Correlating the evolution of spatial-resolved microscale residual stress and the associated dislocation behavior in additively manufactured 316L stainless steel upon short-term annealing

Abstract

Additive manufacturing (AM) processes, such as laser powder bed fusion (L-PBF), often introduce significant residual stresses in components, which are typically mitigated through heat treatments (HTs) to optimize mechanical properties. However, the evolution of microscale residual stresses during annealing and their underlying mechanisms remain poorly understood. In this study, we employed quasi in-situ electron channeling contrast imaging (ECCI) combined with cross-correlation electron backscatter diffraction (CC-EBSD) to track the spatially resolved evolution of microscale residual stresses and associated dislocation behaviors in a L-PBF fabricated 316L stainless steel upon annealing. A direct correlation is established between dislocation arrangements within dislocation cells and sub-grain boundaries (SGBs) and the distribution of microscale residual stresses. Our results reveal that dislocation activity is modulated by the presence of these microscale residual stresses, which, subsequently, dictate their redistribution during annealing. Furthermore, the influence of different HTs on governing deformation mechanisms and microscale residual stress evolution under plastic deformation is quantitatively estimated. This work provides new insights into the intricate interplay between dislocation dynamics and microscale residual stress evolution during annealing, with implications for optimizing the mechanical properties of AM components.