METHOD OF QUENCHING ALLOY SHEET TO MINIMIZE DISTORTION

The invention relates to a method of producing a sheet article or other elongated product of solution heat-treated aluminum alloy substantially free of permanent thermal distortion. The article is subjected to a solution heat treatment at a solutionizing temperature to dissolve precipitates present in the alloy, cooled in a gas from the solutionizing temperature to an upper critical temperature below which precipitation of second phase particles of the alloy may occur, further cooled in a liquid from the upper temperature t o a lower critical temperature below which precipitation of the components may no longer occur, and optionally additionally cooled to a temperature below t he lower critical temperature. The cooling of the article in the gas is carried out at a rate of cooling at which the yield strength of the article remains high enough to resist permanent deformation caused by thermal stress generat ed within the article by the cooling.