This study investigates the potential of high-speed friction stir processing (HS-FSP) to enhance the corrosion resistance and electrochemical stability of commercially pure titanium (CP-Ti) for biomedical applications. Unlike Ti-6Al-4 V alloys, which release toxic aluminum and vanadium ions, CP-Ti offers superior biocompatibility but suffers from lower mechanical and corrosion performance. To overcome these limitations, CP-Ti surfaces were modified using HS-FSP with varying pass numbers, and their microstructural, mechanical, and electrochemical properties were evaluated in Hank’s solution at 37 °C. HS-FSP induced severe grain refinement, reducing grain size from 52 µm² to 0.32 µm² after three passes, while microhardness increased from 241 Hv to 537 Hv. Electrochemical tests revealed a significant improvement in corrosion resistance; corrosion current density decreased from 0.25 µA·cm⁻² to 0.02 µA·cm⁻², and impedance rose from 317.81 kΩ·cm² to 811.27 kΩ·cm². Mott–Schottky analysis confirmed a reduction in donor density and an increase in passive film thickness, indicating fewer defects and enhanced barrier properties. These findings demonstrate that HS-FSP not only strengthens CP-Ti but also forms a dense, protective oxide layer, making it a viable, safer alternative to Ti-6Al-4 V for long-term implants. Beyond biomedical applications, this approach offers opportunities in aerospace, marine, and chemical industries where corrosion resistance and mechanical integrity are critical.

Keywords