CN-121204453-B - Aluminum alloy strip for power battery cover plate and preparation method thereof

Abstract

The invention belongs to the technical field of aluminum-based materials, and particularly relates to an aluminum alloy strip for a power battery cover plate and a preparation method thereof. According to the preparation method of the aluminum alloy strip, disclosed by the invention, the soaking-free treatment and the intermediate annealing-free treatment are successfully realized through the unique component design and the accurate cooperative control of key process parameters, so that the excellent performance of a product is ensured, the production energy consumption and the cost are greatly reduced, and the processing efficiency is improved.

Inventors

• LU JINXU
• LI XIAODU
• DING RONGHUI
• LI JIGANG
• SHEN MEIZHEN

Assignees

• 广西国潮铝业有限公司

Dates

Publication Date

20260508

Application Date

20251127

Claims (4)

1. 1. A method for preparing an aluminum alloy strip for a power battery cover plate, comprising the steps of: s1, proportioning and smelting, namely preparing raw materials ：Si:0.15%～0.25%,Fe:0.4%～0.6%,Cu:0.09%～0.13%,Mn:1.03%～1.15%,Cr:0.05%～0.25%,Zr:0.03%～0.15%,Mg≤0.015%,Zn≤0.018%,Ti:0.02%～0.03%, according to the following mass percentage, wherein the total amount of other impurity elements is less than or equal to 0.15%, and the balance is Al; smelting the raw materials, refining, degassing and deslagging, and performing semicontinuous casting to obtain an aluminum alloy slab ingot; S2, heating, namely heating the slab ingot to 490-550 ℃ after sawing and milling the surface, and preserving the heat for 3-24 hours, and performing heating; s3, hot rolling, namely hot rolling after heating, namely discharging from a furnace, and determining the finish rolling temperature T of hot finish rolling by the following formula: T=290+30×[Mn]+20×[Cr]+35×[Zr]-8×[Zr]2; wherein [ Mn ], [ Cr ], [ Zr ] respectively represent numerical parts of mass percent of manganese, chromium and zirconium elements, and the unit of the finish hot finish rolling temperature T is DEG C; S4, cold rolling, namely rolling the hot rolled strip to the thickness of a finished product on a cold rolling mill after cooling, wherein the cold rolling cold working rate R in the S4 is determined by the following formula: R=25-2×[Mn]-3×[Cr]-4×[Zr]-0.03×(T-325); Wherein R is cold rolling cold working rate in percent, mn, cr and Zr are numerical values of the mass percentage of the corresponding elements respectively, and T is finish rolling temperature of hot finish rolling in percent; The roughness of the cold-rolled working roll is 0.25-0.35 mu m, and the rolling speed is 150-300 m/min; S5, cleaning the cold-rolled strip on a rewinding machine; And S6, slitting the cleaned strip into a preset finished product width through a slitting machine to obtain the aluminum alloy strip.
2. 2. The preparation method according to claim 1, wherein in S2, the temperature of the slab ingot heat treatment is 520-540 ℃ and the heat preservation time is 3h.
3. 3. The method according to claim 1, wherein the finish hot rolling thickness in S3 is 2.5 to 3.0mm.
4. 4. An aluminum alloy strip produced by the method of any one of claims 1-3.

Description

Aluminum alloy strip for power battery cover plate and preparation method thereof Technical Field The invention belongs to the technical field of aluminum-based materials, and particularly relates to an aluminum alloy strip for a power battery cover plate and a preparation method thereof. Background With the transition of global energy structures to clean and low-carbon, new energy automobile industry is coming to be expanded. As the heart of the new energy automobile, the performance, safety and cost of the power battery directly determine the endurance mileage, reliability and market competitiveness of the automobile. The cover plate of the power battery shell is used as a key structural member for protecting the internal core body of the battery, isolating the external environment and ensuring the sealing safety, and the comprehensive performance requirement of the material is very strict. It is not only required to have excellent strength, formability and corrosion resistance to ensure structural integrity and long service life under complicated working conditions, but also must possess good electrical conductivity, thermal conductivity and laser welding performance to meet the requirements of battery charge and discharge management and efficient production and assembly. Among the numerous materials, 3003 aluminum alloy has long been considered as one of the ideal candidates for battery case cover plates due to its good processability, moderate strength, and excellent corrosion resistance. The traditional 3003 aluminum alloy cover plate material preparation generally follows a classical and complicated process flow of casting, homogenization treatment, hot rolling, cold rolling, intermediate annealing, cold rolling, finished product annealing and the like. Among these, "homogenization" and "intermediate annealing" are two vital links, but are also the main focus of energy consumption and time costs. First, during casting, severe dendrite segregation and large amounts of coarse brittle second phases (e.g., iron and manganese rich intermetallic compounds) can occur within the ingot due to non-equilibrium solidification. These non-uniform textures can significantly reduce the plasticity, toughness, and subsequent processability of the material. Therefore, it is necessary to uniformly diffuse the element by a high temperature (usually higher than 580 ℃) for a long time (usually up to 10 to 24 hours) "homogenization treatment" to dissolve the soluble brittle eutectic phase, thereby improving the processing characteristics of the material. The process has extremely high energy consumption, occupies most of the time of the whole production period, and is one of the bottlenecks for restricting the improvement of the production efficiency and the reduction of the cost. Secondly, during cold rolling deformation, a large amount of dislocation is accumulated in the material, a remarkable work hardening phenomenon is generated, the strength and hardness are increased, and the plasticity and toughness are drastically reduced. When work hardening reaches a certain degree, without softening treatment, the material cannot continue rolling deformation and even has the risk of cracking. Therefore, an "intermediate annealing" process must be interposed between the conventional multipass cold rolling. The process eliminates work hardening by a recrystallization process, restores the plasticity of the material, and facilitates subsequent cold rolling. However, the intermediate annealing is also a high-energy process, and can increase the production process, prolong the production period, and possibly bring about quality control problems such as surface oxidation, grain coarsening, and the like. Although the traditional process can produce qualified battery shell cover plate materials, the inherent problems of high energy consumption, long period and high cost are increasingly outstanding, and the urgent requirements of the new energy automobile industry on cost reduction and efficiency increase are difficult to adapt. In order to break through the technical bottleneck, various researches are performed in the industry. A main technical idea is to try to optimize the alloy composition, for example, by adding trace amounts of transition group elements such as manganese (Mn), chromium (Cr), zirconium (Zr), and the like, and using the dispersed nano intermetallic compound particles (Al 6Mn, al12Mn, and the like) formed by the transition group elements to generate dispersion strengthening and substructure strengthening, and at the same time, inhibit the recrystallization process and refine grains. However, simple adjustments of the ingredients are often insufficient to completely eliminate the homogenization treatment, because insufficient dissolution of the brittle phase can directly result in hot rolling cracking or unacceptable finished product properties. On the other hand, if an intermediate anneal is to be eliminated, the mi