我国首台超临界机组X20CrMoV121钢受热面管状态分析

为全面了解火电厂X20CrMoV121钢受热面管长期运行后的安全状况，对某电厂X20CrMoV121钢末级过热器管及高温再热器管进行了力学性能测试、显微组织分析及高温持久强度试验。试验结果表明，运行管与原始管相比强度有所下降；沉淀相发生熟化，同时还出现了局部板条特征减弱，板条内出现亚结构，位错密度明显降低，且在亚结构内位错呈定向排列的趋势；高温持久强度仍然高于设计值。综合分析认为，经12万h运行后的X20CrMoV121钢管产生了一定程度的老化，但仍可满足设计工况下安全运行的要求。

State Analysis of X20CrMoV121 Steel Used in the First Supercritical Unit in China

In order to comprehensively understand the security situation of heating surface tube made of X20CrMoV121 steel after long-term operation in thermal power plant， the mechanical performances tests， microstructure analysis and high temperature creep rupture strength tests were carried out on final superheater tube and high temperature reheater tube in a power plant. The results show that compared with original tubes， the strength of operating tubes decreases; when the precipitation phase occurs ripening， the local lath characteristics becomes weak， substructure appears in the martensite laths， the dislocation density obviously declines; and the substructure dislocation has the trend of directional arrangement， but the high temperature creep rupture strength is still higher than the design value. From the comprehensive analysis it is concluded that although the X20CrMoV121 steel tubes have aging phenomenon in some extent after 12000-hour operation， they still can meet the requirements of safe operation under design conditions.