Strengthening of aluminium alloy 7005 through imposition of severe plastic deformation supplemented by different ageing treatments

Strengthening of aluminium alloys 7xxx through the imposition of severe plastic deformation supplemented by ageing treatments is a challenge due to the limited workability of these alloys in cold deformation regimes. This study aims to comprehensively investigate the strengthening of aluminium alloy 7005 through the imposition of severe plastic deformation supplemented by two different ageing treatments: pre-deformation artificial ageing or post-deformation natural ageing. For this purpose, microstructure evolutions of the alloy processed through mentioned procedures were studied using X-ray diffraction and scanning electron microscopy while the alloy strengthening was evaluated using Vickers hardness measurement. Results show that a superlative strengthening is obtained through the imposition of severe plastic deformation supplemented by post-deformation natural ageing. For instance, the yield strength of the alloy increases to more than 400 MPa, about one-third greater than the counterpart amount after the usual T6 treatment. This superlative strength mainly occurs due to refinement of grains, an increase of dislocation density and an increase of volume fraction of the precipitates that appeared during natural ageing. Considering the applied models, it is inferred that the increase of volume fraction of precipitates that appeared during natural ageing has a determinative role in the strengthening of the alloy.

Automated summary

The study shows that a superior strengthening effect is achieved through the imposition of severe plastic deformation supplemented by post-deformation natural ageing. The yield strength of the alloy increases to over 400 MPa, which is about one-third higher than the value obtained after the usual T6 treatment. This superior strength is mainly attributed to grain refinement, increased dislocation density, and an increased volume fraction of precipitates during natural ageing.