Corrosion behavior of additively manufactured Ti-6Al-4V parts and the effect of post annealing

Abstract

This paper evaluates the corrosion behavior of Ti-6Al-4V alloy parts produced by laser-based powder bed fusion additive manufacturing (AM). The effect of post annealing heat treatment on the corrosion resistance of AM parts is studied by comparing the heat treated samples with cold rolled commercial titanium alloy samples. The results obtained via corrosion tests show that the corrosion rate of as-fabricated AM parts is almost sixteen times worse than the commercial grade samples. The accelerated rate was due to the presence of non-equilibrium phases and can be ameliorated by a proper post heat treatment process at 800°C for 2 h. The proposed heat treatment makes the corrosion behavior of AM parts comparable to the commercial grade samples, due to the stress relief of the martensitic phase and formation of BCC phase of β Ti-6Al-4V which has a higher corrosion resistance. CALculation of PHAse Diagrams (CALPHAD) method was used to identify the equilibrium phases.