Residual stress relief in the aluminium alloy 7075

The residual stresses in heat-treated 7075 aluminium alloy blocks have been characterised using two neutron diffraction strain scanning instruments. The influence of uniaxial cold compression on relieving the residual stress has been determined. Systematically increasing the magnitude of cold compression from 1 to 10% has been shown to have a small beneficial effect on the final residual stress distribution, by reducing the magnitude of the range in the triaxial residual stresses. The effect of an overaging precipitation treatment on the residual stress has also been characterised, and this was found to have a significant stress relieving influence (25–40%). A relationship between the width of the {311} diffraction peaks and the amount of cold compression was also observed.