Abstract The cast iron is often considered to be rigid and fragile material that cracks even from a slight tap. It is true only in case when we speak about gray iron. The gray iron contains graphite in the form of flakes that are sharp incisions inside the metal provoking crack formation. The ductile iron with spheroidal graphite combines the corrosive resistance properties of the ductile iron and exceptional mechanical low carbon steel properties of strength, plasticity and impact hardness. These unique properties are the result of the adjunction of a magnesium and additional master alloys to gray iron.