Background: Ductile irons provide a more viable alternative for malleable cast iron in
areas that do not demand extreme wear resistance. Austempering of ductile irons was a well researched
area in the last two decades. Attempts to further improve the wear resistance led to the
development of Carbidic austempered ductile iron (CADI), wherein the carbides contribute to wear
resistance. Combination of ausferritic matrix, graphite nodules, and carbides (eutectic and alloy)
symbolizes the microstructure of CADI.
Methods: Two principal approaches adopted by the researchers to change the microstructure are (i)
addition of carbide forming elements (ii) heat treatment (s).
Results: Both the above methods result in the refinement of graphite nodules, carbide precipitations,
along fine ausferrite.
Conclusion: Improvement in hardness, toughness and wear resistance was observed largely as a
consequence of fine carbide precipitations and formation of martensite.