Study On The Evolution Of Texture Of 1050 Aluminum Alloy During Processes Of Deformation And Recrystallization

Aluminum alloy sheets used in deep-drawing products need have high strength, thin sheet, little earing and excellent formability. The textures in polycrystalline material developed during thermomechanical plastic processing and heat treatment lead to the generation of anisotropy, which result to the formation of ears. Therefore, it is very important to take better account of the influence of deformation textures and recrystallization textures on anisotropy for improving performance of the sheets.In this work, the evolution of texture and microstructure in 1050 aluminum alloy sheets occurring during hot rolling, cold rolling and annealing have been studied. In addition, laser-textured process has been examined. This work involves both experimental and theoretical approach. Effects of several technological parameters on the microstructures and textures of 1050 aluminium alloy sheets are then discussed to some extent.The research results of different rolling process showed that the hot rolling textures were composed of the {001}<110> rotated cube component, as the reduction increasing, the intensity of {001}<110>rotation cubeis decreased and the rolling texture component increased. The cold rolling textures were typical Cu-type ones, i.e. consisting of mainly three texture components as Cu- {112}<111>, S- {123}<634> and Bs- {110}<112>. The orientation densities of the main texture components increased as the increasing of the cold rolling reduction. Iinitial texture before cold rolling and cold rolling reduction in pass can effect the composition of rolling texture. Results showed that increasing the number of passes in cold rolling can decrease the intensities of deformation texture. The results of OM showed that some deformed structures were formed; these structures were elongated along the rolling direction and contained some subgrains in some fields. After cold rolling, there are lots of dislocation cell formed in the fiber structures, cell-walls were composed of high density dislocation tangles around cell, and dislocation density was low within cell. As the increasing of cold rolling reduction, the number of dislocation cell increase and the size reduced.The research results of different annealing process showed that cold rolling reduction and annealing temperature were the important factors affecting the degree of recrystallization. The larger cold rolling reduction leads to the higher deformation stored energy which accordingly increased the driving force of recrystallization. Therefore, the degree of recrystallization is higher and the size of recrystallization grain is smaller after annealing at same temperature. Annealing temperature had great effect on recrystalization textures. For 97% hot rolled and 90% cold rolled sample, the intensity of cube texture was increased and the deformation texture decreased as the annealing temperature increased, recrystallization was finished on the whole after annealed at 400℃for 120min, and the orientation density of cube texture reached its maximum; but some cold rolling textures still retained. Mechanical property after annealing changed as the degree of recrystallization. The tensile strength decreased slightly at recovery stage, but reduced sharply at recrystallization stage and the elongation change reverse with tensile strength.The relationship between earing and texture is analysed based on the CMTP method (Continuum Mechanics of Textured Polycrystals). The Quantitative relationship of earing rate and texture are investigated with experimental and theoretical analysis which is the base for forcast the ears of the sheet. The results show that, the recrystallization texture mainly consisted ofβ-fiber texture at low annealing temperatures which tend to leads 45°ears. After recrystallization begin, the recrystallization cube and R texture increase, the rolling texture and recrystallization texture coexist in the specimen which is apt to leads 0°/90°and 45°ears, the earing rate is low. After complete recrystallization, the high intensity of cube texture is developed, which leads to high 0°/90°ears and the earing rate is increased again. The influence of laser-textured process on the texture and performance of 1050 aluminum alloy is investigated and analyzed systematically. Experimental results show that the sheets deformed with laser-textured roll developed the typical rolling textures, which consist of Bs, Cu and S components. After annealing, the specimen shows a substantially different recrystallization texture compared with conventional sheet, which comprising only a weak cube-orientation and rotated-cube orientation as well as a much higher fraction of randomly orientation. The results of mechanical property show that the tensile strength of the textured sheet is approach to that of conventional sheet, but the plastic is slightly higher. The deep drawing test result show that the earing rate of the textured sheets after annealed at different temperature is all lower than the conventional sheets. After annealed at 360℃, the earing rate is less than 3%, which get the lowest anisotropy.