Influence of temperature conditions on grain refinement of pure Cu solidified with low-voltage pulsed magnetic field

The influence of temperature conditions on the grain refinement of pure Cu solidified with low-voltage pulsed magnetic field (LVPMF) was investigated. With the pouring temperature (T-p) and mould temperature (T-m) increasing, the solidified microstructure of pure Cu was gradually changed from fine equiaxed grains to coarse columnar grains and then to the mixed structure of coarse equiaxed grains and columnar grains. Little change was observed from the microstructure of pure Cu solidified with and without LVPMF for the low T-p and T-m. But for the high T-p and T-m, applying LVPFM remarkably reduced the coarse columnar grains and obtained fine equiaxed grains. The grain refinement by LVPFM is considered to be caused by the electromagnetic flow. The smaller cooling rate resulted by higher T-p and T-m offers much acting time for LVPMF and thus better grain refinement can be achieved.