Microstructure Evolution and Wear Resistance of Cu-Bearing Carbidic Austempered Ductile Iron after Austempering

Abstract

The influence of the austempering process on microstructure evolution, mechanical properties, wear resistance, and corrosion resistance of Cu-bearing carbidic austempered ductile iron (CADI) was investigated. The results show that with an increase in the austempering temperature, the amount of acicular ferrite decreases, the volume fraction and carbon content of retained austenite increase gradually, the hardness and tensile strength decrease, and the impact toughness and corrosion resistance increase. Wear tests show that as the austempering temperature increases, the wear resistance of Cu-bearing CADI is improved and decreases when the temperature exceeds 300 °C. Comparing to the conventional single-step austempering process, two-step austempering process (namely added pre-quenching at 260 °C) significantly improves the wear resistance of Cu-bearing CADI by more than 16% without compromising toughness.