Effects of Iron Content on Microstructure and Crevice Corrosion of Grade-2 Titanium Available to Purchase

The effects of iron content on the microstructure and crevice corrosion of Grade-2 titanium (Ti-2) were studied using a galvanic coupling technique combined with optical microscopy and secondary ion mass spectrometry (SIMS) imaging. This study reveals that iron content has a significant effect on the microstructure and crevice corrosion behavior of Ti-2. The grain size decreased significantly with increasing iron content. For a Ti-2 material with medium iron content, crevice corrosion readily initiated and the metal exhibited extensive intergranular attack that could be associated with the more reactive iron-stabilized β-phase within the α-phase matrix, as revealed by SIMS imaging. By contrast, Ti-2 materials with low and high iron contents showed suppressed crevice attack. The smaller surface area of available grain boundaries in Ti-2 of low iron content could account for this limited attack. For the material with high iron content, SIMS imaging suggests that some Ti_xFe intermetallic particles were formed. These particles may act as proton reduction catalysts and enhance crevice corrosion resistance via cathodic modification.