Abstract:

Experiments show that special processing techniques such as asymmetrical rolling (ASR), equal channel angular pressing (ECAP) and equal channel angular rolling (ECAR) can weaken the basal texture of the magnesium alloys and therefore improve their plasticity. However, the deformation mechanisms related are different. In this paper, we determine the deformation mechanisms activated during ASR, ECAP and ECAR by calculation of orientation factors. Analysis shows that during ASR the shear stress σ₁₃ on the rolling plane of the samples obviously weakens the basal slip and tension twinning that all produce basal texture and improve plasticity due to the promotion of tilt basal texture. During ECAP the shear stress  σ_s on the intersecting plane of two channels promotes tension twinning in the basal
oriented grains, whereas under ECAR the shear stress σ₁₃   induced by roller friction on the rolling plane produces the shear stress  σ_s on the intersection plane of the two channels that also promotes tension twinning. Although the shear strain is lower in ECAR than in ECAP, the channel clearance in ECAR facilitates tension twinning.

Key words: Magnesium, Asymmetrical rolling, Equal channel angular pressing, Equal channel angular rolling, Deformation