Abstract
This study investigated the effect of annealing temperature on the microstructure and electrochemical behavior of commercially pure titanium (CP Ti) subjected to cold rolling and heat treatments between 400 and 900°C. Microstructural characterization and microhardness measurements were performed, along with potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests in artificial saliva following exposure to a fluoridated agent. Three independent specimens were evaluated for each electrochemical condition, and results are reported as mean ± standard deviation. Microstructural characterization revealed recovery, recrystallization, and grain growth with increasing annealing temperature, as well as α′ martensite formation, evidenced by acicular morphologies that were more pronounced under the higher-temperature conditions. The electrochemical response varied depending on the parameter considered: cold-rolled and annealing at 900°C (CR900) exhibited the lowest Icorr (1.40 ± 0.18 μA/cm²), whereas CR600 and CR800 showed the lowest Ipass values (8.95 ± 0.20 and 9.1 ± 1.1 μA/cm², respectively). CR800 reached the highest Rf after 72 h of immersion (102 ± 12 MΩ·cm²), while for CR900, the Rf values decreased from 0.847 ± 0.022 to 0.293 ± 0.010 MΩ·cm². The occurrence of α′ martensite at higher annealing temperatures and the differing responses of Icorr, Ipass, and Rf demonstrate that microstructural evolution affects corrosion-related parameters in distinct ways. Accordingly, the influence of annealing can only be properly understood through the combined analysis of microstructure, polarization behavior, and EIS results.
Keywords
CP titanium, Fluoride, Corrosion resistance, Annealing