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The effect of time and austempering
temperature on the mechanical properties and microstructure of austempered ductile iron (AD I)
has been investigated. Impact specimens were prepared from 0.5 % Wt Mn ductile iron and austempered at 275, 315 and 3500 C over different periods of 1 to 240 minutes. In the next step,
specimens with optimal mechanical properties were tempered at 350 and 5000 C over different periods. The developed microstructure was studied by optical and electron microscopes.
The results show that the optical impact energy was achieved by austempering at 3500 C for 90 minutes, and the increase of nodule count
increases the impact energy. In addition, the results show that tempering at 350 and 500 0 C
decreases the impact energy while tempering at a higher temperature causes more reduction of the
impact energy.