Analysis of Fatigue behaviour and Impact strength of IS 500/7 Grade Ductile Iron Subjected to Austempering Heat treatment

ABSTRACT Austempered Ductile Iron (ADI) is replacing steel and it is finding applications in agriculture, mining, construction and automotive sector due to its superior mechanical properties and cost-effectiveness in manufacturing. In this study IS500/7 grade ductile iron castings were made subjected to austempering heat treatment to get ADI i.e., to bring about changes in microstructure and hence therefore mechanical properties. Austempering heat treatment involves austenisation at 9000C temperature for 2 hours duration, austempering temperatures selected was 3600C and 4300C and austempering duration selected were 50,100,150,200 and 250 minutes.Fatigue behaviour and impact strength of the ADI specimens were analysed and compared with as cast condition specimen. The results of the investigation indicate that the ADI castings possess better impact strength compared to as cast specimens and fatigue strength decreases with increase in austempering temperature.