Transient strain age hardening of Al–Mg alloys

Abstract

The static strain aging response of an Al–Mg alloy is investigated by means of tensile pre-deformation followed by annealing. The mechanical response following re-testing in tension reveals a lower flow stress and raised work hardening rate at yield. The enhanced work hardening rate is shown to be transient, the behaviour returning to that of the non-aged material at high flow stress. In order to decouple the various effects arising from solute segregation and dislocation loss via recovery, a simplified version of the two internal state variable model originally proposed by Kubin and Estrin is introduced. It is proposed that the response, yield strength and work hardening rate, following pre-deformation and annealing can be ascribed to the combined effects of the loss of mobile dislocations and a transient hardening that is interpreted to come from dislocations that have had solute segregated to them.