Study of wear behaviour of austempered ductile iron

An investigation was carried out to examine the influence of austempering temperature on microstructural parameters and the wear behaviour of austempered ductile iron. Ductile iron was austenitised at 900 A degrees C for 30 min and austempered for 2 h at 260, 280, 300, 320, 350, 380 and 400 A degrees C. Resulting microstructures were characterised through optical microscopy and X-ray diffraction. Wear test was carried out using a pin-on-disc machine with sliding speed of 289 m min(-1). Coarse ausferrite microstructure exhibited higher wear rate than fine ausferrite microstructure. At high austempering temperature large amounts of austenite was instrumental in improving the wear resistance through formation of deformation induced martensite. Study of the wear surface under scanning electron microscope showed that, under dry sliding condition, wear occurred mainly due to adhesion and delamination. Wear rate was found to be dependent on the yield strength, austenite content and its carbon content.