The effects of strain path reversal, using forward and reverse torsion, on the
microstructure evolution in the aluminium alloy AA5052 have been studied using high resolution
electron backscatter diffraction. Deformation was carried using two equal steps of forward/forward
or forward/reverse torsion at a temperature of 300°C and strain rate of 1s-1 to a total equivalent
tensile strain of 0.5. Sections of the as-deformed gauge lengths of both test specimens were then
annealed at 400°C for 1 hour in a salt bath in order to investigate their subsequent recrystallisation
response. In both strain path histories the deformation substructure in the grains analysed consisted
of microband arrays within an equiaxed dislocation cell structure. The material subjected to
forward/forward deformation did, however, have a slightly greater number of low angle boundaries,
i.e. boundaries < 15° misorientation, whilst the forward/reverse material had some grains containing
little evidence of substructure. On annealing both materials had significantly reduced levels of low
angle boundaries but only the forward/forward material had an increased number of high angle
boundaries and a reduced grain size, indicating recrystallisation had only occurred in this material.
This would suggest that the deformation microstructure within the forward/forward condition was
sufficient to initiate and maintain recrystallisation whilst the microstructure produced by the
forward/reverse test contained insufficient nuclei or internal energy to produce a recrystallised
material within 1 hour. Further work is now required at different annealing times in order to
determine if the major effect of strain path is on retarding nucleation, growth or both.