DSC analysis of the precipitation reaction in AA6005 alloy

Abstract

DSC analysis is applied to investigate the precipitation reaction in the AA6005 extrusion alloy for different heat treatment practices often presented in commercial production. The quenching practice is shown to have a big impact on the response of the AA6005 alloy to an artificial ageing treatment. The range of β″ precipitation is displaced to lower temperatures in samples quenched in air following the solution treatment. This acceleration, however, does not produce a favorable effect on age hardening capacity since much of the solute Mg and Si is removed from the solid solution before the principal hardening phase can precipitate. The DSC results are in good agreement with the age hardening curves. Natural ageing before artificial ageing promotes clustering activities during a subsequent thermal exposure and produces a strong delay in β″ precipitation.