Study of Austempered Ductile Iron (ADI) on Varying Austempering Temperatures

Austempered ductile iron (ADI) proven itself as a significant manufacturing material due to its remarkable properties like withstanding high fatigue behavior, fracture toughness, wear resistance, ductility, etc. This paper reports the experimental results obtained on subjecting ADI specimens to thermal treatment, i.e., austempering and austenitization. All austempered ductile iron ADI specimens are subjected to mechanical and metallurgical testing. Within the given range of varying austempering temperatures, tensile strength and metallurgical changes were analyzed. The tensile studies show that as the austenitization temperatures increased from 900 °C, strength values increased, but a reverse trend was observed at temperatures higher than 1100 °C. With increasing the austenitization temperatures, the carbon percentage was observed to increase, leading to decrease in elongation, and an increase in the hardness. For metallurgical analysis, SEM factographs were employed to test the heat-treated ADI specimen. The microstructure images show that high austenitization temperatures give coarse properties to the ADI. At austempering temperature 420 °C, it shows the rise of retained austenite from 35 to 46% of volume.