| Magnesium alloy is until now the lightest structural material in the project application. At the same time, magnesium alloy is being increasingly wider using in the automobile industry, the communication electron, aviation and aerospace industry and other fields because of its merit, such as high specific strength, good electromagnetic shielding and good damping property. There is abundant storage resource of magnesium on the earth, and at the present time, many of the traditional metal mineral resources become depleting, the development of the application of magnesium alloy to maintain the sustaining development is strategic significance. Most of magnesium alloy has the hexagonal close-packed structure, and formability is not very well, and most of magnesium alloy has the good casting property, so most of magnesium alloy components are mostly produced by die-casting at the present time. However, mechanical properties of the casting products are not very ideal, which restricts the application of AZ31 magnesium alloy. Therefore, research on deforming magnesium alloy become very important in the magnesium industrial fields.In order to enhance the comprehensive mechanical properties of AZ31 magnesium alloy, particularly plasticity, in the present study, based on experiments, AZ31 magnesium alloy was chosen as object of material, AZ31 billets with diameters ofΦ153mm, after homogenization treatment, were extruded at 250℃,300℃and 350℃, respectively. AZ31 extruded plates were rough-rolled at 330℃and 370℃, respectively. Finally, AZ31 thin sheets were obtained after finishing rolling, AZ31 thin sheets were annealed at 250℃and 400℃, respectively. In order to study the contribution of extruding temperature, rolling temperature and heat treatment temperature on mechanical properties of AZ31 magnesium alloy sheets, microstructures were examined, tensile property were tested, fractures were scanned and X-ray texture measurement were also performed. Effect of cold-rolling and hot-rolling on AZ31 magnesium alloy sheet was also explored in this article, and the main conclusions are followings:1. Extruding temperature has a great influence on surface qualities and mechanical properties of AZ31 magnesium alloy sheet. AZ31 magnesium alloy extruded plate with good surface and mechanical properties can be obtained when ingots was extruded at 300℃. Therefore appropriate extruding temperature is 300℃.2. Rolling temperature has also a great influence on mechanical properties of AZ31 magnesium alloy sheet. When AZ31 extruded plates were rolled at 370℃, the maximal reduction reached 49.14%, homogeneous and fine grains were obtained, whose average size is 3-4μm with good mechanical properties. Therefore appropriate rolling temperature is 370℃.3. Proper heat treatment system is 250℃×20min, crystal grains of hot-rolled AZ31 magnesium alloy sheet became regular, twin which formed in deforming disappeared, and recrystallization nearly finished, after annealling at 250℃. Tensile strength of AZ31 magnesium alloy sheet was decreased, at the same time, elongation percentage increased largely. The tensile strength of AZ31 magnesium alloy sheet decreased from 305MPa to 280MPa (transverse direction). Meanwhile, the elongation percentage increased from 18.24% to 21.37%(transverse direction).4. After annealling at 250℃, the cold-rolled AZ31 magnesium alloy sheet with thickness of 0.9mm has good mechanical properties, whose transverse tensile strength get to 265MPa, while transverse elongation percentage get to 30.08%, and longitudinal tensile strength get to 260MPa, while longitudinal elongation percentage get to 27.36%.5. AZ31 magnesium alloy has formed the different texture types under the different rolling ways (cold rolling and hot rolling). In cold-rolled sheet, texture type are mainly (0117) [0772] (90°,15°,0°) and (1129) [1239] (75°,20°,30°). In hot-rolled sheet, texture is basal fiber. In pole figures, two peaks appears in AZ31 cold-rolled sheet, meanwhile one peak appears in AZ31 hot-rolled sheet, which shows different foming mechanisms in cold rolling and hot rolling. Cold rolling changes the texture type and weakens the intensity, which shows cold rollinghas the property of enhancing formobility of AZ31 sheet. Heat treatment can not change texture type, but weaken intensity of texture.6. Grain size, twin and texture are three key factors which affect strength, elongation and aeolotropy of AZ31 magnesium alloy sheet. By controlling the parameters of rolling, heat treatment and other technologies, grain size, twin and texture can be changed, the perpose of increasing plasticity and decreasing aeolotropy can be achieved without the decrease of strength.
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