The Validation of Feeder Modeling for Ductile Iron Castings

Abstract

A precise feeder design for a ductile iron casting is difficult, due to the complexities of its liquid–solid states transformation. During solidification , a negative pressure in castings is developed from the volumetric shrinkage as liquid iron solidified, while a positive pressure is added from the volumetric expansion as spheroidal graphite crystallized from the liquid iron. A unique crystalline structure of Austenite shell surrounds the spherical graphite and also increases the viscosity of feeding fluid flow. First principle model was applied for modeling the flow behavior of the residual liquid iron during solidification . The phenomenon of volumetric expansion as spheroidal graphite crystallized was also considered. The model was validated by real casting a cube-shaped cast. The predictions of the shrinkage area and porosities were confirmed by the hardness contours in the cross-sectional area of the castings. An optimized solidification modulus ratio of the feeder to this cube cast was suggested.