| In recent years,with the iterative upgrading of automobile industry,the new energy vehicle has become the key development direction of automobile industry,and lightweight technology is one of the important ways to realize the weight loss of new energy vehicle,technology upgrading is imminent.At present,aluminum alloy is the most widely used lightweight material in the automotive materials of new energy vehicles.However,there are still many technical problems in the application of aluminum alloy in new energy vehicles,such as high processing difficulty and poor welding performance.Therefore,it is particularly critical to explore new forming technology to improve the forming performance of aluminum alloy.In this paper,5052 aluminum alloy sheet is taken as the research object,and the warm bulging deformation law of aluminum alloy sheet under the combined action of magnetic pulse impact and elastic particle medium is explored,which provides a theoretical basis for improving the application of aluminum alloy material in new energy vehicles.The effects of different forming processes on the formability of 5052 aluminum alloy sheets were studied by quasi-static rigid spherical punch and elastic particle medium bulging test.The results show that the major principal strain on fracture section of quasi-static rigid spherical punch is only 9.51%,while the major principal strain of elastic particle medium is 19.95%,and the major principal strain is increased by 109%.The height of the quasi-static rigid spherical punch bulging "failure" specimen is only 14.39 mm,the location of the third measuring point is broken,the wall thickness is only 0.766 mm,and the stress concentration is obvious,while the height of the quasi-static elastic particle medium bulging "failure" specimen is 17.43 mm,and the contour is uniform.With the increase of temperature,the ratio of height to diameter of the specimen after bulging also increased significantly,and the forming property of the sheet was improved.In this paper,the effect of magnetic pulse and elastic medium on the warm expansion of aluminum alloy sheet was studied.The results show that with the increase of discharge energy,the bulging height and strain value of aluminum alloy sheet increase obviously.At the temperature of 200 ℃,the temperature softening effect is obvious,and the bulging height and the major strain of the sheet are obviously improved;In discharge energy of 7.0 kJ,temperature 150 ℃ primary and secondary aluminum sheets bulging specimen major principal strain were 8.98%,25.59%,200 ℃,the major principal strain were 24.19%,27.16%,The major strain of the secondary impact bulging at 150 ℃ exceeds that of the primary impact at 200 ℃.The results show that the effect of secondary bulging is remarkable,and the plastic deformation ability of aluminum alloy sheet can be improved by multiple impact at low temperature.Based on the bulging test of 5052 aluminum alloy sheet under different forming modes,the microstructure evolution of aluminum alloy sheet under different experimental parameters was analyzed by means of optical microscope and scanning electron microscope.Research has shown that magnetic pulse under repeated impact,150 ℃ when magnetic pulse a shock in a small amount of fine grain,metallographic found tiny grain increased significantly after the second impact,get a degree of grain size,shape of aluminum alloy sheet deformation was promoted,the plastic deformation of aluminum alloy sheet is improved.The microstructure of the fracture under the two forming modes,the fracture band of the secondary bulging specimen of elastic particle medium driven by magnetic pulse is narrow and has good extensibility.The number of dimples increases obviously and the dimples are enlarged and deepened,and the plastic deformation capacity is significantly improved. |
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