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D型石墨又称“枝晶石墨”或“过冷石墨”。其石墨呈点状或小片状,在奥氏体枝品中呈无方向性分布。这类石墨在碳硅当量较低,过冷度较大的亚共晶铁水中易于出现,往往被认为是降低机械性能的石墨类型。 1972年[1]曾用碳当量为4.1,4.3,4.5和4.6％的铁水在砂型和金属型中分别浇注φ30毫米的圆棒试样,各得到A型石墨和D型石墨(加入0.45％Ti)。证明:金属型和砂型中获得的D型石墨铸铁试棒,其机械性能都优于砂型中A型石墨的铸铁试棒。特别是近年来美
D-type graphite, also known as “dendritic graphite” or “too cold graphite.” The graphite was point or small pieces, in austenitic branches were non-directional distribution. Such graphite is prone to occur in hypo-eutectic hot metal with low carbon-silicon equivalent and large degree of undercooling, and is often considered as a type of graphite that reduces mechanical properties. In 1972, [1] castings of φ30 mm round rods were respectively cast into hot metal with carbon equivalent of 4.1, 4.3, 4.5 and 4.6% to obtain type A graphite and type D graphite (0.45% Ti ). It is proved that the D-type graphite cast iron test bars obtained from the metal type and the sand type have better mechanical properties than the A type graphite cast iron test bars in the sand type. Especially in recent years the United States