Tensile Properties of Copper Alloyed Austempered Ductile Iron: Effect of Austempering Parameters

摘要

A ductile iron containing 0.6 percent copper as the main alloying element was austenitized at 850 deg C for 120 min and was subsequently austempered for 60 min at austempering temperatures of 270, 330, and 380 deg C. The samples were also austempered at 330 deg C for austempering times of 30-150 min. The structural parameters for the austempered alloy austenite (X_(gamma)), average carbon content (C_(gamma)), the product X_(gamma)C_(gamma), and the size of the bainitic ferrite needle (d__(alpha)) were determined using x-ray diffraction. The effect of austempering temperature and time has been studied with respect to tensile properties such as 0.2 percent proof stress, ultimate tensile strength (UTS), percentage of elongation, and quality index. These properties have been correlated with the structural parameters of the austempered ductile iron microstructure. Fracture studies have been carried out on the tensile fracture surfaces of the austempered ductile iron (ADI).