STUDY ON CORROSION OF TI-6AL-4V ALLOY IN 3.5% NACL SOLUTION BY WIRE BEAM ELECTRODE.

This work aims to study the variation mechanism of corrosion-resistance performance of the oxidization film spontaneously generated on Ti-6Al-4V (TC4) titanium alloy surface by using the open circuit potential (OCP), Alternating Current (AC) impedance, and polarization curve. Combined with the method of wire beam electrode, the corrosion behaviors of the microregion of TC4 titanium alloy immersed in 3.5% NaCl solution during the formation of film were investigated. Results show that the corrosion-resistance performance of TC4 titanium alloy increased with the formation of oxidization film, with the electrochemical testing results showing that the OCP and AC impedance values were increased, while the corrosion current density reduced. When the time of film formed on the surface of the alloy was 24 h, the impedance value of the TC4 alloy was an order of magnitude greater than that before oxidation, then the impedance value was no longer increased and the corrosion-resistance performance was best. The anode current and localized corrosion characteristics of the TC4 titanium alloy submerged in 3.5% NaCl solution during the earlier formation stage of film were great. With the formation of oxidized film, the peak value of anode current and its region gradually reduced, and both standard deviations of the circuit potential and circuit were narrowed, as well as the reduction in the difference of localized corrosion. [ABSTRACT FROM AUTHOR]