Effects of Molybdenum on the Wear Resistance and Corrosion Resistance of Carbidic Austempered Ductile Iron

The effects of molybdenum on the microstructure, wear resistance, and corrosion resistance of carbidic austempered ductile iron were studied. The results show that the microstructures of as-cast samples are mainly composed of nodular graphite, pearlite and carbides, and the nodularization grade is 2–3 and graphite size is 6–7 magnitude in all samples. With the increase of Mo content, the amount of nodular graphite decreases, but the pearlite and carbides increase. The microstructures of all heat-treated samples mainly consist of nodular graphite, acicular ferrite, retained austenite, and a certain number of carbides. As the molybdenum content increases, the quantity of retained austenite and carbides increases, the acicular ferrite becomes finer, and the wear resistance and corrosion resistance increased. When the concentration of molybdenum reaches 0.570 wt%, the average wear weight loss decreased to 0.218 mg/m, the corrosion potential reached to −0.5626 V, and the corrosion current density decreased to 6.361 × 10⁻⁸ A/cm².