A new phenomenological constitutive model for hot tensile deformation behaviors of a typical Al-Cu-Mg alloy

The hot tensile deformation behaviors of a typical Al-Cu-Mg alloy are investigated by uniaxial tensile tests with the strain rate range of (0.05-0.001) s−1 and temperature range of (673-748) K. The experimental results show that the true stress-strain curves exhibit a peak stress at a very small strain, after which the flow stresses decrease slowly until fracture, showing an obvious dynamic softening behavior. This hot tensile deformation is a thermally activated process, which indicates the competitions of work hardening, dynamic recovery, dynamic recrystallization, and the initiation and growth of voids or cracks. Considering the coupled effects of forming temperature, strain rate, and strain on the material hardening and softening behavior, a new phenomenological constitutive model is proposed to describe the hot tensile deformation behaviors of the studied Al-Cu-Mg alloy under relatively low strain rates. In the proposed constitutive model, the material constants are expressed as functions of forming temperature and strain rate. A good agreement between the predicted and measured results shows that the proposed model can give an accurate estimate of flow stress for the studied Al-Cu-Mg alloy.