长期服役T91钢的微观组织定量分析及演化规律

Analysis and evolution of microstructure of T91 steel after long-time service

针对超临界锅炉广泛使用的T91钢,采用金相显微镜、扫描电镜、透射电镜、X射线衍射等材料学分析手段,对长期服役条件下T91钢的微观组织进行定量化分析,研究服役前后微观组织演化规律。结果表明:长期服役后,T91钢析出第二相的总量增加。M23C6和MX相占析出相总量的百分比降低,Laves相占析出相总量的百分比增加。M23C6和Laves相的尺寸增加。Laves相尺寸在运行50000h后呈加速增长趋势。

For the T91 steel widely used in supercritical boilers,quantitative analysis of the microstructure of T91 steel after long-term service was carried out by means of metallographic microscope,scanning electron microscopy,transmission electron microscopy,X-ray diffraction and so on.And microstructure evolution of T91 steels before and after service was studied.The results show that after long-term service,the total amount of precipitated second phase increases.The percentage of M23C6 and MX phase in the total amount of precipitates decreases,and the percentage of Laves phase in the total amount of precipitates increases.The size of the M23C6 and Laves phases increases.The growth of the size of the Laves phase accelerates after 50 000 h operation.