The stress state dependence of cavitation in commercial superplastic Al5083 alloy

The cavitation behaviour of superplastic alloys has relatively been less examined under biaxial tension, though it has been demonstrated by some researchers that stress state does affect the cavitation behaviour. In this paper, a commercial superplastic Al5083 alloy was investigated under stress ratios of 1, 0.8293, 0.6667, 0.5985 and 0. It is found that at the same effective strain, the amount of cavities under equi-biaxial tension is significantly larger than that under unaxial tension, which is in agreement with the trend of the theoretical predictions. The cavitation data under stress ratios from 1 to 0.5985 are very close and have much overlaps. These results are consistent with the theoretical predictions, as the difference between the predicted cavity growth rates is not significant. It is considered that more effort is required to improve the accuracy of both the experimental measurements and the theoretical predictions.