Study On Microstructures And Textures Of Magnesium Alloy Deformed Plastically

The strong anisotropy of deformation Magnesium alloy which comes from the plastic deformation textures affects the further materials process. The techniques controlling and optimization to improve the texture component and intensity are important approach of Magnesium alloy forming properties, and a key factor to expand the application in more fields. So the texture controlling of deformation Magnesium alloy has become one of the continuously research fields.In this paper, the as-received AZ31 Mg alloy was possessed and annealed in different conditions. Microstructures and textures in the present samples were performed by optical microscopy (OM), scan electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction, respectively, the microstructure and crystal orientation of material flow behavior are studied in detail. All the results have remarkable theoretical significance of the study in deformation and recrystallization hexagonal lattice materials, and also providing the technical antitype for industry production.By the hot extrusion deformation at 162℃, the mixed metallurgical structure with precipitation of Mg17Al12 and MnAl are obtained. The precipitation decreases with the increase of hot extrusion temperature. When hot extrusion at 258℃, there are no MnAl precipitation and fewer Mg17Al12 precipitation. The dynamic recrystallization is easy occurring during hot extrusion, the average grains size decrease and microstructure homogeneous with the increase of true strain. The average grains size is 7.3μm with homogeneous microstructure at the extrusion ratioλ=25, which provides advantaged condition for improving plastic forming ability of Magnesium alloy. The microstructure becomes more homogeneous and fewer precipitation at 320℃hot extrusion. The texture results show: at deformation early stage of AZ31 Magnesium alloy, the typical {0001} fiber texture can be obtained, the dynamic recrystallization texture components of {0221},{1231} occur and the dispersion degree increase. Deformation and dynamic recrystallization texture can not be developed fully by the collective effect of deformation and recrystallization. The intensity of deformation texture component {0110} is similar to the recrystallization texture components {0221},{1231} with weak intensity, this situation is benefit to decrease the anisotropy, therefore to improve the forming properties. The annealing at electric field and normal is different. Rerystallization process of AZ31 Magnesium alloy is delayed, the grain growth blocked and grain orientation is dispersed at electric field annealing.Based on the hot extrusion forming, the microstructure and texture are studied on the flat die forging. The heterogeneous microstructure and {1217},{1214},{0115} texture components change with the increase of forming rate. Strong texture enhances the anisotropy of materials, which make against the plastic deformation ability.and mechanics properties of Magnesium alloy. The design of die should be considered the effect of anisotropy during forging.Directional rolling, cross rolling and cross shear rolling (CSR) with different mismatch speed ratios (MSR) are performed on 1.4mm thickness hot rolling sheet. The intensity of {0001} texture component presents homogeneous distribution and increase with the increase of strainεduring directional cold rolling. The intensities of {0001}<1010> and {0001}<2110> texture components increase by wave way, shear bands occur and then breakage when strainε≥15%.{0001} texture component gathers to {0001}<2110> texture component with the strain increase during cross rolling, and {0001}<1010> texture component has a light increase at the beginning then this texture component decrease, otherwise {0001}<2110> increase continuously, shear bands occur and then breakage when strainε≥5.8%. Cross rolling have no merit for this kind of alloy.Textures are affected by the speed ratio and deformation degree at room temperature cold cross shear rolling:the center zone has no remarkable change, the surface near to the fast mill roll side is obvious different to that near to the slow mill roll side. On the fast mill roll side, the main texture component of {0117}<514192> and {0001}<1210> increase rapidly with the increase of speed ratio; on the slow mill roll side, the main texture components {0117}<514192>和{0001}<1210> alternate increase with the increase of speed ratio. The main texture components {0117}<514192> and {0001}<1210> increase with the increase of strain, but fast mill roll side is more remarkable than that of slow roll side. With appropriate techniques by cold cross shear rolling, the smooth surface of Magnesium alloy sheet can be obtained by using of 20% deformation degree each gate under room temperature. It is feasible to produce the Magnesium alloy sheet by cold cross shear rolling.