The effects of Se, $CaCO_3$ and CaO addition on the 1st stage graphitization of malleable cast iron

흑심가단주철의 제 1 단 흑연화에 미치는 Se, $CaCO_3$ 및 CaO첨가의 영향

The effects of Se, $CaCO_3$ and CaO addition on the first stage graphization of malleable iron were evaluated. The results obtained in this work were as follows. 1. Many gas bubbles were found in the white cast iron under Se, $CaCO_3$ addition. 2. Nodular graphite were formed by annealing of the white cast iron with remained gas bubbles. 3. When specimens were annealed, bubbles provided the nucleation sites that were needed in graphite precipitation, so the nucleation rate of graphite was increased. 4. The remained gas bubbles and defects were more effective for the graphitization than metallic compounds.