Effect of Deep Cryogenic Treatment on Aging Processes of Al–Mg–Si Alloy

Abstract—This study investigated the effect of deep cryogenic treatment (DCT) on the aging processes of Al–0.43Mg–1.27Si alloy. Differences in the mechanical properties and precipitation behavior between conventional treatment and DCT were analyzed by means of hardness test, tensile test, optical microscopy (OM), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and transmission electron microscopy (TEM). DCT promoted the precipitation of Si phases, which is accompanied by an increase in hardness. The content of Si was improved from 0.84 to 1.08% and the hardness was increased from 46.11 to 48.89 HV. The temperature of precipitation of GP zones and β'' phase was lower, which accelerated precipitation of the β'' phase and then improved the aging hardening response of the alloy.