The thermo-mechanical behavior of 6061 aluminiummagnesiumsilicon alloy

Abstract

The strength of age hardening aluminummagnesiumsilicon alloy 6061 has been analyzed in terms of thermally activated dislocation motion. Petinent models for the athermal component of the flow stress were modified for application to the needle-shaped GP zones in this alloy because existing treatments have been developed and evaluated only for spherical or disk-shaped zones. The results of that step were combined with an equation for the kinetics of aging to produce a relation which could be compared with experiment. Results indicate that the athermal flow stress is controlled primarily by the work required for dislocations to shear through the GP zones. It is shown that the thermal component of the flow stress cannot be adequately explained either by long range elastic stresses at the zones, or by the mechanism of jog formation at intersecting dislocations. Instead, the shear of GP zones contributes significantly to the thermally activated flow stress. The measured thermal stress component is compared with the predictions of a model which is physically consistent with the mechanism for the athermal stress, and the contributions of compatibility slip and dislocation bowing are taken into account.