EFFECT OF ROTATING MAGNETIC FIELD ON MACROSTRUCTURE OF A CENTRIFUGAL CASTING Al-1%Cu ALLOY

Rotating electromagnetic field was applied to the centrifugal casting, and the macrostructure of centrifugal casting Al-1%Cu alloy stirred with driving or braking magnetic field was both examined. It is shown that both kinds of electromagnetic field can enforce the columnar-equiaxed transition, and the driving one decrease the tendency of porosity occurring due to the increase in the bulk liquid pressure. Stirring with braking electromagnetic field produces the mixture of outer fine grains and inner coarse grains in the casting, this is analyzed to be contributed to the differences both in electric conductivity and density between the crystal and the melt, as well as skin effects.