Deformation behaviour, microstructure and processing of accumulative roll bonded aluminium alloy AA6016

The technologically relevant aluminium alloy AA6016 was successfully processed using accumulative roll bonding to 8 cycles (epsilon(von Mises) = 6.4) in order to obtain an ultrafine-grained microstructure with an average grain size of approximately 200 nm. With the aim of optimising the accumulative roll bonding process detailed investigations on the robustness, the type of rolling mill, the influence of temperature, the microstructural evolution and the mechanical properties have been carried out. Processing at 230 degrees C provided a good compromise between thermal stability and interlamellar bonding. Samples strained up to 6 cycles (epsilon(von mises) = 4.8) showed an increase in the yield strength by a factor of 3 in comparison to the as-received material. The ductility of the roll bonded samples was slightly sacrificed, although an increase in ductility can be achieved by increasing the number of accumulative roll bonding cycles. The mechanical properties depend on the strain rate, as has also been found for many other ultrafine-grained materials. Annealing of ultrafine-grained samples revealed a stability limit of approximately 200 degrees C.