Effect of nodule count and cooling rate on as-cast matrix of a Cu-Mo spheroidal graphite

The transformation of austenite to ferrite and graphite or to pearlite in s pheroidal graphite cast iron depends on a number of factors, among which ar e the nodule count and the cooling rate. In this study, the pearlite fracti on decreased as the nodule count increased for a given cooling rate. Furthe rmore, as the cooling rate increased, the fraction of pearlite increased. B oth effects were more sensitive at low nodule count. The effects of alterin g these parameters on the relative amount of pearlite and ferrite in the ma trix of a copper-molybdenum (Cu-Mo) spheroidal graphite cast iron were addr essed using heats carried out in an induction furnace, and the melts were t reated with magnesium ferrosilicon in a ladle. To vary the nodule count, th e melts were inoculated with two different amounts of ferrosilicon. Pouring was performed into sand molds of cylindrical cavities with different secti on size in order to achieve various cooling rates. Both the nodule count an d the cooling rate affected the relative amount of ferrite and pearlite in the matrix.