Electrochemical polishing mechanism and process of medium-carbon steel 1144

• Published in: Precision engineering Vol. 96; pp. 770 - 786
• Main Authors: Yang, Xu, Sun, Wei, Zhang, Shenglong
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.10.2025
• Subjects: Electrochemical polishing; Medium-carbon steel; Polishing mechanism; Salt film; Surface performance; Surface roughness; Polishing mechanism; Electrochemical polishing; Medium-carbon steel; Surface roughness; Surface performance; Salt film
• ISSN: 0141-6359
• DOI: 10.1016/j.precisioneng.2025.07.028

Medium-carbon steel is a crucial engineering material, which is widely used in digital hydraulic systems, particularly in high-performance hydraulic components, because of its excellent mechanical properties, good machinability, and cost-effectiveness. Electrochemical polishing (ECP), an efficient and nondestructive surface finishing method, has been extensively applied to the surface treatment of various workpieces. However, research on the ECP of medium-carbon steel is limited, and the effects and mechanisms of polishing parameters on surface quality remain poorly understood. This work systematically investigates effective methods for enhancing the surface quality of medium-carbon steel through ECP technology and explores the underlying polishing mechanisms. The experimental results revealed that the optimal polishing effect of medium-carbon steel 1144 was achieved in the gas evolution region (6 V), rather than in the limiting current plateau region (2 V), which is typically favored in most ECP studies. Through microstructural observation and elemental analysis, the ECP mechanism of medium-carbon steel was elucidated, and a novel high-voltage ECP salt film deposition mechanism was identified. Furthermore, the influence of processing parameters on ECP was investigated. The surface quality initially improves and subsequently deteriorates with increasing time, as prolonged durations induce over-dissolution. Likewise, a moderate temperature rise enhances reaction activity and improves surface quality, whereas excessive temperatures accelerate over-dissolution, leading to quality degradation. The optimal processing parameters were determined to be a voltage of 6 V, temperature of 50 °C, processing time of 30 min, and a sulfuric acid‒phosphoric acid ratio of 1:2. Under these optimal parameters, surface roughness (Sa) of the medium-carbon steel decreased from 0.611 to 0.056 μm, demonstrating the effectiveness of ECP. In addition, ECP was found significantly enhance the corrosion resistance and lubricity of the medium-carbon steel surface. This study has significant implications for advancing the understanding of the ECP mechanism and for guiding process control in practical applications. [Display omitted] •ECP mechanism of medium-carbon steel was firstly clarified and a novel model was established.•Dominant factors and their effects on the ECP of medium-carbon steel were revealed.•Surface roughness reduced from 0.611 to 0.056 μm Sa after ECP.•Significant improvement in corrosion resistance and oleophilicity were achieved after ECP.