Evaluating Corrosion Resistance of Additive-Manufactured Ti-6Al-4V Using Electrochemical Critical Localized Corrosion Temperature

A new concept to evaluate the localized corrosion resistance of stacked Ti alloys such as additive-manufactured (AM) Ti-6Al-4V alloy is proposed. Crevice corrosion of subtractive-manufactured (SM) Ti-6Al-4V occurred on the surface beneath the crevice former, whereas localized corrosion of the AM alloy occurred in any vulnerable site irrespective of the crevice assembly. The electrochemical critical localized corrosion temperature (E-CLCT) was measured to evaluate the resistance of AM Ti-6Al-4V alloys to localized corrosion. The results showed that the localized corrosion of AM Ti-6Al-4V was attributable to the anisotropy and microstructure that resulted from rapid cooling, which were completely different from the anisotropy and microstructure of SM Ti-6Al-4V. The optimum applied potential of AM Ti-6Al-4V in 25 wt% NaCl aqueous solution was deduced. The E-CLCT provides a useful criterion for determining the resistance of AM Ti alloys to localized corrosion and for comparing their resistances.