Austempered ductile iron (ADI) gears: Power loss, pitting and micropitting

This work is a systematic experimental evaluation of austempered ductile iron (ADI) as a gear material. The evaluation of this ADI as a gear material concerns two main aspects: power loss and contact fatigue resistance (pitting and micropitting). All gear tests were performed on the FZG test rig. For the micropitting and power loss evaluation two gear lubricants were considered. The results show that ADI is a material to be considered by gear designers, once the energetic behavior of ADI gears is similar to carburizing gears, being although slightly worst at high input power. The pitting life is infinite for contact pressures below 1.2 GPa. The best wear behavior of ADI is attained if combined with ester biodegradable lubricant, both on power loss and micropitting tests, so the best overall behavior of ADI gears is obtained with biodegradable ester lubricant.