Abstract
Superplastic deformation behavior of a Zn-22%Al eutectoid alloy was investigated based on the changes in m values and true strain rate during the tensile deformation. Transition from the uniform elongation to the neck formation stage was changed by changing the initial strain rate taking account of the maximum m value against the true strain rate. Preliminary estimation of the fracture elongation was also given from the initial strain rate. Transition from the uniform elongation to the necking stage could be predicted from the differentiation of the m values with regard to the true strain rate during the tensiles uperplasticd eformation. Fracture elongation changed in accordance with the distribution of the true strain rate and m values. The wide distribution of high m value resulted in the increased fracture elongation. The elongationo btained in the first superplastic deformation stage (uniform deformation) was estimated using the experimentally proposed equation based on the initial strain rate.
