Microstructural Behaviour of Austempered Ductile Iron Automobile Components

Austempered Ductile Iron (ADI) has emerged in the recent years as a technologically important engineering material. Heat treatment of ductile iron in a salt bath at a temperature range between 250 and 450°C produces ADI. The advantages of ADI are excellent strength, fracture toughness and wear resistance that suit the service conditions of automobile components. It is further considered as an economic substitute for forged steels in certain automobile components. In this present investigation, spheroidal graphite iron, with as-cast ferritic microstructure was cast into automobile components of two different thicknesses. The components were initially austenized and suitably austempered. The effect of austempering heat treatment on the microstructure and mechanical properties were analyzed. The study demonstrates a significant improvement in the ferrite volume fraction and mechanical properties in thinner components.