A 3-series aluminum alloy plate and strip for explosion-proof cap of new energy battery and its preparation method

Abstract

The present invention discloses a 3-series aluminum alloy plate and strip for explosion-proof caps of new energy batteries and a preparation method thereof. The 3-series aluminum alloy plate and strip for explosion-proof caps of new energy batteries has a second phase number of grains with a particle size of less than 5 μm greater than 6*10 5 / square millimeter, the number of second phases in grains with a particle size of 5μm or more is less than 1*10 4 The production process is as follows: 1. Melting and semi-continuous casting; 2. Homogenizing the resulting ingot; 3. Hot-rolling the homogenized ingot to produce a hot-rolled slab; 4. Cold-rolling the hot-rolled slab to produce a cold-rolled sheet of a certain thickness, with intermediate annealing during the cold rolling process; 5. Finishing annealing the cold-rolled sheet to produce a 3-series aluminum alloy sheet and strip. This approach controls the size and distribution of the second-phase compounds in the aluminum material, promotes complete grain recrystallization, and improves the aluminum material yield, meeting the technical requirements for aluminum alloy sheets and strips used in explosion-proof caps for new energy batteries.

Description

Technical Field

[0001] The present invention belongs to the field of aluminum alloy materials, and specifically relates to a 3-series aluminum alloy plate and strip for an explosion-proof cap of a new energy battery and a preparation method thereof. Background Art

[0002] New energy battery explosion-proof caps are primarily used for cylindrical lithium batteries, and are widely used in new energy vehicles and electric motorcycles. Power battery explosion-proof caps are the most critical safety components in power batteries. Cylindrical lithium battery caps are equipped with a flip plate. When the internal pressure of the lithium battery exceeds a certain value, the flip plate flips upward, causing a short circuit between the positive and negative electrodes of the lithium battery, causing the lithium battery to stop working and thus preventing the internal pressure from increasing. If the flip plate fails, the internal pressure of the lithium battery continues to increase, and once it reaches a certain value, the bursting disc will explode, thereby achieving the safety protection function of preventing battery explosion. Therefore, it is necessary to ensure a stable burst pressure. To achieve this, the aluminum material must have strict and stable mechanical properties.

[0003] The current 3 series aluminum alloy has excellent comprehensive properties such as moderate strength, high plasticity, good welding performance, strong corrosion resistance, and smooth surface. However, its tensile strength and stamping performance are unstable, and it cannot meet the battery cap flipping force, flipping height, and performance consistency requirements of explosion pressure, resulting in low yield. The new energy vehicle industry is in urgent need of high-quality aluminum materials for power battery explosion-proof caps. Summary of the Invention

[0004] In order to achieve the above-mentioned objectives and solve the above-mentioned problems existing in the prior art, the present invention provides a 3-series aluminum alloy plate and strip for explosion-proof caps of new energy batteries and a preparation method thereof, which controls the size and distribution of the second phase compounds in the aluminum material, promotes complete recrystallization of the grains, improves the aluminum material yield, and meets the technical requirements of aluminum alloy plates and strips for explosion-proof caps of new energy batteries.

[0005] One of the purposes of the present invention is to provide a 3 series aluminum alloy plate and strip for explosion-proof caps of new energy batteries, wherein the number of second phases of grains with a particle size of less than 5 μm is greater than 6*10 5 / square millimeter, the number of second phases in grains with a particle size of 5μm or more is less than 1*10 4 pieces / square millimeter.

[0006] As a preferred solution, the degree of recrystallization in the aluminum alloy sheet and strip is greater than 80%.

[0007] As a preferred embodiment, the aluminum alloy sheet and strip comprises the following components in mass percentage: 0.9%≤Mn<1.3%; 0.3%<Fe<0.7%; Si<0.2%; Zn<0.15%; Mg<0.1%; Cr<0.1%; 0.03%≤Cu<0.3%; 0.015%<Ti≤0.045%, and the remainder of Al and unavoidable impurities.

[0008] As a preferred solution, the aluminum alloy plate and strip has a tensile strength of 105 to 125 MPa, a yield strength of 40 to 70 MPa, and a Vickers hardness of 25 to 35.

[0009] As a preferred solution, the elongation of the aluminum alloy plate and strip is 30% to 40%.

