Microstructures and Strengthening Mechanism of Oxygen Soluted Titanium by Selective Laser Melting

Abstract

The mechanical properties of selective laser melting (SLM) titanium (Ti) materials can be enhanced by solid solution with oxygen (O) element. However, the microstructure changes and their relationship with mechanical properties of SLM Ti materials have not been clearly revealed in the view point of the dissolved oxygen amount. In this study, we investigated the effect of oxygen element on the microstructures and mechanical properties of SLM α-Ti materials. Furthermore, the strengthening mechanism of SLM Ti materials was also investigated quantitatively. The SLM Ti material without additional oxygen consisted of coarse grains, whereas the SLM materials with 0.35 ~ 0.89 mass% O consisted of acicular α-Ti grains. As the oxygen amount increased, tensile strength was increased while maintaining a high elongation at break. The tensile strength of the 0.89 mass% O material increased by 764 MPa compared to the material without additional oxygen. The strengthening mechanism of SLM Ti-O alloys was quantitatively clarified to be oxygen solid solution and grain refinement strengthening.