Multiple damage mechanisms facilitated by planar dislocation glide in a commercial-grade precipitation-strengthened Fe–Ni–Cr-based steel

The present study addresses the damage evolution mechanism in precipitation-strengthened Fe–Ni–Cr-based steel (SUH 660) at ambient temperature in air. Specifically, damage quantification and associated microstructure characterization were performed. The damage initiation sites were inclusion and grain boundaries impinging dislocation slip. The early stage of damage evolution was observed before necking of the specimen. Subsequent plastic straining caused damage growth along slip planes and coalescence of damage via localized shear in ligaments between damages, for which the behavior was associated with the planar character of the slip. The damage evolution behavior observed in the post-mortem specimen was consistent with fractographic characteristics.