[0010] The second object of the present invention is to provide a method for preparing a 3 series aluminum alloy plate and strip for an explosion-proof cap of a new energy battery, and the specific steps are as follows:

[0011] Step ①, melting and semi-continuous casting, adding the prepared aluminum alloy raw material into a melting furnace, uniformly mixing and then melting into liquid aluminum alloy, and semi-continuously casting the liquid aluminum alloy into ingots;

[0012] Step ②, homogenizing the obtained ingot;

[0013] Step 3: hot rolling the homogenized ingot to obtain a hot-rolled slab;

[0014] Step ④, cold rolling the hot-rolled plate to obtain a cold-rolled plate of a certain thickness, and performing intermediate annealing during the cold rolling process;

[0015] Step ⑤: anneal the cold-rolled sheet to obtain a 3 series aluminum alloy sheet or strip.

[0016] As a preferred solution, in step ①, the melting temperature of the melting furnace is 740-760°C, the semi-continuous casting temperature is 685-710°C, the stable ingot production speed is 46-54 mm / min, and the cooling water flow rate of the crystallizer is 135-150 m 3 / h, cooling water temperature 15 ~ 30 ℃.

[0017] As a preferred solution, in the aluminum alloy raw material of step ①, primary scrap accounts for 30% to 50%, and secondary scrap accounts for 15% to 25%.

[0018] As a preferred solution, in step ②, the ingot is trimmed and milled, and then homogenized in a heating furnace at a heating temperature of 530°C to 640°C for a holding time of 10 to 18 hours.

[0019] As a preferred solution, the homogenized ingot is rolled into a hot-rolled slab of 6 to 10 mm in a hot continuous rolling mill, wherein the starting rolling temperature is 450 to 520°C and the finishing rolling temperature is 260 to 320°C.

[0020] As a preferred solution, the step ④ is to cold-roll the plate to a finished thickness of 0.5 to 1 mm.

[0021] As a preferred solution, in step ④, intermediate annealing is performed when the cold rolling is reduced to 0.8-1.5 mm at a temperature of 320-380°C.

[0022] As a preferred solution, in step ⑤, the finished product annealing temperature is 330-390°C.

[0023] The present invention has at least the following beneficial effects:

[0024] First, the present invention promotes complete recrystallization of grains by controlling the size and distribution of second-phase compounds in aluminum. By controlling the number of nano-sized particles, the finished aluminum material exhibits a completely recrystallized structure, thereby improving the aluminum material yield.

[0025] Secondly, the present invention optimizes the preparation process. By regulating the homogenization treatment and annealing process, it promotes the complete recrystallization of the aluminum grains, ensures the uniformity of the surface and center grains, and achieves high mechanical properties of the aluminum sheet and strip while significantly improving the forming performance. The tensile strength reaches 105-125MPa, the yield strength reaches 40-70MPa, the Vickers hardness reaches 25-35, and the elongation reaches 30-40%. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The longitudinal cross-section grain morphology of the 3-series aluminum alloy finished plate of Example 1 with a homogenization temperature of 630°C, a holding time of 16h, and a finished annealing temperature of 340°C.

[0027] Figure 2 The AlFeMn phase morphology and distribution of the 3-series aluminum alloy finished plate in Example 1 with a homogenization temperature of 630°C, a holding time of 16h, and a finished annealing temperature of 340°C.

[0028] Figure 3 The longitudinal cross-section grain morphology of the 3-series aluminum alloy finished plate of Example 2 with a homogenization temperature of 580°C, a holding time of 12h, and a finished annealing temperature of 370°C.

[0029] Figure 4 The longitudinal cross-section grain morphology of the 3-series aluminum alloy finished plate in Example 3 with a homogenization temperature of 600°C, a holding time of 14h, and a finished annealing temperature of 350°C.

[0030] Figure 5The longitudinal cross-section grain morphology of the 3-series aluminum alloy finished plate of Comparative Example 1 with a homogenization temperature of 540°C, a holding time of 14h, and a finished annealing temperature of 320°C.

[0031] Figure 6 The AlFeMn phase morphology and distribution of the 3-series aluminum alloy finished plate in comparative example 1 are shown with a homogenization temperature of 540°C, a holding time of 14h, and a finished annealing temperature of 320°C.

[0032] Figure 7 The longitudinal cross-section grain morphology of the 3-series aluminum alloy finished plate of Comparative Example 2 with a homogenization temperature of 460°C, a holding time of 8h, and a finished annealing temperature of 370°C.

[0033] Figure 8 The figures are the statistics of AlFeMnSi phases of different sizes in 3 series aluminum alloy plates prepared in various embodiments and comparative examples. DETAILED DESCRIPTION

[0034] In order to make the technical means, creative features, objectives and beneficial effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific implementation methods.

