Effect Of Initial Texture On Texture Evolution Of AZ31Magnesium Alloy During The Cold Rolling

Magnesium alloys have drawn great interest in recent years due to their excellent mechanical properties such as high specific strength and superior damping capacities. However, magnesium alloys exhibit limited room temperature ductility and poor cold workability which have been attributed to that deformation modes other than the basal slip and twinning are difficult to activate at low temperature. In the magnesium alloys research of texture, people found that magnesium alloys always have the strong basal texture after rolling, and the presence of this texture will result in low ductility and anisotropy to the alloys. The initial textures have a great effect on the mechanism of magnesium alloys.The present work is concerned with the effect of initial texture on evolution of textures of magnesium alloys during the cold rolling. The material used in this study was a hot rolled AZ31Mg alloy plate. Seven specimens with different initial texture were fabricated from the plate, and designated as0°,15°,30°,45°,60°,75°,90°specimens, which were then prepared by homogenizing at400℃for4h. All of the specimens were rolled with8passes at room temperature respectively. Microstructures were observed by an optical microscope and textures were also examined by XRD and EBSD. The primary conclusions were as follows:After the first rolling pass,{0001} basal texture appeared in the0°and15°specimens with initial texture of (1120)[1100]. Meanwhile, the texture of (1120)[1100] weakened rapidly. The initial texture of75°and90°specimens was {0001} basal texture, and the strength of basal texture gradually weakened with the increase of rolling reductions.The initial textures of30°,45°and60°specimens were pyramidal textures. The results of {0002} pole figures showed that the poles are gradually close to the center of the pole figure for30°,45,60°specimens. However,30°specimen finally formed four poles around the center of the figure.In the latter stages of rolling, the main textures formed in all of the specimens are {1127} and {11212}, and {1127} is much stronger than {11212} in0°and15"specimens.The results of micro structures showed that grain size was no significant change during the cold rolling of all specimens. Because of the difference of initial texture, the amount of twinning in75°and90°specimens were much less than others, and which of the specimens with the initial texture (1120)[1100] was most. Meanwhile, the shear bands occurred in different rolling passes while the initial texture was different.