The paper presents the microstructure and selected properties of ausferritic nodular cast iron annealed at the temperature 520 and 550°C.

This choice was dictated by the temperatures used in the practice of nitriding. Nodular graphite in cast iron was obtained with use of

Inmold process. Cast iron containing molybdenum and copper ensuring obtaining an ausferrite in the cast iron matrix without the use of

heat treatment of castings was tested. The effect of annealing temperature on the microstructure and the kind of fracture of the ausferritic

nodular cast iron was presented. The effect of an annealing temperature on hardness, impact strength and the microhardness of ausferritic

nodular cast iron matrix was shown too. The lamellar structure of phases in the cast iron matrix after annealing has been ascertained. There

has been an increase in hardness of an annealed cast iron and microhardness of its matrix. The reduction in the impact strength of the cast

iron annealed at 520 and 550°C was approximately 10-30%. Both an increase in the hardness of cast iron as well as an decrease in its

impact strength is probably due to the separation of secondary carbides during the heat treatment.