Abstract: The plastic properties of different composition ductile iron bars which were prepared by continuous casting and sand casting have been investigated. The maximum reduction of unalloyed ductile iron has little difference between continuous casting bar and sand casting bar. The plastic properties of continuous casting bars in high temperature are much, better than that of sand casting bar for alloyed ductile iron. The continuous casting ductile iron bar can be changed into different shapes by free forging and can be formed in to spherical shape by die forging. The properties of die forging ball can be as high as tensile strength 1420N /mm2, elongation 8.7% and impact value 118J/em2 when it is direct austemped. The segregation of continuous casting bar is less than that of sand casting bar. The nodular graphite has changed into stripe form, and the shape of ferritic structure has also been changed along the graphite and its amount has increased

Key words: 连续铸造, 球铁, 塑性变形