| The Al-Mn alloy has excellent forming processing characteristics,high corrosion resistance,and good weldability.The power battery casing made of the alloy sheet has the advantages of impact resistance,cracking and leakage,and can meet the strength and rigidity requirements of the power battery casing.Based on cost considerations,the battery shell sheet is produced by casting and rolling billet.Compared with the hotrolled billet,the formability and forming efficiency are slightly inferior under the premise of the same mechanical properties.In this paper,the 3003 aluminum alloy sheet produced by casting blank is taken as the research object.The microstructure and surface morphology of the sheets under different preparation processes were analyzed by metallographic microscopic analysis,SEM and EDS analysis,confocal microscopy and EBSD.The mechanical properties of the test and cupping test were carried out.The effects of homogenization annealing,cold rolling and finish annealing on the microscopic mechanism of the forming process of 3003 sheet produced by casting and rolling were discussed.Study as follows:1.The effects of different homogenization temperatures on the microstructure of 3003 cast-rolled sheet were studied.The results show that in the unannealed cast-rolled sheet,a large amount of Mn is still dissolved in the matrix,and most of the smallersized nascent compounds are distributed in the grain boundaries and branches.When the temperature is 520-600 ℃ and the holding time is 22 hours,the grain size is gradually refined as the homogenization annealing temperature increases.When the temperature reaches 580 ℃,the grain structure is fine and uniform.The uniformity is good.When reaching 600 ℃,the grains are swallowed and grown,and the grains are coarsened.2.After the mechanical properties of the cold rolled to finished product sheet at different finish annealing temperatures,the tensile strength required for the O-state battery shell is satisfied at 380 ℃ finished annealing temperature: σb: 115-125 MPa,yield strength σs: 55 ~65MPa,ear rate: >3% and elongation: >35% of the forming performance requirements,while ensuring the formation of the battery shell requires 45 ° type earing requirements.3.The influence of the key preparation process of casting blank on 580 ℃ homogenization annealing and 380 ℃ finished annealing after cold rolling on the microscopic mechanism of sheet formability was discussed.The experimental results show that:(1)During the final annealing process,after annealing at 360 ℃ × 3 hours and 400 ℃ × 3 hours,a large amount of dispersed second phase particles(<1 μm)were precipitated inside the sheet.The second phase particle size in the plate annealed at 380 ℃ × 3 h is 1 ~ 3 μm,which reduces the pinning effect of the atom,reduces the work hardening rate,and improves the formation quality of the battery shell compared with other annealing temperatures.(2)As the annealing temperature increases,the grain size tends to grow.The strength and hardness of the alloy increase with the smaller grains,resulting in fine grain strengthening.(3)The texture formed at the annealing temperature of 360 ℃ is mainly {112}<162> texture and {110}<221> texture,forming 45° earing,and when annealing at 400 ℃,it mainly forms {111}<144> textured and formed 0 ° / 90 ° earing;when anneal at 380 ℃,there are mainly {112} <110> texture,which is conducive to the formation of 45 ° earing,thus ensuring the yield of battery shell forming.4.the surface quality of the 3003 casting blank has a large roughness,affecting the surface quality of the cold rolled product sheet is larger than that of the hot rolled billet,and the roughness of the sheet surface and the thickness of the oxide film are large,which affects the efficiency of forming the battery shell. |
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