Crevice corrosion damage function for grade-2 titanium of iron content 0.078 wt% at 95 °C

A crevice corrosion damage function has been developed for grade-2 titanium in 0.27 mol/dm3 NaCl at 95 °C. Crevice corrosion experiments were conducted for various durations using a galvanic coupling technique, and corrosion depth profiles subsequently measured using a combination of metallographic and image analysis techniques. The damage function was then determined by plotting the maximum penetration depth (dmax) in μm as a function of time (days). This function possessed two clear stages; an initial stage in which dmax = 89.4t0.87, and a second stage in which corrosion spread laterally without an increase in dmax, before the crevice finally passivated. The initial high penetration rate was associated with an intergranular attack down Fe-containing grain boundaries. In the second stage, further increases in dmax were limited by the IR drop between the propagation sites deep within the grain boundaries and the external cathode.