Microstructure and room temperature formability of AZ31 magnesium alloy produced by differential speed rolling

To explore the possibility for enhancing the room temperature formability of AZ31 magnesium alloy sheets by multiple pass differential speed rolling(DSR) technic with small-speed ratio, the characteristic of microstructures and formation mechanisms for DSRed sheets were studied, and the intrinsic relationship between the microstructure and formability was discussed. The results show that the accumulated shear strain induced by multiple pass differential speed rolling promotes the interaction of compression twins. Furthermore, fine-grained microstructure and weakened (0002) basal texture can be achieved. A higher ductility with elongation of 32% and an evidently enhanced press formability with Erichsen value of 6.14 mm at room temperature are presented for as-DSRed/annealed specimen. The weakened (0002) basal texture intensity and lower plastic strain ratio are thought to be mainly responsible for the enhancement of room temperature formability. Key word: AZ31 magnesium alloy; differential speed rolling; texture; twins; formability