Residual stresses, microstructure and tensile properties in Ti–6Al–4V friction stir welds

This paper reports the results of a systematic investigation of residual stresses as a function of welding speed in a set of Ti–6Al–4V friction stir welds. The investigation focuses on residual stress but links these data with microstructural information derived from micrographs and hardness measurements as well as mechanical testing results. Residual stresses were determined using energy dispersive synchrotron X-ray diffraction, which allows phase specific stresses to be distinguished. The data presented in this paper demonstrate that welds with high tensile properties can be obtained, which also have relatively low peak tensile residual stress values of ∼30% of the tensile strength. The data also show a clear correlation between heat input and the width of the residual stress profile.