Fatigue life cycle
Figure 6 shows the stress –number of cycles to failure curves for the
AA6082/AA8011 and AA8011/AA6082 friction stir processed FSWed joints.
The AA8011/AA6082 joint had a fatigue life of
4.489×105 while the AA6082/AA8011 had a a life span of
1.765×106. The AA6082/AA8011 had a longer fatigue life
cycle compared to the AA8011/AA6082 joint and similar behaviour is alos
found in the literature [37-39]. The fatigue life behaviour was
found to be in agreement with the findings by Park et al. [20],
which reports that the fatigue life increases as the microstructural
grains decreases.