Effect of deformation twinning on microstructure and texture evolution during cold rolling of CP-titanium

Abstract

The evolution of microstructure and texture during cold rolling of commercial-purity titanium (CP-Ti) was studied with particular reference to deformation twinning and dislocation slip. For low to intermediate deformation up to 40% in thickness reduction, the external strain was accommodated by slip and deformation twinning. In this stage, both compressive ({1 1 2¯ 2}〈1 1 2¯ 3¯〉) and tensile ({1 0 1¯ 2}〈1 0 1¯ 1¯〉) twins, as well as, secondary twins and tertiary twins were activated in the grains of favorable orientation, and this resulted in a heterogeneous microstructure in which grains were refined in local areas. For heavy deformation, between 60 and 90%, slip overrode twinning and shear bands developed. The crystal texture of deformed specimens was weakened by twinning but was strengthened by slip, resulting in a split-basal texture in heavily deformed specimens.