Influence of inoculation on shrinkage defects in spheroidal graphite cast iron

Defective castings produce unnecessary costs for foundries. Common flaws in spheroidal graphite cast iron castings are shrinkage defects. The literature on the subject suggests that by controlling the precipitation of graphite, it is possible to suppress the shrinkage propensity of the melt. The most influential way of affecting the precipitation of graphite is inoculation. In this work, the effectiveness of different commercial inoculant products and inoculation methods in reducing the shrinkage defects for cast components were researched. Significant differences in performance were observed between ladle inoculation and stream inoculation methods in preference of stream inoculation. Differences were also observed for different inoculants and, when both ladle and stream inoculants were used, also for their behaviour as a combination. It was observed that not all of the combinations were beneficial. In order to decrease the cost caused by shrinkage defects, a proper selection of inoculation method and inoculant is of importance.