In-situ investigation on fatigue behaviors of Ti-6Al-4V manufactured by selective laser melting

Abstract In-situ fatigue tests were conducted for exploring the fatigue crack propagation process for Ti-6Al-4V manufactured by selective laser melting (SLM). Fatigue specimens were prepared with two printing orientations by SLM and characterized by scanning electron microscopy (SEM). In-situ fatigue experiments were carried out at 25 °C, 200 °C, 400 °C and 600 °C, respectively. Results show that vertically printed specimens have more and larger defects than horizontally printed ones. The fatigue property of horizontally printed specimens is better than that of vertically printed specimens. The anisotropy caused by printing orientation is the reason for the difference in fatigue property. Crack propagation rate increases with temperature. A large number of secondary cracks occurred during the crack propagation at elevated temperature. The branching of secondary cracks releases the energy at the crack tip, and thus slows down the crack growth.