Research on the Material Removal Mechanism and Experiments of Electrolytic Plasma Polishing for High-Strength Steel

Abstract This study aims to reduce the surface roughness of high-strength steel to meet the stringent requirements for high surface quality in engineering applications. To achieve this, the electrolyte plasma polishing (EPP) technology is proposed for precision machining of its surface. Centering on the material removal mechanism of EPP, a systematic investigation is carried out by integrating multi-physics field modeling and simulation with experimental validation. The paper elucidates the fundamental principles and material removal mechanism of electrolyte plasma polishing. It establishes mathematical models for the electric and flow fields, gas-liquid two-phase flow, and the process characterizing "peak removal". Dynamic simulation analysis is conducted on key physical phenomena during polishing, focusing on simulating the formation and evolution of the gaseous insulating layer on the anode surface and the "peak removal" behavior reflecting the surface leveling process. Research shows that the "peak removal" process is initiated by electrochemical dissolution at the workpiece surface along with the associated bubble evolution and collapse. The material removal mechanism is ascribed to the combined action of fluid erosion, formation of local discharge channels, and discharge at the tips of surface asperities. A series of polishing experiments was conducted, enabling systematic characterization of the specimens' surface roughness, microscopic morphology, 3D topography, elemental composition, and microhardness both pre- and post-polishing. The results indicate that the polishing treatment significantly enhances surface smoothness, imparting a metallic luster, substantially reduces surface roughness, and leads to a marked improvement in surface morphology. A significant decrease in surface oxygen content, a slight increase in chromium content, and a minor reduction in microhardness were observed. This research deepens the mechanistic understanding of the Electrolyte Plasma Polishing process, thereby furnishing a theoretical foundation and experimental data to support its optimization and precise control.