Electrohydrodynamic modeling and experimental study of electrolyte plasma polishing of high-strength steel surfaces

To enhance the inner surface quality of artillery barrels, this work introduces Electrolyte Plasma Polishing (EPP) for finishing the internal artillery surface and systematically examines the effect of electrode gap on the material removal mechanism and the resultant surface quality. An electrohydrodynamic mathematical model was developed. Using this model, the spatial distribution of electric potential, current density, flow velocity, and pressure in the polishing zone was systematically studied for electrode gaps of 0.5 mm, 1.0 mm, and 1.5 mm. Simulation results reveal that the microscopic "tip effect" constitutes the dominant physical mechanism for material removal. The inter-electrode gap significantly governs the physical field distributions. A small gap (0.5 mm) promotes the establishment of a high electric field intensity at the anode surface for plasma initiation, whereas a large gap (1.5 mm) enables the generation of high-velocity turbulent flow (reaching 84.7 m/s), substantially improving mass transfer and heat dissipation, thereby favoring process stability. Experimental results demonstrate that the EPP process effectively eliminates machining marks and burrs on the rifling surface, producing smooth edge transitions and a uniform metallic gloss. The peak-to-valley height of the surface profile was drastically reduced from a range of -16µm to +14 µm before polishing to within ±1 µm, indicating a significant reduction in surface roughness. Simultaneously, it removed near-surface porous defects and achieved a surface composition optimized. This work clarifies the material removal mechanism driven by electrohydrodynamic coupling and verifies the distinct advantages of EPP technology in improving the surface integrity of artillery barrel inner surfaces.