Grain Size Controls How Ultrafine TWIP Steel Begins to Deform
Researchers have revealed how microstructure — especially grain size and orientation — governs the initial plastic deformation behavior in an ultrafine-grained Fe–22Mn-0.6C TWIP (twinning-induced plasticity) steel, a high-manganese steel known for its combination of strength and ductility. By comparing specimens with fine (2 µm) and ultrafine (≈0.86 µm) grain sizes, and using digital image correlation (DIC) and electron microscopy, the team showed that the dominant deformation mechanism shifts dramatically as grains become very small. In larger grains, plasticity is dominated by dislocation glide and tangling, whereas in ultrafine grains it transitions to stacking faults and mechanical twinning, which affects strain localization and the characteristic serrations in stress-strain curves. This insight clarifies how grain refinement alters early deformation behavior in TWIP steels, which is valuable for designing advanced structural materials with superior mechanical performance.

Journal: Materials Science and Engineering: A (2022)
DOI: 10.1016/j.msea.2022.144506