The effect of low frequency-electromagnetic field on temperature field and microstructure during magnesium slab casting process

Abstract

The effect of low-frequency electromagnetic field (LFEF) on temperature pattern and microstructure on both symmetry planes was investigated during the semi-continuous direct chilling (DC) casting process of magnesium slab. The distribution characteristics of magnetic flux density (B) and time average electromagnetic volume force density (F) were calculated. The weak value of F was found near the slab corner, which was clearly distinguished from the distribution of B. According to the temperature measurement results, LFEF made the mushy region much flatter than that of conventional DC casting and it was much more obvious in the thickness direction. Compared with conventional DC casting, the low-frequency electromagnetic casting (LFEC) process could decrease the average temperature gradient between the centre and border in the mushy zone. The microstructures on both symmetry planes were also refined at different levels during the LFEC process.