CN108220692A - The preparation method of drawing aluminum alloy plate materials is thinned in a kind of high intensity - Google Patents

Abstract

The invention belongs to the technical field of processing aluminum alloy plates, strips and foils, and in particular relates to a preparation method for producing high-strength aluminum alloy plates for thinning and deep drawing by using casting and rolling slabs. The invention discloses a method for preparing high-strength aluminum alloy plates for thinning and deep drawing. The specific steps are as follows: industrial aluminum ingots, Fe agent, Si agent, copper agent, magnesium ingots, etc. are used as raw materials to prepare aluminum alloys, and the aluminum alloys are smelted and refined. , stand still, add titanium wire, cast and roll after online deslagging and degassing, and process it into a cast-rolled slab blank coil; perform homogenization annealing when the blank coil is cold-rolled, and the annealing is carried out in a nitrogen annealing furnace, and then the coil Perform intermediate annealing, and finally cold rolling to a finished product thickness of 0.5 mm. The aluminum alloy plate prepared by the invention has high tensile strength, low earing rate, controllable surface roughness, satisfies good deep drawing and thinning performance, and improves the utilization rate of the material at the same time. The casting and rolling billet produced by the invention can reduce the cost by about 20% compared with the conventional hot-rolled plate, and has broad application prospects.

Description

A method for preparing high-strength aluminum alloy sheet for thinning and deep drawing

technical field

The invention belongs to the technical field of processing aluminum alloy plates, strips and foils, and in particular relates to a method for preparing high-strength aluminum alloy plates for thinning and deep drawing.

Background technique

As the country promotes the construction of an energy-saving and resource-saving society, the lightweight of automobiles and the development of new energy vehicles, the application of aluminum materials in automobiles is increasing. The key to new energy vehicles is the development of power batteries. The current problems that need to be solved in the power battery industry are concentrated in: the energy density of batteries cannot be low, the battery life cannot be short, the ability to control battery costs must be strengthened, and the weight of batteries must be reduced. . One of the important materials for the production of power batteries is aluminum. Mainly used for battery case, battery lug, battery explosion-proof cover, soft connection material, etc. Compared with other materials, the comprehensive cost performance of aluminum alloy materials is higher than that of steel, magnesium, plastics and composite materials, and it has relatively large advantages in terms of application technology, operation safety and recycling. For the battery casing, the technical problems to be solved are to improve the strength of the battery casing, increase the volume, increase the production efficiency, reduce the cost, optimize the thinning and deep drawing process of the casing, etc. This is also a common problem in the existing battery casing production industry.

Al-Mn series alloys are widely used in the manufacture of new energy power battery cases due to their good corrosion resistance, heat dissipation, weldability and deep drawing properties. The punching process of the power battery case has a large amount of deformation, many punching passes, and a complicated production process, which puts forward high requirements for the comprehensive performance of the material, especially the deep drawing performance. To have excellent deep drawing performance, the material not only requires small thickness deviation and good surface quality, but also needs to have good plasticity, small yield ratio and excellent isotropy. At present, the stamping and forming method of the aluminum shell of the power battery of domestic enterprises is to use a general punching machine and a hydraulic press to punch and blank the aluminum sheet and then go through a multi-channel drawing and thinning process, which requires high mechanical properties and process properties of the material. The continuous improvement of equipment and the improvement of deep drawing efficiency have also continuously increased the requirements for materials, and strived to continuously reduce costs. At present, there are two production methods for preparing battery shell plates: ingot hot rolling + cold rolling and cast rolling + cold rolling. Using hot rolling + cold rolling plate rolling can break the coarse grains in the casting state and re-heal microscopic cracks. , to reduce or eliminate some casting defects, and the material isotropy is better than cast-rolling + cold-rolling. Compared with hot rolling, the casting and rolling production method has the advantages of less energy consumption, less investment in equipment, short production cycle, favorable recycling of waste and low production cost.

