Abstract
The influence of chill thickness and applied load were studied on wear behaviour of a carbidic austempered ductile iron containing Cu and Ni. Ductile iron with chemical composition Fe-3.6C-2.6Si-0.53Cu-0.51Ni (in wt.%) was cast into standard moulds with copper end chills of different thicknesses. Wear test samples were prepared from the chilled surface of the blocks. Austenitizing heat treatment was carried out at 870 °C followed by austempering at 270, 320, 370 and 410 °C in electrically heated salt bath furnaces for optimum times. A block-on-ring testing machine was used to carry outwear tests in dry sliding condition under applied loads of 100 and 150 N. Scanning electron microscopy was used to examine the worn surface of the samples. The results indicated an improvement in wear resistance of austempered ductile iron by introducing carbides into the matrix compared to that of non-carbidic samples. Best wear performance in carbidic austempered ductile iron was achieved for a matrix containing about 30 vol.% carbides.

Key words
carbidic austempered ductile iron, sliding wear, chill thickness, block-on-ring

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