The anisotropy of corrosion and passive behavior in selective laser melted Ti-5Al-5Mo-5 V-3Cr-1Zr alloy

Ti-5Al-5Mo-5 V-3Cr-1Zr (Ti-55,531) alloys is favored for aerospace applications due to excellent mechanical properties and good corrosion resistance. Meanwhile, selective laser melting (SLM) might be an effective way to solve the complex geometry manufacturing of Ti-55,531 alloys. However, the anisotropy of microstructure generated during the SLM process will badly affect the corrosion and passive behavior. Herein, the crystallographic-texture-induced anisotropy of SLM-produced Ti-55,531 was comparably investigated in 3.5 wt% NaCl solution. Electrochemical methods were employed to acquire the information about the corrosion and passive behavior of Ti-55,531 samples. The formation of beta 100 texture along the building direction (VP) is strongly correlated to the epitaxial elongation. The oxygen vacancies flux of passive film has been improved in the VP due to strong beta < 100 > texture. Excess vacancies are converted into a void in the inner layer of passive film, resulting in the nucleation of pitting corrosion. In addition, chloride ions prevent the formation of passive film by the adsorption of redundant oxygen vacancies. This study reveals the effect of crystallographic texture on the passive film of SLM-produced Ti-55,531, which also provides a way for the practical understanding of corrosion anisotropy in additive manufacturing (AM) industries.