At present, most enterprises use 3003 aluminum alloy plates produced by hot rolling to produce power battery shells, but the cost is relatively high. The mechanical properties of the 3003 plate produced by casting and rolling are close to it, especially in cost control, but its strength is low, the internal structure of the alloy is difficult to control, and the surface quality of the plate surface is difficult to meet high-volume and high-efficiency production.

Contents of the invention

The purpose of the present invention is to provide a method for producing high-strength thinning and deep drawing aluminum alloy plates by using cast-rolled slabs, so that it can adapt to the high-efficiency deep drawing and deep drawing thinning process and quality requirements of battery shells, so as to overcome the problems in the prior art. The cost of producing battery shells is high, the strength of the plates used is low, the internal structure of the alloy is difficult to control, and the surface quality of the plates is difficult to meet high-volume and high-efficiency production.

The purpose of the present invention is achieved through the following technical solutions:

(1) The chemical composition of the aluminum alloy plate of the present invention is calculated by mass percentage, as shown in Table 1:

Table 1 Chemical Composition of Aluminum Alloy Sheet Unit: %

(2) Casting and rolling processing:

According to the composition of the aluminum alloy in step (1), 99.70% industrial pure aluminum ingot, manganese agent, iron agent, silicon agent, copper agent, and magnesium ingot are used as raw materials to prepare the aluminum alloy, after smelting, refining, and standing, Add titanium wire, remove slag and gas online, and send it to the continuous casting and rolling machine through the casting nozzle, and cast and roll it into (6.5-7.6mm)×1500mm×L cast-rolled slab stock coils. Among them, the smelting temperature is 745-760°C; powder spraying refining and argon refining are used for refining; standing is carried out in a standing furnace; the diameter of titanium wire is Φ10mm, and the adding speed of titanium wire is 80-150mm/min; online slag removal adopts 50 The online degassing medium is argon, and the pressure of the degassing gas is 0.37MPa; the rotor speed during the online degassing process is 217r/min; the casting and rolling area is controlled at 40-60mm, and the temperature of the front box is controlled at 695- 705°C, the casting and rolling speed is controlled at 600-850mm/min. During the preparation process of the above aluminum alloy, waste materials of the aluminum alloy may be added, and the amount of waste materials added shall not exceed 15%, and the waste materials must be pure aluminum or waste materials generated during the production process of the alloy.

(3) Cold-roll the cast-rolled slab stock coil prepared in step (2), and perform homogenization annealing when the cold-rolling reaches 4.0-5.0 mm. It is carried out in a nitrogen annealing furnace; when the cast-rolled slab stock coil is cold-rolled to a thickness of 1.0 mm, the cast-rolled slab stock coil is subjected to intermediate annealing. The coil is cold-rolled to a thickness of 0.5 mm to obtain a finished aluminum alloy plate.

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

1. Compared with the existing deep-drawn battery shell plates, the aluminum alloy plate prepared by the present invention has a tensile strength of up to 230Mpa, an earring rate≦2.5%, a controllable surface roughness, and an Ra value of 0.300 μm to 0.600 μm Between, to meet the good deep drawing thinning performance, while improving the utilization of materials.

2. The aluminum alloy plate prepared by the present invention adopts cast-rolled billet, adopts twice annealing in cold rolling, in order to improve the surface quality and reduce deep oxidation of the plate surface, nitrogen annealing furnace is used when homogenizing annealing for the first time. However, the current hot rolling method needs to mill the billet to ensure the quality of the surface, while the casting and rolling materials cannot be operated. The quality of the surface is guaranteed through the control of protective atmosphere annealing and cold rolling. Through uniform annealing, the problems of coarse grain size, compound size and distribution, and partial intermediate segregation are solved, and at the same time, the phenomenon of high-temperature oxidation and blackening of the plate surface caused by the addition of magnesium is solved, and it is prevented from pulling during deep drawing, thinning and stretching And the mold is stuck too quickly.

The thickness of the second annealing is rolled to 1.0mm. The main purpose of annealing is to eliminate work hardening and ensure that the processing rate of the finished product is above 50%, so as to ensure the high-strength mechanical properties of the strip and improve the deep drawing thickness of the battery case. Efficiency and quality of deep drawing.

