Enhancement of strength and ductility in 6061Al alloy processed by cross accumulative roll bonding

To achieve a good match between strength and ductility, plates of 6061 Al alloy were prepared by cross accumulative roll bonding (CARB) at ambient temperature for up to 7 cycles. The microstructures were analyzed by X-ray diffraction, transmission electron microscopy, scanning electron microscopy and electron backscatter diffraction. The results show that both the ultimate tensile strength and elongation of the CARB specimens are significantly better than those of ARB. Grain size of the samples processed by CARB is smaller, and more low-angle grain boundaries transform into high-angle grain boundaries. Also, the dislocation density in the CARB sample is higher. The rolling texture of the 6061 Al alloy processed by CARB is obviously weakened, and the Brass {011}〈211〉 texture is the main one. The higher strength of CARB 6061 Al alloy is mainly dominated by fine grain strengthening and dislocation strengthening, while the higher ductility is due to the finer grains and weak texture.