EFFECT OF ANTIMONY ON THE WEAR RESISTANCE AND IMPACT TOUGHNESS OF CARBIDIC AUSTEMPERED DUCTILE IRON (CADI)

This work investigated the effect of antimony on the impact toughness and wear resistance of carbidic austempered ductile iron (CADI). Six alloys with a carbon equivalent value of 4.44 (hyper-eutectic composition) were used to evaluate the produced CADI, with antimony content ranging from 0.096 to 0.48 wt. %. The produced carbidic ductile irons (CDI) were heated to austenitic temperature of 910oC and held for 1 hour, then austempered at temperature of 325oC and held at different times (1-3 hours) to obtain carbidic austempered irons. Microstructural characterization was then carried out. The wear resistance was evaluated using a wear tester, it was noted that the wear resistance values of the CADI ranged from 2.35E8 cm-2 to 3.74E9 cm-2. The impact toughness of the CADI was determined using Charpy method, the results obtained ranged from 46.5 – 55J. It was observed that the as-cast CDI has graphite nodules, blocky carbides with a pearlitic matrix, the samples with antimony addition had granular carbides, the heat-treated samples had their matrix transformed to ausferrite while other structures remained unchanged. Sample with antimony content of 0.288 wt. % has the highest wear resistance value while sample with 0.096 wt. % has the best impact toughness value.