1. A method for preparing an explosion-proof sheet and a turnover sheet for a battery cover plate by using 8-series aluminum alloy strips is characterized by comprising the following steps of: the 8-series aluminum alloy comprises the following components in percentage by mass: less than or equal to 0.09wt% of Si, 1.20-1.35 wt% of Fe1.20-1.35 wt%, less than or equal to 0.01 wt% of Cu, 0.45-0.55wt% of Mn, less than or equal to 0.01 wt% of Mg, less than or equal to 0.01 wt% of Cr, less than or equal to 0.01 wt% of Zn, 0.008-0.03 wt% of Ti, less than or equal to 0.01 wt% of other elements, less than or equal to 0.01 wt% of single element.

2. The method for preparing the explosion-proof sheet and the turnover sheet for the battery cover plate by using the 8-series aluminum alloy strip as claimed in claim 1, which is characterized by comprising the following steps of:

the method comprises the following steps: melting 99.90 of high-precision aluminum ingot AL, casting into cast ingot according to design components, strictly controlling the contents of Fe and Mn and other elements, wherein the content of each element is less than or equal to 0.01 wt%, and the total content is less than or equal to 0.15 wt%;

step two: carrying out homogenization annealing on the cast ingot, keeping the temperature at 580-610 ℃, preserving the heat for 8-20h, then cooling to 500 ℃, and preserving the heat for 2 h;

step three: discharging and hot rolling into coiled materials with the thickness of 3-8 mm;

step four: cooling a hot rolled coil with the thickness of 3-8mm, rolling to the thickness of 1-4mm, and annealing in a continuous air cushion furnace at the annealing temperature of 460-520 ℃ for 20-60 s;

step five: and rolling the coiled material with the thickness of 1-4mm to the thickness of a finished product, annealing to form an O state, and delivering after the coiled material is qualified.

3. The method for preparing the explosion-proof sheet and the turnover sheet for the battery cover plate by using the 8-series aluminum alloy strip as claimed in claim 2, wherein the method comprises the following steps: the temperature of the hot rolling and the finish rolling in the third step is controlled to be 300-330 ℃.

4. The method for preparing the explosion-proof sheet and the turnover sheet for the battery cover plate by using the 8-series aluminum alloy strip as claimed in claim 2, wherein the method comprises the following steps: the annealing temperature in the fourth step is 460-520 ℃, and the heat preservation time is 20-60 s.

Background

With the new energy industry, the lithium battery industry is rapidly developed and widely applied to the fields of power, energy storage and digital. The explosion-proof sheet and the turnover sheet on the battery cover plate are used as important parts on the battery and can directly influence the most critical index of the battery performance, namely the safety, so that the stability of the performance of the explosion-proof sheet and the turnover sheet is very important, and the aluminum material for the explosion-proof sheet and the turnover sheet is required to have excellent stamping and welding performance and stable explosion pressure.

The 8-series alloy has good stamping performance and welding performance, is widely used in electronic product structural parts, and in order to obtain stable bursting pressure, the material must have a fine and uniform microstructure, such as fine grains and fine and dispersed intermetallic compounds. In order to improve the corrosion resistance, the welding performance and the strength of the material, a certain amount of Mn element is usually added to realize the purpose. Fine and uniform crystal grains and structures are guaranteed by a special processing technology, so that an 8-series aluminum alloy material containing Mn, which has excellent stamping, welding and corrosion resistance and stable bursting pressure, is needed to be developed for the battery cover plate explosion-proof sheet and the turnover sheet and the processing technology thereof.

Therefore, it is necessary to provide a method for preparing an explosion-proof sheet and a turnover sheet for a battery cover plate from an 8-series aluminum alloy strip to solve the above problems.

Disclosure of Invention

The invention aims to provide a method for preparing an explosion-proof sheet and a turnover sheet for a battery cover plate by using an 8-series aluminum alloy strip, so as to solve the problems in the background technology.

