Stress corrosion behavior and mechanism of Ti6321 alloy in seawater with different dissolved oxygen concentrations

Abstract

The stress corrosion behavior of Ti-6Al-3Nb-2Zr-1Mo (Ti6321, in wt%) alloy in seawater with different dissolved oxygen (DO) concentrations was investigated using X-ray photoelectron spectroscopy, energy dispersive spectrometer, electrochemical measurements, and other advanced methodologies. The results indicate that when the DO concentration in seawater is insufficient, the passivation film will preferentially form on the α-phase surface. Meanwhile, insufficient DO concentration leads to incomplete oxidation of the surface passivation film, resulting in an increase in surface defects. Hydrogen produced by reactions at crack tips is more likely to enter the surface of the titanium alloy through these defects, and under the influence of HEDE and HELP mechanisms, promote crack propagation.