[0035] This embodiment provides a 3 series aluminum alloy plate and strip for explosion-proof caps of new energy batteries. In the aluminum alloy plate and strip, the number of second phases of grains with a particle size of less than 5 μm is greater than 6*10 5 / square millimeter, the number of second phases in grains with a particle size of 5μm or more is less than 1*10 4 pieces / square millimeter.

[0036] In this solution, the degree of recrystallization in the aluminum alloy plate and strip is greater than 80%.

[0037] In this embodiment, the aluminum alloy plate and strip has the following components in percentage by mass: 0.9%≤Mn<1.3%; 0.3%<Fe<0.7%; Si<0.2%; Zn<0.15%; Mg<0.1%; Cr<0.1%; 0.03%≤Cu<0.3%; 0.015%<Ti≤0.045%, and the remainder of Al and unavoidable impurities.

[0038] In this embodiment, the aluminum alloy plate and strip has a tensile strength of 105 to 125 MPa, a yield strength of 40 to 70 MPa, and a Vickers hardness of 25 to 35.

[0039] In this embodiment, the elongation of the aluminum alloy plate and strip is 30% to 40%.

[0040] This embodiment also provides a method for preparing a 3-series aluminum alloy plate and strip for an explosion-proof cap of a new energy battery, characterized in that the specific steps are as follows:

[0041] Step 1: Melting and semi-continuous casting: adding the prepared aluminum alloy raw materials into the melting furnace, uniformly mixing and melting into liquid aluminum alloy, and semi-continuously casting the liquid aluminum alloy into ingots; the melting temperature is 740-760℃, the semi-continuous casting temperature is 685-710℃, the ingot stable production speed is 46-54mm / min, and the crystallizer cooling water flow rate is 135-150m 3 / h, cooling water temperature 15 ~ 30 ℃. In the aluminum alloy raw materials of step ①, the mass of primary scrap accounts for 30% to 50% (including 3 series alloy ingots and hot-rolled plate heads and tails, thick plate scraps, etc.), the mass of secondary scrap accounts for 15% to 25% (including 3 series alloy thin plate scraps and trimmings, etc.), and the remaining raw materials are mainly industrial pure aluminum, industrial pure copper, and intermediate alloys or fluxes of elements such as Al-Mn, Al-Fe, and Al-Cu.

[0042] Step ②, homogenizing the obtained ingot; wherein the ingot is subjected to homogenization treatment in a heating furnace after being cut off at the head and tail and milled at the surface, with a heating temperature of 530° C. to 640° C. and a holding time of 10 to 18 hours.

[0043] Step ③: The homogenized ingot is rolled into a hot-rolled slab of 6 to 10 mm in a hot continuous rolling mill, wherein the starting rolling temperature is 450 to 520° C. and the finishing rolling temperature is 260 to 320° C.

[0044] Step ④, cold rolling the hot-rolled plate to obtain a cold-rolled plate with a thickness of 0.5 to 1 mm, and performing intermediate annealing at a temperature of 320 to 380° C. when the cold rolling thickness reaches 0.8 to 1.5 mm;

[0045] Step 5: annealing the cold-rolled sheet to obtain a 3-series aluminum alloy sheet or strip. The annealing temperature is 330-390°C.

[0046] In this embodiment, 0.5-1.5 mm thick 3 series aluminum alloy strips are prepared by melting and semi-continuous casting, homogenization, hot rolling and cold rolling (intermediate annealing), and the second phase and grain characteristics in the strips are controlled. The size and amount of the second phase are less than 5 μm and the amount of the second phase is greater than 6*10 5 / square millimeter, the number of second phases above 5μm is less than 1*10 4 / square millimeter (SEM experiments were carried out using a JSM6460 scanning electron microscope. The cross-sectional size of the sample should not be greater than 50mm×50mm. ≥4 SEM photos of the sample at different positions were selected, and Image-Pro Plus 6.0 software was used to count the number of second phases. For example, in Table 1, the number distribution density is obtained based on the ratio of the number of grains and the area of ​​the graph obtained by statistics in the figure); the proportion of equiaxed crystals is greater than 80%, the degree of recrystallization is high, and the size distribution of the surface and center grains is uniform (the proportion of surface and center grains both meet the requirement that the equiaxed crystals are greater than 80%). Ultimately, the tensile strength of the 3 series aluminum alloy sheet and strip reaches 105-125MPa, the yield strength reaches 40-70MPa, the Vickers hardness reaches 25-35HV, and the elongation reaches 30%-40%, meeting the technical requirements of power battery-related products for high formability of aluminum alloy sheet and strip.

