Abstract
The effect of pig iron, steel scrap and ductile iron returns content in metallic charge on the nucleation potential and metallurgical quality of the base iron and ductile iron and the final microstructure and tensile properties of ductile iron is analyzed in this paper. The obtained results confirm the beneficial effect of pig iron addition on the nucleation potential of base and ductile iron producing an increase in nodule count and a decrease in chilling tendency of both base and ductile iron. The steel scrap has a price much more convenient than pig iron, but the use of high percentage of steel scrap in the charge was limited due to decrease in nucleation potential and increase of chilling tendency. Ductile iron returns also contributed to lower nucleation. Preconditioning did not completely correct the negative effect of high percentage of steel scrap in metallic charge. The results showed that the base iron must have had enough nucleation potential in order to obtain efficient inoculation. It was found that the tensile properties of ductile iron, especially the elongation, increased with the increase of the percentage of pig iron in metallic charge, due to increase of nodularity and nodule count.

Key words
ductile iron, metallic charge materials, metallurgical quality, nucleation potential, thermal analysis

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