Wear and corrosion resistant Mn-doped austenitic cast iron prepared by powder metallurgy method

摘要

Wear and corrosion resistant austenitic cast irons were prepared by powder metallurgy (P/M). In this system, equivalent Mn were doped to replace nickel with a constantNieq(the Ni equivalent number) to reduce the cost. Conventional high nickel cast iron was employed as a reference in this study. The hardness, dry sliding wear behavior and corrosion behavior of conventional and P/M cast iron were investigated under the same conditions. The result demonstrates that a little difference in hardness is found between Mn0-C (Mn-0wt% prepared by cast) and Mn0-PM (Mn-0wt% prepared by P/M). However, the wear resistance of Mn0-PM is better than Mn0-C due to the evenly distributed lubricating graphite. The wear resistance of P/M cast iron increases with the increase of Mn content which is attributed to the increased hardness. The corrosion behaviors for all the materials tested by using potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) are almost the same, largely due to the formation of austenite matrix. Thereinto, Mn5-PM holds the best corrosion behavior with the lowest corrosion current density and highest polarization resistance. Because the potential difference between matrix and carbide is lower than that between matrix and graphite. The decreased graphite with the increased carbide induces a strong corrosion resistance in Mn5-PM.