Patent ID: 6406567
Filing Date: 2002-06-18
Classification: C21D,C22F

Abstract:
A stress relieved rolled product made of age hardenable aluminium alloy, said product being subjected to a process comprising solution heat treatment, then quenching and after quenching to stress-relieving by applying a permanent cold plastic deformation comprising the steps of:(a) applying a stress-relieving cold mechanical stretch to said product wherein permanent deformation, defined as the permanent elongation in the direction of stretching, is in the range 0.3-5%, and (b) applying a stress-relieving cold compression to said product, wherein permanent deformation, defined as the permanent reduction in the direction of compression, is in the range 0.2-5%; wherein the distortion after machining is less than 50 &mgr;m and said product is a thick plate having a final thickness of at least 6 inches.