Superplastic deformation behaviours of Zn-22%Al of eutectoid.

Abstract

Superplastic deformation behaviours in superplastic Zn-22%Al eutectoid alloy were investigated. Smooth and notched specimens having the thickness of 1, 2 and 3mm were applied in the present experiment in view points of the change of true strain rate and m values during the course of the tensile superplastic deformation and variation of the fracture elongations. The results are summarized as follows: (1) Superplastic deformation of the smooth specimens was reasonably explained by dividing the deformation into sequential five steps. (2) Superplastic deformation of the notched specimens was reasonably explained by dividing the deformation into sequential two steps without passing the first three steps observed in case the smooth specimens. (3) Fracture elongations of the smooth specimens were effected by the variation of the specimen thickness and increased by 12 to 25% with the increase of the specimen thickness from 1 to 3mm. (4) The fracture elongation of the notched specimens was also effected by the specimen thickness and increased by 2 to 20% with the increase of the thickness of the notched specimen.