Work Hardening of Non-Heat Treatable Aluminium Alloys towards Large Strains

The work hardening behaviour of non-heat treatable aluminium alloys is followed up to large strains. The evolution in strength and microstructure during cold rolling is analysed in commercially pure aluminium, AlMg alloys and AlMn alloys, covering both solid solution strengthening, particle strengthening, grain size effects and effects of impurities. A recently developed model for work hardening is applied to these alloys and discussed in relation to the experimental observations. The model successfully predicts the effects of Mg in solid solution on the strength and work hardening in stage II-III. Mn, Fe and Si in solid solution are suggested to create solute clusters that increase the strength significantly. At higher strains, stage IV, an unexpectedly low work hardening rate of high-Mg alloys is ascribed to a different storage pattern of dislocations caused by an increased amount of shear bands and a higher dislocation density inside subgrains.