[0047] Example 1

[0048] A 3-series aluminum alloy plate and strip for an explosion-proof cap of a new energy battery is prepared with the following alloy composition: Si=0.08%; Fe=0.56%; Cu=0.14%; Mn=1.2%; Mg=0.04%; Cr=0.02%; Zn=0.02%; Ti=0.027%, and the remainder is Al and unavoidable impurities.

[0049] The aluminum alloy plate and strip preparation method comprises the following steps:

[0050] (1) Melting and semi-continuous casting: Melting temperature 742℃, primary waste accounts for 45%, secondary waste accounts for 17%, and the melt is refined and degassed by blowing high-purity Ar gas into the melt with a Na-free refining agent. Plate-type two-stage filtration and tubular filtration are used for filtration. The semi-continuous casting temperature is 687℃, the casting speed is 53mm / min, and the crystallizer cooling water flow rate is 147m 3 / h, cooling water temperature 28℃;

[0051] (2) Homogenization treatment: after the ingot is cut off at the head and tail, the upper and lower surfaces are milled by 12 mm, the heating temperature is 630 ° C, and the holding time is 16 h;

[0052] (3) Hot rolling: starting rolling temperature 480°C, finishing rolling temperature 285°C, hot rolled slab 7.35mm;

[0053] (4) Cold rolling: 7.35 mm plate is thinned to a thickness of 1.48 mm and then annealed at 335 °C, and then cold rolled to a finished thickness of 0.73 mm;

[0054] (5) Finished product annealing: annealing temperature 340℃.

[0055] Figure 1This photograph shows the grain morphology of a longitudinal cross-section of a 3-series aluminum alloy plate produced in Example 1 using a homogenization temperature of 630°C, a holding time of 16 hours, and a final annealing temperature of 340°C. As can be seen, the surface and central grains of the aluminum alloy plate produced using this process exhibit essentially complete recrystallization before final annealing, with a recrystallization degree of 90%, demonstrating a significant softening effect. Figure 2 This is the AlFeMn phase morphology of the finished plate prepared in Example 1. It can be seen that the aluminum alloy plate prepared by this process has a large number of second phase particles and a small size; Table 1 is the statistical results of the number of AlFeMnSi phases in the longitudinal section of the finished plate of 3 series aluminum alloy with different sizes. The area in the figure is 45000um 2 (It should be pointed out that the number of AlFeMnSi phases corresponding to the following embodiments and comparative examples in Table 1 is the result of statistics under this area, and the second phase number distribution density is calculated based on this.) As can be seen from the figure, the aluminum alloy plate prepared by this process has a large number of particles with a second phase size of about 1 μm, which is conducive to promoting particle-induced nucleation, thereby accelerating the recrystallization process.

[0056] The aluminum alloy plates and strips produced by this process have a tensile strength of 107 MPa, a yield strength of 45 MPa, a Vickers hardness of 30, and an elongation of 36%. The strength and hardness meet the standards, meeting the technical requirements for aluminum alloy plates and strips for explosion-proof caps of new energy batteries.

[0057] Example 2

[0058] A 3-series aluminum alloy plate and strip for an explosion-proof cap of a new energy battery has the following alloy composition: Si = 0.07%; Fe = 0.49%; Cu = 0.23%; Mn = 1.02%; Mg = 0.02%; Cr = 0.02%; Zn = 0.01%; Ti = 0.041%, and the remainder is Al and unavoidable impurities.

[0059] The aluminum alloy plate and strip preparation method comprises the following steps:

[0060] (1) Melting and semi-continuous casting: Melting temperature 757℃, primary waste accounts for 32%, secondary waste accounts for 24%, and the melt is refined and degassed by blowing high-purity Ar gas into the melt with a Na-free refining agent. Plate-type two-stage filtration and tubular filtration are used for filtration. The semi-continuous casting temperature is 706℃, the casting speed is 47mm / min, and the crystallizer cooling water flow rate is 138m 3 / h, cooling water temperature 16℃;

[0061] (2) Homogenization treatment: after the ingot is cut off at the head and tail, the upper and lower milling surfaces are 12 mm each, the heating temperature is 580 ° C, and the holding time is 12 h;

[0062] (3) Hot rolling: starting rolling temperature 510°C, finishing rolling temperature 315°C, hot rolled slab 6.5 mm;

[0063] (4) Cold rolling: The 6.5 mm plate is thinned to a thickness of 1.25 mm and then annealed at 350 °C, and then cold rolled to a finished thickness of 0.68 mm.

