PRESSURE MOLD FILLING OF SEMI-SOLID DUCTILE CAST IRON

The processing of metals in the semi-solid state is becoming an innovative technology for the production of globular structure and high quality cast parts. Ductile irons because of spherical graphite have specific properties such as good mechanical properties, strength and toughness together and suitable castability. This engineering alloy along with growing application has several shortcoming which have limited its applications such as non-formability, dendritic structure and alloying element segregation, micro-porosity resulted from solidification mode and fabrication of thin section pails. It seems that replacing dendritic structure with globular structure and thixoforming results in improving of mechanical properties, controlling of alloying element segregation, decreasing of micro-porosity and increasing of ability to thin section filling. This paper reports successful high pressure, semi-solid mold filling of ductile iron containing Mn and Mo. Filling properties, fluidity, liquid segregation and defects like shrinkage and cracks are characterized.