Acta Metallurgica Sinica (English Letters) ›› 2021, Vol. 34 ›› Issue (2): 169-173.DOI: 10.1007/s40195-020-01176-z

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Dislocation Source and Pile-up in a Twinning-induced Plasticity Steel at High-Cycle Fatigue

Rendong Liu1, Zhiyuan Liang2(), Li Lin1, Mingxin Huang3()   

  1. 1Iron and Steel Research Institute, Ansteel Group, Anshan, 114021, China
    2Songshan Lake Materials Laboratory, Dongguan, 523808, China
    3Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, China
  • Received:2020-09-29 Revised:2020-10-22 Accepted:2020-11-06 Online:2021-02-10 Published:2021-02-09
  • Contact: Zhiyuan Liang,Mingxin Huang

Abstract:

Dislocation behaviour of a twinning-induced plasticity (TWIP) steel subjected to high-cycle fatigue tests is investigated in the present study. Grain boundaries are the important sources of dislocation generation during fatigue tests, contributing to the increase in dislocation density. Continuous emission of dislocations from grain boundaries is observed in many grains. Inclusions can sustain large dislocation pile-ups at the inclusion interfaces, leading to a high stress concentration and therefore acting as potential sites of microcrack nucleation. In contrast, annealing twin boundaries are relatively weak boundaries for dislocation pile-ups. When the number of dislocations in a pile-up is large, dislocations can crossover twin boundaries and glide inside the annealing twins. The stress concentration at the twin boundary is relatively low so that twin boundaries could not act as the sites for microcrack initiation.

Key words: Dislocation source, Grain boundary, Twin boundary, Fatigue, Inclusion