Ti-6Al-4V-Ru and Ti-3Al-2.5V-Ru alloy products, in both alpha-beta and transformed-beta conditions, exhibited complete resistance to sulfide- and chloride-induced stress corrosion cracking (SSC and SCC) in various synthetic deaerated, acidic, sweet and sour geothermal and worst-case sour-gas well produced-fluid brines to temperatures as high as 330°C. SCC test methods included NACE sustained-load tensiles, C-ring, U-bend, and slow-strain-rate tensile testing. The two alloys also fully resisted localized and crevice oomosion in these hkgh-temperature acidic, sweet and sour brines, whether deaerated or naturally-aerated. Based on these results, the Ti-6Al-4V-Ru and Ti-3Al-2.5V-Ru alloys are considered to be prime candidate materials for downbole tubulars and components for the more corrosive, high temperature geothermal and sour-gas well fluid applications.
Keywords: titanium alloys, crevice corrosion, stress corrosion cracking, corrosion, chlorides, sulfides, sour brines, sour gas, geothermal