Ping YANG
材料科学技术（英文）
Channel die compression and initial textures are used to activate different deformation mechanisms in a fine-grained magnesium alloy AZ31. The $\sigma$-$\varepsilon$ curves, microstructures and, particularly, textures are analyzed to reveal different deformation mechanisms and to compare with those of coarse grained samples. Dominant double-prismatic slip, {101ˉ2} twinning and basal slip are detected in three types of samples, respectively, which is similar to those of coarse grained samples. The detrimental effect of shear band formation or {101ˉ1} twinning is limited in fine grained microstructure. In addition to the higher flow stress at low temperature an early decrease in flow stress at higher temperature is also found in fine-grained samples in comparison with their coarse-grained counterparts. This softening is ascribed to the early dynamic recrystallization or grain boundary glide.
关键词:
Magnesium alloy
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Ping YANG
金属学报(英文版)
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 σs 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 σs 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.
关键词:
Magnesium
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asymmetrical rolling
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equal channel angular pressing
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equal channel angular rolling
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deformation
