Modification of carbidic austempered ductile iron with nano ceria for improved mechanical properties and abrasive wear resistance

Abstract

Carbidic austempered ductile iron (CADI) is a new type of ductile cast iron containing carbides, providing enhanced wear resistance, compared to conventional ADI. However, the improvement in the wear resistance due to the introduced hard carbides is generally accompanied by a decrease in the impact toughness, which limits its applications. Controlling the morphology, size and quantity of carbides is an approach to achieve the optimal combination of wear resistance and impact toughness. In this work, we modified CADI by adding nano ceria to tailor the morphology, size and quantity of carbides and investigated effects of the added nano ceria on mechanical properties and abrasion resistance of the CADI. It was demonstrated that carbides were refined by the nano ceria, which improved the toughness of the CADI in addition to raised hardness. The abrasive wear resistance of the material was correspondingly enhanced with the change in hardness, largely benefiting from the variations in the volume fraction and size of carbides. However, only a small amount of nano ceria was effective; the benefits of nano ceria diminished if excessive nano ceria was added.