2007 Volume 47 Issue 4 Pages 612-618
Effect of melt flow on the solidified structure of middle carbon steel was examined by a levitation method using alternating and static magnetic fields. In this study, solidification in the lower undercooling region (less than 70 K) was studied. As the static magnetic field increased, the melt flow in the levitated melt was continuously reduced. Portion of the equiaxed structure in the solidified structure also decreased with decreasing the melt flow velocity. The equiaxed structure was not observed when a static magnetic field exceeding 0.8 T was imposed during solidification. Average of the relative velocity, which was defined from motion between the inclusions for representing the melt flow velocity, was reduced to be approximately 0.01 m/s at a magnetic field of 0.8 T. The present results showed that fragmentation of the dendrite arms could be suppressed when the flow velocity in the melt was reduced to be in the order of 10−3 m/s.
