5083アルミニウム合金の超塑性挙動

抄録

Superplastic behaviors were observed in a commercial JIS A5083 aluminum alloy which had been heat-treated to have an equiaxed recrystallization structure with a grain size of about 7 μm.
In the optimum condition in this work, at 763 K and at 1.11×10⁻³ s⁻¹, the specimen showed the maximum elongation of 460%. The plots of the maximum engineering stress against the initial strain rate in the temperature range from 613 to 783 K showed the characteristic S-shape feature, and the maximum m-values measured from these plots were about 0.5. The grain coarsening during the superplastic deformation was found to be proportional to the true strain of the specimen, and to be more remarkable with rising temperature. In conditions of an appreciable grain coarsening, the strain rate corresponding to the maximum elongation shifted to a lower value with rising temperature, which was a tendency different from that predicted by deformation behaviors in common superplastic materials.
Generation and development of striation bands on the specimen surfaces deformed superplastically and disintegration of the texture during deformation were also observed.