600 MW机组汽轮机低压第5级动叶片断裂故障分析

Reason analysis for the fifth stage blade fracture in low pressure cylinder of a 600MW unit steam turbine

对某亚临界600MW机组汽轮机低压第5级断裂动叶片进行了材料理化检验和断口分析,并采用有限元方法对叶片离心应力和轮系振动特性进行了计算。综合分析表明:叶片为高周疲劳断裂,其主要原因为在工作状态下轮系的1阶8节径振动频率落入了"三重点"共振区。

Particular investigations on the failure site,operation files and history data of a 600MW unit steam turbine were performed.The material physical and chemical tests and fracture analysis for the fifth stage blade in low pressure cylinder were implemented.The finite element method(FEM)was employed to analyze the blade centrifugal stress and the vibration characteristics of the blade disk system.The results showed that,the first order vibration frequency of the blade disk system under the eighth nodal diameter fell into the 'triple coincidence criterion' resonance region was considered as the critical reason for the blade high cycle fatigue failure