Recovery and recrystallization in the superplastic deformation of AA5182

The coarse-grained Al alloy AA5182 exhibits poor superplasti-city with a maximum elongation to failure not exceeding 220 % at 450 C and at 10-2 s-1. The low values of the strain rate sensitivity indicate that the dislocation velocity is quite high and necking is developed quite soon during extension. The size (often exceeding 1 lm) and the distribution of the precipitates render them incapable of pinning the subgrain boundaries efficiently. As a result recovery and reconstruction by grain refinement occurs only within the neck-ing region where the applied stress is concentrated. A fabrication method which will be able to introduce a large number of submi-cron sized precipitates will most likely result in sufficient pinning of the subgrain boundaries. This will promote recovery and recon-struction to take place more uniformly in the material rendering it appreciably superplastic