Influence of Heat Treatment Parameters on the Corrosion Resistance of Additively Manufactured Ti–6Al–4V Alloy

Abstract

The corrosion resistance of a heat-treated Ti–6Al–4 V alloy fabricated using the additive manufacturing (AM) method was investigated through a series of electrochemical techniques, including potentiodynamic polarization, electrochemical impedance spectroscopy, and critical pitting temperature measurements, in an effort to improve the corrosion resistance of AM Ti–6Al–4 V subject to different stages of heat treatment. During this process, we reported that the corrosion resistance of the AM Ti–6Al–4 V alloy significantly reduced, which we attributed to both preexisting α′ phases and newly emerging precipitates. After heat treatment at 650 °C and 750 °C, the corrosion resistance of AM Ti–6Al–4 V worsened further after cooling compared to the original as-received sample because of the existence of the α′ phase (without decomposition) and precipitates. However, at 850 °C and 1000 °C, the heat-treated samples demonstrated much better corrosion resistance compared to the as-received sample, possibly because of the complete transformation of the α′ phase into the α phase and the evolution of a β phase. Based on these experimental results, we believe that adequate heat treatments such as rapid cooling illustrate added advantages for the enhanced corrosion resistance of AM Ti–6Al–4 V alloys.