在吊装重364.8 t的船用机座过程中由于吊具断裂造成人员伤亡和机座严重摔坏的重大事故。采用化学分析、金相检验和断口分析等方法对断裂件材质、断裂机理和显微组织等方面进行了分析和研究,并从力学及断裂力学两方面对断裂件的安全性进行了分析和评价。金相分析证实,卸扣锻造质量不佳、锻后没有进行适当的热处理、卸扣拐点处的分型面存在补焊现象和焊接微裂纹等缺陷。上述诸多因素均导致卸扣的承载能力和安全性下降,静载荷检验达不到JB 10603-2000技术要求。断裂力学计算也证实在上述条件下卸扣的实际承载能力将大大下降,实际断裂卸扣裂纹的深度已经非常接近所允许的临界裂纹长度。基于上述结果进一步对断裂事故的发生过程、断裂次序等进行了分析和讨论。事故中卸扣G最先断裂,其次是卸扣D;之后,螺栓B,E,F由于卸扣G和D断裂后受较大的弯曲载荷而断裂。

The serious accident occurred during the engine pedestal of 364.8 t was hoisted into ship,which lead to casualties and pedestal seriously break. The chemical analysis,metallograph examination and fracture analysing method was used to analyze and assess material,fracture mechanism,microstructure etc. The security was appraised from two aspects of fracture toughness and mechanics. The metallographic examination verified that forge quality of shackles was poor,the appropriate heat treatment of shackles was not carried on,and there existed weld phenomenon and defect of welding micro-crackles in the inflection point of shackles. A great deal of above-mentioned factors cause to decline bearing capacity of the shackle and its security and the static load examines didn′t reach the technology requirement of JB 10603-2000. It was also verified by fracture mechanics calculation under above-mentioned conditions that the maximum depth of crack of actual fracture shackle had already been very close to the length of critical crackle allowed. Emergence course,fracture order of parts in the fracture accident,etc. had been analysed and discussed further on above-mentioned results. Shackle G ruptures at first in the accident,secondly shackle D;later,bolt B,E,F ruptured by bigger crooked load after shackle G and D ruptured.