Effect of Plasma Electrolytic Polishing Technology on Stainless Steel Surface Composition and Cr/Fe

Plasma electrolytic polishing (PEP) is a technology with high efficiency, environmental friendly, simple manufacturing process, high quality and ability to improve corrosion resistance. Plasma electrolytic polishing improves corrosion resistance by forming oxides on the surface of workpieces and achieving passivation. In this study, the SUS 316 was polished with different plasma electrolytic polishing electrolytes. We observed the influence of electrolyte on the ratio of chromium to iron to understand the effect of plasma electrolytic polishing technology on improving the corrosion resistance of materials. After plasma electropolishing of SUS 316 using different electrolytes (voltage: 320 V; time: 180 s; temperature: 80 °C), it was found that the surface components were mainly oxides of iron and oxides of chromium. The oxide is concentrated on the surface of the workpiece with a thickness of about 3–750 nm. Plasma electrolytic polishing with different electrolytes will produce oxide layers with different thicknesses. After plasma electrolytic polishing, the stainless steel workpiece has a surface chromium-iron ratio of 1.64 (optimal condition). This study shows that plasma electrolytic polishing technology can optimize the oxide layer on the surface of stainless steel and achieve the effect of improving corrosion resistance.