Kinetic Regularities of the Electrochemical Processes of Corrosion Fatigue in Titanium Alloys

We studied the mechanism and the kinetics of corrosion-fatigue fracture of titanium alloys with the use of electrochemical methods: changes in the electrolytic potential E during deformation of the specimens (relations E vs. log N and E vs. ΔK) and external polarization (relations Epol vs. ΔK). We investigated the electrochemical processes on a newly formed surface during the time (τ = 5 msec) of its interaction with sodium chloride solutions of different concentrations (0.1, 0.5, 1.0, and 1.5N NaCl solutions). The main stages of corrosion fatigue of titanium alloys of different structural and phase states were identified on the basis of correlation changes in the surface and the electrolytic potential. We showed that the newly formed surfaces of these alloys possess all properties of the material that can pass to a passive state. Activation of the surface of cyclically deformed alloys is accompanied by a significant discharge of the electrolytic potential (−1.2 V) and a sharp increase in the current (159 A/m2). Repassivation is characterized by a three-stage change in both the potential and current. The characters of changes in the curves current vs. time of nondeformed and cyclically deformed alloys are identical, but the current decreases more rapidly in the last case.