Effects of Different Silicon Content and Flow Inoculants on Microstructure and Properties of High Silica Solution Ductile Iron

High silicon ferrite ductile iron specimens with various Si contents and different types of flow inoculants were prepared. The microstructure was analyzed using optical microscopy（OM） and scanning electron microscopy（SEM）, and the mechanical properties were tested. The results show that, the silicon content and the type of inoculant have an important impact on the microstructure and properties of high-silicon solution ductile iron. When the Si content of high silicon solid solution ductile iron increases from 4.0wt% to 4.8wt%, the matrix of the specimens are full ferrite phase. As the Si content increases, the morphology of graphite deteriorates, the tensile strength of the sample increases, while the elongation first increases and then decreases. For the sample using Bi containing flow inoculant, the graphite has small size. However, the roundness of the graphite is poor, and the ductility of the sample is low. While using the flow inoculant contain Sb, the size of graphite is small. In particular, the distribution of graphite is significantly uniform, and it owns high degree roundness. As a result, the sample shows good comprehensive mechanical properties and meets the performance requirements of QT600-10.