Changes of microstructures and some mechanical properties due to long time high temperature annealing treatment in 5083 alloy sheet

Abstract

Yield strength and hardness of the 5083 sheet annealed at 520°C especially for 2000min or more are considerably lowered. The surface and interior portion of the sheets annealed for 4000 and 14400min have substantially different hardness. The fact is attributed to difference in Mg concentration resulted from vaporization of Mg. An intermetallic compound Mg₂Si remarkably decreases during prolonged annealing for 4000min or more. Another intermetallic compounds composed of Al, Fe, Mn, Cr and Si relatively increase with respect to decrease of Mg₂Si. Initial Mg content 4.59wt% reduces. down to 0.26wt% by annealing for 14400min.