High temperature deformation kinetics of Al-4Mg alloy

Abstract

The flow behaviour and kinetics of deformation in the temperature and strain-rate range encountered are important and relevant in material processing since this information will be useful in the calculation of working loads and in identifying the mechanisms of deformation. An evaluation of the mechanism of high-temperature deformation suggests directions of control for enhanced workability and for developing superior properties. In this study, solid cylindrical specimens of Al-4Mg alloy were subjected to insiute compression tests in the temperature range of 550–800 K and at strain rates of 0.02, 0.2, 8 and 200 s^-1. The flow stress, true strain, strain rate and temperature rise were evaluated from the transient measurements made during the tests. The flow stress values have been represented in terms of actual or adiabatic temperature instead of initial test temperature. The kinetics of high temperature deformation are expressed by means of some empirical rate equations. Based on the activation parameters, a mechanism of dynamic recovery involving cross-slip of dislocations has been identified to be the high temperature rate controlling mechanism in the Al-4Mg alloy.