The aim of the present investigation was to study the effect of austempering temperature and soaking periods on the impact strength of ductile iron samples poured in permanent moulds. ADI is an exciting alloy of iron which offers the design engineers the best combination of high strength-to weight ratio, low cost design flexibility, good toughness, along with fatigue strength. A part of the samples were annealed and the whole lot is then austempered at different temperatures and the above mentioned properties of these samples were investigated. The samples of ductile iron were austempered by single step Austempering process at temperatures 3000C, 3500C, 4000C and 4500C for 30, 60 and 120 minutes. Then respective tests were carried out and thus above mentioned properties were found out. From the results obtained we were able to conclude that the hardness of the material was maximum when austempered at 3000C for a time period of 120 Minutes The surface hardness of the material reduced with increase in Austempering Temperature. The surface hardness of the material increased with increase in Austempering duration. The Microstructure of the samples was studied for different austempering temperatures and soaking times durations , showed graphite nodules of size varying from 6 to 7 with distribution of nodules/mm' varying from 75 to 250 depending on the Austempering Temperature and time duration
