Residual stress relief in Al–Zn–Mg–Cu alloy by a new multistage interrupted artificial aging treatment

Abstract

A novel multistage interrupted artificial aging treatment was designed for reducing residual stresses in quenched Al–Zn–Mg–Cu alloy thick plates. The results show that residual stress magnitudes were reduced significantly and even eliminated completely by this novel treatment while the conventional artificial aging only contributed to a reduction 10%-35%, because an inverse stress was ingeniously employed during rapid heating to release the internal residual stress. Meanwhile, the mechanical properties were maintained, and the corrosion resistance was improved comparing to conventional artificial aging. The maintained mechanical property and improved corrosion resistance were resulted from rearranging of dislocations and precipitates characters in multistage interrupted artificial aged alloys.