Patent ID: 7615125

Claim:
A process for manufacturing aluminum alloy products of an AA6056 alloy or AA6156 alloy with high toughness and fatigue resistance, said process comprising: preparing an alloy bath, adding a refining agent containing particles of AITiC type phases into the bath, casting an as-cast form, hot transforming the as-cast form, optionally after scalping, to form (i) a blank or (ii) a product having a desired final thickness between 3 and 12 mm, optionally cold transforming the blank to a desired final thickness between 3 and 12 mm if a blank is formed during said hot transformation, applying solution heat treatment and quenching to the product, followed by relaxation by controlled stretching with permanent elongation between 0.5 and 5%, and optionally annealing, wherein the quantity of refining agent is selected such that the average casting grain size of the as-cast form is at least about 500 μm, and wherein a recrystallized fraction measured between a quarter thickness and a mid-thickness of said product is at least about 70%.