Effect of carbides on the electrochemical dissolution behavior of solid-solution strengthened cobalt-based superalloy Haynes 188 in NaNO3 solution

Abstract

The electrochemical dissolution behavior of cobalt-based superalloy Haynes 188 was observed by an in-situ observation device. The results showed that at low current density, a dense oxide film was formed on the carbide surface to protect its dissolution. But at high current density, carbide dissolved and produced CO bubbles until falling off. The dissolution of carbide at high current density resulted in the reduction of the high ten-point mean roughness (Rz) and the improvement of surface quality. A dissolution model under different current densities was established to reveal the mechanism of influence of carbide on surface quality under different current densities.