低硬度P91钢弯头的组织与性能分析

火力发电通过提高发电机组的蒸汽参数可以获得更高的发电效率，但更高的蒸汽参数给火电厂的安全运营带来新挑战。蒸汽管道弯头是火电机组系统中的事故多发区，其组织性能的研究对于指导管件生产与电厂设备运营管理具有重要意义。某电厂某1 000 MW超超临界机组在进行金属监督检验时，发现材质为P91钢的管道弯头背弧面局部硬度偏低。通过硬度试验、拉伸试验、金相检测、扫描电子显微镜、透射电子显微镜等分析，对其硬度偏低部位的显微组织与力学性能进行研究。经分析，P91弯头局部区域硬度偏低的主要原因是组织老化、析出相长大导致其各项强化作用减弱。

Analysis of microstructure and properties of low hardness P91 steel pipe elbow

Thermal power generation can achieve higher power generation efficiency by improving the steam parameters of the generator units, but the higher steam parameter also brings new challenges to the safe operation of thermal power plants. Cracking accident occurs frequently at the elbow of steam pipe in thermal power units. The study on microstructure and properties of the elbow is great significance for guiding the pipe production and the operation of the power plant equipment. It was found that the local hardness value of a P91 pipe elbow was low during the inspection of a 1 000 MW ultra-supercritical boiler. The microstructure and mechanical properties of the part with low hardness values was studied by hardness tests, tensile tests, metallographic tests, scanning electron microscope tests and transmission electron microscope tests, respectively. The results show that the low hardness of P91 elbow is caused by the degradation of microstructure and coarsening of precipitated phases, which weakens its various strengthening effects.