关键词: 蠕墨铸铁, 脉冲磁场, 凝固, 石墨生长, 蠕化率

Abstract: A pulse (commutative traveling wave) electromagnetic field was designed as an experimental setup for solidification, where the effect of pulse electromagnetic field on the graphite in cast iron in solidification process and its solidified microstructure was investigated. The results showed that in solidified grey cast iron the number of austenite dendrites reduced clearly with graphite coarsened. After nodulizing process, the number of nodular graphite decreases and the rate of vermicular graphite increases greatly. A new approach to stabilizing the rate of vermicular graphite of compacted graphite cast iron is thus proposed. The mechanism that how the electromagnetic field affects the formation of graphite is discussed. The effect of electromagnetic stirring of electromagnetic field and thermal effect of induced current can damage the stability of the austenite shell around graphite cores, thus bring about the growth of branched graphite to form vermicular graphite. The interference of pulse electromagnetic field can stabilize the rate of vermicular graphite only if the residue of Mg and Re is sufficient or nearly sufficient, otherwise, the insufficient Mg and Re as additives will cause the interference to form flake graphite.