Direct observations of collinear dislocation interaction in a Fe-17.4 Mn-1.50 Al-0.29 C (wt.%) austenitic steel under cyclic loading by in-situ electron channelling contrast imaging and cross-correlation electron backscatter diffraction

Abstract

In this study we present an integrated experimental approach combing in-situ electron channelling contrast imaging under controlled diffraction conditions (cECCI) and cross-correlation based electron backscatter diffraction (CC-EBSD) to explore the dislocation pattern evolution in a high-Mn austenitic steel under low-cycle fatigue. We experimentally observed that the interactions between dislocations of same Burgers vectors gliding on intersecting slip systems led to the annihilation of the screw parts and the formation of edge dislocation dipoles. This collinear dislocation interaction facilitated the construction of edge dislocation walls in the studied material deforming in planar slip mode.