2001 Volume 14 Issue 1-2 Pages 35-42
Cu-30mass%Zn alloys with various grain sizes were tensile tested under various strain rates from 3.3×10-5s-1 to 3.3×10-3s-1 and at temperatures from 523K to 773K. Elongation to fracture for fine-grained specimens shows high ductility and a maximum value in a range of intermediate temperature. The peak ductility increases with increasing in strain rate though it does not depend on the initial grain size. Type of the flow curves is controlled by the factors of temperature, strain rate and initial grain size. The flow curve of coase-grained specimens shows a serrated flow at lower temperatures and at higher strain rates while shows the work softening processes at other conditions. The flow curve of fine-grained specimens shows a typical flow behavior of dynamic recrystallization. It should be noted that these flow curves tend to change from a type having simple peak due to dynamic recrystallization to another type having multiple peaks with decreasing initial grain size and strain rate and/or with increasing temperature.
The values of stress exponent and apparent activation energy for deformation range from 3 to 5 and from 120 to 135KJ/mol, respectively. The main reason for this can be explained by a fact that the both mechanisms of dislocation glide and grain boundary sliding occur simultaneously.
