通过扫描电子显微镜观察了不同温度(-30～-150 ℃)下粗晶粗碳化物组织16MnR钢的三点弯曲解理断口, 分析了解理断裂起裂源的类型。结果表明: 试验条件下起裂源的类型主要为晶界碳化物开裂、夹杂物开裂、较大的碳化物界面分离、球状碳化物与铁素体基体界面分离、晶粒边界开裂; 起裂源距塑性裂纹尖端的距离Xf对解理断裂起着决定性作用, 并随温度升高呈增大的趋势; 起裂源的类型对Xf值没有直接影响。

Based on observation of scanning electron microscopy, three point bending cleavage fracture of 16MnR steel with coarse grain and coarse carbide was observed under different temperatures, and the style of crack origin of cleavage was analyzed. The results show that the types of crack origin were mainly carbide cracking on grain boundaries, inclusion cracking, interface separation of larger carbide, separation between spherical carbide and ferrite matrix and cracking of grain boundary in the experimental condition. The distance Xf between cleavage crack origin and plastic crack tip had a decisive effect on cleavage fracture and increased with temperature, and the Xf was not directly affected by the type of cleavage crack origin.