A critical assessment of work hardening in TWIP steels through micropillar compression

Mechanical twinning and dislocation slip of a TWIP steel were investigated by compression of micropillars in twin-preferred orientations, i.e. [1 1 1] and [4 4 33], and slip-preferred orientations, i.e. [1 0 0] and [20 2 9]. The individual effects of twinning and slip on work-hardening behaviour were investigated. The orientation that showed the highest work hardening rate was typified by the concurrent activation of multiple slip systems. The specimens with the lowest work hardening rates deformed principally by mechanical twinning, followed by dislocation slip after the twinning strain was exhausted. It has therefore been concluded that dislocation slip, rather than mechanical twinning, was responsible for the high work hardening rates observed in the present specimens. A comparison of these results with macroscopic single crystal and polycrystal behaviour is also discussed.