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 multipass 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 multipass 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.