NaCl induced corrosion of Ti-6Al-4V alloy at high temperature

• NaCl deposits are harmful for Ti-6Al-4V alloy at high temperature.
• Synergistic effect of NaCl and water vapour on titanium alloys corrosion.
• An active oxidation mechanism is proposed.
• The mechanism relies on the vapour pressure of the solid deposited NaCl.

This paper presents a study on the Ti-6Al-4V behaviour in presence of NaCl deposit under dry and moist air environments at 560 °C. The results evidence a detrimental effect of the NaCl deposit with a synergistic effect in presence of moist air environment. Treatments under dry and moist air with NaCl deposit for 600 h, lead respectively to weight gains per unit area 5 and 15 times higher than observed under classic oxidation in dry air. Enhancement of the corrosion phenomenon is attributed to the presence of gaseous metal chlorides, leading to the establishment of an active corrosion process.