Five kinds of typical titanium alloy materials (Ti-6Al-4V, Ti-6Al-4V-0.1Ru, Ti-6Al-2Sn-4Zr-6Mo, Ti-3Al-8V-6Cr-4Zr-4Mo and Ti-5.5Al-4.5V-2Zr-1Mo) used for oil & gas exploration were investigated. The influence of different alloy composition on anti-corrosion properties of these titanium alloys in China typical service environment were studied by high-temperature high-pressure autoclave simulation test. The corrosion morphology and corrosion products were also analyzed and summarized by scanning electronic microscopy (SEM) and energy dispersive spectrometer (EDS), and the corrosion resistance mechanism of different alloys was discussed by electrochemical method. The results show that the corrosion reactions of all titanium alloy materials are anode-controlled under the test conditions, the uniform corrosion rates of all tested titanium alloy are lower than 0.001 mm/a, and the resistance to stress corrosion cracking (SCC) of all titanium alloys is excellent. However, Ti-6Al-4V and Ti-5.5Al-4.5V-2Zr-1Mo alloys have obvious pitting and crevice corrosion problems. The corrosion mechanism results show that under the test conditions, the self-corrosion potential and polarization resistance of all titanium alloys decrease and the corrosion current increases with the decrease of pH value, which illustrates that corrosion resistance of titanium alloys is reduced, especially for Ti-6Al-4V. The research results provide a theoretical basis for material selection and crack corrosion prevention of titanium alloy oil country tubular goods (OCTG) used in oil and gas exploration.
