Effect of material positioning on fatigue life of the friction stir processed dissimilar joints

The investigation on the fatigue behavior of the friction stir processed (FSPed) dissimilar joint is reported in this work. The main focus was to analyze the influence of material positioning on the fatigue life of the joint. The 1pass friction stir processing technique was applied on the friction stir welded AA8011/AA6082 and AA6082/AA8011 dissimilar joints (AA8011/AA6082 means AA8011 on the advancing side, AA6082/AA8011 means AA6082 on the advancing side). The friction stir processing was conducted under normal conditions (room temperature). The samples were prepared for different analyses using waterjet cutter technology. The tests conducted include tensile, microstructural analysis, microhardness, fatigue, and fracture surface morphology. The microstructural analysis revealed a correlation between material positioning and grain sizes. There was a notable decrease in grain size when AA6082 was positioned on the advancing side during processing. The tensile properties of the FSPed AA6082/AA8011 joint were found to be higher compared to the AA8011/AA6082 joint. The AA6082/AA8011 joint was found to be more ductile compared to the AA8011/AA6082 joint. The stir zone microhardness values for the AA8011/AA6082 and AA6082/AA8011 joints were found to be approximately 68HV and 73HV, respectively. The fatigue strength of AA6082/AA8011 was found to be higher compared to that of AA8011/AA6082.