Crack spreading area and transient breaking are observed, typical fatiguestriations, fatigue steps and secondary cracks are observed on some of the fractures.
微观上在少数油管断口中观察到了典型的疲劳辉纹，在很多断口上观察到了疲劳台阶和二次裂纹。
3
The correlative nature is revealed between the morphology and orientation of the striations on fatigue fracture surfaces.