PSI - Issue 53

Serhii Lavrys et al. / Procedia Structural Integrity 53 (2024) 246–253 Serhii Lavrys et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 3. Microhardness and microstrain of Ti6Al4V titanium alloy: wrought ( 1 ), AM ( 2 ), AM after post HT at 800°C ( 3 ) and 850°C ( 4 )

The evolution of OCP for Ti6Al4V titanium alloy, made by different technologies and after post HT, in 20 wt.% HCl is presented in Fig. 4, a. At the initial stage of immersion, the potential of all samples decreases, which is probably the result of dissolution or local destruction of the native passivation film. However, over time the potential gradually stabilizes and becomes stationary, which is associated with the formation of a new passive film on the surface of the titanium alloy. It should be noted that OCP for the AM titanium alloy is stable over longer period of time and has lower values (Fig. 4, a). This indicates that the AM titanium alloy is characterized by lower tendency to passivation than the wrought one. Also, post HT treatment at a temperature of 800°C allows to reduce the stabilization period of OCP and approaches its value to the wrought one. It can be concluded that post HT at a temperature of 800°C leads to nobler AM titanium alloy. On the other hand, post HT at higher temperature (850°С) does not effect almost the change and value of the OCP of AM titanium alloy (Fig. 4, a).

Fig. 4. OCP vs time (a), polarization curves (b), Nyquist plots (c) and Bode plots (d) of Ti6Al4V titanium alloy: wrought ( 1 ), AM ( 2 ), AM after post HT at 800°C ( 3 ) and 850°C ( 4 )