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 T_m where T_m 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.