Low current density electropolishing and corrosion resistance study of 304 stainless steel

Abstract

In response to the challenge posed by electrical breakdown occurrences during the conventional current density electrolytic polishing of large-scale stainless steel workpieces, this investigation delved into the parameters of low current density electrolytic polishing process. The study scrutinised the surface morphology and corrosion resistance of 304 stainless steel, employing tools such as metallographic microscopy, a roughness gauge, and an electrochemical workstation. Within a sulphuric acid–phosphoric acid-based electrolyte characterised by a volume ratio of 1:2, the optimal mass concentration ratio of salicylic acid and saccharin was ascertained to be 3:3. By configuring the process parameters to 10 A dm−2 and 20 min, outcomes of electrolytic polishing were obtained that stood on par with the conventional current density approach. The stainless steel surface exhibited a surface roughness measuring a mere 0.08 µm and characterised by a corrosion current density of 1.907 × 10−8 A cm−2 and a corrosion potential of −0.0965 V.