对600MW超临界机组液氨罐筒体超声波检测异常的分析

Analysis of Abnormality during Ultrasonic Testing of Liquid Ammonia Pot in the 600MW Supercritical Power Plant

用超声波测厚仪对某电厂600MW超临界机组液氨罐筒体(Q345R钢板)进行测厚,发现超声波测厚仪显示数值只有钢板实际壁厚的一半。通过对测厚异常钢板进行超声波检测、化学成分分析、金相分析、拉伸、弯曲、低温冲击等试验,发现钢板芯部金相组织为3级带状铁素体和珠光体组织,钢板的力学性能满足标准要求。分析认为钢板生产工艺不当是导致铁素体和珠光体3级带状组织形成的主要原因。

While measuring cylinder＇s thickness of the liquid ammonia tank（Q345R steel）in the600 MW supercritical power plant by ultrasonic measurement,we found that the displayed value is only half of the actual thickness.According to the test results from ultrasonic testing,chemical analysis,metallurgical analysis,tensile,bending,low temperature impact testing,it has been found that the microstructure of the steel core is the third level banded ferrite and pearlite,with the mechanical properties conforming to standards.It is concluded that improper production process has mainly led to the formation of the third level banded ferrite and pearlite structure.