Investigation of microstructural and mechanical properties of austempered steel bar-reinforced ductile cast iron composite

In this study, the effect of reinforcing nodular cast iron with steel bar on impact toughness was investigated. The composite material was produced by the sand mould casting technique. Afterwards, austempering heat treatment was applied to the specimens at two different temperatures of 350 °C and 400 °C. The samples were evaluated by optical and scanning electron microscopies; then, hardness and Charpy impact toughness tests were conducted at ambient temperature on the cast iron specimens with or without reinforcement. The results revealed that impact toughness of the nodular cast iron increased by reinforcing with the steel bar. Furthermore, austempering heat treatment greatly influenced the impact toughness of reinforced specimens; however, the impact toughness of the austempered composite at 350 °C was more than that of the austempered specimens at 400 °C.