In situ electron backscatter diffraction study of twinning in commercially pure titanium during tension-compression deformation and annealing

Abstract

Tension-compression forward and reverse loading followed by annealing at 773K for 1h was carried out on commercially pure titanium using an in situ heating stage with tensile testing facility in scanning electron microscope fitted with electron backscatter diffraction setup. Twins of four different variants were observed during tension in load control mode in a relatively large grain within the area of inspection. Morphology of the twins changed during subsequent deformation stages and un-indexed points within the twins decreased or increased which may be due to changes in dislocation density during unloading and compression loading stages. Reloading in tension caused barrelling of the twins. Some of the twins disappeared and new twins formed during annealing. Although all the variants show similar Schmid factor for extension twinning, there is variation in lateral thickening of different twin variants within the same grain which can be explained from variation in elastic modulus. It is also observed that twin intersections can play an important role in nucleation and growth of new twins.