3. The present invention uses cast-rolled blanks to produce plates, which can reduce the cost by about 20% compared with the existing commonly used hot-rolled plates.

4. The roughness of finished aluminum alloy plates is controlled, and the nitrogen annealing furnace is used for uniform annealing to reduce the deep oxidation caused by high-temperature uniform annealing. further oxidation.

5. This patent adopts casting and rolling for billet, and on the basis of 3003 alloy, appropriate amount of trace alloy elements such as Mg and Cu are added, through optimization of casting and rolling process, optimization of uniform annealing process, and optimization of cold rolling and finished annealing process Combination, improve the mechanical properties and surface quality of the battery shell plate. The workpiece that has been thinned and drawn by deep drawing has better surface quality, which reduces the phenomenon of pulling and cracking, and can improve the drawing efficiency and reduce the production cost of the battery case. Combined with the numerical simulation method to study and analyze the thinning and deep drawing behavior on the optimized combination of material process performance and mechanical properties, through the cooperation of simulation and plate production process, the plate material suitable for high-efficiency and low-cost battery shell is prepared. This achievement has very good economic benefits and social benefits.

Description of drawings

Fig. 1 is the ear picture of rolling 0.5mm sheet material in Example 1 of the present invention;

Fig. 2 is the ear making picture of the production plate of embodiment 2 of the present invention;

Figure 3 shows the plate produced after annealing in a conventional homogenizing annealing furnace.

Detailed ways

The present invention will be further elaborated below in conjunction with implementation examples. The implementation examples are only used to illustrate the present invention, but not to limit the present invention in any way.

Example 1:

(1) The chemical composition of the aluminum alloy plate of Example 1 is calculated by mass percentage, as shown in Table 2:

Table 2 Chemical Composition of Aluminum Alloy Sheets Unit: %

(2) Casting and rolling processing:

According to the composition of the aluminum alloy in the step (1), adopt 99.70% industrial pure aluminum ingot, manganese agent, iron agent, silicon agent, copper agent, magnesium ingot, 8% 1060 pure aluminum scraps as raw material preparation described aluminum alloy, satisfy The 20-ton-capacity charge is configured. After the raw materials are smelted, refined, and allowed to stand still, titanium wire is added, and after online deslagging and degassing, they are sent to the continuous casting and rolling machine through the casting nozzle. They are produced on an inclined casting and rolling machine with a specification of Ф980×2000mm. Cast and rolled into 7.6mm×1500mm×L cast-rolled slab stock coils. The smelting temperature is 745°C; powder spraying refining and argon refining are used for refining; standing is carried out in a standing furnace; the diameter of titanium wire is Φ10mm, and the adding speed of titanium wire is 80mm/min; 50 mesh ceramic filter plate is used for online slag removal ; The online degassing medium is argon, the degassing gas pressure is 0.37MPa, and the rotor speed is 217r/min during the online degassing process; during the casting and rolling process, the casting and rolling area is controlled at 60mm, and the temperature of the front box is controlled at 695°C. The casting and rolling speed is controlled at 600mm/min; the grain size is controlled at the second level, and defects such as segregation, surface scratches, and abrasions are not allowed.

(3) Cold rolling processing:

Cold-roll the cast-rolled billet coil prepared in step (2), and perform homogenization annealing when the cast-rolled billet coil is cold-rolled to 4.0 mm. The homogenization annealing system is: 540 ° C for 32 hours, and the annealing is carried out in a nitrogen annealing furnace ; when the cast-rolled billet coil is cold-rolled to a thickness of 1.0 mm, the cast-rolled billet coil is cold-rolled for intermediate annealing, the annealing system is: 450 ° C for 3 hours; finally, the cast-rolled billet coil is cold-rolled to a thickness of 0.5 mm, The finished aluminum alloy plate is obtained, which meets the thickness requirement of the battery case.

