Influence of HPT or Rolling on Age-Hardening in Al-Mg-Si Alloys

Severe plastic deformation (SPD) techniques, such as equal channel angular pressing (ECAP), accumulative roll bonding (ARB) and high pressure torsion (HPT), have been extensively researched to achieve. SPD process makes use of the plastic deformation where no change in the cross-sectional dimension of a work piece occurs during straining. In this work, the effect of HPTed or rolled on aging behavior and microstructure in Al-Mg-Si alloys were investigated. The results show that processing by HPTed leads to significant grain refinement with a grain size of ~400nm. Age-hardening phenomenon was confirmed at 343K and 373K but not at 423K for the HPTed Al-Mg-Si alloy. For the rolled alloys, there is little difference between the hardness of the alloys with different rolling rate. On the other hand, crystal grain with high dislocation density and grain boundary precipitates are observed with TEM analysis for HPTed samples aged at 473 K.