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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。
In the scanning electron microscope with tension device, the deformation and fracture process of low-carbon slab martensitic steel were observed in situ. The results show that the deformation of lath martensite takes the slip mode and the dislocation slips along the sliding surface, which leaves a wavy deformation zone on the specimen surface. Before and after the stress peak, the main crack starts to crack. During the main crack growth, weak cracks in the front of the main crack such as inclusions will start to crack and then form small cracks or voids. With the increase of stress, adjacent micro pores will be aggregated and connected Grow into a new crack; in the fracture process, the crack in the slab bound. Although the original austenite grain size small specimen cracking load large, different grain size martensite deformation and fracture process is no essential difference.