The cold rolling process is 7.6mm—5.5mm—4.0mm (homogenization annealing)—2.6mm—1.8mm—1.3mm—1.0mm (intermediate annealing)—0.75mm—0.5mm

The mechanical properties of the finished product were tested, and the results are as follows:

Tensile strength σ _b : 215MPa; Yield strength σ _0.2 : 200MPa; Earning rate: ≦3.0%, as shown in Figure 1, the earing is relatively large. Surface roughness: 0.032μm～0.060μm.

Example 2:

(1) The chemical composition of the aluminum alloy sheet material of embodiment 2 is calculated by mass percentage, as shown in table 3:

Table 3 Chemical Composition of Aluminum Alloy Sheet Unit: %

(2) Casting and rolling processing:

According to the composition of the aluminum alloy in the step (1), adopt 99.70% commercially pure aluminum ingot, manganese agent, iron agent, silicon agent, copper agent, magnesium ingot, 8% 1060 pure aluminum waste material to prepare described aluminum alloy as raw material, satisfy The 20-ton furnace charge is configured. After the raw materials are smelted, refined, and allowed to stand still, titanium wire is added. After online deslagging and degassing, they are sent to the continuous casting and rolling machine through the casting nozzle. They are produced on an inclined casting and rolling machine with a specification of Ф980×2000mm. Cast and rolled into 7.6mm×1500mm×L cast-rolled slab stock coils. Among them, the smelting temperature is 750°C; powder spraying refining and argon refining are used for refining; standing is carried out in a standing furnace; the diameter of titanium wire is Φ10mm, and the adding speed of titanium wire is 120mm/min; 50 mesh ceramic filter is used for online slag removal The on-line degassing medium is argon, and the pressure of the degassing gas is 0.37MPa; the rotor speed is 217r/min; The particle size is controlled at the first level, and defects such as segregation, surface scratches, and abrasions are not allowed.

(3) Cold rolling processing:

Cold-roll the cast-rolled slab stock coil prepared in step (2), and perform homogenization annealing when the cast-rolled slab stock coil is cold-rolled to 4.5 mm. The annealing system is: 570 ° C for 26 hours, and the annealing is carried out in a nitrogen annealing furnace ; When the cast-rolled slab stock coil is cold-rolled to a thickness of 1.0mm, intermediate annealing is performed on the cast-rolled slab stock coil. , to obtain the finished aluminum alloy plate, which meets the thickness requirements of the battery case.

The cold rolling process is 7.6mm—5.5mm—4.5mm (homogenization annealing)—2.6mm—1.8mm—1.3mm—1.0mm (intermediate annealing)—0.75mm—0.5mm

The mechanical properties of the finished aluminum alloy sheet were tested, and the results are as follows:

Tensile strength σ _b : 228MPa; Yield strength σ _0.2 : 210MPa; Earning rate: ≦2.5%, the earing is small, see Figure 2. Surface roughness: 0.037μm～0.050μm.

Example 3:

(1) The chemical composition of the aluminum alloy sheet material of embodiment 3 is calculated by mass percentage, as shown in table 4:

Table 4 Chemical Composition of Aluminum Alloy Sheet Unit: %

(2) Casting and rolling processing:

According to the composition of the aluminum alloy in step (1), 99.70% industrially pure aluminum ingot, manganese agent, iron agent, silicon agent, copper agent, and magnesium ingot are used as raw materials to prepare the aluminum alloy to meet the configuration of the furnace charge with a capacity of 20 tons. After smelting, refining, and standing still, titanium wire is added, and after online slag and gas removal, it is sent to the continuous casting and rolling machine through the casting nozzle. It is selected to be produced on the inclined casting and rolling machine with the specification of Ф980×2000mm, and the casting and rolling is 7.0mm×1500mm× L of cast-rolled slab stock rolls. The smelting temperature is 750°C; powder spraying refining and argon refining are used for refining; standing is carried out in a standing furnace; the diameter of titanium wire is Φ10mm, and the adding speed of titanium wire is 120mm/min; online slag removal adopts 50 mesh ceramic filter The on-line degassing medium is argon, and the pressure of the degassing gas is 0.37MPa; the rotor speed is 217r/min; The particle size is controlled at the first level, and defects such as segregation, surface scratches, and abrasions are not allowed.

