Effect of copper on the properties of austempered ductile iron castings

Abstract

Two types of ductile iron has been taken for the present investigation. Both austempering time and temperature are considered as the main variables for structure property correlation of Austempered Ductile Iron. The two types of spheroidal graphite iron (differ by copper percentage) were austempered at four differing austempering temperatures viz. 250oC, 300oC, 350oC and 400oC for 60min, 90 min and 120 min respectively. The effect of austempering variables on the mechanical properties of spheroidal graphite iron was investigated as a function of austempering time and temperature. The cooling rate and the quenching techniques followed in the present study plays an important role for the property development of spheroidal graphite iron. The tensile properties have been correlated with the graphite morphology for both grades of ADI. SEM micrographs have been taken from fracture surfaces of the tensile specimen under different austempering conditions. It has been found from the result that ADI having the alloying element (copper) achieved significant mechanical properties as compared to ADI without having copper throughout the different austempering processes adopted in this study.