摘要
AZ31 alloy billets of 200 mm in diameter were produced by three different processes of conventional direct chill （DC） casting, low-frequency electromagnetic casting （LFEC） and low-frequency electromagnetic vibration casting （LFEVC）, respectively. The effect of LFEC and LFEVC on the microstructures, macmsegregation and mechanical properties of AZ31 alloy billets was investigated. In conventional DC casting, the AZ31 alloy billets exhibited coarse grains （about 370 μa） and severe segregation of A1 and Zn. In the presence of a solo low-frequency alternating magnetic field or a low-frequency electromagnetic vibration field applied during DC casting of Ф200 mm AZ31 billets, grains in the AZ31 alloy billets were effectively reffmed （about 210 μa） and the macrosegregation of A1 and Zn in the billets was greatly decreased. Furthermore, the tensile strength, fracture elongation and hardness of the as-cast AZ31 alloy billets were improved by the processes of LFEC and LFEVC relative to that cast by the process of conventional DC casting.
AZ31 alloy billets of 200 mm in diameter were produced by three different processes of conventional direct chill （DC） casting, low-frequency electromagnetic casting （LFEC） and low-frequency electromagnetic vibration casting （LFEVC）, respectively. The effect of LFEC and LFEVC on the microstructures, macmsegregation and mechanical properties of AZ31 alloy billets was investigated. In conventional DC casting, the AZ31 alloy billets exhibited coarse grains （about 370 μa） and severe segregation of A1 and Zn. In the presence of a solo low-frequency alternating magnetic field or a low-frequency electromagnetic vibration field applied during DC casting of Ф200 mm AZ31 billets, grains in the AZ31 alloy billets were effectively reffmed （about 210 μa） and the macrosegregation of A1 and Zn in the billets was greatly decreased. Furthermore, the tensile strength, fracture elongation and hardness of the as-cast AZ31 alloy billets were improved by the processes of LFEC and LFEVC relative to that cast by the process of conventional DC casting.
基金
supported by the Major State Basic Research Development Program of China (Nos. 2007CB613701 and 2007CB613702)
the National Natural Science Foundation of China (Nos. 50904018, 51004032 and 50974037)
the Program for New Century Excellent Talents in Chinese Universities (No. NCET-08-0098)
the Fundamental Research Funds for the Central Universities of China (Nos. N090409002 and N090209002)
the China Postdoctoral Science Foundation (No. 20100471468)
