Influence of dislocation structures on precipitation phenomena in rolled Al–Mg–Si alloy

Abstract The effect of heavy deformation on precipitation strengthening in a commercially available 6082 alloy was studied. Three levels of deformation were applied to a supersaturated solid solution (including two accumulative roll bonding cycles) followed by artificial ageing at the conventional temperature. The sample with the lowest accumulative strain was the only one that exhibited a strengthening effect. However, the initial examination of deformation induced dislocation structures has shown no differences between various deformation levels. In-situ heating TEM experiments were performed on all specimens to verify the impact of defects on precipitation and the results followed the behaviour of the bulk specimens. Then, dislocation structures were re-examined. It was found that the appearance of dislocation structures depend on the specimen thickness since in the thinnest area of observation dislocation density is significantly reduced in specimens after accumulative roll bonding. The mechanism of precipitates nucleation and further growth is discussed in the light of these observations.