化学取样架预冷器断裂原因分析

Analysis on the Cause for Fracturing of Precooler of Chemical Sampling Frame

某电厂化学取样架初级预冷器材料为1Cr18Ni9Ti奥氏体不锈钢,运行过程中断裂。对断裂的预冷器进行了宏观分析、金相检验和硬度检验。结果表明:该预冷器组织异常,导致其抗疲劳性能下降,在交变的机械应力和热应力的作用下产生疲劳裂纹,最终裂纹沿周向扩展而断裂。

A primary precooler of chemical sampling frame in a power plant,made from 1Cr18Ni9Ti austenitic stainless steel,fractured in operation.The fractured precooler was subjected to macro-check,metallographic testing and hardness measurements.The results showed that the abnormal microstructure was present in the precooler,leaded to its reduced fatigue resistance and to generation of fatigue crack under the action of alternating mechanical stress and thermal stress,and to finally fracturing due to expansion of crack in the circumferential direction.