Influence Of Annealing And Dynamic Plastic Deformation On The Microstructure And Texture Of Pure Magnesium

Microstructure and texture of pure magnesium were investigated in this paper.Optical microscope, electron backscatter diffraction (EBSD) detector and X-raydiffraction (XRD) were used. The comparison of static compression(QSC) and dynamicplastic deformation(DPD) of0°-sample was conducted in the paper.The microstructure and texture of hot pressing and annealing were investigated.Dynamic recrystallization during the hot pressing of pure Mg. The size of graindecreased from134um to110um.{1012}tension twin and {1011}-{1012}-{1012}secondary twin appeared in the pressed sample.{1012}tension twin produced duringthe unloading. The texture of the pressed sample was basal texture, that is the (0002)face parallel to the pressed face. The intensity of basal texture decreased, owing to thefunction of cylindrical sliding, cone sliding and compression twinning. The grain sizewas not obviously changed after200℃and0.5hour annealing. The intensity of basaltexture increased after annealing.The compression twin and most of tension twin disappeared during annealing.The compression of static compression and dynamic plastic deformation wascarried out in the paper. The amount of compression twin of DPD was more than theamount of QSC, if the strain of the two samples was equal. The value of localorientation angle of sample deformed in the low strain rate was bigger than the sampleof DPD with the same strain. Increasing the strain rate inhabited the compressiontwining and promoted the sliding. With the increasing of the strain, the intensity of basaltexture decreased. With the increasing of the strain rate, the intensity of basal textureincreased.Contraction twins were produced in the0°-samples. More contraction twinswas found in the DPD samples and no tension twins in QSC samples. Contraction twinswere only activated in matrix grains whose C-axis was less than45°from LD, and therelated twin orientations were tilted about30-60°with respect to LD. Tension twinswere activated in matrix grains whose C-axises were less than50°from LD, and therelated twin orientations were more than60°with respect to LD. It was proved in thepaper that most of tension twins was activated during unloading.Tension twins existed in most of grains at=2%in90°-samples. It was found thetwin morphologies developed in a grain were complicated, showing differentorientations when compressed along RD. With the strain increasing, the growth and intersection of twins began，and local peak misorientation at~60°appeared at=5%byEBSD. At=8%, tension twins in the large grains except for those near the grainboundaries were vanished, and some contraction twins appeared in the sample90-DPD-8%. With the increasing of strain, the texture of matrix turned to the texture oftwin.The samples of5%and8%were mainly nucleated during0-15min of240℃annealing. With the increase of time, the recrystallization grain grew. The nucleation sitewere mainly in grain boundary, twin boundary and inside the compression twin. Themechanism of nucleation was the bowing of grain boundary. The type of texture ofannealing sample was not changed compare of the texture of DPD. With the increasingof time, the C-axis of grain of the grain shift from LD to the ND of the sample.