Wear Behavior of an Austempered Ductile Iron Containing Mo-Ni-Cu

The aim of the this investigation is to study the influence of Ni on tribiological behavior of an austempered ductile iron (ADI) containing Mo, Ni and Cu. Ductile irons with chemical composition Fe-3.56%C– 2.67%Si –0.25%Mo–0.5%Cu and Ni contents of 0.8 and 1.5% were cast into standard Y-blocks. Wear test samples were machined off from the bottom section of blocks. Austenitizing heat treatment was carried out at 870°C temperature followed by austempering at 270, 320, and 370°C for 5-1140 minutes. The wear test was carried out by using block-on-ring test machine. Sliding dry wear behavior was studied under applied loads of 50, 100 and 150N. The results show that wear resistance is independent of austempering temperature with an applied load of 50N, but there is a strong dependence at higher austempering temperatures with applied loads of 100 and 150N. Wear mechanism is described as being due to subsurface fatigue, with cracks nucleated at plastically, deformed graphite interfaces. The wear controlling mechanism is the crack growth when wear shows a dependence on applied load and austempering temperature.