Visualization of dislocations through electron channeling contrast imaging at fatigue crack tip, interacting with pre-existing dislocations

The dislocation pattern at the tip of a non-propagating fatigue crack in an Fe-25Cr-1N steel (mass%) was characterized by electron channeling contrast imaging. Planar dislocation arrays on two different slip planes were observed at the crack tip. Each planar dislocation array acts as a barrier to the motion of the other planar dislocations on different slip planes, contributing to the enhancement of the resistance to the crack propagation. This paper employs ‘electron-channeling-contrast-imaging (ECCI) in scanning electron microscope’ technique to visualize fatigue crack tip dislocations in high nitrogen steel, and it showed highly planar dislocations interacting with pre-existing dislocations assisting non-propagating fatigue crack.