Effect of Ethylene Glycol and Electrochemical Characteristics on the Electropolishing of Austenitic Stainless Steel

Inorganic electrolytes are commonly used in commercial electropolishing. However, interest in eco-friendly electrolytes is on the rise. This investigation presented how electropolishing with choline chloride, an eco-friendly electrolyte, affects the molar ratio of ethylene glycol and applied potential. Electrochemical experiments were conducted in natural seawater on stainless steel electropolished under ideal conditions. The passive current density increased as the ethylene glycol molar ratio rose (1:1, 1:2, 1:3) in choline chloride. However, the plateau of the passive current density was most clearly observable in a solution composed of choline chloride and ethylene glycol at a 1:2 molar ratio. Electropolishing under optimal conditions reduced the surface roughness and height by 67.3% and 90.5%, respectively, compared to mechanical polishing. The corrosion current density of the mechanically polished and electropolished stainless steel was calculated as 0.35 ㎂/cm2 and 0.01 ㎂/cm2, respectively, and the pitting potential was 286.08 mV and 410.11 mV, respectively.