Fatigue behaviour of the multi-pass friction stir processed AA8011-H14 and AA6082-T651 dissimilar joints

Abstract

The AA8011-H14 and AA6082-T651 were used to produce dissimilar joint through the use of friction stir welding (FSW) technique. The produced dissimilar joint was processed using multi-pass friction stir processing (FSP). The microstructural analysis revealed that the grain sizes reduced with an increase in the number of FSP passes irrespective of material positioning. However, the multi-pass AA6082-AA8011 joints had finer grain structure compared to the multi-pass AA8011-AA6082 one. The ultimate tensile strength of the multi-pass FSP had an increase of 11.6% compared to that of the single-pass one, but only for the AA8011-AA6082 joints, while the AA6082-AA8011 had an increase of 9% on the two-pass FSP. The number of FSP passes was found to have a marginal effect on the microhardness of the joints. The two-pass FSP joints were found to be more ductile compared to the other passes. The fatigue results revealed that the AA6082-AA8011 joints had longer fatigue life compared to that of the AA8011-AA6082 joints. The increase in the number of FSP passes increased the fatigue life of the AA8011-AA6082 joints, while AA6082-AA8011 joints experienced extended fatigue life cycle on the single-pass FSP.