异速比对异步轧制AZ31镁合金板材组织和织构的影响

Effects of differential speed ratio on the microstructure and texture of AZ31 magnesium alloy sheets processed by differential speed rolling

采用不同异速比对AZ31镁合金板材进行异步轧制,并将轧后样品进行显微组织和X射线衍射分析,研究异速比对镁合金板材组织和织构转变的影响.结果表明:异速比的变化对晶粒形貌影响较大但晶粒细化效果不明显;当异速比为2.800时,板材内出现了长条晶粒;快速辊侧{0002}基面织构强度高于慢速辊侧,且板材两侧表面{0002}晶面的偏转方向相反;异速比对基面织构的强度影响显著,随着异速比的增大,基面织构的强度先增加后下降.这种特殊的织构变化与异步轧制过程中沿厚度方向引入的剪切变形有关.

The effects of differential speed ratio on the microstrueture and the texture of AZ31 magnesium alloy sheets processed by differential speed rolling （DSR） were investigated by optical microscopy and X-ray diffraction analysis. The results show that differenti- al speed ratio has a significant effect on the grain morphology but a little influence on the grain size. As the differential speed ratio in- creases to 2. 800, lots of long-strip grains are found. The intensity of {0002} basal textures is much higher on the side of fast rolling than on the side of slow rolling and the distributions of {0002} orientations are different between the two surfaces of the sheet. Differential speed ratio has also a great influence on the strength of basal textures and when the differential speed ratio increases, the intensity of （0002） basal textures increases firstly and then reduces. This special texture change could be attributed to shear deformation introduced throughout the thickness during the differential speed rolling process.