the object of the invention is a rolled , forged or extruded aluminum alloy product more than 12 mm thick , heat treated by solutionizing , quenching and artificial aging , with a microstructure characterized by the following parameters : the fraction of recrystallized grains measured between one - quarter thickness and mid - thickness of the final wrought product is smaller than 35 % by volume ; the characteristic intercept distance between recrystallized areas is greater than 250 μm , preferably greater than 300 μm and most preferably greater than 350 μm .