Pragna Bhaskar¹, Josh Kacher ¹; ¹Georgia Tech

Twin and high angle grain boundaries are known to play important roles in crack initiation processes during cyclic loading in ductile FCC materials such as stainless steel 316L. However, little is known of the developing dislocation state leading up to crack formation. To study the evolving deformation state at twin and grain boundaries, a multiscale characterization approach combining electron backscatter diffraction (EBSD)-based geometrically necessary dislocation density measurements with site specific transmission electron microscopy (TEM) analysis was applied at interrupted stages of fatigue loading. In this approach, EBSD data are used to generate a statistical understanding of how microstructure characteristics such as grain size and grain boundary characteristics influence dislocation accumulation and to guide site selection for TEM analysis. Results will be discussed in terms of crack formation mechanisms at grain and twin boundaries and how boundary characteristics influence dislocation accumulation patterns.