Study on Effect of Austempering Temperature and Time on the Corrosion Resistance of Carbidic Austempered Ductile iron (CADI) Material.

Corrosion Resistance of ductile cast iron is improved by the incorporation of an extra phase in the matrix, typically consist of carbides. The objective of the present work is to produce carbides in a ductile cast iron which is subsequently austempered, to obtain the carbidic austempered ductile iron (CADI). Six variants of CADI were produced by heating carbidic ductile iron (CDI) to a austenitization temperature of 975ºC for the period of 1hr and quenching in salt bath at temperature 325ºC and at 250ºC for a period of 1hr, 2hr and 3hr.The Corrosion Resistance was evaluated by using Salt Spray Fog test in accordance with ISO 9227 standard. Heat treatments affect the mechanical properties such as Bulk hardness and microhardness also the microstructure of the carbidic austempered ductile iron which can be characterized by optical microscope and SEM.