Abstract: Liquid quenching method was used to investigate inoculation process in cast iron with flake graphite. The following results were obtained, the original form of flake graphite is globular or spheroidal, the major effect of inoculation is to reinforce the capacity of heterogeneous nucleation of graphite. By using WDX and EDAX to examine the original graphite the authors have found that there exist three types of compounds which serve as substrates for graphite nucleation, namely, MnS including its complex compounds, SiO2 and CaC2. Among them the complex sulphides are the most effective nuclei. Finally the authors have put forward the basic principles for designing reasonable composition of inoculants.

Key words: 孕育处理, 铸铁