The microstructure of annular parts in centrifugal casting has been observed

in which hypereutectic high chromium cast iron semi-solid slurry prepared by slope cooling body method is used. The results indicate that not only segregation phenomenon of primary carbide in the semi-solid structure but also sharp dividing line of the segregation

where the dividing line locates at the distance of about 6 mm from the radial outer face of the annular parts

can be observed. At the given experimental condition

the shrinkage porosity tendency in the structure can only be partially eliminated by centrifugal forces. The dividing line of shrinkage porosity appearance in the microstructure also locates at the distance of about 6mm from the radial outer of the annular one

that is

as the distance from the radial outer of the annular one is less than 6mm

there are no shrinkage porosities in the radial area

contrarily

there are shrinkage porosities.