Recovery and recrystallization of 3004 and 5083 aluminum alloys prepared by two-directional rolling at liquid nitrogen temperature.

Grain refinement by inducing large amount of deformation strain at very low temperature restricted a recovery and annealing subsequently, is an effective method to develop an aluminum alloy with fine grain. In paticular, a two-directional rolling at very low temperature is very effective method compared with a one-directional rolling at room temperature. However, recovery and recrystallization behavior during static annealing for aluminum alloys severely rolled by two-directionally at very low temperature is not clear. In the present work, 3004 and 5083 aluminum alloys were two-directionally rolled to 80% reduction in area at liquid nitrogen temperature and were subsequently annealed for various temperatures and times. The recovery and recrystallization was investigated by hardness and microstructure changes compared with one-directional rolling at room temperature. In 3004 and 5083 aluminum alloys annealed at from 498 K to 623 K for short time, softening ratio of two-directionally rolled specimen at liquid nitrogen temperature was larger than that of one-directionally rolled specimen at room temperature. After long time annealing, order of softening ratio was reversed. For both the alloys average grain size after primary recrystallization was smallest at 623 K annealing and was increased with decreasing annealing temperature. The grain size after primary recrystallization obtained by two-directional rolling at liquid nitrogen temperature was refiner than that obtained by one-directional rolling at room temperature at all annealing temperatures. In either rolling method and all annealing temperatures, softening ratio of 5083 alloy was larger than that of 3004 alloy and the grain size after primary recrystallization of 5083 alloy was smaller than that of 3004 alloy.