The Influence of Extended and Variable Pre-Stretching on the Strength of AA2195 Alloy Taper-Rolled Plates

The influence of larger pre-strains, than are currently used in industry, has been investigated on the ageing behaviour of the Al-Cu-Li alloy 2195 - in the context of producing near-net-shape, taper-rolled, thickness-tailored, plates for aerospace applications. FE modelling and simulations have demonstrated it is viable to stretch plates with rolled tapers of up to 1:1.6 in thickness. Increasing the pre-strain level at the thin end of the plate, up to 15%, resulted in a continued increase in microstructure refinement and yield strength, which rose to ~ 670 MPa without an unacceptable loss of ductility. It is shown that, even with such high pre-strains, a relatively low level of recovery occurs after artificial ageing and increasing the pre-strain is predicted to result in a reduction in strengthening from the T1 phase, due to precipitate refinement, in favour of a higher contribution from strain hardening.