Impact toughness and fracture toughness of austempered ductile iron

The impact toughness and fracture toughness ofaustermpered ductile iron (ADI) are described. The notched and un-notched charpy impact toughness of ADI at room temperature are somewhat lower than that of steel castings or forged steel pieces, however, they are approximately three times higher than that of mormal pearlitic ductile iron. The impact toughness of ADI decreases with decreasing temperature; but at -40 ℃ it still maintains about 70% of the value at room temperature. The properties of fracture toughness are important in safety design and failure analysis. In this study all fracture toughness data of ADI are higher than that of conventional ductile iron, and are equivalent to or better than that of steel castings o forged steel pieces with the tensile strength equivalent to ADI