Fundamental wear mechanisms when machining Austempered Ductile Iron (ADI)

Austempered Ductile Iron (ADI) is characterised by improved mechanical properties but low machinability compared to conventional ductile iron materials and steels of similar strengths. The mechanical properties of ADI are achieved by a very fine austenitic-ferritic microstructure. However this unusual microstructure significantly affects mechanical and thermal machining properties. A keen understanding for the interactions of microstructure, chip formation, machining properties, cutting material and wear mechanisms is essential for the optimisation of the cutting process. This paper describes material and machining investigations as well as cutting simulations to reveal the wear mechanisms being responsible for the low machinability of ADI.