Twinning Behavior of Commercial-Purity Titanium Subjected to Cryorolling

Deformation twinning was investigated in a commercial-purity titanium alloy cryorolled to 4% reduction. Significantly more twins were found in the cryorolled sample compared with that rolled at room temperature. {11 (2) over bar2} twinning was the dominant twin type, with some {11 (2) over bar4} twins as the most abundant accompaniment. The twin variant selection is discussed in terms of the Schmid factor (SF). Most of the {11 (2) over tilde2} and {11 (2) over bar4} twins obeyed Schmid's law, resulting in considerable external strain accommodation. The c-axes of the parent grains with {11 (2) over tilde2} and {11 (2) over tilde4} twinning were nearly parallel to the normal direction, with the latter being closer. Both the {11 (2) over tilde2} and {11 (2) over tilde4} twins tended to have high SF in one grain, and they usually accompanied each other. Furthermore, the cryorolled sample exhibited better mechanical properties compared with that rolled at room temperature.