Electron channeling contrast imaging of dislocation structures in fatigued austenitic stainless steels

Dislocation structures of fatigued austenitic stainless steel polycrystals were analyzed by electron channelling contrast imaging. The formation of persistent slip bands (PSBs) and vein structures were recognized in some grains. Effects of both grain size and Schmid factor on the PSB formation were investigated. The average diameter of the grains containing PSBs was higher than that without PSBs. On the other hand, there was no significant difference in the average Schmid factor between the grains with PSBs and the other grains. PSB formations was detected even in grains, where the Schmid factor was low, and the grain diameter was small. It was proposed that the stress concentration coming from piled-up dislocations in a neighboring grain was one of the reasons for the PSB formation in such grains.