Optimization of interpass annealing for a minimum recrystallized grain size and further grain refinement towards nanostructured AA6063 during equal channel angular pressing

Grain structure evolving during severe plastic deformation (SPD) and interpass annealing strongly influences grain refinement occurring during subsequent SPD. The aim of this research was to determine an optimum interpass annealing condition that could lead to the formation of a nanostructure of the AA6063 alloy during subsequent equal channel angular pressing (ECAP). Different interpass annealing temperatures and times as well as different prior ECAP passes were used to define an optimum annealing condition that led to a minimum grain size for further ECAP by route A. TEM confirmed the attainment of nano-scale grains with sizes around 500 nm after six passes of ECAP. EBSD revealed the majority of grain boundaries being high-angle ones.