The Research Of Electric Current Pulse On Microstructure And Properties Of Twin Roll Casting Aluminum Alloy

Twin Roll Casting is a kind of process, which can produce directly coiling of aluminum strip when liquid aluminum put into gap between the two rotating rollers. The rollers are as for crystallizers directly while solidification while rolling because of cooling water Internal. Twin roll casting is an economical process for the sheet production because of its simple process, low investment, short working procedure and energy saving. However, there are no reports on Al-Mg alloys produced by Cast-rolling precently. Mainly there are many defects, for example ganizational differences, composition segregation, many cracked edges by cast-rolling because of crystallization non-uniform. Therefore controlling homogeneity of liquid aluminum in cast-rolling area become the technical difficulties for developmenting Al-Mg alloys cast-rolling process.And it is expected to caving new kinds of ways with new technology and process for expanding cast-rolling alloy species.Process of the twin roll casting of 5182 alloy was studied in this paper, the control test with and without imposing electric current pulse to casting roller in cast-rolling. In virtue of optical microscopy,EMPA, we observed and analyzed the microstructures of samples with different electric current pulse and without electric current pulse treatment,including the morphology of the matrix,the distribution. Accordingly, the mechanical properties of the specimen prepared previously were tested.The results indicate that the microstructure of alloy is refined and uniformizaed apparently with suitable pulse current strength.The phenomenon of composition segregation is reduced obviously, but it is not disappeared altogether. Finally, we derived the best process parameter for electric current pulse on Al-Mg alloys from the testing of the tensile strength, elongation and microhardness of alloys prepared. According to that electric current pulse can broken branches crystal and Improve subcooling accelerate the nucleation, we explain the reasons of microstructure and mechanical properties of alloy are improved.The phenomenon of composition segregation is analysed, and set up different homogeneous treatment process. The results indicate that composition segregation is diffusion dissolve and mechanical property obviously improved with 500℃×4h.