Fatigue and Strength Studies of Titanium 6Al-4V Fabricated by Direct Metal Laser Sintering

Abstract

Vibratory bending fatigue life behavior of Titanium (Ti) 6Al-4V plate specimens has been assessed. The plates were manufactured via direct metal laser sintering (DMLS), which is a powder bed, laser deposition additive manufacturing process. Motivation for this work is based on unprecedented performance demands for sixth generation gas turbine engine technology. For example, the inclusion of a third stream flow for improving engine performance may add complexity and weight that could offset anticipated thrust and fuel efficiency gains. Therefore, complex, lightweight components with improved functionalities are desired. Novel component design concepts have been cost, schedule, and feasibility limited when using conventional manufacturing methods. Additive manufacturing, however, can extend the thresholds of component concepts. Though additive manufacturing can be a promising addition to the turbine engine community, the manufacturing process controls required to achieve consistency in material properties have not been fully identified. The work presented in this manuscript investigates variability in vibration-based bending fatigue life of DMLS Ti 6Al-4V compared to cold-rolled Ti 6Al-4V. Results show discrepancies between the fatigue life variation of DMLS and cold-rolled data. Along with the support of fusion and post-fusion process parameters, the fatigue results are also supported by tensile property characterization, fractography, and microscopy.