Effects of Austempering Time and Temperature on the Wear Resistance of Carbidic Austempered Ductile Irons (CADI)

The effects of austempering time and temperature on the wear resistance of carbidic austempered ductile iron (CADI) were studied in the present work using a pin-on-disk wear test machine. Results showed that matrix micro structure contains upper and lower bainites associated with a lower amount of carbide and martensite in terms of austempering time and temperature. Based on XRD analysis, retained austenite volume fraction increased with austempering temperature upto 375ºC, and the high carbon austenite volume fraction also increased with austempering time upto 60 min. The carbide formed using the metallic chillers during casting process were finely distributed within the matrix upon austenitazing process. If was shown that the wear resistance decreased when increasing austempering temperature. If was also found that the wear resistance increased with decreasing austempering time (upto 2min) at the low applied load of 85N, while at the higher applied load the increase wear resistance was resulted from applying a longer austempering time.