Effect of twinned-structure on deformation behavior and correlated mechanical properties in a metastable β-Ti alloy

A microstructure design approach, which leads to twinning-induced plasticity (TWIP) effects through twinned structures, is investigated in this study to tune deformation behavior and correlated mechanical properties in Ti-Nb based Gum Metal (Ti-23Nb-0.7Ta-2Zr-1.3O, at.%). The pre-twinned Gum Metal exhibits a pronounced improvement in uniform elongation and work hardening rate, but a lower yield strength with increasing a twin fraction in the microstructure. To shed light on the underlying deformation mechanism responsible for the mechanical response under tensile stress, a global Schmid factor and a Kernel average misorientation are evaluated from experimentally observed results by electron backscattering diffraction (EBSD) analysis. The deformation behavior of the twinned Gum Metal demonstrates that intentional introduced twins are strongly related to the overall softening behavior, and enhanced uniform ductility, attributed to well-distributed twins throughout the entire microstructure based on the 'composite effect'. (C) 2019 Elsevier B.V. All rights reserved.