Acoustoelasticity to measure residual stresses in plates of 5052 aluminum joined by FSW

The present work evaluates the use of acoustoelasticity techniques to measure residual stresses produced by friction stir welding (FSW) in joints of 5052 aluminum alloys after milling to develop an inspection tool for production lines. A set of experiments was adequately planned to obtain the acoustoelastic coefficient of the material, considering the welding zones. Then, the magnitude and distribution of longitudinal residual stresses throughout the perpendicular direction were obtained using an improved measurement procedure for the ultrasonic method. The technique was shown to be effective for the proposed application, as the results were validated by another residual stress measurement method. It was demonstrated that the magnitude of the stresses depends on the combination of FSW parameters, which must be selected according to the characteristics of the alloy. The results showed that lower rotational and traverse tool speed produced higher residual stress levels, indicating a significant propensity to failure that results in a decrease in welding quality.