Although nodular cast iron has popular characteristics, its toughness and tensile strength are insufficient in many applications. In the present research, it was tried to produce a nodular cast iron composite reinforced with medium carbon steel bar, in order to investigate its influence on the improvement of toughness of this material. The composite material was produced by sand mould casting technique. Then, the samples were annealed at 900℃ for 1 hour. Afterwards, the microstructures of the composite in as cast and annealed conditions was analyzed by optical and electron microscopes. Later on, the hardness and impact toughness of the cast iron specimens with reinforcement were compared with the samples without reinforcement. The results revealed a pearlitic diffusion bond between the cast iron and the steel bar in the composite with higher hardness, due to the diffusion of carbon atoms from cast iron to steel fiber. Furthermore, the impact toughness of the composite material showed better results in comparison with the simple specimens.

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