In order to achieve the purpose, the invention provides the following technical scheme: a method for preparing an explosion-proof sheet and a turnover sheet for a battery cover plate by using 8-series aluminum alloy strips is characterized by comprising the following steps of: the 8-series aluminum alloy comprises the following components in percentage by mass: less than or equal to 0.09wt% of Si, 1.20-1.35 wt% of Fe1.20-1.35 wt%, less than or equal to 0.01 wt% of Cu, 0.45-0.55wt% of Mn, less than or equal to 0.01 wt% of Mg, less than or equal to 0.01 wt% of Cr, less than or equal to 0.01 wt% of Zn, 0.008-0.03 wt% of Ti, less than or equal to 0.01 wt% of other elements, less than or equal to 0.01 wt% of single element, less than or equal to 0.15 wt% of Al in total, and the balance of Al.

Preferably, the method comprises the following steps

The method comprises the following steps: melting 99.90 of high-precision aluminum ingot AL, casting into cast ingot according to design components, strictly controlling the contents of Fe and Mn and other elements, wherein the content of each element is less than or equal to 0.01 wt%, and the total content is less than or equal to 0.15 wt%;

step two: carrying out homogenization annealing on the cast ingot, keeping the temperature at 580-610 ℃, preserving the heat for 8-20h, then cooling to 500 ℃, and preserving the heat for 2 h;

step three: discharging and hot rolling into coiled materials with the thickness of 3-8 mm;

step four: cooling a hot rolled coil with the thickness of 3-8mm, rolling to the thickness of 1-4mm, and annealing in a continuous air cushion furnace at the annealing temperature of 460-520 ℃ for 20-60 s;

step five: and rolling the coiled material with the thickness of 1-4mm to the thickness of a finished product, annealing to form an O state, and delivering after the coiled material is qualified.

Preferably, the temperature of the hot rolling and the final rolling in the third step is controlled to be 300-330 ℃.

Preferably, the annealing temperature in the fourth step is 460-520 ℃, and the heat preservation time is 20-60 s.

The invention has the technical effects and advantages that:

according to the invention, the microscopic grains and the microstructure of the material are finely controlled by adjusting the contents of alloy elements and trace elements and controlling the processing technology, so that the material has the effects of stable blasting performance, deep drawing performance, corrosion resistance, good weldability and the like.

Drawings

FIG. 1 is a schematic diagram of the grain size and distribution of the surface of the embodiment of the present invention.

FIG. 2 is a schematic diagram of the size and distribution of compounds on the surface of an example of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention provides a method for preparing an explosion-proof sheet and a turnover sheet for a battery cover plate by using 8-series aluminum alloy strips, which is characterized by comprising the following steps of: the 8-series aluminum alloy comprises the following components in percentage by mass: less than or equal to 0.09wt% of Si, 1.20-1.35 wt% of Fe1.20-1.35 wt%, less than or equal to 0.01 wt% of Cu, 0.45-0.55wt% of Mn, less than or equal to 0.01 wt% of Mg, less than or equal to 0.01 wt% of Cr, less than or equal to 0.01 wt% of Zn, 0.008-0.03 wt% of Ti, less than or equal to 0.01 wt% of other elements, less than or equal to 0.01 wt% of single element, less than or equal to 0.15 wt% of Al in total, and the balance of Al.

Further, in the above technical solution, the method comprises the following steps:

the method comprises the following steps: melting 99.90 of high-precision aluminum ingot AL, casting into cast ingot according to design components, strictly controlling the contents of Fe and Mn and other elements, wherein the content of each element is less than or equal to 0.01 wt%, and the total content is less than or equal to 0.15 wt%;

step two: carrying out homogenization annealing on the cast ingot, keeping the temperature at 580-610 ℃, preserving the heat for 8-20h, then cooling to 500 ℃, and preserving the heat for 2 h;

step three: discharging and hot rolling into coiled materials with the thickness of 3-8 mm;

step four: cooling a hot rolled coil with the thickness of 3-8mm, rolling to the thickness of 1-4mm, and annealing in a continuous air cushion furnace at the annealing temperature of 460-520 ℃ for 20-60 s;

step five: and rolling the coiled material with the thickness of 1-4mm to the thickness of a finished product, annealing to form an O state, and delivering after the coiled material is qualified.

