Fig.14 Instantaneous fracture area
As shown in Fig.12, the surface of
the origin area is rough, and the striation is generally divergent,
showing the micro morphology of cleavage. The red circle is the crack
origin location.
The surface of the expansion area is bright (Fig. 13), showing
river pattern, which is quasi cleavage micro morphology with obvious
stripe fatigue striae.
The surface of the instantaneous fracture area is rough (Fig. 14), where
the crack finally breaks rapidly, with many tear marks and a small
amount of dimples, showing the micro morphology of quasi cleavage.
It can be concluded that the fracture is fatigue fracture.