Effect of Inoculant on Microstructure and Annealing Process of As-cast Malleable Cast Iron

The study has been made of the inoculation mechanism and the graphitizing annealing process of as-cast malleable cast iron,of which results indicated that as the microelements-Bi,Sb,B added,the nucleating rate of graphite in solidification process increased;the formation of pearlite promoted and the decomposition of eutectoid cementite in the graphitizing annealing process accelerated. As selecting suitably compositions in melted iron;adopting the inoculation treatment with Bi,Sb and the compound inoculation treatment with Sb-B and Sb-B-RE.the as-cast malleable cast iron was obtained,of which the pearlite is as matrix basically,especially the graphite slices was finer in the latter process.the as-cast malleable cast iron with the ferrite as matrix was obtained after the graphitizing annealing 4 hours at 740 ℃ on the compound inoculated as-cast malleable cast iron.as a little ledeburite in the cast structure existed,it was heated to eliminate the cementite 1 hour at 770 ℃,following the graphitizing annealing 3 hours at 740 ℃.