Origins of cube recrystallization textures in heavily rolled high purity Al

In high purity (4N) Al containing 50 ppm Cu, very strong cube textures can be developed by cold rolling 98 % and annealing at 500 degrees C. The orientation density in this material amounted to as much as 220 times random, i.e. about 3 times stronger than that observed in standard 4N Al. It is expected that the origins of cube textures should be most unambiguously clarified by using this material. Commercial hot bands of this materials were cold rolled 98 % to the thickness of 132 mu m and isothermally annealed at 230 degrees C. Detailed EBSP analyses were made both on the rolling plane and on the longitudinal section at each stage of annealing. It was found that in the hot band of this high purity Al, cube orientations were mostly rotated away into other orientations due to low temperature hot rolling with high rolling reductions. Therefore, regions having cube orientations were very few. They were not present in the form of so called cube bands, which had been reported in previous investigations, but in the form of isolated, rather equi-axed recrystallized grains. After 98 cold rolling, these remaining cube regions were fragmented, and further rotated away into other orientations, so that only very few cube oriented regions were observed in the cold rolled materials. However, it was from such deformed cube oriented regions that the most potential exact cube recrystallized grains were formed. They were nucleated much earlier and grew much faster than grains of other orientations.