The effects of geometric dimension and grain size on impact properties of 316L stainless steel were clearly revealed based on the analysis of impact properties and fracture morphologies. Results showed that the large Charpy impacting samples exhibited a higher impact toughness than the small samples, which was ascribed to the higher value of Splain-strain/Stotal (70–80%). The mean size of the dimples in the plain-strain region increased with the increasing of grain size. For large-sized grains with smaller grain boundaries, the cracks are prone to form larger dimples during the propagation process, which can consume a high impact energy accompanied by a high impact toughness.
