| There is abundant storage resource of magnesium on the earth, Magnesium alloys are extensively used in the automobile industry, the communication electron, aviation and aerospace industry and other fields, because of its many special advantages, such as light, high specific strength, high specific stiffness, good damping property and good electromagnetic shielding. Magnesium has hcp crystal structure and little slip system, so its plastic deformation is difficult, and plasticity processing is limitedly used in the magnesium processing. However, plasticity processed magnesium alloy are highly improved in the microstructure and properties, so research on deforming magnesium alloy become very important in the magnesium industrial fields.In the present study, based on experiments, AZ31 magnesium alloy was chosen as object of material. Hot compression tests of AZ31 magnesium alloy extrusion plate were performed on Gleeble 2000 under Conditions of different deformation temperatures,different deformation velocity and deformation degree in order to research on flow stress behavior, we have got the deformation properties and flow stress of magnesium alloy at deformation temperature ranged in 150-450℃,strain rates 0.01-20s-1 and deformation degree 20%-70%. After the compression, the alloy was annealed, and the changes of microstructure were observed under different annealing condition. We calculated the grain size of the Samples, and analyzed the relationship of annealing and grain size. Summarized the basic rule of hot compression deformation of experimental magnesium alloys and provided theory basis for magnesium alloys rolling production. AZ31 sheets were annealed at 250℃,32℃,and 400℃after hot-rolled and cold-rolled from lmm to 0.7mm, respectively. In order to study the influence of rolling system and heat treatment temperature on mechanical properties of AZ31 magnesium alloy sheets, microstructures were examined, tensile property and stamping property were tested, fractures were scanned,TEM measurement were also performedEffect of cold-rolling and hot-rolling on AZ31 magnesium alloy sheet was also explored in this article, and the main conclusions are followings: 1. Factors which effect hot compression tests are deformation temperatures deformation velocity and deformation degree and so on. Through the comparison of the microstructure and the hot compress microstructure we can conclude that the most appropriate compression technology system is:deformation temperatures 250-350℃, deformation degree 40%, deformation velocity Is-1. We also gained the deformation activation energy and the constitutive equation through analysis the data of AZ31 magnesium alloy extrusion sheet hot compression. The deformation activation energy is 159.5kJ/mol, the constitutive equation is:2.90% hot-rolling at 370℃and 10% cold-rolling and heat treatment after rolling at 250℃is the best system of heat treatment and rolling. We concluded that the best comprehensive tensile properties of cold-rolled plate:the tensile strength reached 273 MPa, the yielding strength reached 179 MPa. The elongation percentage reached 24.5%.3. The strength and hardness value was greatly improved from 0.7mm to 0.5mm by cold-rolling. The tensile strength of longitudinal direction increased from 273 to 295 MPa, the yielding strength of longitudinal direction increased from 179 to 210 MPa.4. The stamping property of cold-rolled sheet after heating treatment was greatly increased. We concluded that erichsen value ascended as temperature raised, and reached the highest at 400℃, the value was 4.82. Heat treatment. Erichsen value of cold-rolled sheet sheet was higher than hot-rolled. Erichsen value has relationship with yield tensile ratio, Erichsen value ascended as the yield tensile ratio decreased.5. We can conclude that the cold-rolled sheet have more advantages than the hot-rolled sheet by comparing the experiment results. It provides theory basis for productions. |
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