Electrochemical regularities of stress corrosion fracture of titanium alloys
The mechanism and kinetics of corrosion-fatigue fracture of titanium alloys are considered using the electrochemical investigations, namely, the change of electrode potential E during specimens deformation (E - lgN and E - DK dependences), external polarization (Е pol - DK dependences). The main stages of corrosion fatigue of titanium alloys of different structural and phase state have been identified on the basis of the correlation changes of the surface and the electrode potential. Under plane strain conditions, the dependence of the stabilized electrode potential Е st on DK is of а rectilinear type. The alloy structure and solution concentration increase or decrease it. The increasing role of the electrochemical factor during corrosion fatigue is proved by the results of electrochemical protection effectiveness, namely, during cathodic polarization the process of corrosion-fatigue crack propagation can be completely stopped. The kinetics and the mechanism of corrosion-fatigue fracture of titanium alloys are analyzed.