A joint research team from Purdue University and Argonne National Laboratory used high-energy X-ray diffraction microscopy and micro-CT to non-destructively characterize the effects of porosity on micromechanical response and fatigue behavior in additively manufactured IN718 alloy under cyclic loading. The study found that specimens with lack-of-fusion pores initiated more fatigue cracks in fewer cycles, with a higher proportion of propagating cracks. Porosity amplified the global variability of microstress and diffraction spot width (a proxy for plastic deformation), but no local correlation was observed between these indicators and grain distance to crack initiation sites or pores, highlighting the limitations of grain-averaged metrics in fatigue prediction.