Hydrogen Embrittlement of Grade 2 and Grade 3 Titanium in 6% Sodium Chloride Solution

Hydrogen embrittlement (HE) of grade 2 and grade 3 titanium was investigated in 6% sodium chloride (NaCl) at pH 1 under potential control at 70°C. Grade 2 titanium was, at most, slightly susceptible to HE under the test conditions, whereas grade 3 titanium was very susceptible at an electrochemical potential below −800 mV_SCE and at a low crosshead speed. Hydride phases began to form on the surface of the grade 3 titanium at a potential of −700 mV_SCE. This phase could be observed in the interior of grade 3 titanium at lower potentials (e.g., −1,400 mV_SCE) after extended cathodic charging. Hydrides were never observed in the interior of grade 2 titanium. Formation of these hydrides in the interior of grade 3 titanium and not in grade 2 was attributed to the higher oxygen content of grade 3.