2014 Volume 55 Issue 2 Pages 270-274
Grain refinement of a magnesium alloy, AZ80, was studied in multi-directional forging (MDF) with decreasing temperatures from 683 to 573 K. The MDF was carried out up to accumulative true strains of around 7 with changing the loading direction from pass to pass. The structural changes are characterized by the alternate appearance of fine dynamic recrystallized (DRXed) grains (with many dynamic granular Mg17Al12 phases) and coarse DRXed grains (without Mg17Al12 phases) in the sample, the expansion of the fine grains area, and the refinement of (DRXed) grains in the fine grains area during the MDF process. The non-uniform dynamic precipitation of the Mg17Al12 phase may attribute to the inhomogenous Al content distribution in the Mg matrix. These Mg17Al12 phase retards the growth of the DRX grains, which in turn results in the formation and the expansion of the fine grains area during the MDF process with decreasing temperature.