Elastic-plastic stress/strain response of friction stir-welded titanium butt joints using moire interferometry

An experimental investigation is conducted to examine, evaluate, and characterize the fundamental elastic-plastic stress/strain response of friction stir-welded butt joints in thin-sheet, fine grain Ti-6Al-4V titanium alloy under normal tensile loading using the full-field optical strain analysis technique of moire interferometry. It was found that the overall strength of friction stir-welded Ti-6Al-4V is comparable to the accepted values for pure mill-annealed Ti-6Al-4V and the overall strain performance of friction stir-welded Ti-6Al-4V is roughly half that of the accepted values for pure mill-annealed Ti-6Al-4V. In addition, friction stir-welded Ti-6Al-4V demonstrates a consistent pattern of strain localization between the onset of yielding and ultimate failure. The resolvability of such strain localizations and their impact on far-field behavior can only be realized with full-field measurements such as those obtained using the moire interferometry technique. Published by Elsevier Ltd.