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借助于扫描电镜从细观和材料角度，研究了具有环状“Ｖ“型切口的冷拨圆棒料在超低周恒挠度下的断裂机理。同时指出，冷拨钢原材中存在轴向缺陷使得主裂纹在沿径向扩展的同时要发生轴向窜动，它是造成疲劳裂纹扩展区呈“馒头状”的原因之一，而冷拨钢特殊的组织形态决定了它的空洞形核必然受控于剪应力，这是造成疲劳裂纹扩展区呈“馒头状”的根本原因，另外，还发现冷拔铜在超低周疲劳条件下空洞形核主要有珠光体优先断裂形核、晶界形核、脆性颗粒断裂形核三种方式。
With the help of SEM, the fracture mechanism of cold-drawn circular bar with annular “V” notch at ultra-low-cycle shear strength was studied from the perspective of microstructure and material. At the same time, it is pointed out that the existence of axial defects in the cold-formed steel causes the main crack to move axially along with the radial expansion, which is one of the causes of the “bread-like” fatigue crack growth zone. The special microstructure of steel determines that its hollow nucleus is bound to be controlled by shear stress, which is the fundamental reason causing the fatigue crack growth zone to be “steamed bread”. In addition, it is also found that the cold drawn copper has cavities under ultra-low cycle fatigue The nucleation is mainly preferential pearlite nucleation, grain boundary nucleation, fragile nucleation three ways.