Using the stress-strain relationships to propose regions of low and high temperature plastic deformation in aluminum

The plastic deformation of pure aluminum was investigated by tensile testing over a wide range of temperatures. In the region of positive work-hardening, it is shown that the stress-strain relationship can be described by an exponential-power law constitutive equation that was proposed recently and, in addition, this equation leads to a definition of the low and high temperature deformation regions. In the low temperature region, the macroscopic stress-strain behavior increases monotonously over a wide range of strain whereas at high testing temperatures the flow stress increases only up to a critical strain level. For pure aluminum, it is shown that the boundary between these two regions occurs at an homologous temperature of the order of ∼0.51 Tm where Tm is the absolute melting temperature. It is demonstrated that some important characteristics of the high temperature deformation process may be determined through the application of this new constitutive relationship.