(3) Cold rolling processing:

Cold-roll the cast-rolled slab stock coil prepared in step (2), and perform homogenization annealing when the cast-rolled slab stock coil is cold-rolled to 4.3 mm. The annealing system is: 560 ° C for 28 hours, and the annealing is carried out in a conventional annealing furnace ; and then cold-roll the cast-rolled slab stock coil to a thickness of 1.0 mm, and perform intermediate annealing on the coil again, the annealing system is: 450 ° C for 3 hours; finally cold-roll the cast-rolled slab stock coil to a thickness of 0.5 mm, and obtain an aluminum alloy The finished sheet meets the thickness requirements of the battery case.

The cold rolling process is 7.0mm—5.8mm—4.3mm (homogenization annealing)—2.6mm—1.8mm—1.3mm—1.0mm (intermediate annealing)—0.75mm—0.5mm

The mechanical properties of the finished aluminum alloy sheet were tested, and the results are as follows:

Tensile strength σ _b : 220MPa; yield strength σ _0.2 : 205MPa, lug rate: ≦2.6%, the lug is small, and the board surface is black and bright, as shown in Figure 3, it is difficult to meet the surface quality requirements of the battery case; the board surface Roughness: 0.030μm～0.070μm.

Example 4:

(1) The chemical composition of the aluminum alloy sheet material of embodiment 4 is calculated by mass percentage, as shown in table 5:

Table 5 Chemical Composition of Aluminum Alloy Sheet Unit: %

(2) Casting and rolling processing:

According to the composition of the aluminum alloy in step (1), 99.70% industrial pure aluminum ingot, manganese agent, iron agent, silicon agent, copper agent are used to meet the configuration furnace charge with a capacity of 20 tons. After the raw materials are smelted, refined and left to stand, add Titanium wire is sent to the continuous casting and rolling machine through the casting nozzle after online deslagging and degassing. It is selected to be produced on an inclined casting and rolling machine with a specification of Ф980×2000mm, and cast and rolled into a 6.5mm×1500mm×L cast-rolled slab stock coil. The smelting temperature is 760°C; powder spraying refining and argon gas refining are used for refining; standing is carried out in a standing furnace; the diameter of titanium wire is Φ10mm, and the adding speed of titanium wire is 150mm/min; online slag removal adopts 50 mesh ceramic filter The on-line degassing medium is argon, and the pressure of the degassing gas is 0.37MPa; the rotor speed is 217r/min; The particle size is controlled at the second level, and defects such as segregation, surface scratches, and abrasions are not allowed.

(3) Cold rolling processing:

Cold-roll the cast-rolled slab stock coil prepared in step (2), and perform homogenization annealing when the cast-rolled slab stock coil is cold-rolled to 5.0 mm. The annealing system is: 600 ° C for 26 hours, and the annealing is carried out in a nitrogen annealing furnace ; when the cast-rolled slab stock coil is cold-rolled to a thickness of 1.0 mm, the coil is subjected to intermediate annealing again, and the annealing system is: 400 ° C for 3 hours; finally, the cast-rolled slab stock coil is cold-rolled to a thickness of 0.5 mm to obtain an aluminum alloy The finished sheet meets the thickness requirements of the battery case.

The cold rolling process is 6.9mm—5.7mm—5.0mm (homogenization annealing)—2.6mm—1.8mm—1.3mm—1.0mm (intermediate annealing)—0.75mm—0.5mm

The embodiments of the present invention show that the finished aluminum alloy plate prepared by the present invention has a thickness of 0.5mm, which meets the thickness requirements for making automobile battery cases; the tensile strength can reach 230Mpa, which meets the requirements for plates when making battery cases; the aluminum alloy plate It has high hardness and is easy to process, which can improve the efficiency of producing plates; the ear-making rate is ≦2.5%, and the ear-making rate is small; the surface roughness is moderate and controllable, and the surface roughness Ra value is between 0.300 μm and 0.600 μm, which is easy Production, less material loss, saving production costs.

