The ageing behavior of 6063 aluminum alloy produced with grain-refining aluminum ingot has been examined by TEM and DSC. It is found that the 6063 aluminum alloy exhibits better ageing hardening behavior with ageing at 200 ℃

which can not only obtain higher ageing hardness at a short time （about 80 min）

but also remain higher ageing hardness at a longer time （80

3

20 min）. The formation of cell structure and existence of amounts of dislocation tangle resulting in the prior precipitation of precipitates before artificial ageing can be responsible for higher ageing hardness with ageing at 200℃ for 80 min. The remaining higher ageing hardness with ageing at 200℃ for 80

3

20 min is attributed to the β" precipitate in the alloy. Si/Mg cluster and many kinds of precipitates occur in the alloy aged at 30 and 270℃

resulting in the change of ageing hardness of the alloy.