-aging-treated rolled plate is placed at room temperature for more than 14 days to produce a 2xxx series aluminum alloy plate for an automotive battery box upper cover.

[0094] Comparative Example 1

[0095] A method for preparing an aluminum alloy plate comprises the following steps:

[0096] 1) Ingot preparation: Direct water-cooled semi-continuous casting was used to prepare a 2xxx series aluminum alloy ingot with a thickness of 170 mm. The ingot contained the following components and their mass percentages: Si: 0.30-0.50%, Fe: 0.30-0.50%, Cu: 0.30-0.50%, Mn: 0.30-1.00%, Mg: 1.20-1.80%, Zn≤0.25%, Cr≤0.10%, Ti≤0.15%, impurity elements≤0.15%, and the balance being Al.

[0097] 2) Place the 2xxx series aluminum alloy ingot into a circulating air furnace, heat it to 495°C over 2 hours, hold it for 24 hours, then air-cool it to room temperature.

[0098] 3) Heating: After the cooled 2xxx series aluminum alloy ingot is cut and milled, it is heated to 450°C and kept warm for 2 hours;

[0099] 4) Hot rolling: The 2xxx series aluminum alloy ingot after holding is hot rolled in a manner of 14 passes along the length of the flat ingot to form a hot rolled plate with a thickness of 4 mm;

[0100] 5) Intermediate annealing: After the hot-rolled plate is cut to length, it is heated to 450°C in a circulating air furnace, kept at this temperature for 2 hours, and then cooled to room temperature to obtain the annealed plate;

[0101] 6) Cold rolling: The annealed sheet is cold rolled for 5 passes to obtain a cold rolled sheet with a thickness of 2 mm;

[0102] 7) Solution treatment: The cold rolled plate is solution treated in a circulating air furnace. The heating temperature of the solution treatment is 495°C, the holding time is 110 minutes, and the cooling method is water quenching to room temperature to form a solution treated rolled plate;

[0103] 8) Place at room temperature: Place the rolled plate at room temperature for 20 minutes after solution treatment;

[0104] 9) Pre-stretching treatment: the rolled plate is subjected to pre-stretching treatment after being placed at room temperature, and the pre-stretching is 3% to form a pre-stretched rolled plate;

[0105] 10) Standing at room temperature: The pre-aging treated rolled plate is placed at room temperature for more than 14 days to produce a 2xxx series aluminum alloy plate.

[0106] The difference between this comparative example 1 and the above embodiment is that comparative example 1 uses a traditional heat treatment process, adopts 24h high-temperature homogenization treatment for the ingot, and adopts traditional direct longitudinal rolling for hot rolling. The above embodiment cancels the homogenization process, extends the heating time and temperature, and adopts longitudinal and transverse cross rolling for hot rolling, extending the intermediate annealing time and temperature.

[0107] Figure 3 This is a grain size diagram of the aluminum alloy plate prepared in Comparative Example 1;

[0108] Figure 4 This is the crystal phase distribution diagram of the aluminum alloy plate prepared in Comparative Example 1;

[0109] The 2xxx series aluminum alloy plate prepared in this comparative example was subjected to a tensile test, and the relevant performance index data are shown in Table 1 below.

[0110] Table 1

[0111] Example 1 Comparative Example 1 tensile strength 500MPa 470MPa Yield strength 400MPa 370MPa Elongation after break 28.8％ 25％

[0112] Comparative Example 2

[0113] Example 1 was repeated, except that the ingot was first homogenized at 495° C. for 24 h and then air-cooled before being heated and hot-rolled.

[0114] Testing revealed no significant differences in performance between this comparative example and Example 1 (tensile strength 498 MPa, yield strength 407 MPa, elongation 29%). This suggests that the hot rolling performance of Example 1, without homogenization prior to hot rolling, is comparable to that of this comparative example, which performed after homogenization. This demonstrates that the present invention reduces steps and saves energy.

[0115] Comparative Example 3

[0116] Example 1 was repeated, with the only difference being that only conventional longitudinal rolling was used for hot rolling.

[0117] After testing, the performance of this comparative example was lower than that of Example 1 (tensile strength 460 MPa, yield strength 365 MPa, elongation after fracture 23%) and did not meet the requirements of the present invention.

[0118] The present invention is not limited to the above-mentioned embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention shall be considered as equivalent replacement methods and shall be included in the scope of protection of the present invention.

[0119] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications based on the above description are possible. It is not possible to enumerate all embodiments here. Any obvious variations or modifications arising from the technical solution of the present invention remain within the scope of protection of the present invention.

Claims

1. A method for preparing a 2xxx series aluminum alloy sheet for an automobile battery box cover, characterized in that: It consists of the following steps: 1) Ingot preparation: 2xxx series aluminum alloy ingots were prepared by direct water-cooled semi-continuous casting method; 2) Hot rolling: The 2xxx series aluminum alloy ingot is subjected to head and face milling treatment, heated to 480-500°C, kept at this temperature for 2-6 hours, and then directly hot rolled in a longitudinal and transverse direction, first rolling 2-3 times in the width direction and then rolling 6-9 times in the length direction to obtain a hot rolled plate with a thickness of 4-7 mm; 3) Intermediate annealing: The hot-rolled plate is heated, kept warm, and then cooled to room temperature in the furnace to obtain the annealed plate; 4) Cold rolling: cold rolling the annealed sheet to obtain a cold rolled sheet; 5) Solution treatment: subjecting the cold rolled sheet to solution treatment to obtain a solution treated sheet; 6) Place at room temperature: Place the solution treated plate at room temperature; 7) Pre-stretching treatment: stretching the solution treated plate after step 6) by 1% to 5%; 8) Placement at room temperature: Place the plate at room temperature for more than 14 days to obtain a 2xxx series aluminum alloy plate for a vehicle battery box cover; In step 1), the aluminum alloy ingot has a thickness of 160-180 mm and contains the following components by mass percentage: Si: 0.30-0.50%, Fe: 0.30-0.50%, Cu: 0.30-0.50%, Mn: 0.30-1.00%, Mg: 1.20-1.80%, Zn≤0.25%, Cr≤0.10%, Ti≤0.15%, impurity elements≤0.15%, and the balance is Al; In step 3), the heating temperature is 480-500° C. and the holding time is 2-6 hours; In step 4), the thickness of the cold-rolled sheet is 1-4 mm; In step 5), the solution treatment temperature is 480-500° C., the time is 1-3 hours, and the cooling method is water quenching to room temperature; In step 6), the time of standing at room temperature is 5 to 30 minutes.

Images