利用光学显微镜、X射线衍射仪、扫描电镜及能谱仪和冲击试验研究了运行了8000 h的1000 MW超超临界机组主蒸汽管道P92钢的显微组织和韧性。结果表明,主蒸汽管道P92钢在600℃服役8000 h后,显微组织呈现大量析出相分布于马氏体基体之上的形貌,析出相除了供货状态(正火+高温回火)存在的MX相以及M23C6相之外,还有时效后在原奥氏体晶界和马氏体板条界处产生的Laves相;运行8000 h后,P92钢的韧性明显地下降,这主要与Laves相的析出和粗化有关。 The microstructure and toughness of P92 steel in main steam pipe of 1000 MW ultra-supercritical unit operating for 8000 h were studied by optical microscope, X-ray diffraction, scanning electron microscopy, energy dispersive spectrometer and impact test. The results show that after the main steam pipe P92 steel has been in service at 600 ℃ for 8000 h, the microstructure shows a large number of morphologies of precipitated phases distributed on the martensite matrix. The precipitated phases are present except for the supply status (normalizing and high temperature tempering) Of MX phase and M23C6 phase, as well as the Laves phase produced by aged austenite grain boundaries and martensite slab boundaries. After 8,000 h of operation, the toughness of P92 steel decreased obviously, which was mainly related to Laves phase The precipitation and coarsening.