[0064] (5) Finished product annealing: annealing temperature 370℃.

[0065] Figure 3 This is a photograph of the grain morphology of a longitudinal cross-section of a 3-series aluminum alloy finished plate produced in Example 2 using a homogenization temperature of 580°C, a holding time of 12 hours, and a final annealing temperature of 370°C. As can be seen, the aluminum alloy plate produced by this process has a large number of recrystallized grains, a recrystallization degree of 86%, and a high degree of softening.

[0066] The high-strength and high-formability aluminum plates and strips produced by this process have a tensile strength of 109MPa, a yield strength of 49MPa, a Vickers hardness of 32, and an elongation of 33%. The strength and hardness meet the standards, meeting the technical requirements of aluminum alloy plates and strips for explosion-proof caps of new energy batteries.

[0067] Example 3

[0068] A 3-series aluminum alloy sheet and strip for explosion-proof caps for new energy batteries has the following alloy composition: Si = 0.08%; Fe = 0.42%; Cu = 0.18%; Mn = 1.10%; Mg = 0.03%; Cr = 0.03%; Zn = 0.01%; Ti = 0.030%, with the remainder being Al and unavoidable impurities. The preparation method comprises the following steps:

[0069] The aluminum alloy plate and strip preparation method comprises the following steps:

[0070] (1) Melting and semi-continuous casting: Melting temperature 752℃, primary waste accounts for 35%, secondary waste accounts for 22%, and the melt is refined and degassed by blowing high-purity Ar gas into the melt and adding a Na-free refining agent. Plate-type two-stage filtration and tubular filtration are used for filtration. The semi-continuous casting temperature is 704℃, the casting speed is 49mm / min, and the crystallizer cooling water flow rate is 140m 3 / h, cooling water temperature 18℃;

[0071] (2) Homogenization treatment: after the ingot is cut off at the head and tail, the upper and lower surfaces are milled to 12 mm, the heating temperature is 600 ° C, and the holding time is 14 h;

[0072] (3) Hot rolling: starting rolling temperature 500°C, finishing rolling temperature 310°C, hot rolled slab thickness 8.2 mm;

[0073] (4) Cold rolling: The 8.2 mm plate is thinned to a thickness of 1.42 mm and then annealed at 360 °C, and then cold rolled to a finished thickness of 0.85 mm.

[0074] (5) Finished product annealing: annealing temperature 350℃.

[0075] Figure 4 This is a photograph of the grain morphology of a longitudinal cross-section of a 3-series aluminum alloy finished plate produced in Example 3 using a homogenization temperature of 600°C, a holding time of 14 hours, and a final annealing temperature of 350°C. As can be seen, the aluminum alloy plate produced by this process has a large number of recrystallized grains, a recrystallization degree of 82%, and a high degree of softening.

[0076] The high-strength and high-formability aluminum plates and strips produced by this process have a tensile strength of 113MPa, a yield strength of 52MPa, a Vickers hardness of 34, and an elongation of 32%. The strength and hardness meet the standards, meeting the technical requirements of aluminum alloy plates and strips for explosion-proof caps of new energy batteries.

[0077] Table 1

[0078]

[0079]

[0080] Comparative Example 1

[0081] This comparative example is an aluminum material with the same composition as that of Example 1, with a homogenization heating temperature of 540° C., a holding time of 14 h, a finished product annealing temperature of 320° C., and other preparation process conditions being the same as those of Example 1.

[0082] Figure 5 This is a photo of the grain morphology of the longitudinal section of the plate prepared by this process. It can be seen that the plate still has obvious fibrous grain structure, indicating that the recrystallization of the plate is insufficient and the processed structure before annealing still remains. Figure 6 This is the AlFeMn phase morphology of the finished plate prepared in Comparative Example 1. Table 1 shows the statistical results of the number of AlFeMnSi phases in the longitudinal section of the finished plate of 3 series aluminum alloy with different sizes. It can be seen that the aluminum alloy plate prepared by this process has a small number of second-phase particles and a large size, especially a small number of second-phase particles around 1μm, which is not conducive to promoting particle-induced nucleation. At the same time, the annealing temperature of the finished product is low, resulting in a low degree of recrystallization and an unobvious softening effect. The aluminum alloy plate and strip have a tensile strength of 105-125MPa, a yield strength of 40-70MPa, a Vickers hardness of 25-35, and an elongation of 30%-40%.

