Abstract: The process is for ageing heat treatment of an age-hardenable aluminium alloy which has alloying elements in solid solution. The process includes holding the alloy at an elevated ageing temperature which is appropriate for ageing the alloy to promote precipitation of at least one solute element, herein termed “primary precipitation” for a period of time which is short relative to a T6 temper. Resultant underaged alloy then is cooled from the ageing temperature to a lower temperature and at a sufficiently rapid rate to substantially arrest the primary precipitation. The cooled alloy then is exposed to an ageing temperature, lower than the elevated ageing temperature for primary precipitation, so as to develop adequate mechanical properties as a function of time, by further solute element precipitation, herein termed “secondary precipitation”.

Abstract: The heat treatment of an age-hardenable aluminium alloy, having alloying elements in solid solution includes the stages of holding the alloy for a relatively short time at an elevated temperature TA appropriate for ageing the alloy; cooling the alloy from the temperature TA at a sufficiently rapid rate and to a lower temperature so that primary precipitation of solute elements is substantially arrested; holding the alloy at a temperature TB for a time sufficient to achieve a suitable level of secondary nucleation or continuing precipitation of solute elements; and heating the alloy to a temperature which is at, sufficiently close to, or higher than temperature TA and holding for a further sufficient period of time at temperature TC for achieving substantially maximum strength.

Abstract: The heat treatment of an age-hardenable aluminium alloy, having alloying elements in solid solution includes the stages of holding the alloy for a relatively short time at an elevated temperature TA appropriate for ageing the alloy; cooling the alloy from the temperature TA at a sufficiently rapid rate and to a lower temperature so that primary precipitation of solute elements is substantially arrested; holding the alloy at a temperature TB for a time sufficient to achieve a suitable level of secondary nucleation or continuing precipitation of solute elements; and heating the alloy to a temperature which is at, sufficiently close to, or higher than temperature TA and holding for a further sufficient period of time at temperature TC for achieving substantially maximum strength.