Ultra-fine grained structure in Al–Mg induced by discontinuous dynamic recrystallization under moderate straining

This paper reports a novel strategy to produce an ultra-fine grained (UFG) structure in an Al–4Mg (weight percent, wt%) alloy via discontinuous dynamic recrystallization under moderate straining (true strain <2.5) as imposed during conventional extrusion at 400 °C. The mechanisms underlying the occurrence of discontinuous dynamic recrystallization and the formation of the UFG structure were analyzed and discussed in detail. The UFG Al–4 wt%Mg alloy exhibits both high tensile yield strength and elongation.