The tensile response of a fine-grained AA5754 alloy produced by asymmetric rolling and annealing

Asymmetric rolling (ASR) followed by annealing has been used to produce very fine grain sizes in the commercial Al-3 wt pct Mg alloy, AA5754. The appropriate rolling and annealing practice can produce grain sizes as small as 1 fim, and the tensile response of this fine-grained material has been compared with that of other fine-grained alloys produced by alternative methods. It is shown that the material obeys a Hall-Petch relationship, with a slope very similar to that of AA5754 produced by equal-channel angular extrusion (ECAE) and by conventional hot and cold rolling. The high yield strengths at fine grain sizes are accompanied by a low tensile elongation, which reflects the stress-strain response of very fine grain sizes. The stress-strain response can be described by the Voce equation, with the dislocation-accumulation rate decreasing with decreasing grain size and the rate of dynamic recovery being controlled by the Mg solute. Tensile elongations generally decrease with decreasing grain size, but a duplex grain structure appears to provide a good compromise between strength and elongation.