CONICET | Buscador de Institutos y Recursos Humanos

This work aims to evaluate the influence of part size on microstructure and properties of dual phase ADI and to compare with fully ferritic and fully ausferritic matrices. Samples taken from Y blocks of 25, 50 and 75 mm thickness, cast from an industrial ductile iron melt, were used to perform metallographic studies and mechanical tests. Differences in cooling rate, due to changes in part size, promote different characteristics of microsegregation, affecting solid state transformations at the last to freeze zones and therefore final microstructure and properties. For all the studied matrices, mechanical properties decrease when the part size increases, while yield stress does not suffer changes. The stronger effect when increasing thickness has been established for the case of fracture toughness of ADI samples. Drops of nearly 40% were reached when comparing specimens taken from the thinner Y blocks against those taken from the thicker ones. Dual phase ADI samples exhibit the less deleterious part size effect. KEY WORDS: Ductile iron, dual phase ADI, piece size, microstructures, properties