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采用着色腐蚀金相显示球铁中奥氏体枝晶，借助扫描电镜观察球铁缩松区形貌，研究了过共晶球铁中奥氏体枝晶形貌特征、分类及形成条件。结果表明，过共晶球铁中奥氏体枝晶具有典型三维空间结构，可分两种类型，即初生枝晶和晕圈枝晶。过冷度是影响枝晶析出的显著性因素，铸件模数ＭＣ增加，枝晶数量减少，形态趋于不发达，由初生枝晶向晕圈枝晶过渡。
Austenitic dendrites in ductile iron were characterized by colored corrosive metallography. The morphologies of the dendrites in hypereutectic ductile iron were observed by scanning electron microscopy. The morphology, classification and formation conditions of austenite dendrites were investigated. The results show that the austenite dendrite in hypereutectic nodular iron has a typical three-dimensional structure, which can be divided into two types: primary dendrites and halo dendrites. Undercooling is a significant factor that affects the dendrite precipitation. The modulus MC of the casting increases, the amount of dendrite decreases, and the morphology tends to be underdeveloped, resulting in the transition from primary dendrite to halo dendrite.