Deformation twinning

Microstructure evolution and strengthening mechanisms of Fe–23Mn–0.3C–1.5Al TWIP steel during cold rolling

“…Austenitic steels with high Mn content exhibit the most attractive combination of tensile strength and superior ductility due to their extraordinary strain-hardening rate, which is interpreted in terms of twinning-induced plasticity (TWIP) [2][3][4][5][6]. It is known that in face-centered cubic (fcc) metals with low stacking fault energies (SFEs),extensive deformation twinning results in the formation of deformation twins with a plate-like shape as well as nanometer spacing and thickness [2,[7][8][9]. The twin boundaries, which are special (low ÀΣ coincidence site lattice) high-angle boundaries [7] and contain a high density of sessile dislocations [8], act as equally effective obstacles to dislocation gliding as conventional grain boundaries in polycrystalline austenitic steels [10].…”

“…It is known that in face-centered cubic (fcc) metals with low stacking fault energies (SFEs),extensive deformation twinning results in the formation of deformation twins with a plate-like shape as well as nanometer spacing and thickness [2,[7][8][9]. The twin boundaries, which are special (low ÀΣ coincidence site lattice) high-angle boundaries [7] and contain a high density of sessile dislocations [8], act as equally effective obstacles to dislocation gliding as conventional grain boundaries in polycrystalline austenitic steels [10]. The subdivision of initial grains into lamellas with thicknesses ranging from 10 to 40 nm [2][3][4][5][6]8] leads to a significant decrease in the effective grain size and, therefore, results in remarkable strengthening in accordance with the Hall-Petch relationship [11-13]: σ 0:2 ¼ σ 0 þK H d À 0:5 ð1Þ where σ 0.2 is the offset yield strength; d is the effective grain size, which is the distance between barriers to dislocation glide and can be estimated to be twice the width of lamellae [14]; σ 0 is the friction stress; and K H is the Hall-Petch coefficient.…”

Twinning effects on strength and plasticity of metallic materials

“…Deformation twinning in hcp materials is directional, with a unique sense of shear, and results in the formation of a sheared domain, contributing to plastic deformation along the c -axis. 2 The article by Liao et al highlights several of these studies with a focus on the twinning system {10 1 2}〈10 11 〉, which is commonly activated in most hcp materials. The authors point out several technical challenges associated with deformation twinning in hcp materials.…”

Proceedings of the 13th World Conference on Titanium

“…This is particularly the case during compression loading [7]. In α titanium, four different twinning modes have been reported [8]. At room temperature, the predominant twinning mode is the {10-12}<-1011> tensile twin [9,10] , which corresponds to a rotation of 85° around the <11-20> axis.…”