从图中可以看出，断口形貌呈现出塑性变形痕迹，均有明显的韧窝形态和撕裂痕，具有一定的塑性，断裂类型为塑性断裂。回火温度到200℃后断口中有较大且深的韧窝，到600℃时，断口中韧窝较均匀且深，塑韧性较好。

It can be seen from the figure that the fracture morphology shows signs of plastic deformation, all with obvious dimple morphology and tear marks, with a certain degree of plasticity, and the fracture type is plastic fracture. After the tempering temperature reaches 200°C, there are larger and deep dimples in the fracture. When it reaches 600°C, the fractures are more uniform and deep, and the plasticity is better.