Counter-gravity casting of thin wall ductile iron.

The purpose of the first series of experiments was to investigate the castability of thin wall ductile iron using the counter-gravity method. The castability in 1,2,3 and 4 mm. experimental sections was compared to that of traditional gravity casting. This study also included two time periods in an effort to observe possible changes in castability during magnesium and inoculation fade. It was concluded that counter-gravitational castability increased over gravity casting. The gravity process exhibited only minimal or no filling of the 1 mm plates; the only noticeable fil for the 1 mm plates, utilizing the static gravity process, was in the lowest level of the mold. Castability in both casting methods decreased with holding time, but the casting yield in the counter-gravity casting process was found to be greater. The second part of this study involved the investigation of different inoculants for counter-gravity of ductile iron and their effect on the magnesium fading rate and chill reduction tendency during isothermal holding. Experimental inoculant A, a foundry grade ferrosilicon 75% alloy, was chosen as the control group. Experimental inoculant B contained a moderate level of barium, while inoculant C contained high levels of calcium and barium. Results obtained from the experiments regarding any beneficial effect on magnesium fade, showed that there were no substantial differences among the three experimental inoculants. It was evident that the experimental inoculants B and C held the nodule count better during the first 15 minutes after magnesium and inoculation treatment and demonstrated more impact on chill reduction tendency.