Abstract
Manganese in liquid high manganese cast steel volatilized and mostly penetrated through the serpentine and the cracks in the olivine sand. The penetrated manganese lowered the melting point of the surface of the olivine sand, and a smooth shell (semi-fused layer) was formed at the metal-mold interface. After cooling, the shell easily peeled off from the metal and had no-burning as a result of low affinity. The same reaction was seen both in green and calcine sand, but as the green sand was dehydrated and the mold cooled, the shell of the mold was thinner than the calcine one. Calcine sand may cause neither blow hole nor pin hole, but the dehydrated gas from green sand will cause blow hole and pin hole when the mold permeability is not sufficient.