Further, in the above technical scheme, the temperature of the hot rolling and the finish rolling in the third step is controlled to be 300-;

further, in the above technical scheme, the annealing temperature in the fourth step is 460-520 ℃, and the heat preservation time is 20-60 s.

It should be noted that:

fe in the 8 series aluminum alloy is a main alloying element and can form with matrix Al and Si: the FeAl3, α (AlFeSi), and β (AlFeSi) phases act as solid solution strengthening, and improve the alloy strength. When the content of Fe element is high, the formed compounds have many phases and are accumulated at the crystal boundary, the compounds are not tightly combined with the Al matrix, when the subsequent processing deformation is carried out, fracture is easily formed at the crystal boundary, the stamping processing performance of the compounds is influenced, meanwhile, the consistency of the material structure is also influenced, the stability of the explosion value of the finished explosion-proof sheet and the turnover sheet is adversely influenced, if the content of Fe is lower, the strength and the plasticity of the material are reduced, the stamping deformation of the explosion-proof sheet and the turnover sheet is not facilitated, and the content of Fe is preferably controlled to be 1.20-1.35 wt%. Si is generally an impurity element, and free Si is formed when the Si content is high, which is a hard and brittle item and reduces the plasticity of the material, so the content is preferably controlled to be less than or equal to 0.09 wt%.

The Mn element can improve the alloy strength and the corrosion resistance, simultaneously can change the shape of a needle-shaped or sheet-shaped Fe-containing compound, spheroidize to reduce the brittleness and improve the plasticity of the material, and can improve the recrystallization temperature, effectively inhibit the growth of crystal grains and make the crystal grains and the tissues of the material finer and more uniform. However, the content of Mn is too high, the strength of the alloy is very high, the deep drawing deformation is not facilitated, if the content is low, the corrosion resistance of the alloy is reduced, the electrolyte resistance is reduced, and the alloy is not beneficial to batteries, and tests show that: the Mn content is controlled to be 0.45-0.55wt%, and the comprehensive performance is good.

The Ti element mainly plays a role in grain refinement, the content is preferably controlled to be 0.008-0.03%, the effect of grain refinement is poor when the content is too low, when the content is more than 0.03%, the grain refinement effect reaches a saturated state, and the cost is increased. Other impurity elements such as Mg, Cu, Cr, Zn and the like can form hard and brittle phase compounds with an Al matrix to reduce the plasticity of the aluminum alloy material, so that the content of single element is required to be less than or equal to 0.01 wt%, and the total content is less than or equal to 0.15 wt%.

After 8-series aluminum alloy cast ingots with the components are obtained, sawing and milling the cast ingots, and then performing subsequent processing:

(1) carrying out homogenizing annealing on the cast ingot, keeping the temperature for 8-20h at the temperature of 580-610 ℃, then cooling to 500 ℃, keeping the temperature for 2h,

discharging and hot rolling into coiled materials with the thickness of 3-8mm, and controlling the temperature of the hot rolling final rolling to be 300-330 ℃.

(2) And cooling the hot-rolled coiled material with the thickness of 3-8mm, and then rolling to the thickness of 1-4mm for continuous air cushion furnace annealing at the annealing temperature of 460-520 ℃ for 20-60 s.

(3) And rolling the coiled material with the thickness of 1-4mm to the thickness of a finished product, annealing to form an O state, and delivering the O state to a customer after the O state is inspected to be qualified.

Through the above components and process control, the microscopic grains and tissues of the 8-series aluminum alloy material are fine and uniformly distributed, as shown in the grain size and distribution (average 23 μm) on the surface of FIG. 1 and the compound size and distribution (3-10 μm) on the surface of FIG. 2, the material has small anisotropy and good stability during processing deformation, the blasting value range after the explosion-proof sheet and the turnover sheet are manufactured is less than or equal to 0.05MPa, and the tensile strength of the material in macroscopic performance is as follows: 100-120 MPa, yield strength: 40-60 MPa, elongation: 35-45%, completely meets the stamping requirements of the explosion-proof sheet and the turnover sheet, and has corrosivity and weldability matched with the existing cover plate material for the battery.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments or portions thereof without departing from the spirit and scope of the invention.