Abstract
Nodular cast iron was cast into metal mold to study occurrence of defects similar to seams, while varying casting conditions such as chemical compositions of molten metal, pouring temperature, gating systems and coating materials. Detailed investigation was made on the relation between the seams and the dilatation by graphitization at the eutectic solidification which has so far been believed to be the cause of seams. As a result, however, no apparent relation was observed. In an experiment on seams using bismath, it was found that the occurrence of seams decreased when rouge was used as a mold coating material. Therefore, it was suggested that the viscosity of molten metal and the interfacial tension between molten metal and mold were closely related with the seam formation.
