Combination deformation mode for manufacturing ultra-thick plates of 7075 aluminum alloy

A combination large deformation mode of multidirectional forging and sequent rolling is proposed for producing high performance aluminum alloy ultra-thick plates in this paper. The experiment shows that 2～3μm fine-grained structures in 7075 aluminum alloy can be obtained when total deformation coefficient λ=32 is achieved at the range of 250-350℃ under a strain rate of about 0.1s -1 . The development of fine-grained structure can be characterized by the formation of strain-induced high energy dislocation areas and then the areas transforming into nucleuses of recrystallization under large deformation at moderate temperature. The very fine secondary particles play an important role in retaining the stability of the fine-grained structures.