Surface oxide film formation: When titanium is exposed to air, it rapidly reacts with oxygen to form a very thin (usually only a few nanometers thick) but very dense titanium dioxide (TiO₂) film on the surface. This film effectively prevents further contact between oxygen and moisture inside the titanium metal, thus preventing further oxidation reactions.

Self-healing ability of the oxide film: If this oxide film is damaged for some reason (such as scratching or wear), as long as there is oxygen, a new oxide film will immediately begin to form, quickly covering the damaged area, and continue to play a protective role. This ability to self-repair allows titanium to maintain good corrosion resistance in long-term use.
Chemical stability: Titanium dioxide is an extremely stable chemical compound that is not easy to decompose or dissolve even in harsh environments, which further enhances the corrosion resistance of titanium.

Low potential difference: Titanium has low electrochemical activity, which means that in electrolyte solutions, titanium tends to become a cathode rather than an anode, thus reducing the possibility of corrosion through electrochemical reactions.
High temperature resistance: In addition to good corrosion resistance at room temperature, titanium can also maintain good oxidation resistance at high temperatures, which is particularly important for some specific applications (such as aerospace and chemical industries).


In summary, the corrosion resistance of titanium mainly comes from the naturally formed and self-repairing titanium dioxide film on its surface, as well as the chemical stability and low electrochemical activity of titanium itself. These properties make titanium a very corrosion-resistant material that maintains good performance even under extreme conditions.