Rolling and recrystallization textures in Al-Mg alloys

By using the orientation distribution function analysis, rolling and recrystallization textures developed in Al-Mg alloys containing 6, 7 and 9 wt.% Mg were studied in detail. Also recrystallization behavior and precipitation of the beta phase particles during annealing were investigated by using both optical and scanning electron microscopy. It turned out that cold rolling textures of these alloys were generally weak and random. The recrystallization textures of Al-6 wt.% Mg alloy annealed at 450degreesC were found to be strongly dependent on the heating rate to the annealing temperature. Annealing by rapid heating enhanced the formation of {103}<321> and {100}<013>, suppressing the development of {100}<001> strongly. This is because {103}<321> and {100}<013> recrystallized grains were preferentially formed at shear bands and at peripheries of deformed cube bands, respectively. {100}<001> recrystallized grains were consumed during grain growth by grains of these orientations. In annealing by slow heating, precipitation of the beta phase particles, which occurred preferentially at shear bands at low annealing temperatures, suppressed the nucleation of {103}<321> recrystallized grains. In this case, {100}<001> formed during recrystallization at low annealing temperatures, further developed during subsequent grain growth at higher annealing temperatures, yielding {100}<001> and {123}<634> recrystallization textures, which were commonly observed in Al alloys. Increase in the Mg content suppressed the development of all these texture components. In Al-9 wt.% Mg, the recrystallization textures were quite random. They were affected neither by the annealing temperature nor by the heating rate to the annealing temperature. This was ascribed to its random rolling texture, and also to a large amount of the beta phase particles which precipitated homogeneously within grains at low annealing temperatures, suppressing nucleation of recrystallized grains of all orientations equally.