This talk discusses two related investigations on electron beam melted (EBM) titanium alloy (Ti-6Al-4V).  In the first, the effects of internal pores and residual stress on high-cycle fatigue properties of EBM Ti-6Al-4V material in as-built, stress-relieved, and hot isostatic pressed (HIPed) conditions were evaluated.  Conventional techniques were used to measure the chemical composition and quantify microstructures, and neutron scattering was utilized to measure residual stresses.  Post-processing did not alter chemical composition.  Compared to the as-built condition, microstructure was unchanged for stress-relieved material and coarser for HIPed material.  No significant residual stresses were measured for any of the three conditions.  This indicates build platform and layer preheating lead to sufficient process temperatures to achieve full stress relief in-situ.  The fatigue strengths at 10^7 cycles measured for the as-built and stress-relieved conditions were statistically similar and were measured to be 200 MPa to 250 MPa.  A significantly higher fatigue strength at 10^7 cycles of 550 MPa to 600 MPa was measured for the HIPed condition and attributed to a reduction in internal porosity.  In the second piece of work, the effects of internal pores and crystallographic texture on fatigue crack growth rate of EBM Ti-6Al-4V were investigated by studying material in the as-built and HIPed conditions as well as in two orthogonal crack growth directions with respect to the build direction.  Significant texture variation was found to occur due to small changes in an often-ignored processing variable. Both internal porosity and crystallographic texture were found to affect the onset of unstable crack growth, but neither were found to affect Paris Law behavior.  Implications on threshold behavior will also be discussed.

Effect of Internal Porosity, Residual Stress, and Crystallographic Texture on High-Cycle Fatigue and Fatigue Crack Growth Rate Behavior of Additively Manufactured Titanium Alloy (Ti-6Al-4V)

The Virtual Technical Meeting of the Society of Engineering Science 2020 is the first fully virtual meeting of the SES community to envision and connect during the hiatus created by Covid-19, providing a platform for the exchange of ideas, and to showcase the latest research in the field of engineering science.

[Visit the Programme](https://drive.google.com/file/d/1BoCPBzrr1IQFANuzQI8a-paXCJoOcCkB/view?usp=sharing) | [Visit the Prerecorded Video/Poster List](https://drive.google.com/file/d/1XHLeEXJxEFjCSsNScuLDfMwy1X7oy7oJ/view?usp=sharing) | [View the Session Grid](https://drive.google.com/file/d/1VeDOC-Ev5m_ymYjXnjaXSZHR3_DARiLt/view?usp=sharing)