The effect of heat treatment on the electrochemical properties of additive manufactured TC4 titanium alloy

The relationship between microstructure and surface electrochemical properties of additive manufactured TC4 titanium alloy with heat treatment was investigated by measuring polarization curve and electrochemical impedance spectroscopy, using artificially synthesized seawater as electrolyte, and combined with SEM and XRD. The results showed that there were mainly microstructures of metastable α' phase and few β phase in the additive manufactured TC4 titanium alloy, and the electrochemical performance was relatively poor. The metastable α' phase was decomposed into a stable α + β biphasic structure after heat treatment. When the heat treatment temperature was increased within a certain range, the self-corrosion potential was increased and the corrosion resistance was enhanced. After the holding time of samples at 800 °C was extended from 1 h to 4 h, α' phase decomposed into more α+β biphasic structure, the self-corrosion potential was significantly increased, and the electrochemical performance was improved. After the holding time of 940 °C was extended from 1 h to 4 h, the α grain became coarse, the self-corrosion current density and passivation current density of the material increased significantly, and the electrochemical properties of the material decreased.