Investigation of tensile deformation behavior of pure titanium at 20 K

Abstract

The cryogenic tensile properties and deformation behaviors of pure titanium at liquid hydrogen temperature (20 K) were investigated. Compared with 298 K, high ultimate tensile strength (UTS) of 978 MPa and the excellent elongation-to-fracture (El) of 48 % were achieved. A large number of {101‾2}<1‾011 > and {112‾2}<112‾3‾ > deformation twins released local stress concentration and lead to high work hardening rate, which endow pure titanium with excellent strength and ductility. In addition, the inhibition of multiple necking of pure titanium at 20 K is due to a large number of deformation twins released the stress concentration and produced a strong dynamic hardening effect, which relieved the local plastic deformation. And the serrated stress-strain curve is caused by intermittent activation of twining and dislocation slip. Finally, the twins are thinner at 20 K are attributed to the more obvious stress concentration. The cryogenic deformation mechanism and fracture behavior are explained from two aspects of dislocation accumulation and thermal physics.