Improved corrosive wear resistance of carbidic austempered ductile iron by addition of Cu.

In this work, different contents of Cu were added into carbidic austempered ductile iron (CADI) to improve the corrosion resistance and the corrosive wear resistance. Microstructures of CADI have been systematically investigated by scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), atomic force microscope (AFM). The results showed that with the addition of Cu elements, the thickness of bainitic ferrite plates and the potential difference (ΔU matix- graphite nodules and ΔU matix- carbides) were reduced significantly. The effect of Cu on the corrosion resistance and the corrosive wear resistance has been studied by an electrochemical workstation and two kinds of corrosive wear tester. In addition, worn surfaces and corroded surfaces of the samples have been examined by SEM, 3D laser scanning microscope and X-ray photoelectron spectroscopy (XPS). As the Cu content increased, the corrosion resistance of CADI under acidic condition increased. When the Cu content was 1 wt%, both corrosive wear resistance without load under alkaline condition and corrosive wear resistance with load under alkaline and acidic condition were optimal. Nevertheless, under acidic condition, the corrosive wear resistance without load of CADI with 1.5 wt% Cu was optimal. • Electrochemical potentials of CADI's microstructural components are: U graphite > U carbides > U matrix. • Cu element is mainly distributed in the retained austenite. • The corrosion resistance of CADI can be improved by adding Cu element. • Corrosive wear resistance of CADI with 1 wt% Cu is significantly better than that of Cu-free CADI. [ABSTRACT FROM AUTHOR]