Effect of compositional changes and heat treatment on microstructure and mechanical properties of gray cast iron

Cast iron is used in machine tools to cast various components because of its wear resistance and vibration-damping ability. However, the relationship between its microstructure and damping capacity has not been studied. In this study, the effect of microstructure on the damping capacity and mechanical properties of cast iron was investigated by controlling the chemical composition and heat treatment of the prepared specimens. The results show that in conventional gray cast iron specimens, the damping capacity is related to the graphite type, content, and size, and increases with the increase of carbon content; the damping ratio of the specimens also increases after heat treatment. The damping capacity of white cast iron, however, is better than that of some conventional gray cast iron specimens. Therefore, the damping capacity of cast iron is related to graphite to a certain extent, but there also exists a relationship with the content of each physical phase. The more the phase interfaces are, the more significant the interfacial slip and friction are and the higher the damping ratio is.