在备有拉伸装置的扫描电镜上，原位观察了低碳板条马氏体钢的变形和断裂过程。结果表明，板条马氏体的变形是以滑移方式进行的，位错沿滑移面的滑移受阻，在试样表面留下呈波纹状的变形带。在应力峰值前后，主裂纹开始起裂；在主裂纹扩展过程中，在主裂纹前面的薄弱区域如夹杂等会先起裂形成小裂纹或空洞，随应力加大相邻的微孔聚合、连接长大成新裂纹；在断裂过程中，裂纹在板条束界发生转折。尽管原奥氏体晶粒尺寸小的试样起裂载荷大，不同晶粒尺寸马氏体组织的变形和断裂过程没有本质差别。
SEM in-situ observation of deformation and fracture process for low carbon steel with lath martensitic microstructure was investigated. The results show that plastic deformation of lath martensite steel occurs by means of slipping. Deformation band is found in a wave manner because dislocation motion is hold along slip plane. The main crack is initiated under the stress peak. In the propagation process of the main crack, micro-crack occurs first in the weak zones in the front of the main crack. With increasing load, the cracks are connected into a new crack and the new crack further propagates in the same manner, resulting in final fracture of the specimen. In the fracture process of the samples, the crack deflects by a larger angle at the packet boundary. Despite the initial fracture stress is relatively high for the specimens with fine prior austenite grain size, the process of deformation and fracture of the specimens with different prior austenite grain sizes is essentially the same.
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