论文部分内容阅读
在双相钢物理短裂纹门槛区，观察到稳定的位错胞和墙结构；长裂纹门槛区，在铁素体／马氏体相界堆垛位错密度大，有形成位错胞的趋势．长裂纹扩展第二阶段，铁素体晶粒内具有单向滑移线（Ｒ＝０，－１）和正交网状（Ｒ＝－１）的位错结构，长裂纹扩展第三阶段，位错稀少，但单滑移、双交滑移位错线明显拉长，说明裂纹尖端位错组态是应变历史的产物．疲劳裂纹扩展门槛区形成的位错胞和墙是一亚稳态结构，与门槛循环应力应变处于动态平衡，也是一微观结构参数．
A stable dislocation cell and wall structure was observed in the short-cracked dual-phase steel plate, and the long-cracked threshold area had a high density of dislocations in the ferrite / martensite phase boundary and a tendency to form dislocation cells . In the second stage of long crack propagation, the dislocation structure with unidirectional slip line (R = 0, -1) and orthogonal network (R = -1) in ferrite grains, the third stage of long crack propagation, Dislocation sparse, but a single slip, double slip slip line significantly elongated, indicating that the crack tip dislocation configuration is the product of strain history. The dislocation cells and walls formed by the fatigue crack growth threshold are a metastable structure, which is in a dynamic equilibrium with the threshold cyclic stress and strain and is also a microstructure parameter.