THERMO-MECHANICAL PROCESSING OF Al-Mg-Si ALLOYS THROUGH EQUAL CHANNEL ANGULAR PRESSING FOLLOWED BY COLD ROLLING

Abstract

This thesis aims to investigate the effect of thermo-mechanical processing through equal channel angular pressing (ECAP) followed by cold rolling on the mechanical properties of some Al-Mg-Si alloys. A combination of different heat treatments, ECAP levels and cold rolling reductions was performed on the alloys. First, the effect of 1 ECAP pass followed by different rolling reductions was investigated for AA6101. The effect of different ECAP processing routes for 4 passes followed by 50% rolling reduction was also investigated for AA6101. It was found that the alloy could withstand large plastic strain without cracking, with a significant improvement in the yield strength and ultimate tensile strength. A third study investigated the effect of combining two heat treatments with two ECAP levels and two rolling levels on AA6061. Under-aged samples deformed through 1 ECAP pass followed by 40% rolling reduction exhibited a significant improvement in both the YS and UTS. On the other hand, it was remarked that the strength of over-aged AA6061 samples did not significantly increase after ECAP processing. Finally, the effect of 1 and 2 ECAP passes on the aging curve of the AA6061 was investigated. It was found that ECAP has accelerated the aging of the alloy and improved the mechanical properties.