A study of the microstructures and mechanical properties of Ti6Al4V fabricated by SLM under vacuum

Ti6Al4V components with complex structures, excellent performance and good surface quality, can be fabricated by selective laser melting (SLM). The conventional SLM process is carried out in an inert gas filled chamber, at slightly greater pressure than ambient, to avoid oxidation at high temperature. However, the inert gas may cause pores in as-fabricated parts. In this study, the SLM process was carried out under vacuum in order to improve the quality of the SLM-fabricated Ti6Al4V samples. The as-fabricated Ti6Al4V samples then were subjected to hot-isostatic pressure (HIP). The remaining porosity was evaluated using X-ray computed tomography (CT). The microstructures and mechanical properties of the samples were evaluated with and without HIP. The test results showed that SLM under vacuum could reduce the porosity of Ti6Al4V samples, compared to material that was produced using the conventional SLM process. After HIP, porosity could be further reduced and the Ti6Al4V samples could achieve better elongation.