Machinability study of manganese alloyed austempered ductile iron

Austempered ductile iron (ADI) is a heat-treated ductile cast iron with ausferrite microstructure. ADI has high strength and hardness with good ductility and toughness. However, because of the high strength and hardness of ADI, there is a concern regarding its machinability. In the present study, machinability of ADI is assessed using tool life and the surface roughness. Machining tests are conducted using Taguchi experimental design. The effects of machining parameters, heat treatment parameters, on manganese alloyed ADI in the dry turning operation are studied and it was found that austempering temperature and cutting speed have the major contributions on tool life, whereas feed rate has the major contribution on surface roughness of the material within the range of values under study. Metallographic study has revealed coarser structure at higher austempering temperature of 420° which resulted in better tool life. 0.64 wt% of manganese in the ADI has resulted in lower surface roughness value.