Effect of ECAP on Microstructure and Corrosion Resistance Properties of SLM Pure Titanium

In order to improve the corrosion resistance of pure titanium in Ringer's simulated body fluid and simulated oral saliva environment, the equal channel angular pressing (ECAP) technique was used to modify the commercial pure titanium prepared by selective laser melting (SLM). The microstructures of SLM pure titanium and SLM+ECAP pure titanium were detected by transmission electron microscope and electron back-scattered diffractometer, and their corrosion resistance was tested by the three-electrode system. Results show that compared with SLM pure titanium, SLM+ECAP pure titanium has smaller grain size, more grain boundaries, higher dislocation density, and modest preferred orientation of the pole diagram with increased pole density. In Ringer'. s simulated body fluid and simulated oral saliva environment, SLM+ECAP pure titanium has lower self-corrosion current density, higher polarization resistance, and larger impedance radius than SLM pure titanium does. The equivalent circuit fitting of alternating current impedance spectrum was conducted by ZSimpWin software, and the fitting results are in good agreement with the experiment data. The corrosion resistance of SLM+ECAP pure titanium is better than that of SLM pure titanium.