[0083] The aluminum sheet and strip produced by this alloy composition and process has a tensile strength of 135MPa, a yield strength of 89MPa, a Vickers hardness of 40, and an elongation of 21%. The strength and hardness are too high and the elongation is insufficient, resulting in unstable stamping performance of the aluminum sheet and strip and low yield. It does not meet the technical requirements of aluminum alloy sheet and strip for explosion-proof caps of new energy batteries (tensile strength of 105-125MPa, yield strength of 40-70MPa, Vickers hardness of 25-35, and elongation of 30%-40%).

[0084] Comparative Example 2

[0085] The aluminum material of this comparative example has the same composition as that of Example 1, the homogenization heating temperature is 460° C., the holding time is 8 h, the finished product annealing temperature is 370° C., and other preparation process conditions are the same as those of Example 1.

[0086] from Figure 7 It can be seen that the plate has a low degree of recrystallization and still contains a large number of fibrous grains. The aluminum plate and strip produced by this process has a tensile strength of 140MPa, a yield strength of 119MPa, a Vickers hardness of 47, and an elongation of 14%. The strength and hardness do not meet the standards and do not meet the technical requirements for aluminum alloy plate and strip for explosion-proof caps of new energy batteries.

[0087] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Those skilled in the art should understand that the specific implementation methods of the present invention can be modified or replaced with equivalents with reference to the above embodiments. Any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention are within the scope of protection of the pending claims.

Claims

1. A 3 series aluminum alloy plate and strip for explosion-proof caps of new energy batteries, characterized by: In the aluminum alloy plate and strip, the number of second phases of grains with a particle size of less than 5 μm is greater than 6*10 5 / square millimeter, the number of second phases in grains with a particle size of 5μm or more is less than 1*10 4 / square millimeter; the second phase distribution makes the recrystallization degree of the aluminum alloy plate and strip greater than 80%; the aluminum alloy plate and strip has the following components in mass percentage: 0.9%≤Mn<1.3%; 0.3%<Fe<0.7%; Si≤0.08%; Zn<0.15%; Mg<0.1%; Cr<0.1%; 0.03%≤Cu<0.3%; 0.015%<Ti≤0.045%, and the remainder of Al and unavoidable impurities.

2. The 3 series aluminum alloy sheet and strip for explosion-proof caps of new energy batteries according to claim 1 is characterized in that: The aluminum alloy plate and strip has a tensile strength of 105-125 MPa, a yield strength of 40-70 MPa, and a Vickers hardness of 25-35.

3. The 3 series aluminum alloy sheet and strip for explosion-proof caps of new energy batteries according to claim 1 is characterized in that: The aluminum alloy plate and strip has an elongation of 30% to 40%.

4. The method for preparing a 3-series aluminum alloy sheet and strip for an explosion-proof cap for a new energy battery according to any one of claims 1 to 3, characterized in that: The specific steps are as follows: Step ①, melting and semi-continuous casting, adding the prepared aluminum alloy raw material into a melting furnace, uniformly mixing and then melting into liquid aluminum alloy, and semi-continuously casting the liquid aluminum alloy into ingots; Step ②, homogenizing the obtained ingot; wherein the ingot is subjected to homogenization treatment in a heating furnace after being cut off and milled, with a heating temperature of 530°C to 640°C and a holding time of 10 to 18 hours; Step ③, rolling the homogenized ingot into a hot-rolled slab of 6-10 mm in a hot continuous rolling mill, wherein the starting rolling temperature is 450-520° C. and the finishing rolling temperature is 260-320° C.; Step 4: cold rolling the hot-rolled sheet to obtain a cold-rolled sheet with a thickness of 0.5-1 mm, and performing intermediate annealing during the cold rolling process; intermediate annealing is performed when the cold rolling thickness reaches 0.8-1.5 mm, at a temperature of 320-380° C.; Step ⑤: anneal the cold-rolled sheet to obtain a 3-series aluminum alloy sheet or strip, with the annealing temperature being 330-390°C.

5. The method for preparing the 3 series aluminum alloy sheet and strip for the explosion-proof cap of the new energy battery according to claim 4, characterized in that: In the step ①, the melting temperature of the melting furnace is 740-760°C, the semi-continuous casting temperature is 685-710°C, the ingot stable production speed is 46-54 mm / min, and the crystallizer cooling water flow rate is 135-150 m 3 / h, cooling water temperature 15~30℃.

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