620℃汽轮机转子13Cr9Mo2Co1NiVNbNB钢的组织稳定性分析

Analysis on Microstructure Stability of 13Cr9Mo2Co1NiVNbNB Steel for 620℃ Turbine Rotor

对620℃汽轮机转子锻件(13Cr9Mo2Co1NiVNbNB)进行高温持久考核,并采用光学显微镜(OM)、场发射扫描电镜(FESEM)和透射电子显微镜(TEM)对高温持久试验后的试样和原始试样进行了微观组织对比,分析了高温持久试样的组织稳定性。结果表明,B元素在初生奥氏体晶界聚集,进入M23C6碳化物中替代C形成M23(C,B)6,并限制M23(C,B)6的长大。持久试样的组织由板条马氏体+M23C6碳化物+MX相组成,马氏体板条宽度略有增大,M23C6碳化物密度显著提高,分布更加弥散,其尺寸也略有增加。马氏体板条内形成位错胞亚晶,细小的MX相沿位错胞亚晶边界析出,对提高材料蠕变强度作用明显。

The creep rupture test of the sample extracted from 620 ℃ turbine rotor forging （13CrgMo2ColNiVNbNB） was performed. The microstructure examinations for both the creep rupture sample and the original sample were compared using optical microscope （OM）, field emission scanning electron microscopy （FESEM） and transmission electron microscope （TEM） method. As a result, the Boron was found to gather in primary austenite grain boundaries （PAGBs）, enter in the M23 （C, B）6 and prevent the coarsening of the M23 （C,B）8. The microstructure of the creep rupture sample mainly consists of lath martensite and M23 C6 carbides and MX phase. The width of lath martensite and the size of M23 C6 carbides grows slightly, however the density of M23 C6 carbides increases significantly. The dislocation cells can be found inside the lath martensite. The fine MX phase is indicated to precipitate in dislocation cells and subgrains boundary, which can substantially improve the creep strength of rotor forging.