Reversed evolution of dislocation structures during high–low strain-controlled fatigue for interstitial-free steel

This work aimed to understand the relationship between gliding behavior of dislocations and reversed evolution of dislocation structures in pure BCC (body-centered cubic) metals, using automotive-grade interstitial-free steels (IF steel) under strain ratio (R) = 0 for case studies. The corresponding dislocation structures for ɛmax = 0.2% and 1.2% are loop-patch structure and dislocation-cell structure, respectively. However, dislocation cells were converted into loop-patch structures and the gilding behavior of dislocations would have changed from the original multiple-slips to single-slip when the ɛmax was reduced from 1.2% to 0.2%.