Mechanical Behavior and Deformation Kinetics of Aluminum Alloys Processed through Cryorolling and Subsequent Annealing

The influence of cryorolling (CYR) on the microstructure, mechanical properties, and formability of heat-treatable (AA 6061) and non heat-treatable (AA 5083) aluminum alloys was investigated. Solutionized (SL) AA 5083 and AA 6061 alloy plates are cryorolled to reduce the thickness from 6.5 to 1 mm (the total true strain of 1.87). Short annealing treatment is performed on cryorolled samples at different temperatures with a fixed annealing time to improve ductility. The effect of annealing temperature on microstructure, mechanical properties, and formability was systemically studied. The results showed grain refinement after CYR with higher dislocation density when compared to the SL condition, and their effect is reflected in the mechanical properties. The limiting dome height test is used in the present work to compare the formability of cryorolled and annealed samples. The formability characteristics correlated well with the strain hardening behavior, which is modeled using the Kocks–Mecking–Estrin (KME) dislocation density model. The dislocation density evolution in the original KME model was modified to consider the contributions of grain size, solutes, and precipitates. The tensile curves predicted from the KME model correlated well with the experimental curves in all the conditions investigated. In addition to that, the predicted dislocation density using the modified KME model agreed well with the dislocation density determined experimentally.