Effect of ultrasonic processing on a direct chill cast AA6082 aluminium alloy

Abstract

For many years now, ultrasonic melt treatment (UST) has proven itself to promote grain refinement in aluminium alloys. The current work presents cavitation-aided grain refinement obtained on commercial AA6082 DC-cast billets. Grain refinement was achieved while applying UST in the crucible away from the sump, prior to casting. Since in high strength alloys, Zr and Ti are commonly present as alloying elements for anti-recrystallization and corrosion resistance properties, their as well as UST parameters influence on the microstructure are studied and presented. Primary Al3(Zr1-x-y ,Tix , Siy) intermetallics were found in the centre of the α-Al grains. This suggests that UST may have forced the nucleation and refinement of primary intermetallics influencing the subsequent solidification process when Al3(Zr1-x-y , Tix , Siy) act as nucleation sites.