显然，V00焊后热处理试样的裂纹萌生能量（E1+E2）和裂纹扩展能量（E3+E5）高于V10和V20焊后热处理试样，如图（a）所示。如图（b）所示，对V20夏比V型缺口焊后热处理试样的断口进行了检查，可以观察到，由于枝晶间位错密度高于枝晶干，二次裂纹萌生位置位于枝晶间。

It is clear that the crack initiation energy (E1+E2) and the crack propagation energy (E3+E5) for V00 PWHT specimen were higher than them for V10 and V20 PWHT specimens, as shown in Fig (a). The section through the fracture surface of the V20 Charpy V-notch PWHT specimen was examined, as shown in Fig (b). It could be observed that the secondary crack initiation location was at ID region owing to the higher dislocation densities than DC region.