Abstract Scope |
Fatigue failure of additively manufactured Ti-6Al-4V in machined surfaces can almost always be traced back to volumetric defects, such as gas-entrapped pores, key holes, and lack-of-fusion defects. The variability in the defect content can influence the initiation of fatigue cracks, which occupies a major portion of fatigue lives in the high cycle fatigue regime. This presentation highlights some length-scale aspects in the critical effects of volumetric defects, namely, their size, aspect ratio, and distance from surface. Linear elastic finite element analysis on small cracks initiated from defects is performed to evaluate their stress intensity factors and how they are influenced by defect features. Assuming that the stress-life behaviors of defect-laden materials converge at a certain low life cycle, fatigue life is estimated by applying relative knock-downs to the endurance limit of a reference stress-life data. These findings are validated using the fatigue data of laser powder bed fused Ti-6Al-4V. |