Influence of the structural state on the anodic dissolution of TA 6V alloy in concentrated hydrochloric acid : Handling the results to study the anodic behaviour of welded elements

Abstract

This study reports the determination of the effect of microstructural modifications on the anodic dissolution of titanium in TA 6V alloy. On the basis of current-potential curves, of analyses (X-ray diffraction, absorption spectrometry of the electrolytic medium) and observations of surfaces by scanning electron microscopy, it is established that passage into the β fields limits the overall kinetics. However, the martensite-type, α' phase, when it does exist, increases at least the rate of one of the determining steps of the reaction mechanism, despite the lack of hydride. These results account for the satisfying electrochemical behaviour of submerged arc-welded joints, for which the higher oxygen content in the welded zone further limits the dissolution process.