Claims (10)

1. A preparation method for high-strength thinning and deep-drawing aluminum alloy sheet, characterized in that, comprising the following steps: (1) Casting and rolling: After preparing industrially pure aluminum ingot, iron agent, manganese agent, silicon agent, copper agent, and magnesium ingot in a certain proportion as raw materials for aluminum alloy plates, after smelting, refining, and standing still, titanium wire is added, and after online deslagging and degassing It is sent to the continuous casting and rolling machine through the casting nozzle, and cast and rolled into a cast-rolled slab stock coil of a certain specification; the aluminum alloy raw material contains zinc impurities; (2) Cold rolling: Cold rolling the cast-rolled slab stock coil prepared in step (1), and then cold-rolling the cast-rolled slab stock coil to a thickness of _δ1 , performing homogenization annealing, which is carried out in a nitrogen annealing furnace; When the billet coil is cold-rolled to a thickness of δ ₂ , intermediate annealing is performed; finally, it is cold-rolled to a thickness of δ ₃ to obtain a finished aluminum alloy plate. 2. The method for preparing high-strength aluminum alloy sheet for thinning and deep drawing according to claim 1, characterized in that, in step (1), the addition amount of each component in the raw material of aluminum alloy sheet is calculated according to the mass fraction, and iron 0.3~0.6% of manganese agent, 1.0~1.3% of manganese agent, 0.05~0.3% of silicon agent, 0.1~0.4% of copper agent, 0.1~0.5% of magnesium ingot, zinc≦0.0005%, industrial pure aluminum ingot is the balance; The purity of pure aluminum ingot is 99.70%. 3. The method for preparing high-strength aluminum alloy sheets for thinning and deep drawing according to claim 1, characterized in that, in step (1), the melting temperature is 745-760°C; the refining adopts powder spraying refining and argon refining ; On-line deslagging adopts 50-mesh ceramic filter plate; on-line degassing medium is argon, and the pressure of degassing gas is 0.37MPa; during the process of on-line degassing, the rotor speed is 217r/min; ~7.6mm)×1500mm×L. 4. The method for preparing high-strength aluminum alloy sheets for thinning and deep drawing according to claim 1, characterized in that, in step (1), the diameter of the added titanium wire is Φ10 mm, and the adding speed of the titanium wire is 80-150 mm/min , the mass fraction of titanium wire in the aluminum alloy sheet is 0.01%. 5. The preparation method of high-strength aluminum alloy sheet for thinning and deep drawing according to claim 1, characterized in that, in step (1), the casting and rolling area is controlled at 40-60 mm, and the temperature of the front box is controlled at 695-705 ℃, the casting and rolling speed is controlled at 600-850mm/min. 6. The method for preparing high-strength aluminum alloy sheets for thinning and deep drawing according to claim 1, characterized in that, in step (1), during the casting and rolling process of aluminum alloy sheets, the amount of aluminum alloy scrap added does not exceed 15 %; The aluminum alloy scrap is pure aluminum or the scrap produced in the production process of this alloy. 7. The method for preparing high-strength aluminum alloy sheets for thinning and deep drawing according to claim 1, characterized in that, in step (2), _δ1 is 4.0-5.0mm; the homogenization annealing system is 540°C-600 ℃ insulation 26 ~ 32h. 8. The preparation method of high-strength aluminum alloy sheet for thinning and deep drawing according to claim 1, characterized in that, in step (2), _δ2 is 1.0mm, and the intermediate annealing system is 400°C-450°C for 3 hours ; δ ₃ is 0.5mm. 9. The high-strength aluminum alloy sheet for thinning and deep drawing processed by the preparation method according to claim 1, wherein the content of each element in the aluminum alloy sheet is calculated according to the mass fraction, and the iron element is 0.3~0.6% , manganese element 1.0~1.3%, silicon element 0.05~0.3%, copper element 0.1~0.4%, magnesium element 0.1~0.5%, zinc element≦0.0005%, titanium element 0.01%, aluminum element is the balance. 10. The high-strength aluminum alloy plate for thinning and deep drawing as claimed in claim 9 is used for producing automobile battery casings.