Estimation of cooling rates in suction casting and copper-mould casting processes

Abstract

The cooling rates associated with suction and copper-mould casting of φ2, φ3 and φ5 mm rods made in Fe-25wt%Ni and Al-33wt%Cu alloys were determined based on their cellular and lamellar spacings, respectively. The work showed that the temperature profile in cylindrical samples can not be determined merely by microstructural examination of eutectic sample alloys. A concave solidification front, as a result of eutectic transformation, caused decrease of a lamellar spacing while approaching to the rod centre. The minimum axial cooling rates, estimated based on the cellular spacing in the Fe-25wt%Ni alloy, were evaluated to be about 200 K/s for both φ2 and φ3 mm and only 30 K/s for the φ5 mm suction cast rods. The corresponding values were slightly lower for the copper-mould cast rods.