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

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.

Dynamic Precipitation of Laves Phase and Grain Boundary Features in Warm Deformed FeCrAl Alloy: Effect of Zr

“…Another strategy for improving the properties of Fe-Cr-Al alloys was grain boundary processing [21][22][23]. It is well known that grain boundaries (GBs) play an important role in influencing a wide array of properties such as diffusivity, conductivity and resistance to failure through intergranular creep and corrosion [24,25].…”