Corrosion and passive behavior of SLM and wrought TA15 titanium alloys in hydrochloric acid solutions

Abstract

The corrosion behavior of Ti–6Al–2Zr–1Mo–1V (TA15) alloy fabricated through selective laser melting (SLM) technology and traditional wrought technology in hydrochloric acid solutions was investigated using electrochemical testing and surface characterizations, including electron backscattered diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy analyses. The results showed that both types of TA15 alloy underwent spontaneous passivation reactions in HCl solution, and with the increase in HCl concentration, the surface of SLM-TA15 sample exhibited larger and deeper pits. In comparison to SLM-TA15 sample, the pits on the wrought-TA15 sample were shallower and the surface was more uniform. Analysis of the passive current density, breakdown potential, and electrochemical impedance revealed that the corrosion resistance of both alloys decreased as the concentration of HCl increased, and SLM sample exhibited poorer corrosion resistance compared with the wrought sample. Analysis of Mott–Schottky test curves and calculation of passive film thickness indicated that the passive film of wrought-TA15 sample was superior to that of SLM-TA15 sample.