Development of grain structure in β-phase field during friction stir welding of Ti–6Al–4V alloy

The electron backscattered diffraction technique was employed to examine the microstructural evolution in the high-temperature β-phase field during friction stir welding of a Ti–6Al–4V alloy. Reconstruction of the β-grain structure demonstrated that development of the grain structure is presumably governed by grain elongation and transverse grain subdivision. Orientation measurements in the retained β-phase showed that the material flow may be described in terms of a simple-shear deformation arising from the {1 1 0}〈1 1 1〉 slip.