Simultaneous improvement in strength and ductility of CT20 titanium alloy at cryogenic temperature

Revealing the Superior Post-Necking Elongation in the Fine-Grained Ti-6Al-4V ELI at Cryogenic Temperature

“…Within the fibrous zones, crack cores are formed. The surface of the shear lip appears smoother, with an angle of approximately 45 • with respect to the tensile stress axis, indicative of the enhanced ductility of the specimens at 77 K. This smoother surface and the characteristic angle further underscore the heightened ductility observed at 77 K [13].…”

“…However, the CRSS value associated with pyramidal slip is considerably larger than that of the basal slip and the Prismatic slip, rendering the activation of pyramidal slip challenging at a 77 K temperature. Previous research has indicated that the Prismatic slip has the lowest CRSS [11,13]. Although the SF of the prismatic slip, at 77 K deformation temperature, is slightly lower than the average value of pyramidal slip, prismatic slip is still significantly activated.…”

“…Due to the refined grain size and hindered dislocation mobility, the high strength of FG Ti-6Al-4V ELI at 77 K is typically accompanied by a reduced ductility, with the uniform elongation in FG materials (<3%) notably inferior to that seen in CG materials [10]. In the case of CG titanium alloys, deformation twins can enhance the tensile elongation through twinning-induced plasticity, fostering homogeneous deformation at 77 K [11][12][13]. According to the published investigations, FG metals exhibit the potential to maintain their ductility without compromising their strength to a considerable extent [14][15][16][17].…”