Pseudo-Superplastic Characteristics of ZK60 Alloy with Fibrous Microstructure

Abstract

The superplasticity of ZK60 alloy was investigated after thermomechanical treatments (combination of rolling at 473 K and 673 K). ZK60 alloy, with an equiaxial grains microstructure (average grain size 2.6 mu m), showed a maximum elongation of 865.2% with the strain rate 1 x 10(-4) s(-1) under high temperature tensile test at 573 K. Surprisingly, hot-rolled ZK60 samples with fibrous microstructure also displayed pseudo-superplastic behavior with an elongation of 535.2% at the same temperature. Microstructures indicated that the hot-rolled samples with elongated grains exhibited dynamic recovery and recrystallization during high temperature deformation, transforming the fibrous to fine-grained crystals, and thus retaining pseudo-superplastic behavior.