某钢厂铁水包耳轴在34炉包龄时发生早期断裂，采用探伤检验、宏观观察、化学成分分析、力学性能试验、金相检验、扫描电镜以及能谱分析等方法对耳轴断裂的原因进行了分析。结果表明：耳轴中心部位存在裂纹缺陷是耳轴发生早期脆性断裂的主要原因，耳轴中心孔内壁粗糙的加工刀痕是耳轴发生早期断裂的次要原因。耳轴服役期间，在应力作用下裂纹扩展并最终断裂。

The ladle trunnion of a steel plant was early fractured at the use of 34 times. The causes of trunnion fracture were analyzed by means of flaw detection, macroscopic observation, chemical composition analysis, mechanical property test, metallographic examination, scanning electron microscope and energy spectrum analysis. The results show that the main reason for the early brittle fracture of the ladle trunnion was the presence of cracks in the center of the trunnion. The secondary reason for the early fracture of the ladle trunnion was rough machining marks of the inner wall in center hole of the trunnion. During the service of the trunnion, the cracks expanded and eventually fractured under stress.