The Al-6061 alloy was received in the form of a plate,
10mm in thickness, after a T651 heat treatment involving
a solution treatment at 823 K, tensile straining to ∼2% at
room temperature and aging at 433K for 18 h. Samples with
diameters of 10mm and lengths of 70mm were cut from
the plate and annealed at 693K for 4 h with a heating and
cooling rate of 10Kh−1. The initial grain size of the alloy in
the unpressed condition was ∼50m.