A constitutive description of an aluminum-0.32 Pct iron under hot-deformation conditions

Abstract

The constitutive behavior of an aluminum-0.32 wt pct Fe alloy deformed under hot-working conditions has been analyzed on the basis of the concept of the mechanical threshold stress \((\hat \sigma )\). The evolution of this parameter has been described in terms of a generalized form of the exponential-saturation equation earlier advanced by Sah et al., whereas the characterization of the ratio between the flow stress at any strain rate and temperature (s(\(\dot \in \), T)), and \(\hat \sigma \) has been carried out by means of the model advanced by Follansbee and Kocks. In the generalized form of the Sah et al. law employed for the description of the change of \(\hat \sigma \) with e, it has been considered that the relaxation strain is only dependent on the strain rate and that such a dependence can be expressed by means of a simple parametric relationship. It has been shown that the experimental values of the flow stress can be accurately described following this approach and that, in general, the maximum difference between the experimental and calculated values of such a parameter is less than ±8 MPa. It has also been shown that it is possible to determine unambiguously all the parameters required for the description of the current flow stress in terms of the mechanical threshold stress from stress-strain data obtained at a constant temperature and strain rate.