Impact toughness and microstructure of continuous medium carbon steel bar-reinforced cast iron composite

Although nodular cast iron has popular characteristics, its toughness and tensile strength are insufficient in many applications. In the present research, an attempt was made to produce a nodular cast iron composite reinforced with medium carbon steel bar, in order to investigate its effects on improving the toughness of the material. The composite material was produced by the sand mould casting technique. Then, the samples were annealed at 900 °C for 1 h. Afterwards, the microstructures of the composite in as cast and annealed conditions were analyzed by optical and electron microscopes. Later on, the hardness and impact toughness of the cast iron composite specimens were compared with the samples without reinforcement. The results revealed a pearlitic diffusion bond between the two components of the composite, due to the diffusion of carbon from the cast iron towards the steel bar. Furthermore, the impact toughness of the composite material showed better results in comparison with that of the simple specimens.