Corrosion of titanium alloys in high temperature near anaerobic seawater

Grades 2, 5 and Grade 7 were investigated in near anaerobic (<1 ppm oxygen) seawater up to 200 °C with and without CO2. All three grades were found to resist stress corrosion cracking and pitting corrosion. Grades 2 and 5 suffer crevice corrosion at temperatures 80 °C and 200 °C respectively. In the presence of CO2 Grade 5 becomes more vulnerable to crevice corrosion, with attack starting at 80 °C with preferential dissolution of the beta phase. An analysis of the threat of hydrogen induced cracking leads to the conclusion that this was not a likely threat to any of the Ti alloys investigated.