10 t吊钩在使用过程中发生断裂失效。采用化学成分分析、断口分析和金相检验等方法对吊钩断裂的原因进行了分析。结果表明: 由于该吊钩柄部与螺纹尾部的过渡处R角太小, 并且有明显的机加工刀痕, 造成应力严重集中, 使得裂纹在此处萌生; 吊钩在作业过程中, 由于存在起吊倾斜角和吊运时的前后摆动, 使得吊钩柄部两侧承受了较大的拉、压应力, 促使裂纹不断扩展, 最终导致吊钩发生了双向弯曲疲劳断裂。

The 10 t lifting hook fractured in use. By means of chemical composition analysis, fracture analysis and metallographic examination, the fracture reason for the hook was analyzed. The results showed that, as R angle of the transition area between the hook shank and thread tail was too small, and there were obvious machining marks, causing severe stress concentration and crack initiation. And in the work process there existed the lifting tilt angle and the phenomenon of front and rear swing, led to a greater tensile and compressive stress on both sides of hook shank, the crack expanded in hook continuously, and the two-way bending fatigue fracture occurred at last.