对低碳２０号钢经正火，淬火和回火处理后在高速扭转过程中变形局部化的发生，发展演化过程以及最后形成的剪切带的微结构特征进行了观察。结果表明，变形局部化敏感于材料的强度，强度越高，越容易出现变形局部化。局部化的产生与发展涉及到一系列相继发生的晶体学和非晶体学的变形现象：析出相－基体间界面发射位错形成六角网络，位错胞形成并沿剪切带方向拉长；由于高速率大应变导致剪切带内局部区域产生亚结构；微裂纹的长大与聚合最终导致沿剪切带方向的断裂。
The formation,development and microstructure of shear localization formed during dynamic high speed tornsional testing by split Hopkinson bar with a average strain rate range of 600,650 and 1500 s-1 have been investigated in low-carbon steels.The results showed that the shear localization is sensitive to the strength of the steel.The higher the strength of the steel,the earlier the shear localization occurs.The observations by TEM indicated that the formation and development of the shear localization involved a series of the crystallographic and non-crystallographic events including the dislocation emission from the interfaces between the precipitate and matrix,forming network,cell and tangled structures of the dislocations;the misorientation formation arising from the large accumulated plastic strain in a local area in the band and the growth and coalescence of the microcracks in the band leading to a sharp drop in the load-carrying capacity of the deformed material.
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