A Comparison of Stress Corrosion Cracking Susceptibility in Additively-Manufactured and Wrought Materials for Aerospace and Biomedical Applications

Additive manufacturing (AM) is becoming an increasingly popular method in both aerospace and biomedical industries. Titanium alloys are increasingly common in additive manufactured applications due to their excellent strength to weight ratio and biocompatibility. Traditional wrought Ti-6Al-4V alloys show little sensitivity to stress corrosion cracking (SCC) when subjected to in-vitro conditions. In AM applications the alloy powder is often sifted and reused multiple times which often results in a degradation of the powder’s shape. Recent studies have also shown that the oxygen content of additive powders increases with repeated powder use which may increase the susceptibility of the resulting parts to SCC. This research compares the microstructural characteristics and tensile SCC behavior of AM Ti-6Al-4V parts fabricated from new and recycled powder in distilled H2O, salt water, and Ringers solution. Additionally, the effect of surface finish is investigated for each microstructure comparing the as-built surfaces to machined and polished surfaces.