부산대학교 도서관

In heavy-walled pearlitic spheroidal graphite iron castings, ferrite precipitates along the prior austenite grain boundaries. Using specimens with a modulus of 1.25 to 5 cm, we investigated the cooling curve, microstructure, and element segregation and clarified the causes. The results revealed that the most influential cause was not alloy elements such as Mn and Cu, but the long solidification cooling time in the mold. When the modulus exceeds 3 cm, network ferrite precipitated, along the prior austenite grain boundaries in a network manner. Since this network morphology and distribution may affect the mechanical properties, it is necessary to avoid the precipitation of network ferrite to ensure the required mechanical properties of castings.