Effect of annular electromagnetic stirring on microstructure and property of squeeze casting 7075 aluminium alloy
HU Bin1, GAO Zhi- hua2, GAO Ming- wei2, YANG Yu- jie2, WEN Xiao- fan3
1. General Research Institute for Non- Ferrous Metals，Beijing 100088，China 2. National Engineering & Technology Research Center for Non- ferrous Metal Matrix Composite，General Research Institute for Non- Ferrous Metals，Beijing 100088，China 3. Grirem Advanced Materials Co. Ltd. ，Beijing 100088，China
Abstract：The effect of conventional electromagnetic stirring(EMS)、chemically grain refining and annular electromagnetic stirring(A- EMS) on microstructure and property of 7075 aluminium alloy was investigated. The results indicate that A- EMS melt processing technology could avoid of skin effect efficiently, impose a high shear rate and a high intensity of turbulence to the liquid metal and increase the area of heat dissipation of unit volume melt by means of innovatively combining noncontact electromagnetic stirring and an annular chamber with specially designed profiles, so that the conditioned liquid metal has uniform temperature and uniform chemical composition. The microstructural refinement is achieved through an enhanced heterogeneous nucleation rate and an increased nuclei survival rate during the subsequent solidification processing. The microstructures of squeeze casting 7075 aluminium alloy conditioned by annulus electromagnetic stirring and adding Al- Ti- B chemical refiner become more fine、uniform and globular. The grain size decreases to 69 μm and the shape factor increases to 0. 62. The mechanical property is enhanced.
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2017, Vol. 24 
