An EBSD examination of SUS316 stainless steel irradiated to 73 dpa and deformed at 593 K

Local deformation behavior in cold worked SUS316 stainless steels irradiated to 73 dpa at 573 K was examined by SEM and EBSD after deformation to plastic strain of ∼2% at 593 K at a strain rate of 7.8 × 10−8/s in an argon gas environment. Grain boundary separation occurred at random grain boundaries which lay almost normal to the tensile direction and had coarse dislocation channels in grains on one side. Misorientation maps indicated that a local high strain field existed near grain boundaries when coarse channels impinged on grain boundaries forming dislocation pileups. The grain boundary separation occurred more frequently at the grain boundaries where the difference in Schmidt factor was larger between two adjacent grains. These results indicated that the grain boundary separation was triggered by the local high stress field induced by dislocation pileups and high normal component of tensile stress.