Rolling reduction - dependent deformation mechanisms and tensile properties in a β titanium alloy

This work investigated the dependence of deformation mechanisms and mechanical properties on cold rolling reductions of the metastable TB8 titanium alloy. Results shown that the crystal orientation of the matrix changes with the increasing level of reduction, leading to the activation of complex deformation mechanisms in the matrix. When the rolling reduction is 10%, the deformation mechanisms are dominated by dislocations and {332}<113> deformation twins. As the reductions increase to 20%-50%, the secondary deformation twinning (SDT) is triggered in primary deformation twins besides the primary kink band is activated. Meanwhile, the secondary kink bands and {332}<113> twins have be observed in the primary kink bands. When the reduction reaches to 60%, the deformation mechanisms are dominated by dislocations and deformation twins. Furthermore, the matrix refined by crisscrossing among the twins, kink bands and other deformation mechanisms during cold rolling, which shortens the dislocation mean free path and then affects the strength and shape of the alloy. The dynamic Hall-Petch effect and the interaction between multi-scale deformed structures control the work hardening behavior of the alloy.