Metastable pitting corrosion behavior and characteristics of passive film of laser powder bed fusion produced Ti–6Al–4V in NaCl solutions with different concentrations

Abstract

This work investigated the metastable pitting corrosion mechanism of laser powder bed fusion (LPBF) produced Ti–6Al–4V. The passive films of samples were produced by potentiostatic polarization in NaCl solutions with different concentrations, and electrochemical measurements were employed to understand the influence of Cl - on the characteristics of passive films. The frequency of pitting nucleation and the pit dimension increase with increased Cl - concentration. The attack of Cl - promotes the dissolution of passive films. A higher density of oxygen vacancies is produced in passive film because of the ingressive Cl - , resulting in the condensation of voids and pitting corrosion . • A Ti-6Al-4V alloy was fabricated by laser powder bed fusion (LPBF) method. • Metastable pitting corrosion of the samples was investigated in NaCl solutions. • Cl - suppresses the formation of passive film formed on LPBF-produced sample. • The passive film has higher flux of oxygen vacancies in 10 wt% NaCl solution. • The condensation of cation-anion-vacancy associations triggers voids and pitting.