Electrochemical surface modification of GH4742 nickel-based superalloy in C6H5Na3O7 solution

Abstract

GH4742 nickel-based wrought superalloy is an ideal material for aerospace field. Nevertheless, the poor machinability of it poses significant challenges during machining operations, such as severe tool wear and poor machined surface integrity. Here, we demonstrate an electrochemical surface modification strategy that utilizes the complexation of Cit3− to remove the Cr-rich γ matrix to form an easily removable modified layer on the surface of GH4742 to enhance machinability. Microstructural observations, surface hardness and hydrophilicity analysis revealed that the surface modification of GH4742 in C6H5Na3O7 solution at low current was effective. The modification process resulted in the formation of a loose and porous modified layer with a flat surface and uniform thickness. The hardness of the modified layer was notably reduced, and a superhydrophilic surface was generated. In addition, we proposed a simple and convenient method to measure the thickness of the modified layer and investigated the effects of current and time on the thickness of the modified layer to control it. Our results demonstrate the efficacy of the electrochemical surface modification method in enhancing the machinability of GH4742.