Influence of low magnitude plastic strains on residual stress in 7075 aluminium alloy

The effect of post quench delay on residual stress has been determined by subjecting four rectilinear blocks of quenched 7075, containing large residual stress magnitudes, to small (<1.0%) plastic strains applied by cold compression. One experiment kept the plastic strain the same in all samples (∼0.12%) by cold compressing simultaneously in one pressing. The second pressed the blocks separately to the same strain (∼0.45%). The post quench delays were <10, 60, 120 and 240 min. The residual stresses were characterised using neutron and X-ray diffraction. It was possible to detect the impact of the small plastic strains on all samples, but the diffraction measurement techniques could not conclusively isolate the influence of the post quench delay.