Influence Of Processing Technology On Recrystallization Microstructure And Texture For Twin Roll Cast 3003 Aluminum Alloy

The 3003 aluminum alloy contains the major alloying element Mn and cannot be strengthened through heat treatment, which has been wildly used because of its good corrosion resistance and weld ability and mechanical properties. Recently,Twin roll casting has been the popular technique to produce 3003 aluminum alloy sheets considering its low investment, high efficiency and energy saving. However, because of the rapid solification rate during cast rolling process, it leads to a serious center segregation in the matrix and causes a big degree of Mn supersaturation. A large amount of fine dispersoids would precipitate from the matrix have great influence on the recrystallization behavior in the subsequent annealing process, which generally result in a coarse and non-uniform recrystallization microstructure, being harmful to the mechanical properties and surface quality. This study aims to improve the grain size and uniformity, concerning the effect of pre-annealing process, deformation degree and final annealing temperature on the recrystallization microstructures and textures during annealing. The following conclusions can be drawn:(1) A large number of Mn elements are existed in the matrix of the cast rolling plates without pre-annealing process, which have the smaller second phases, mainly exsited in the dendrites and grain boundaries along the rolling direction; the single pre-annealing processes include 460 ? ×12h and 620 ? ×12h, the former can significantly reducing the oversaturation in the matrix, and promote the precipitation of the Mn elements, but the sizes of the precipitations are still relatively small, while the situation for the latter one seems like opposite. During the 620?×12h+460?×12h process, the oversaturation of the plate could be reduced and the quantity of coarse second phase is larger, which could effectively decreased the concurrent precipitation of the dispersoilds in the following annealing process. Besides, this process favors particle-stimulated nucleation.(2) Then the recrystallization microstructures and textures of sheets with different pre-annealing processes, cold rolling reductions and annealing temperatures are investigated. Results show:(1)The plates without pre-annealing process have coarser recrystallization microstructures, this situation goes the same for the plates with 460?×12h pre-annealing process. The grain sizes of the plates are smaller obviously treated by 620?×12h pre-annealing process, but the microstructures between surface and center are heterogeneous, the grain at surfaces seems to be more coarser. 620?×12h+460?×12h has been considered to be the best pre-annealing process, which effectively reduced the size of grain to 50?m, and increased the content of Cube textures.(2)both higher deformation extent and annealing temperature will reduce the coarse recrystallization microstructures, making them more homogeneous and getting more Cube textures. This is because these two factors could reduce the interaction of concurrent precipitation and recrystallization. Besides, big deformation degree could increase the possibility of PSN nucleation and decrease the activation energy(3) Finally, we concluded that the twin roll cast 3003 aluminum alloy plates with 620?×12h+460?×12h pre-annealing process, 90% cold rolling reduction and 500? annealing temperature could have uniform fine grain microstructures(50?m), and the main textures of the plate are cube{001}<100>and ND-cube{001}<310>. In addition, the Avrami exponent n(=2.614) is the highest one and the activation energy Q(=75.55KJ/mol) is the lowest one for the plates under these conditions.