MACHINABILITY OF AUSTEMPERED AND PEARLITIC DUCTILE IRONS IN DRILLING PROCESS

Many materials have their mechanical proprieties improved by heat treatments, but they can worsen machinability, as the case of austempered ductile iron (ADI) that besides of presenting better mechanical proprieties it has poorer machinability when compared with the conventional ductile iron and steel of similar strength. Being presently an important engineering material investigations about the behaving of the ADIs have been intensified. The aim of this work is to contribute further with this, comparing the machinability of three materials: pearlitic ductile iron as cast (FE70003) and two grades of austempered ductile iron having different austenitizing routes (ISO 1.050-6 and ISO 800-10). The machinability was raised in drilling process by drill wear rates. A factorial planning 2 4 was used, consisting of two quantitative variables: cutting speed (Vc) and feed rate (f) and two qualitative variables: work material and cutting fluid application technique. The results showed that the ADI grade ISO 800-10 was the material with higher machinability, followed by the FE70003 ductile iron and then by the ADI ISO 1.050-6 grade.