Abstract The study is to electropolish 316 L stainless steel in a sulfuric acid-free electrolyte, consisting of phosphoric acid, glycerol and distilled water instead of the widely used sulfuric acid-based electrolyte. The influence of water concentration in the electrolyte on the electropolishing characteristics was investigated from the polarization curve, material removal rate and surface roughness Ra. It is confirmed that the limiting current density increases with increasing the water concentration, resulting in a high material removal rate. However, the surface roughness Ra increases because the electropolishing effect is lowered. The surface characteristics were analysed by X-ray photoelectron spectroscopy, and the mechanical properties were studied by nanoindentation. A two-step electropolishing method was proposed to enhance the electropolishing efficiency significantly by utilizing the electropolishing characterizations with different water concentrations. The method contains two electropolishing processes in high and low water concentration electrolyte, respectively. The experimental results show that the material removal rate is increased significantly compared with the one-step electropolishing method with a low water concentration, and the surface roughness is decreased obviously compared with the one-step electropolishing method with a high water concentration.

中文翻译：

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316L 不锈钢在无硫酸电解液中的两步电解抛光

摘要 本研究是在无硫酸电解液中对 316 L 不锈钢进行电解抛光，该电解液由磷酸、甘油和蒸馏水组成，而不是广泛使用的硫酸电解液。从极化曲线、材料去除率和表面粗糙度Ra研究电解液中水浓度对电解抛光特性的影响。经证实，极限电流密度随着水浓度的增加而增加，导致材料去除率高。然而，由于电解抛光效果降低，表面粗糙度Ra增加。通过X射线光电子能谱分析表面特性，并通过纳米压痕研究机械性能。提出了一种两步电解抛光方法，通过利用不同水浓度的电解抛光特性来显着提高电解抛光效率。该方法分别包含在高和低水浓度电解液中的两个电解抛光过程。实验结果表明，与低水浓度一步电抛光方法相比，材料去除率显着提高，与高水浓度一步电抛光方法相比，表面粗糙度明显降低。