Effects of Voltage and Treatment Time on Electrolytic Plasma Polishing of Ti–6Al–1.5Cr–2.5Mo–0.5Fe–0.3Si Alloy

Electrolytic plasma polishing (EPP) is a noncontact surface-finishing technique. This study examined the effects of voltage and treatment time on the TC6 alloy with the nominal composition Ti-6Al-1.5Cr-2.5Mo-0.5Fe-0.3Si. Voltage-series experiments used nominal 260, 270, 280, 290, and 300 V for approximately 300 s. The time series used nominal 280 V and energized durations of 15.1, 30.0, 45.0, 60.2, 90.1, 120.2, 180.3, 240.1, and 900.4 s. One independently prepared specimen was analyzed per condition, with three technical AFM fields per specimen; therefore, between-specimen variability was not estimated. Atomic force microscopy (AFM), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDS), and X-ray diffraction (XRD) were used to characterize the surfaces. Mean arithmetical heights (Sa) were 62.80, 37.70, 26.39, 31.17, and 41.00 nm across the five main voltages. The lowest measured mean occurred at the nominal 280 V, and a quadratic fit to the measured voltages yielded a minimum near 284.3 V. AFM and SEM showed reduced grinding texture. EDS characterizes local elemental distributions and normalized mass fractions. Mass loss and time-integrated charge were used to calculate apparent current efficiency. These results describe the polishing response of mechanically ground TC6 and identify the lowest-roughness condition among the tested voltages.