Effects Of Differential Speed Rolling On Microstructure And Mechanical Properties Of AZ31 Magnesium Alloy Sheets

Now the application of cast magnesium alloys is more widely than that of wrought magnesium alloy. However, the products, such as sheet, rod, profiles and forging can be obtained with high performance by plastic processing. Furthermore, the material with higher strength and better ductility can be achieved through structure controlling and heat treatment for the plastic forming products. Owing to the specific deformation mechanism of magnesium alloys, basal texture is easily fabricated and during plastic deformation process such as extrusion and rolling. Therefore, the development of new plastic deformation processing has significant meaning on the research of wrought magnesium.The results indicate that the grains for AZ31 magnesium alloy can be refined and preferred grain orientation is presented after extrusion and rolling processing. The basal plane (0002) for the extruded material is parallel to the extrusion direction, which showing the strong anisotropy at room temperature. With increasing of total thickness reduction ratio, the grain size decreases and the quantity of twins also declines. Normal rolling sheets have obvious preferred grain orientation and basal plane (0002) is parallel to the rolling plane. The anisotropy for the cross rolling sheet is weakened at room temperature.The influence of processing parameters including pass thickness reduction ratio, rolling temperature, rolling route and mismatch roll speed ratios on microstructure, crystal orientation and mechanical properties are investigated. Compared with the sheet produced by normal rolling, the grains for that of cross shearing rolling is refined and homogeneous with fewer of twins, which can be related to the deforming characterization of cross shearing rolling and the deforming mechanism of magnesium alloy. And X-ray diffract spectrum indicates that the grain orientation can be changed and the (0002) basal plane orientation can be weakened, which improves the deformability. The cross shear rolling is effective for enhancing the elongation to failure of the AZ31 magnesium alloy sheet, which can be improved about 33% at the rolling direction and transverse direction. These indicate that the cross shear rolling can promote the performance of AZ31 wrought magnesium alloy, which will be very meaningful for extending the application of magnesium alloys.