Passivation Behavior of Water‐Quenched and Heat‐Treated Ti–6Al–4V in Hank's Solution

Abstract

Ti–6Al–4V is a prevalent material utilized in various industrial applications, and its microstructure modification commences with quenching, followed by diverse heat treatments. Although many works have concentrated on the mechanical properties of Ti–6Al–4V with tailored microstructures resulting from heat treatments, their corresponding corrosion behavior still lacks attention. In this study, the corrosion behavior of water‐quenched Ti–6Al–4V that undergoes heat treatment between 700 and 850 °C in Hank's solution is investigated. Various electrochemical methods, such as open‐circuit potential tests, potentiodynamic/potentiostatic polarization, electrochemical impedance spectroscopy, and Mott–Schottky tests, are jointly employed. The water‐quenched Ti–6Al–4V displays a quick‐cooling microstructure with a plentiful amount of martensite α/α′ phase. Heat treatment at 700 °C significantly alters the microstructures of the samples. Due to competitive factors, heat treatment at low temperatures results in uneven alloy composition, leading to poor uniformity of the passive film. At this phase, negative effects dominate, and the corrosion resistance of the samples deteriorates. When the heat‐treatment temperature increases to 850 °C, the content of β phase, which possesses better corrosion resistance, increases and becomes dominant. Consequently, the corrosion resistance of the samples improves in Hank's solution.