Experimental Investigation of Electropolishing Process Parameters on the Surface Gloss and Corrosion Resistance of AISI 304 Stainless Steel

Electropolishing (EP) is a commonly used surface finishing technique, particularly known for enhancing the corrosion resistance of treated workpieces. In this study, the effects of EP processing parameters on the surface gloss and corrosion resistance of AISI 304 stainless steel were systematically investigated by examining the influence of applied current densities ranging from 1.5 to 10 A/dm2 and electrolyte operating temperatures between 30°C and 50°C. A Taguchi L9 orthogonal array, along with signal-to-noise ratio analysis, analysis of variance, and second-order regression modeling, was utilized to evaluate and optimize the individual and combined effects of these two control factors. AISI 304 stainless steel was employed as both the anode and cathode in the EP process. The electrolyte consisted of phosphoric acid, sulfuric acid, and deionized water. This study involved treating AISI 304 stainless steel specimens with a standardized process. The treatments included degreasing for 10 min at 25°C, pickling for 15 min at the same temperature, and EP under varying current densities and electrolyte temperatures for 15 min. Afterward, chemical passivation was conducted for 30 min at 25°C. The effects of current density and temperature on surface gloss and corrosion resistance were evaluated. Finally, the specimens were tested for corrosion performance by exposing them to neutral salt spray for 1,000 h. The results indicate that the EP process significantly enhances the corrosion resistance and surface gloss of AISI 304 stainless steel. Unlike most previous studies, which primarily focus on short-term electrochemical characterization, this study provides a systematic experimental assessment of the effect of EP current density on the long-term corrosion performance of AISI 304 stainless steel under standardized ASTM B117, Standard Practice for Operating Salt Spray (Fog) Apparatus, neutral salt spray conditions.