An Investigation into the Corrosion Rates of Inconel 600™ in Different Corrosive Solutions

Abstract

Inconel 600™, an austenitic high nickel alloy, has relatively low corrosion properties and is used extensively for aerospace and nuclear engineering applications. Other applications include exposure of the material to caustic and acidic environments and possible use in prosthetic implants. Electrochemical techniques, which include potentiodynamic polarization and polarization resistance, provide a means to rapidly determine the corrosion rates and the suitability of the alloy in a specific corrosive environment. The results from these two techniques were used to determine the corrosion rates as well as other thermodynamic properties for the alloy exposed to various strong and weak acids, salt and Ringer's solution. The results showed slight differences in the corrosion rates determined by the two electrochemical techniques, with those from the polarization resistance technique being on average larger. The corrosion activation energies determined for the alloy in different solutions were indicative of the corrosion rates with some anomalies in values for results observed in the 10 % acetic acid solution. The microstructural composition of the alloy was also investigated by SEM-EDS and showed peculiar inclusions that can contribute to an acceleration of the corrosion rates.