Abstract
Stripe pattern observed in the rapidly cooled cast iron treated with CV graphitizer was investigated. Castings were obtained using several metallic molds or metal-dry sand composite molds. The change of graphite form in the cast iron structure was related to thermal analysis and observation of the top surface of the castings. Namely the resulting CV graphite structure or spheroidized graphite strucutre was related to undercooling of eutectic temperature and the occurrence of shrinkage cavity. Characteristic periodic macrostructure, i.e. stripe pattern, was observed on the longitudinal section of the casting 30mm in thickness treated with CV graphitizer. A layer of CV or spheroidal graphite in pearlite or cementite and that with fine interdendritic graphite in ferrite appeared alternately. The periodic structure was suspected to form by an interaction between cooling effect of the mold and spheroidizing effect of the additive.
