In this study, irradiation-assisted stress corrosion cracking (IASCC) resistance of as-built AM 316L stainless steel (SS) made by direct energy deposition (DED) was evaluated in a simulated boiling water reactor (BWR) environment. Different from the intergranular cracking typically seen from 316L SS, unique intragranular cracking away from grain boundaries (GB) was observed. The presence of high-density micron-sized delta ferrite near the melt pool boundaries promoted the in-grain strain localization and crack nucleation. Delta ferrite particles can efficiently retard dislocations during deformation, altering the strain localization from the GB to its surrounding area and thus reducing the chance of GB cracking. The phenomenon was further confirmed by the higher nanoindentation hardness measured from the corresponding area, and by characterizing the evolution of microstructure, cracking morphology, and dislocation channels.