长期服役Cr-Mo-V钢汽轮机转子的微观组织分析

Microstructure investigation of Cr-Mo-V steel steam turbine rotor after long-term service

对服役17年的Cr-Mo-V钢的汽轮机高中压转子微观组织进行了详细研究。金相组织观察、扫描电镜和透射电镜分析表明:Cr-Mo-V钢经过长期服役后,组织中的碳化物M3 C发生了明显的粗化,原奥氏体晶界处析出粗大的M23 C6,由于这些碳化物的演变导致材料显微硬度明显下降。用透射电镜观察到以MC碳化物为核心、M2C为两翼的H型碳化物。

The influence of prolonged service on microstructure of Cr-Mo-V steel steam turbine rotor was studied.The samples for this study were taken from three locations of a rotor which had operated for 17 year.The optical microscope,scan electron microscope and transmission electron microscope were used to characterize the evolution of the microstructure.The results show that the coarsening of M3C carbide in steel structure occurs obviously and coarse M23C6 carbide precipitates at prior-austenite grain boundaries after long-term service.The evolution of these carbides causes the microhardness decreasing dramatically.TEM observation indicates the formation of H-type carbide which takes the MC carbide as nucleation sites and M2C carbide on both sides.